GB2322342A

GB2322342A - Energy absorbing lining element for vehicles

Info

Publication number: GB2322342A
Application number: GB9800065A
Authority: GB
Inventors: Walter Mehling
Original assignee: FS Fehrer GmbH and Co KG
Current assignee: FS Fehrer GmbH and Co KG
Priority date: 1997-01-03
Filing date: 1998-01-05
Publication date: 1998-08-26
Also published as: SE9704914D0; SE9704914L; GB9800065D0; DE19700091A1

Abstract

A lining element for the interior of a motor vehicle comprises energy absorbing foamed material (1) which if compressed generates an approximately constant resistive force across an extensive range of the possible deformation path, and which is provided with an armouring layer (8) disposed exclusively in a peripheral region (7) of the foamed material (1). A moulding process for manufacturing the lining element is also described.

Description

1 1 2322342 A LINING ELEMENT The invention relates to a lining element and

in particular to a lining element f or the passenger cabin of a motor 5 vehicle comprising an energy absorbing f oamed material. This invention also relates to a process for the manufacture of such a lining element.

For safety reasons, the inside lining of a motor vehicle, 10 especially the lining of the passenger cabin or the safety cage of a motor vehicle, is constructed so that in case of an accident the passengers are not injured or suffer only minor injuries. For the lining to be ef f ective braking acceleration or deceleration upon impact must be kept below a specified value at which injuries are largely prevented.

It is known to manufacture lining elements, for frames, struts or other rigid parts that support the lining elements, f rom so-called energy absorbing f oamed materials.

Energy absorbing foamed materials are characterised by the fact when they are compressed they generate an approximately constant resistive force which is opposed to the compression pressure across an extensive range of the deformation path and preferably across almost all of the possible deformation path. Thus, the threat of injury can largely be avoided because the magnitude of the resistive force generated in this region (when a suitable thickness of the f oamed material is used) is chosen so as to be sufficiently small. As a consequence of impacting body parts penetrating the foamed material the maximum braking acceleration is correspondingly reduced. Only--- when the foamed material is almost fully compressed and the majority of its cavities are pressed together does the resistive force significantly increase.

The mechanical properties described above are attainable with foamed materials, which deform plastically under pressure. In the case of elastic materials, on the.other hand, the resistive force rises continuously with the 2 deformation path ie. large ranges of constant resistive force are not attainable in the same way.

For protection against injury, the deformability of the energy absorbing foamed material must be sufficiently smooth. A problem exists, however, because irreversible, permanent deformation frequently occurs with everyday loads. For instance, permanent deformation is caused when a passenger supports himself with his hand on the lining.

As a consequence, elements comprising energy absorbing foamed materials can only be used behind linings made from stiff material, which distribute local loads over a large area and reduce damage to the energy absorbing foamed material during routine use. A disadvantage arises however since the tailoring of material properties to provide effective accident protection conflicts with the tailoring of material properties to provide high loading capacity and indeed proves difficult to do simultaneously.

The exterior side of linings is usually provided with a decorative coat which, in addition to an outside visible layer made from e.g. textile material, a film, or leather, includes a layer made from elastic f oamed material. The latter usually has a thickness of a f ew millimetres and acts as padding, which increases the comf ort of the vehicle occupants, but makes only a small contribution toward avoiding injuries in the case of an accident. The elastic f oamed materials are of ten provided with a barrier f ilm facing the energy absorbing foam or slit lining below. The barrier film acts as a seal and prevents the energy absorbing f oam f rom penetrating into the elastic f oamed material layer during the foaming process and changing its mechanical properties in a undesirable way.

It is known in a plurality of applications to provide elements made from elastic foamed materials or highresistance foams which are provided with an armouring made f.

3 of, for example glass, carbon or other fibre materials. These materials increase the mechanical loading capacity considerably, especially vis-avis tensile forces. However, in the case of energy absorbing foamed materials, such armourings are unknown as they impair the plastic deformability and thus prevent the intended protective effect.

Against this background a preferred object of the present 10 invention is to develop a lining element with a layer of energy absorbing foamed material which can be produced in a simplified manner, which obviates use of a stiff cover and which demonstrates improved energy absorption with reduced force peaks.

is Summarv of the Invention In accordance with one aspect of the invention there is provided a lining element for the passenger cabin of motor vehicles comprising an energy absorbing foamed material which has a surface and which is provided with an areal armouring or armouring layer, the armouring layer is disposed exclusively within a peripheral region of the foamed material, which borders the surface, and the armouring layer is aligned substantially parallel to the surface.

The energy absorbing foamed material preferably when compressed generates an approximately constant antagonistic or resistive force -across an extensive range of the possible deformation path. The lining element typically has a stiffened surface and typically is affixed to a supporting element.

The proposed lining element is provided with an armouring layer for the energy absorbing foamed material. The armouring is limited exclusively to a narrow peripheral region of the foamed material. On the other hand, the 1 ep- 4 preponderant volume per cent is f ree of the armouring so that it has an energy absorbing effect in the conventional manner. The armoured layer of the foamed material is typically continuous extending over an area, though the armouring can have openings to improve the f orm-f it with the surrounding material. It extends parallel to the surface of the foamed material and is located immediately thereunder.

Due to the resistance to extension, the armouring effects a stiffening of the surface of the lining part and increases its surf ace elasticity. The consequence is a distribution of local f orces across a large area so that irreversible deformation of the foamed material by everyday pressure load are avoided. If because of higher forces deformations of the energy absorbing foamed material nonetheless occur, they are limited to the interior of the lining part and are covered by the overlying, dimensionally stabile, armoured foamed material layer. Therefore, in the case of minor damage, a costly replacement of the lining element can be avoided, as its external appearance is unchanged.

A considerable advantage of the lining element according to 25 the invention consists in its simplified manufacture since a stif f lining of the visible surface is not needed and the armoured layer is connected permanently to the f oamed material, the element is therefore in one piece. Above and beyond that, the armouring opens up considerably expanded variation possibilities f or the surf ace properties, f or instance, in that the armouring material, the thickness of the armouring or the surface density of armouring elements can be changed. In this way, an improved tailoring in conformity with the requirements of the respective installation site can be effected. For example, the surface can deform even in the case of comparatively minor forces in order to eliminate large force peaks in the case of an accident, or the surface can be adapted so as to be comparatively capable of bearing loads, f or instance, if the lining part is disposed in an installation site which is frequently used for support. If required, the properties of the armouring can vary in different regions of the lining element.

In an advantageous f urther development of the invention, at least the visible surf ace of the lining part is provided with a decorative coat, which serves for decorative purposes and as protection against damage. It can, for example, consist of a textile material.

An especially simple and cost-effective implementation of 15 the lining part is obtained if the decorative coat is a plastic film. In the case of an impervious plastic film, the connection to the foamed materials is suitably produced in that in the moulding tool the material is foamed behind the decorative coat. Thus later affixation is superfluous.

Considerably expanded variation possibilities are obtained with the use of a multi-layered decorative coat. In this case the outermost layer of the decorative coat forms the visible surface of the lining part and consists, for example, of textile cover f abric, a plastic or leather. Furthermore, the decorative cost preferably includes an elastic layer of f oamed material, the thickness of which is suitably several millimetres. It generates a soft surface for the lining part and thus increases the comfort of the vehicle occupants and contributes to their protection against injury. Moreover, it reduces the threat-of damage to the energy absorbing f oamed material in the case of minor f orces that af f ect the surf ace of the lining element.

In so far as the decorative coat includes a layer of foamed material or other porous materials, a barrier film of impervious material is advantageous, which closes off the 6 decorative coat toward the energy absorbing foamed material. In this way, during the foaming process, penetration of the fluid foam material into the cavities or even penetration through the decorative coat is prevented.

Thus the material can be foamed behind it without undesired changes of the material properties occurring or the necessity for postprocessing of the lining part.

Basically, it is conceivable f or the armouring and the decorative coat to be connected o each other solely via the energy absorbing foamed material. However, the production of the lining part is substantially facilitated if the armouring is applied to the decorative coat, f or example, as a laminate. In this case the armouring and the decorative coat are inserted as a uniform element into the foaming tool. Thus handling independent of each other and the alignment of two elements as well as the threat of faulty lining parts owing to a relative displacement of the two is eliminated. Moreoveri a mutual stiffening of the decorative layer and armouring is effected, which facilitates precise handling prior to the foaming process and improves the dimensional accuracy during its course.

Suitable armourings are for example nonwovens, mats or 25 woven materials, which consist of synthetic or natural fibres and combine intensively during the foaming process with the energy absorbing foamed material. An alternative to the generation of a comparatively stiff surface of the lining part, which is-capable of bearing loads, is the use of a injection moulded part as armouring, consisting of, for example, a plastic.

As the armouring impairs the energy absorbing effect of the foamed material to a considerable degree, it is proposed that it is limited to a small fraction of its thickness. Suitably the thickness of the armouring is less than one quarter the thickness of the energy absorbing foamed 7 1-1 material, preferably more or less one tenth. Thereby the maximum thickness depends on to what degree the armouring impairs the effect of the foamed material.

An advantageous process to manufacture one of the lining elements described above comprises of first inserting the decorative coat and the armouring into a moulding tool. Both layers can be inserted into the moulding tool either as a layer composite structure or successively.

Subsequently, the moulding tool is filled with the energy absorbing foam material and subsequently removal is effected in the known way. This manufacturing process is characterised by very low cost and thus enables costeffective production.

Detailed Description of A Preferred Ebmbodiment

The present invention will now be described with reference to the accompanying drawing, which shows a sectional view of an energy absorbing lining element.

The lining element consists of an energy absorbing foamed material (1), the visible surface of which, when installed, is covered with a decorative coat (2). Preferably, the decorative coat (2) consists of three layers, including an outer fabric layer (3) and a middle layer of elastic foamed material (4). The surf ace of decorative coat (2) which faces energy absorbing foamed material (1) preferably comprises a barrier film (5), made from an impervious material. Such a film (5) f acilitates f oaming of the energy absorbing f oamed material (1) behind decorative coat 2, while preventing the penetration of the energy absorbing foamed material (1) into the decorative coat (2). A recess (6) is provided on the backside of the lining f or receiving a support element, e.g.t a carrier or frame element of a passenger cabin.

8 In a narrow peripheral region (7)f marked by a dashed line, of energy absorbing foamed material (1), an armouring layer (8) is disposed which enters into an intensive connection with the foamed material (1) and which comprises for example, nonwoven material. In this way, the surface of the energy absorbing foamed material is stiffened so that an irreversible deformation caused by minor loads is avoided. On the other hand, if a person should impact the lining part during an accident, the armour-free volume in the interior of energy absorbing foamed material (1) deforms in a known way and thereby prevents injuries.

This the present invention provides an energy absorbing lining which can be manufactured in a simplified manner and which allows improved design flexibility. That is the lining element can be designed in accordance with the loads likely to be received.

9

Claims

A lining element for the passenger cabin of motor vehicles comprising:

an energy absorbing foamed material which has a surface and in which the foamed material is provided with an armouring layer; the armouring layer is disposed exclusively in a peripheral region of the foamed material which borders the surface of the foamed material; and the armouring layer is aligned substantially parallel to the surface of the foamed material.
2.
3.

A lining element according to claim 1, in which the energy absorbing foamed material, if compressed, generates an approximately constant resistive force across an extensive range of the possible deformation path.

A lining element according to claims 1 or 2, in which the surface is a stiffened surface.
4. A lining element according to claims 1, 2 or 3, which is affixed to a supporting element.
5.
6.

A lining element according to any preceding claim in which the lining. element is provided with a decorative coat, which covers the surface.

A lining element according to claim 5, in which said decorative coat is or includes a plastic film.
7. A lining element according to claim 5 or 6, in which said decorative coat is multi-layered.

1.
8.

A lining element according to claim 7, in which said decorative coat includes an elastic f oamed material layer.
9. A lining element according to claim 7 or 8, in which said decorative coat is provided with a sealing barrier film on the side of the energy absorbing foamed material.
10. A lining element according to one of claims 5 to 9, in which said armouring layer is applied to the decorative coat.
is A lining element according to any one of the preceding claims, in which said armouring layer is a non-woven material, a mat or woven material.
12. A lining element according to any preceding claim, in which the armouring layer comprises synthetic or natural fibres.
13. A lining element according to any preceding claim in which the armouring layer comprises a material arranged to form an intensive connection with the foamed material.
14. A lining element according to one of claims 1 to 10, in which said armouring is an injection moulded part.
15. A lining element according to one of the preceding claims, in which the thickness of said armoured peripheral region is less than one quarter of the total thickness of the energy absorbing foamed material.
16. A lining element according to claim 15, in which the thickness of said armoured peripheral region is 11 "- t , j - substantially equal to one tenth of the total thickness of the energy absorbed foamed material.
17. A process of manufacturing a lining element for the passenger cabin of motor vehicles comprising an energy absorbing foamed material the process including the following steps:

is inserting an armouring layer in a moulding tool in such a way that the armouring layer is disposed exclusively in a peripheral region of the moulding tool, filling of the moulding tool with the energy absorbing foam material, removal from the mould.
18. A process according to claim 17, further comprising the step of inserting a decorative coat or a combined decorative coat and armouring layer in a moulding tool.
19. A process according to claim 17 or 18, in which the energy absorbing foam material if compressed generates an approximately constant resistive force across an extensive range of the possible deformation path.
20. A lining element substantially as described herein with reference to and/or as illustrated in the accompanying drawing.
21. A process of manufacturing a lining element substantially as described herein with reference to and/or as illustrated in the accompanying drawing.