Skin component for a vehicle

A skin component for a vehicle for use as a roof module, an engine compartment hood or a trunk lid is disclosed. The skin component includes at least one supporting layer and a protective layer. The protective layer includes a fiber-reinforced band that is installed along at least one outer edge of the skin component.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to German Patent Application No. 102013019677.9 filed Nov. 22, 2013, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a skin component for a vehicle, particularly a roof module, an engine compartment hood or a trunk lid of a composite material that includes a thermosetting polymer matrix, at least one supporting layer of reinforcing fibers and a protective layer.

BACKGROUND

Plastic parts or composite material parts with a plastic matrix are increasingly utilized for skin panels of vehicles. If composite materials with a thermosetting polymer matrix and high-strength reinforcing fibers are used for stability reasons, a severe impact during an accident may cause the parts to fracture. Large sharp-edged, slab-shaped fragments may be created in such instances. Splinter protection films are occasionally applied onto the skin panels in order to prevent these sharp fracture edges. However, this can lead to problems with respect to the adhesion and the optical appearance.

WO 2010/006718 A1 describes a skin component of plastic, for example, a roof module, in which the splinter protection lies between the layers of the roof structure. The skin component includes a first supporting layer, a splinter protection fabric, a core layer, a second supporting layer, a splinter protection fabric, a decoupling layer and a skin. The connection between the individual layers is produced in a CMS process. The structure of the skin component with a plurality of layers and the connection between the layers by means of a CMS process are elaborate and expensive.

SUMMARY

In accordance with the present disclosure, skin components of plastic, particularly of composite materials, can be designed in such a way that an effective splinter protection can be realized with little effort. According to an embodiment of the present disclosure, a skin component for a vehicle includes at least one supporting layer and one protective layer. The protective layer includes a fiber-reinforced band that is installed along at least one outer edge of the skin component. The band provides effective protection against mechanical stresses that originate from the edge of the skin component with little material input. In contrast to fabric webs that cover the entire surface of the skin component, scrap can almost be completely eliminated. The total quantity of fibers used for the protective layer therefore is so small that the overall skin component can also be cost-effectively manufactured if expensive high-quality fibers are used in the protective layer.

The fibers of the protective layer may be arranged between two supporting layers. In this way, a stable integration of the protective layer into the skin component is achieved and the component surface is not optically affected. The fibers of the protective layer may include a pre-stretched thermoplastic polymer or steel. Fabrics can be subjected to high stresses in the intact state, but once damage has occurred under a load and initial fibers have been torn, the fibers extending transverse to the torn fibers cause a concentration of the load on a small area and thusly promote a propagation of the tear. The fibers of the protective layer may not be interwoven in order to prevent such a load concentration. The fibers may be oriented, in particular, in the longitudinal direction of the band in order to divert a load along the edges of the skin component without tearing.

The band may be impregnated with a thermosetting polymer matrix of the at least one supporting layer after the completion of the skin component. This can be achieved, in particular, with a loose band of fibers that are not connected to one another. It is more convenient to install a band, the fibers of which are held together by being embedded in a separate matrix or carrier layer of the band. Such a matrix may be fused together with a thermosetting polymer matrix of the at least one supporting layer after the completion of the skin component.

The supporting layer may likewise be reinforced with fibers, but the requirements with respect to the strength of these fibers are not as strict as with the fibers of the protective layer and this can be taken into account in the concentration of the fibers in the matrix, their length and/or their chemical composition. The fibers of the supporting layer may consist, in particular, of carbon fibers, glass fibers or natural fibers of plant origin. The fibers of the supporting layer may be structured in the form of a fabric in order to simplify their handling during the manufacture of the skin component. The fibers of the supporting layer may be pre-impregnated (prepreg fibers). The manufacture of the skin component may be realized by means of infiltration of the supporting layer and the protective layer with a thermosetting polymer matrix, by means of resin-transfer-molding (RTM) processes or by means of gap impregnation. In this way, the fibers of the protective layer are completely enclosed by the matrix.

DETAILED DESCRIPTION

FIG. 1shows a perspective view for part of the roof area of a car body. A roof frame2includes lateral profiles that extend above the doors on the right and the left side of the vehicle and connect A-columns and C-columns to one another, as well as front and rear cross members3,4.FIG. 1only shows one of the two lateral profiles. The front cross member3extends underneath the roof module1adjacent to a front windshield as indicated with a broken line; the rear cross member4extends underneath the rear edge of the roof module1.

The roof module1is a composite component including several layers. It includes at least one supporting layer that extends over the entire roof module1, as well as a protective layer11that extends along the edge of the roof module1in the form of a strip, but not over the center of the roof module1.

In the embodiment according toFIG. 1, a strip of the protective layer11extends along a left outer edge6of the roof module1that faces the viewer as shown and a second strip extends along the right outer edge that is not illustrated inFIG. 1. These are the outer edges that are in contact with the profiles5and therefore most fracture-prone in an accident. Other not-shown strips of the protective layer11may be provided on the front and rear edges of the roof module1.

FIG. 2shows a schematic cross section through the roof module1in the vicinity of the outer edge6. In this case, the roof module1includes two supporting layers8,9that directly contact one another in a central region of the roof module1, wherein the protective layer11extends between these two supporting layers adjacent to the edge.

The first and the second supporting layer8,9respectively include a fabric13, the threads of which includes high-strength carbon fibers, glass fibers and/or plant fibers. The fabric13could also be replaced with a formed fabric of unspun fibers. The fabric13is embedded in a thermosetting polymer matrix12. An epoxy resin, a polyester resin or a polyurethane, in particular, may be considered as thermosetting polymer of the matrix12.

In this case, the protective layer11includes fibers14that are aligned parallel to the edge6. These fibers14were originally placed between the fabrics13of the supporting layers8,9without being firmly connected to one another, e.g. in the form of a longitudinally combed formed fabric, and then impregnated with the thermosetting polymer matrix12together with the fabrics of the supporting layers so as to obtain the roof module1. In order to simplify the impregnation, the fibers14of the protective layer11, as well as of the supporting layers8,9, may be pre-impregnated, i.e. includes so-called prepreg fibers.

The fibers14of the protective layer11need to have a high elongation at fracture. Consequently, they preferably include a pre-stretched thermoplastic polymer, particularly of polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET) and/or of a steel.

In order to simplify the installation, the protective layer11may in addition to the fibers14also contain a band of a carrier material, in which the fibers14are embedded or onto which they are glued. The protective layer may particularly include so-called UD-tape. After the impregnation with the matrix12, the carrier material may be intimately glued or fused thereto such that it cannot be distinguished from this matrix in the illustration inFIG. 2.

Different layer structures are contemplated in the present disclosure, including: a single supporting layer8; a supporting layer8including several fiber fabrics lying on top of one another on at least one side of the protective layer11; a protective layer11respectively realized between several supporting layer is8,9; a protective layer11formed on the outermost layer of the roof module1.

If the roof module1is subjected to a load that originates from one of the lateral profiles5during a side impact, cracks may indeed form in the matrix12and fibers or entire threads of the supporting layers8,9may possibly also be destroyed, but the fibers14of the protective layer11do not break, but rather deform in an elasto-plastic fashion. This prevents propagation of the cracks and the flanks of the cracks are held close to one another. Individual fragments of the roof module1cannot separate. This furthermore prevents sharp corners and edges that could protrude from the roof module1.

Fibers of the protective layer11may also be arranged along the outer edge6of the roof module1along the front and the rear roof frame3,4. The composite material structure chosen for the roof module1may likewise be used for other skin components such as an engine compartment hood, a trunk lid, fenders and doors. In this case, the fibers of the protective layer11extend along the outer edges of the component that are particularly stressed and fracture-prone during an impact due to an accident. However, they may also cover other fracture-prone component areas.

The manufacture of the roof module1takes place in the following steps. The fiber fabric13of the supporting layer8are placed into a mold for the roof module1. The fibers of the protective layer11are placed individually, adjacently or in the form of unidirectional fiber bands such as UD-tapes. The fiber fabric of the second supporting layer9are placed thereon. The supporting layers8,9are infiltrated or interwoven with the protective layer11with a thermosetting polymer matrix12in a resin-transfer-molding (RTM) process or by means of gap impregnation. If a different layer structure is chosen, the placement of the layers8,9,11into the mold is carried out accordingly prior to the infiltration of the layers.

In a first variation, the fiber fabric of the supporting layers8,9is composed of pre-impregnated fibers (prepreg fibers). The impregnation includes a resin and a hardener that react to form a thermosetting polymer during processing. Preferred thermosetting polymers are epoxy resin, polyester resin or polyurethane. Hot-pressing of the layers in a mold or autoclave causes the impregnation to react, as well as to interfuse and completely enclose the supporting layers8,9and the protective layer11, such that the matrix12is formed.

In a first variation, the manufacture of the roof module1takes place in the following steps. The pre-impregnated fiber fabric of the supporting layer8are placed into the mold for the roof module1. The fibers of the protective layer11are placed individually, adjacently or in the form of unidirectional fiber bands such as UD-tapes. The impregnated fiber fabric of the second supporting layer9are placed thereon. The layers8,9,11are hot-pressed in the mold or in an autoclave.