FIELD OF THE INVENTION

The present invention relates to a vehicle body component.

BACKGROUND OF THE INVENTION In the last couple of years, the awareness of the need of sustainable materials for lightweight construction increased continuously. Automotive manufacturers in particular are on an intensive search for new sustainable materials to improve the C02 balance of their vehicles. It is estimated, that if 1 % of steel-based components were replaced with wood-based components, around 140,000t of greenhouse gases, measured in C02 equivalents, could be saved globally per year. Sustainable materials as a natural resource have the further benefits that they can be harvested in large quantities and are easily recycled. However, the sustainable materials also need to fulfill the mechanical requirements of the automotive industry.

Wood or other natural fibrous materials have long since proven to have excellent material properties, while having a low density advantageous for lightweight con structions. Furthermore, wood has suitable reversibly deformable properties as e.g. needed to dissipate crash energy. By using natural fiber composites, a valuable con tribution to cost and weight reduction as well as to the carbon footprint can be achieved. This is also due to the fact, that the production of e.g. wood-based com ponents requires only a fraction of the energy needed to manufacture aluminum, plastic or steel components.

However, the application of wood for structural, resource-efficient and sustainable components within the vehicle body is combined with many challenges and de mands. In the past the automotive industry has focused mainly on processing metal materials allowing a very specific design of the vehicle bodies while fulfilling the structural requirements. In order to use wooden parts in a similar manner, the pro cess chains need to be fundamentally adapted and changed. Furthermore, specific requirements for corrosion such as media and temperature stability need to be taken into account when implementing wood structures into car-bodies.

SUMMARY OF THE INVENTION

The present invention relates to a vehicle body component comprising natural fi brous material. The vehicle body component can e.g. be a roof element or an en- gine hood of the vehicle. The natural fibrous material can be of cell ulosic type such as cotton, wood, flax, etc. The natural fibrous material can thereby be formed by lose fibers which are pressed and glued together or by structurally embedded fi bers. An example for lose fibers are coconut fibers. An example for structurally em bedded fibers is a wood having wood fibers. A further example for structurally em- bedded fibers is a fabric of natural fibers. To meet the requirements necessary for vehicles, for example in terms of load-bearing capacity or durability, the natural fibrous material is preferably used in a composite structure, combining e.g. adhe sives, plastics, metals or other renewable raw materials with the fibrous material. The composite structure can be layered. In a preferred variation such a comprise structure comprises a top sheet, a bottom sheet and a core interconnecting the top sheet and the bottom sheet.

In the present invention the vehicle body component comprises a top sheet, a bot tom sheet and a there between arranged core mechanically interconnecting the top sheet and the bottom sheet. Hereby the top sheet and/or the bottom sheet and/or the core can comprise at least one layer of natural fibrous material. Depending on the application it can be advantageous that at least the core comprises at least one layer of natural fibrous material. In other applications, alternatively or in addition, the top sheet and/or the bottom sheet can comprise at least one layer of natural fibrous material. The top sheet comprising the at least one layer of natural fibrous material is advantageous for applications, where the top layer is visible from the outside. Therefore, the at least one layer of natural fibrous material of the top layer can be formed of wooden veneer (e.g. made of poplar, birch or beech wood). This is due to the fact that the wooden veneer has a good optical appearance. A wooden veneer can be understood as a sheet of wood separated from the log by various sawing and cutting processes. The wooden veneer can have a thickness from is 0.5 to 8 mm. If the at least one layer of natural fibrous material is arranged in the core, all kinds of fibrous materials (e.g. also wooden veneer) can be used. It is under stood that the top sheet and/or the bottom sheet and/or the core may each com prise multiple layers. Only a fraction of these layers can be made of the natural fi brous material. In order to improve the mechanical properties as well as the formability of the ve hicle body component, the at least one layer of natural fibrous material comprises at least one first notch extending in a first direction from a first face of the at least one layer of natural fibrous material, wherein said first notch has a first depth which is less than a thickness of the at least one layer of natural fibrous material. The first notch can be filled with a filler material improving the mechanical properties of the vehicle body component. The filler may e.g. be an adhesive and/or resin. If multiple notches are present, the filler thus forms a matrix through the at least one layer of natural fibrous material. The matrix can improve the mechanical behavior during and after production of the vehicle body component. The first notch is further advantageous for applications, where the vehicle body component comprises a curved section. Vehicle body components, such as roof el ements or engine hoods, have to meet specific geometric requirements, since the car body parts are often curved in a specific manner. Thus, the vehicle body com ponent is often curved around at least one spatial direction, if not two spatial direc- tions. In the context of this application "curved around a direction" is understood, that the curvature is defined in a plane perpendicular to that direction. (For e.g. a two dimensional circle drawn in a plane, the circle is curved around a spatial direc tion perpendicular to the plane of said circle.) For the present application the curved section preferably curves around the first direction of the at least one first notch. Preferably, at least one first notch is thereby arranged in said curved section. Thus a cross-section of the at least one first notch can be at least partially reduced or extended due to a curvature of the curved section. If the first face of the layer of natural fibrous material is the convex side of the layer of natural fibrous material, the cross-section of a respective notch is at least partially extended. If the first face of the layer of natural fibrous material is the concave side of the layer of natural fibrous material, the cross-section of a respective notch is at least partially reduced. In case of a reduction of the cross-section, the cross section can also be reduced to zero, such that the notch is folded in itself in a curved state of the layer of natural fibrous material. The at least one layer of natural fibrous material may also comprise multiple first notches extending parallel with respect to each other arranged in the curved section. This is advantageous in particular for small radii, respectively curved section having a higher curvature. Alternatively, or additionally a density of the mul tiple first notches can correlate to the curvature of the curved section, such that more first notches are arranged in an area with a higher curvature. However, also variations are possible where multiple evenly spaced (first) notches are present, wherein only the notches in the curved section have a reduced or extended cross section due to the curvature of said curved section. The higher the local curvature, the more reduced or extended is the cross section of the respective notches placed in an area of the higher curvature. Depending on the application, at least one layer of natural fibrous material can comprise at least one second notch having a second depth. Preferably the second notch is arranged in a second face opposite to the first face of the at least one layer of natural fibrous material. The at least one second notch may thereby extend in the first or a second direction, perpendicular to the first direction.

Depending on the application, the at least one first notch and the at least one sec ond notch can intersect each other. Therefore, the first depth and the second depth can be configured such that at least one opening extending through the at least one layer of natural fibrous material at the intersection is formed. This is achieved when the first depth and the second depth are together larger than the thickness of the at least one layer of natural fibrous material. Preferably, the first depth and/or second depth are however at least 60%, in particular 80%, of the thickness of the at least one layer of natural fibrous material.

If the at least one layer of natural fibrous material is made of wood, a general fiber direction can be associated with the layer of natural fibrous material. The general fiber direction is usually aligned with the axis of the trunk, limb, or root of the tree from which the wood originates. This is due to the fact that as the tree grows, most of the wood cells, composed of long, thin bundles of fibers, align themselves with said axis. For the further processing of the layer of natural fibrous material it is ad- vantageous, if the general fiber direction is arranged in the first direction of the at least one first notch. For the application on vehicles, such as automobiles, the vehicle body component can further comprise a frame for interconnecting the vehicle body component to a vehicle chassis. The frame may thereby be interconnected, in particular glued, to the composite structure, in particular the bottom sheet. The frame is preferably made of metal. The frame can extend along an outer edge of the composite struc ture, in particular along an outer edge of the bottom sheet.

In one possible variation, at least one layer of natural fibrous material, preferably at least two layers of fibrous material, are arranged in the core of the vehicle body component. The first face can be arranged facing towards the bottom sheet or to- wards the top sheet. Especially for a vehicle body component having a curved sec tion, it may be advantageous that the core comprise at least two layers of fibrous material glued together in a curved manner. In that case the first faces of the re spective layers of fibrous material can face in the same direction or in different di rections. To achieve a good deformability, the at least two layers of fibrous material may each have at least one first notch and/or at least one second notch, such that a three dimensional matrix of notches is formed through the core. The three dimen sional matrix of notches can form one or more intercommunicating systems of notches. The notches can thereby be filled with the filler (such as resin) through the at least one intercommunicating system of notches. Depending on the application and the desired optical appearance, the top sheet and/or the bottom sheet can be made of reinforcing fibers (such as e.g. glas or carbon fibers) or other materials. The top sheet and/or the bottom sheet may thus comprise one or multiple layers of reinforcing fibers. Alternatively or additionally, the top sheet and/or the bottom sheet can also comprise at least one layer of nat ural fibrous material. An outer layer of the top sheet can e.g. be a wooden veneer. The first face, respectively the at least on first notch is thereby preferably arranged towards the bottom sheet, such that the notches are not visible from the outside.

To achieve a three dimensional curved vehicle body component, the layer of natural fibrous material may further have a wedge shaped cutout from an outer edge into the at least one layer of natural fibrous material in the second direction in a non- curved state. The wedge shaped cutout comprises a first and thereto opposite sec- ond wedge surface configured to be interconnected with each other in order to form a curvature visible in view from the second direction.

It is to be understood that both the foregoing general description and the following detailed description present embodiments, and are intended to provide an over view or framework for understanding the nature and character of the disclosure. The accompanying drawings are included to provide a further understanding, and are incorporated into and constitute a part of this specification. The drawings illus trate various embodiments, and together with the description serve to explain the principles and operation of the concepts disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

The herein described invention will be more fully understood from the detailed de scription given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The draw- 5 ings are showing:

Fig. 1 A first variation of a layer of natural fibrous material in a non-curved state;

Fig. 2 The layer of natural fibrous material according to Fig. 1 in a curved state;

Fig. 3 A second variation of a layer of natural fibrous material in non-curved0 state;

Fig. 4 A cross-section of the layer of natural fibrous material according to Fig.

3;

Fig. 5 Examples of various cross-sections of the layer of natural fibrous mate rial; 5 Fig. 6 A variation of two layers of natural fibrous material;

Fig. 7 A generic vehicle body component;

Fig. 8 A first variation of a vehicle body component.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to certain embodiments, examples of which0 are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many dif ferent forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

Figure 1 shows a first variation of a layer of natural fibrous material 5 for a vehicle body component 1 in a rolled out and non-curved state. The layer of natural fibrous material 5 comprises in a first face 6 multiple first notches 8 extending in a first direction and parallel with respect to each other. Also only one first notch 8 may be present. Each first notch 8 has a first depth which is less than the thickness of the at least one layer of natural fibrous material 5. In Figure 2 a curved state of the layer of natural fibrous material 5 can be seen. The shown layer of natural fibrous mate rial 5 thereby comprises a curved section 10 (here two exemplary curved sections 10a and 10b), wherein the first notches 8 are arranged in said curved sections. Thus a density of the multiple first notches 8 correlates of the curvature of the curved section 10, such that more first notches 8 are arranged in an area with a higher curvature. The curved section 10a having the higher curvature has thus three first notches 8, meanwhile the curved section 10b has only two first notches 8. Furthermore, it can be seen that the respective cross-sections of the first notches 8 are at least partially reduced due to a curvature of the curved section 10. In the Figure 2 the cross sections are reduced to zero, however also applications are pos- sible where the cross-sections are only at least partially reduced. If the layer of nat ural fibrous material 5 would be curved in the other direction, it is also possible that the cross-section of first notches 8 are at least partially expanded due to a curvature of the curved section 10. Figure 3 and Figure 4 show a second variation of a layer of natural fibrous material 5 for a vehicle body component 1 in a rolled and non-curved state. The shown var iation of the layer of natural fibrous material 5 additionally comprises at least one second notch 9 arranged on a second face 7 opposite of the first face 6 comprising the first notches 8. As indicated in Figure 4, the first and the second notches 8, 9 each have a depth of 60% - 80% of the thickness of layer of natural fibrous mate rial 5. Since the second notches 9 extend in a second direction perpendicular to the first direction, the first notches 8 and the second notches 9 intersect each other such that at least one opening 1 1 extending through the layer of natural fibrous material 5 is formed at the intersection. The layer of natural fibrous material 5 may be wooden veneer comprising wooden fibers 12 having a general fiber direction arranged in the first direction, as indicated in Figure 3. The cross sections of the first and/or second notches 8,9 may each have different cross sections, as shown in Figure 5. The cross sections can be among others circular, trapezoidal, rectangular or triangular. Figure 6 shows two layers of natural fibrous material 5 for a vehicle body compo nent 1 . Both layers have multiple first notches 8 on a first face 6. In the shown ar rangement, the individual first faces 6 are arranged to face each other, such that a matrix of notches 8 is formed interconnecting the notches 8 to each other. Other arrangements or number of layers are also possible.

The variations of the layer of natural fibers 5 comprising the notches, as illustrated in Figures 1 to 6 are suited for a vehicle body component 1 comprising a top sheet 2, a bottom sheet 3 and a there between arranged core 4 mechanically intercon necting the top sheet 2 and the bottom sheet 3. Such a vehicle body component 1 is shown generically in Figure 7, wherein the top sheet 2, the bottom sheet 3 and the core 4 can each comprise one or multiple layers. In the shown example the top sheet 2 comprises two layer 2a, b2, the bottom sheet 3 comprises two layers 3a, 3b and the core comprises two layers. Thereby, the top sheet 2 and/or the bottom sheet 3 and/or the core 4 may comprise at least one layer of natural fibrous material 5, as explained above. The vehicle body component 1 may further comprise a frame 13 for interconnecting the vehicle body component 1 to a vehicle chassis, as schematically indicated. The frame 13 is preferably interconnected, in particular glued, to the bottom sheet 3.

One variation of such a vehicle body component 1 is shown in Figure 8 with a top sheet 2, a bottom sheet 3 and a core 4 comprising three layers of natural fibrous material 5. Each layer has multiple first notches 8 on the respective first faces 6 of said layers. All first faces 6 are arranged facing towards the bottom sheet 3. The top sheet 2 and a bottom sheet 3 may be made of reinforcing fibers 14. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without depart ing from the scope of the invention.

LIST OF DESIGNATIONS

1 Vehicle body component 8 First notch

2 Top sheet 9 Second notch

3 Bottom sheet 10 Curved section

4 Core 1 1 Opening

5 Layer of natural fibrous 1 2 Wooden fibers material 13 Frame

6 First face 14 Reinforcing fibers

7 Second face