WHEEL ARCH WITH OPTIMIZED WHEEL ARCH LINING

Abstract

Wheel arch for a motor vehicle with a wheel arch housing component for at least partially delimiting the wheel arch for a vehicle wheel of the motor vehicle, and with a wheel arch lining which is arranged on the surface of the wheel arch housing component facing the wheel and extends at least partially along this surface, the wheel arch lining having at least one support layer and one fiber layer, wherein the support layer forms the outer side of the wheel arch lining facing the wheel and the fiber layer is arranged between the wheel arch housing component and the support layer and the support layer and the fiber layer are thermally bonded to one another and formed into a wheel arch lining and wherein at least 50%, preferably at least 65%, preferably at least 80% of the surface of the fiber layer is in contact with the wheel arch housing component.

Claims

1. A wheel arch for a motor vehicle, with a wheel arch housing component for at least partially delimiting the wheel arch for a vehicle wheel of the motor vehicle, and with a wheel arch lining, which is arranged on the surface of the wheel arch housing component facing the wheel and extends at least partially along this surface, wherein the wheel arch lining comprises at least one support layer and one fiber layer, wherein the support layer forms the outer side of the wheel arch lining facing the wheel and the fiber layer being arranged between the wheel arch housing component and the support layer, and the support layer and the fiber layer being thermally bonded to one another and formed to a wheel arch lining and wherein at least 50%, is in contact with the wheel arch housing component.

2. The wheel arch liner of claim 1, wherein the fiber layer comprises a protective layer arranged on the surface of the fiber layer facing the wheel arch housing component.

3. The wheel arch liner of claim 1, wherein the wheel arch lining comprises a third layer arranged between the support layer and the fiber layer, which third layer is formed as a film with a weight per unit area of 5 to 200 g/m.sup.2.

4. The wheel arch liner of claim 1, wherein the support layer and/or the fiber layer comprise sound-absorbing properties and the fiber layer, the optional third layer, and the support layer together have sound-insulating properties.

5. The wheel arch liner of claim 1, wherein the individual layers within the wheel arch lining comprise a variable thickness, density and/or weight per unit area.

6. The wheel arch liner of claim 1, wherein the fiber layer comprises a maximum thickness of 35 mm or less.

7. The wheel arch liner of claim 1, wherein the fiber layer in the finished component comprises a maximum thickness of 27 mm or less.

8. The wheel arch liner of claim 1, wherein the fiber layer in the finished component comprises a maximum thickness of 20 mm or less.

9. The wheel arch liner of claim 1, wherein the wheel arch lining is air-permeable, preferably with an air resistance of 500 to 6000 Rayls, preferably with an air resistance of 1500 to 4000 Rayls.

10. The wheel arch liner of claim 1, wherein the support layer is rigid and comprises a weight per unit area of 500 to 1400 g/m.sup.2.

11. The wheel arch liner of claim 1, wherein the fiber layer comprises a basis weight of 400 to 1600 g/m.sup.2.

12. The wheel arch liner of claim 1, wherein the third layer comprises a thermoplastic material, preferably a thermoplastic material based on a polyester, polyamide, polyurethane or polyolefin, further preferably based on a polypropylene, polyethylene or TPU.

13. The wheel arch liner of claim 1, wherein the fiber layer or the support layer comprises matrix fibers and binder fibers, wherein the matrix fibers are short fibers or continuous filaments, preferably based on a thermoplastic material, further preferably of synthetic, mineral or natural origin.

14. A motor vehicle comprising a wheel arch according to claim 1.

15. A method of manufacturing a wheel arch lining as defined in claim 1, the method comprising the steps of: (a) providing a first fiber layer, a second layer provided as a support layer and, in particular, a third film layer arranged therebetween, in a forming tool; and (b) single-stage thermal forming of the layers provided according to (a).

16. The method according to claim 15, wherein a third film layer is provided between the first fiber layer and the second layer, and the forming includes two substeps (b.1) and (b.2): (b.1) exposure of the first fiber layer, the film layer and the second layer to water vapor through openings which are permeable to vapor and air and are arranged in the wall of the molding tool facing the first fiber layer, wherein the water vapor comprises a temperature and vapor wetness and a vapor pressure such that, on the one hand, the first fiber layer solidifies to form a material bond and, on the other hand, the vapor pressure of the water vapor against the third layer after passing through the fiber layer is sufficient to compress the second fiber layer; (b.2) exposure of the second layer to water vapor through openings which are permeable to vapor and air and are arranged in the wall of the mold facing the second layer, wherein the water vapor comprises such a temperature and vapor wetness and such a vapor pressure that the second layer solidifies to form a material bond and the support layer is formed.

17. The method according to claim 16, wherein the third film layer becomes permeable to air by the steam exposure (b.1).

18. The method of claim 16, wherein the steam exposure takes place at a pressure of up to 15 bar.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0060] FIG. 1 shows schematically the structure of the wheel arch (1) according to the invention.

[0061] The wheel arch lining (4, 5, 6) comprises an inherently rigid support layer (4) with sound-absorbing properties. With its surface facing away from the wheel arch or toward the tire, the support layer (4) also provides protection against external mechanical influences, such as stone impact.

[0062] As can be seen from FIG. 1, a space exists between the wheel arch housing component (7) and the support layer (4) as part of the wheel arch lining (4, 5, 6). This space is predominantly filled by the fiber layer (6).

[0063] In a preferred embodiment, the wheel arch lining (4, 5, 6) comprises a third layer (5). This is arranged as a film or adhesive layer between the support layer (4) and the fiber layer (6).

[0064] FIGS. 2A to D show a wheel arch housing component (1) with a support layer 2. The inner surface (not visible) of the wheel arch housing component (7) and the surface of the support layer facing it together form a space which, as can be seen from FIGS. 2B to 2D, have a different geometry and a different cross-section.

[0065] The cross sections shown illustrate the complex distribution of space to which a wheel arch (1) must be adapted. Each vehicle has its own space limitations and requires an individual solution. The wheel arch (1) according to the invention should allow the available space to be fully utilized.

[0066] FIGS. 3 to 5 show results or the measurement setup (FIG. 4) of acoustic measurements on a state-of-the-art wheel arch compared with the wheel arch according to the invention, each mounted on the same SUV.

EXAMPLE

[0067] Four wheel arch linings according to the invention were realized and installed on an off-road vehicle (hereinafter referred to simply as SUV) currently available for the European market, as a replacement for the standard wheel arch linings usually installed there, which were manufactured according to the specifications of the prior art. Acoustic tests were carried out to demonstrate, by objective measurements, the usefulness of the wheel arch liners according to the invention.

[0068] The wheel arch linings according to the invention consisted of a support layer (4), a fiber layer (6) and an air-permeable intermediate film (5) in between. The support layer (4) was made of a fiber blend consisting of 40% by weight PET/CoPET bicomponent binder fibers and 60% by weight PET short staple fibers. To give it sufficient stiffness, the support layer (4) was selected with a basis weight of around 800 g/m.sup.2 and compacted to 3 mm. The intermediate film (5) consisted of an air-permeable film with a basis weight of 60 g/m.sup.2. Finally, the fiber layer (6) consisted of 30% by weight of PET/CoPET bicomponent binder fibers, 30% by weight of self-crimped PET fibers, and 40% by weight of PET short recycled fibers. The basis weight of the fiber layer (6) was approximately constant over the area and was about 550 g/m.sup.2. This low basis weight, together with the use of self-crimped fibers, makes the fiber layer (6) particularly soft and elastic.

[0069] In each of the four wheel arch linings according to the invention, the fiber layer (6) was shaped three-dimensionally to fill the space between the support layer (4) and the SUV wheel arch housing component (7) in the area where it had to be installed, up to a maximum thickness of about 20 mm. Thanks to its softness and elasticity, the fiber layer (6) was able to adapt well to the very complex shape of the space between the support layer (4) and the SUV wheel arch housing component (7). During assembly on the SUV, it was found that each of the four wheel arch linings according to the invention is in contact with the wheel arch housing component (7) over at least about 85% of its surface area.

[0070] The serial wheel arch linings usually installed on SUVs are realized according to the specifications of the state of the art. In fact, they consist of a support layer to whose surface facing the wheel arch housing component two patches of noise-absorbing material are bonded. The support layer consists of a mixture of PP fibers (45% by weight) and PET fibers (55% by weight), it has a basis weight of about 1200 g/m.sup.2 and a constant thickness of about 4 mm. Each absorbent patch consists of a layer of PET fibers wrapped with a thin nonwoven fabric. The basis weight of the absorbent patches is approximately constant over their surface area and is about 400 g/m.sup.2. The overall thickness of the absorbent patches is constant and is about 10 mm. Furthermore, the absorbent patches have a rectangular shape and cover about 40% of the surface of the support layer facing the wheel arch housing component.

[0071] Due to their constant thickness and the fact that they cover only part of the surface of the support layer facing the wheel arch housing component, the absorbent patches do not adapt at all to the complex shape of this space and fill it only very partially. In the prior art wheel arch linings commonly installed on SUVs, there is no or no practically relevant contact between the absorbent patches and the wheel arch housing component. According to the state of the art, therefore, an air gap is left between the wheel arch lining and the wheel arch housing component over the entire surface of the wheel arch.

[0072] Acoustic tests were performed with the SUV in a semi-anechoic room equipped with a chassis dynamometer. Two different operating conditions were considered: constant speed at 50 km/h and acceleration from about 35 km/h to 95 km/h.

[0073] The noise in the passenger compartment was measured at the ear positions of the rear right front passenger. These positions were chosen because it is known that the rear seat positions are very critical with regard to tire noise. FIG. 3 shows the comparison between the mean value of the sound pressure levels measured at these two positions when the SUV is equipped with the standard prior art wheel arches (dotted line, marked 2) and when the SUV is equipped with the wheel arches according to the invention (solid line, marked 1). These data were measured at a constant speed of 50 km/h. As can be seen, the installation of the wheel arch linings according to the invention in the SUV achieves a significant reduction in the SPL spectrum, especially in the frequency range between 630 Hz and 1600 Hz, which is known to be the most relevant for tire noise.

[0074] The exterior noise was measured at 3 positions arranged as shown in FIG. 4 (the measurement positions are labeled M1, M2 and M3 in FIG. 4). These 3 positions are arranged along a line parallel to the longitudinal axis of the vehicle and at a distance of 7.5 m from this axis, which corresponds to the same distance at which the exterior noise must be measured according to the regulation ECE-R51.03 on exterior noise of motor vehicles currently in force in Europe.

[0075] The dashed line in FIG. 5 shows the mean value of the sound pressure levels measured at the 3 external microphones for the SUV equipped with the standard prior art wheel arch linings, during acceleration from about 35 km/h to about 95 km/h. The solid line (FIG. 5) shows the same magnitude for the SUV equipped with the wheel arch linings according to the invention. As can be seen, a reduction of almost 1 dB(A) is achieved over the entire speed range investigated.

[0076] These results show that the wheel arches according to the invention offer a significant reduction in internal and external noise compared to prior art solutions. This was achieved by recognizing that, contrary to what is usually assumed in the prior art, the existence of an air gap between the wheel arch lining (4, 5, 6) and the wheel arch housing component (7) can be detrimental to the acoustic performance of the part. By forming the fiber layer (6) in three dimensions in such a way that the space between the support layer (4) and the wheel arch housing component (7) is filled, a significant acoustic advantage can be achieved.