Automotive trim component for reducing tire noise and road vehicle equipped with the automotive trim component

Abstract

1. A road vehicle moved by tires, the road vehicle comprising a trim component for reducing noise radiated by said tires, the trim component including a sound absorbing object having an outer surface facing the tread of the tire, the sound absorbing object being at least partially located within a front or rear acoustic radiating horn of the same tire, and the sound absorbing object having a maximum dimension of less than 800 mm and an aspect ratio of less than 10.

Description

[Technical Field]

[0001] The present invention relates to the field of automotive trim components arranged on the exterior of a vehicle to reduce tire noise, and road vehicles including such automotive trim components. [Background technology]

[0002] In recent years, the requirements for the control and reduction of noise emitted by road vehicles have become increasingly stringent. Two factors essentially determine this development. The first factor is the continuous evolution of legislation regarding the external noise of road vehicles and the associated progressive tightening of permissible noise emission levels, as implemented for example in EU directive 540 / 2014. The second factor is the increasingly higher expectations of customers, in particular those relating to the acoustic comfort and perceived quality that a road vehicle can offer them.

[0003] Tyres are the main noise source responsible for the external and internal noise emitted by road vehicles, and this applies in particular to road vehicles that are fully powered by an electric drivetrain, in which case the tyres are by far the most important noise source.

[0004] For over 15 years, automobile manufacturers have been installing coverings with sound-absorbing properties in the areas under the vehicles they produce to reduce noise emitted by tires. "With sound-absorbing properties" means that such materials are capable of dissipating a large portion of the acoustic energy carried by sound waves impinging on them and radiated, for example, by tires. Typical examples of such materials are sound-absorbing underbody shields and sound-absorbing wheel well outer liners.

[0005] Sound-absorbing underbody shields are generally substantially planar components that are attached to the vehicle underbody at a number of fixed points and are obtained by consolidating multiple layers, including one or more porous material layers, under heat and compression. The consolidation process provides the component with the structural properties required for its installation on the vehicle and for resisting aerodynamic loads, while maintaining a significant level of sound absorption thanks to the porous material layers included therein. To enhance their performance, this type of underbody shield can be complemented by an additional absorber, typically installed on the side facing the vehicle body. Traditional prior art underbody shields of this type are described, for example, in US2020307470 or EP3137340.

[0006] Similarly, a sound-absorbing wheelhouse outer liner is a substantially semi-cylindrical member that is fixed to the wheelhouse of a vehicle body and conforms to the shape of the wheelhouse so as to surround the upper portion of the tire. Similar to the underbody shield, a sound-absorbing wheelhouse outer liner is generally obtained by compressing and integrating multiple layers, including one or more layers containing a porous material, under heat, and an additional absorber installed on the side facing the body may complement the sound-absorbing wheelhouse outer liner to enhance the sound-absorbing performance of the sound-absorbing wheelhouse outer liner. Prior art wheelhouse outer liners are described, for example, in EP3371363 and WO22189477.

[0007] Prior art solutions such as those described herein above present a series of problems. First, they have very complex shapes, which can make their design cumbersome, time-consuming, and increase production costs. Furthermore, the complexity of the shapes makes their fixation to the vehicle body very critical, typically requiring several fixation points, which can also result in high production waste.

[0008] Secondly, the extent of these solutions is extremely important, as they generally cover large surfaces of the vehicle body, such as the floor or the area under the wheel wells. Sound-absorbing underbody shields have an area of ​​approximately 2 m 2 The same applies to a series of outer wheelhouse liners. Such a large area obviously leads to high material consumption and production costs.

[0009] Third, despite their extent and geometric complexity, the performance of these solutions can be rather limited: the maximum reduction in external noise obtained by these components is typically in the range of 1 dB(A) or less, measured according to standard ECE 51.03 (EU Directive 540 / 2014). The reduction in internal noise obtained by these components can be relatively small, if not negligible.

[0010] It is therefore an object of the present invention to provide a solution to the above-mentioned problems of the prior art. The invention provided here makes it possible to obtain a road vehicle having similar or lower tire noise than road vehicles equipped with prior art sound absorbing covering components, while at the same time reducing material consumption and waste, improving ease of design and assembly, while reducing costs. Summary of the Invention [Means for solving the problem]

[0011] The object of the present invention is achieved by a road vehicle comprising a trim component according to claim 1 and by a trim component according to claim 6. [Effects of the Invention]

[0012] In a main aspect, the invention relates to a vehicle for moving on a road and having tires, each tire comprising a tread formed by an outer surface of the tire that is in regular contact with the road on which the vehicle moves, and the tread forming, together with the road, front and rear sound radiating horns, the vehicle further comprising a trim component for reducing noise radiated by the tire, the trim component comprising an essentially three-dimensional sound absorbing object, the sound absorbing object having a maximum dimension of less than 800 mm and an aspect ratio of less than 10, at least a part of a surface of the sound absorbing object facing opposite the tire tread, and the at least a part of the surface of the sound absorbing object being at least partially located inside the front or rear sound radiating horn of the tire.

[0013] According to a second aspect, the present invention relates to an automotive trim component for use in a vehicle according to the main aspect of the invention, specifically for reducing noise radiated by a tire of said vehicle, said trim component comprising an essentially three-dimensional sound absorbing object having dimensions of less than 800 mm and an aspect ratio of less than 10, said at least part of the surface of said sound absorbing object being at least partially located inside a front or rear noise acoustic radiating horn of said tire, such that when mounted on said vehicle at least part of the surface of said sound absorbing object faces the tread of the tire.

[0014] An "inherently three-dimensional body" is any solid body that does not take the form of an open shell. An open shell is a body obtained by plastically deforming a flat layer of material, for example by molding. An open shell cannot be considered an "essentially three-dimensional body" because its overall geometric shape is obtained by plastically deforming a flat layer and can therefore be parametrically described in two dimensions. The most obvious example of an open shell is, of course, a plate or a circular arc of a cylinder. Other examples are prior art underbody shields and wheelhouse outer liners, which are typically obtained by molding one or more flat layers of material. Therefore, they cannot be considered "essentially three-dimensional" bodies within the meaning of the invention disclosed herein.

[0015] A "sound-absorbing body" is one that is intentionally designed to absorb sound emitted by a noise source, such as a vehicle's tires. Similarly, a "sound-absorbing material" is a material that is intentionally conceived to absorb sound.

[0016] For a trim component intended to be installed on an associated road vehicle, "longitudinal," "transverse," and "vertical" directions can be defined. These directions are identified by the orientation of the associated road vehicle when the component is installed on the road vehicle. Generally, with respect to a road vehicle, the longitudinal direction is horizontal from front to rear, the transverse direction is left to right in the direction of travel, and the vertical direction is bottom to top. The longitudinal, transverse, and vertical dimensions of a trim component refer to its extent in the longitudinal, transverse, and vertical directions, respectively. Specifically, the maximum dimension of a trim component is the largest of its dimensions.

[0017] For a trim component having a given geometric shape, the aspect ratio is the ratio of the maximum to the minimum of its dimensions.

[0018] Two acoustic radiation horns, a front and a rear, can be associated with each tire of a vehicle moving on a road. Each acoustic radiation horn forms a geometric volume in the vicinity of the tire-road contact patch, as shown in FIG. 1. FIG. 1 shows a side view of a tire 10 during rotation. Arrow 11 indicates the direction of tire rotation, while arrow 12 indicates the resulting direction of movement. Line 13 indicates a semicircle centered at the center point 14 of the tire-road contact patch, with a radius equal to the distance between this point 14 and the top of the tire. This radius is approximately equal to the diameter of the tire 10. Line 13, together with road surface 15 and tire tread surface 16, separates two regions 17, 18: one located in front of the tire in the direction of movement, and the other located behind the tire in the direction of movement. Both regions must be considered as three-dimensional volumes extending laterally across the entire width of the tire tread surface. Region 17, i.e., the region located on the front side of the tire in relation to the direction of travel, is referred to herein as the front sound radiation horn. Similarly, region 18, i.e., the region located on the rear side of the tire in relation to the direction of travel, is referred to herein as the rear sound radiation horn.

[0019] Surprisingly, it has been found that the tire noise emitted by a road vehicle equipped with a trim component according to the invention is comparable to or lower than that emitted by a road vehicle equipped with prior art solutions for reducing tire noise, such as sound-absorbing underbody shields and wheel well outer liners. This is indeed quite surprising, since the trim component according to the invention can be significantly smaller and lighter than typical sound-absorbing underbody shields and wheel well outer liners.

[0020] This remarkable effect is achieved by combining the shape and design of the trim component according to the invention with its position when installed on the vehicle according to the invention. These features enable the trim component to absorb tire noise significantly more effectively than the above-mentioned prior art solutions. Indeed, the trim component according to the invention comprises a sound-absorbing object, which is attached to the road vehicle according to the invention in such a position that at least a portion of its surface faces the tire tread and is at least partially located inside the front or rear acoustic radiating horn of the tire. In this way, this portion of the surface of the sound-absorbing object can effectively block the acoustic energy of the sound waves radiated by the tire towards the front or rear of the vehicle and transport it to the volume of the sound-absorbing object according to the invention, where it can be dissipated. Hereinafter, for convenience, this portion of the surface of the sound-absorbing object will be referred to as the "tread-facing surface" according to the invention. Furthermore, the entire volume of the sound-absorbing object according to the invention, which has a dimension limited to 800 mm and an aspect ratio limited to 10, is effectively involved in the sound absorption process. In contrast, in prior art solutions, due to their large surface area (necessary to conform to the shape of the vehicle panel they cover) and their location, only a small portion of the material used in their production actually participates in the sound absorption process.

[0021] In a road vehicle equipped with a trim component according to the invention, the trim component according to the invention is preferably mounted on or integrated into the longitudinal rocker and / or mounted on or integrated into the bumper, which allows the trim component to be positioned close to the tire, which facilitates locating the tread-facing surface at least partially inside the front or rear sound radiating horn of the tire and improves the noise reduction performance of the trim component according to the invention.

[0022] The trim component according to the present invention may be secured to the vehicle using attachment means known to those skilled in the art, such as clips, screws, rails, etc. The attachment means may be included within the trim component according to the present invention. Because the trim component has a limited geometric extent and aspect ratio, the number of required attachment points can be significantly reduced compared to those typically required for prior art sound-absorbing wheelhouse outer liners and underbody shields. Additionally, the layout of the attachment points can be significantly simplified.

[0023] A further advantage of the limited number of fixing points and simple layout of the fixing points is that it can be significantly easier and cheaper to replace trim components according to the invention compared to prior art sound absorbing wheelhouse outer liners and underbody shields, for example when a certain wear limit is reached.

[0024] In a vehicle equipped with a trim component according to the invention, the minimum distance between the tread-facing surface and the tire it faces is preferably between 20 mm and 150 mm, more preferably between 30 mm and 100 mm, and even more preferably between 40 mm and 70 mm. The distance between the tread-facing surface and the tire it faces is intended to be measured with the vehicle stationary on a flat, level road. The closer the tread-facing surface and the tire it faces, the better the noise-reducing performance of the trim component according to the invention. At the same time, for safety reasons, it follows that a minimum distance between the tread-facing surface and said tire must be maintained.

[0025] Furthermore, to constantly improve performance, in vehicles equipped with a trim component according to the present invention, the trim component according to the present invention is installed so that the minimum distance between the trim component and the road is as small as possible. In fact, the smaller this distance, the closer the sound-absorbing object according to the present invention is to the tire-road interface, which is known to be the area from which most tire noise radiates. At the same time, for safety reasons, it may be necessary to maintain a certain clearance between the trim component according to the present invention and the road. Preferably, in a vehicle according to the present invention, the minimum distance between the trim component according to the present invention and the road is 20 mm to 150 mm, more preferably 40 mm to 100 mm, and even more preferably 50 mm to 80 mm. The distance between the trim component according to the present invention and the road is intended to be measured with the vehicle stationary on a flat, level road.

[0026] In a preferred embodiment, the trim component according to the present invention is attached to the road vehicle by a pivotable bracket, preferably oriented laterally and operated by an actuator. This embodiment is particularly advantageous in that it allows the orientation of the tread-facing surface and the distance between the trim component and the road to be adjusted by operating the actuator depending on road conditions and vehicle speed. In particular, when the road vehicle is not moving, e.g., parked, and / or its speed is very low and external tire noise is irrelevant, e.g., below 30 km / h, the trim component according to the present invention is placed in a fully retracted position and disappears into the vehicle. Of course, for this to be possible, it may be necessary to store the trim component, e.g., by forming a suitable recess in the underbody area of ​​the vehicle. Conversely, when the vehicle is moving at high speed, e.g., on a smooth road, the trim component according to the present invention may be placed in a “fully activated” position to fully utilize its noise reduction potential.

[0027] Furthermore, in the trim component according to the present invention, the sound-absorbing object according to the present invention is preferably at least partially encapsulated in a layer of a rigid material, i.e., a material that is significantly more rigid than the material contained in the sound-absorbing object itself. This can be useful when installing the trim component according to the present invention in a vehicle. It can also be useful for protecting the sound-absorbing object from environmental factors and mechanical impacts, particularly those that may result from impacts against road bumps, curbs, paving stones, etc. Preferably, the synthetic material is a plastic material. Plastics are usually elastically deformable and thus can absorb mechanical impacts well. Furthermore, this can result in good abrasion resistance and durability. For the trim component according to the present invention to properly perform its function, if the rigid material layer is air-impermeable, this layer should not cover the surface facing the tread. However, if the rigid material layer is air-permeable, for example, if it has micropores, covering the surface facing the tread may be possible.

[0028] The function of the tread-facing surface according to the invention is to effectively block the sound waves radiated forward or rearward by the tire it faces, allowing these sound waves to be absorbed by the sound-absorbing object according to the invention. In this regard, it is essential that it is located inside the front or rear sound-radiating horn when the trim component is installed on the vehicle according to the invention and when the trim component is in use.

[0029] In principle, the tread-facing surface according to the invention may have any shape. In a first preferred embodiment, the tread-facing surface according to the invention has the shape of a laterally disposed cylindrical arc, which arc approximately follows the profile of the tire tread surface it faces at a predetermined distance from the tire tread surface. In this particular embodiment, the tread-facing surface according to the invention conforms to the shape of the tire and the wavefronts of the sound waves emitted by the tire. This may improve noise reduction performance.

[0030] A surface is considered to be "laterally disposed" when the normal to the surface at any point has no or negligible lateral component. Such a surface is obtained by extrusion of a line in the lateral direction.

[0031] In a second preferred embodiment, the tread-facing surface according to the invention is flat, which is advantageous in terms of ease of manufacture. Preferably, in this embodiment, the tread-facing surface according to the invention is arranged laterally, more preferably its inclination is between -60 and +60 degrees. The inclination of a laterally arranged flat surface is the angle formed by the normal to the surface oriented outwardly with respect to the volume of the sound-absorbing object and the longitudinal direction. Positive angles are measured counterclockwise.

[0032] Furthermore, to improve the performance of the trim component according to the invention, the lateral dimension of the surface facing the tread according to the invention is preferably at least 120 mm, more preferably at least 180 mm, even more preferably at least 220 mm, and the vertical dimension of the surface facing the tread according to the invention is preferably at least 100 mm, more preferably at least 120 mm, even more preferably at least 150 mm.

[0033] Preferably, the lateral extent of the tread-facing surface of the present invention is greater than that of the tire tread surface it faces, so that the trim component of the present invention can better shield and absorb noise emitted by the tire.

[0034] In order to consistently improve the noise attenuation performance of the trim component according to the invention, when the trim component according to the invention is installed and in use, preferably at least 50%, more preferably at least 75%, and even more preferably at least 90% of the tread-facing surface according to the invention is located inside the front or rear sound radiating horn of the tire of the vehicle according to the invention, so that a large portion of the tread-facing surface can be acted upon by the sound waves radiated by the tire in the forward or rearward direction and can thus transport these sound waves to the sound absorbing object where the energy can be dissipated.

[0035] The sound-absorbing object according to the invention consists of an essentially three-dimensional sound-absorbing object with dimensions of less than 800 mm and an aspect ratio of less than 10. The combination of these characteristics allows the entire volume of the object to participate in the process of absorbing the acoustic energy carried by the sound waves blocked by the surface facing the tread. This is advantageous compared to sound-absorbing underbody shields and wheelhouse outer liners belonging to the prior art, where, due to their non-optimal location and two-dimensional nature, only a small portion of the material used for their production actually participates in the sound-absorbing process, namely the portion closest to the tire-road interface.

[0036] To further improve the performance / volume ratio, the sound absorbing body according to the invention preferably has an aspect ratio of less than 8, even more preferably less than 5, and its largest dimension is preferably less than 600 mm, even more preferably less than 400 mm, the largest dimension being preferably the longitudinal dimension.

[0037] No particular restrictions apply to the shape of the trim component according to the invention. In a first preferred embodiment, the trim element according to the invention has the shape of a wedge. The base of the wedge comprises the surface facing the tread according to the invention.

[0038] In a second preferred embodiment, the trim element according to the invention has the shape of a semi-cylinder, one of the semi-circles constituting the base of the semi-cylinder comprising the surface facing the tread according to the invention.

[0039] In a third preferred embodiment, the trim element according to the invention has the shape of a semi-cone or semi-frustum of a cone, the base of which comprises the surface facing the tread according to the invention.

[0040] In a further preferred embodiment, the trim element according to the invention has the shape of a tapered polyhedron, for example a pyramid or a truncated pyramid, and in this preferred embodiment too, the base of the tapered polyhedron comprises the tread-facing surface according to the invention.

[0041] In all the preferred embodiments listed above, the surface facing the tread preferably takes the form of a cylindrical arc that follows the profile of the tire it faces at a given distance from the tire, or alternatively takes the form of a flat surface oriented laterally, preferably with an inclination of between +60 and -60 degrees.

[0042] The above-mentioned preferred shapes for the trim components according to the invention are particularly advantageous in that they improve the ratio of the area of ​​their tread-facing surface to the volume of the trim component according to the invention, and the corresponding performance / volume ratio.

[0043] Furthermore, trim components according to the invention having these shapes can very advantageously also improve the aerodynamic performance of the vehicle according to the invention. For example, if a wedge-shaped trim component according to the invention is installed on or integrated into the front bumper of a road vehicle according to the invention, the trim component according to the invention can act as an air guide, making the air flow around the front tires smoother and less turbulent. In this way, a reduction in tire noise can be combined with an improvement in the aerodynamic performance of the vehicle according to the invention.

[0044] Additionally, when a trim component according to the present invention is mounted on a pivotable bracket that is laterally oriented and operated by an actuator as described above, the noise reduction and aerodynamic improvement functions of the trim component according to the present invention can be combined and simultaneously adjusted according to environmental factors such as speed and road conditions.

[0045] The trim component according to the present invention is preferably separate, i.e., it is a trim component installed on the vehicle according to the present invention independently and separately from other trim components. However, the trim component according to the present invention may also be connected to and / or integrated with other trim components, such as an underbody shield and / or a wheelhouse outer liner.

[0046] To perform its function, a sound-absorbing object according to the present invention may comprise any type of material known in the art as suitable for sound absorption, in particular porous fibrous materials, and / or open-cell foams, in particular polyurethane foams, and / or air-permeable polymeric films, in particular microperforated films, and / or thin air-permeable nonwovens known in the art as "scrims." In certain embodiments, a sound-absorbing object according to the present invention may also comprise materials that are not suitable for sound absorption as such, but that may participate in sound absorption when combined with other materials. Examples are air-impermeable polymeric films, air-impermeable scrims, and heavy barrier layers formed of polymeric and / or rubbery materials.

[0047] In principle, no restrictions apply to the arrangement of materials within the sound-absorbing body according to the invention.

[0048] In a first embodiment, the sound absorbing object according to the invention is an object made of a first porous fibrous material. Such a layout may be advantageous for its simplicity, which may result in ease and low cost of manufacture, and for its environmental sustainability.

[0049] The first porous fibrous material may comprise any type of natural and / or synthetic fiber common in the industry. Examples of natural fibers include cotton, wool, flax, hemp, bamboo, sisal, jute, and abaca fibers. Examples of synthetic fibers include polypropylene fibers, polyethylene fibers, polyester fibers, such as polyethylene terephthalate (PET) fibers, polylactic acid (PLA) fibers, and polyamide (PA) fibers, specifically polyamide 6 or polyamide 6.6 fibers. Synthetic fibers may be monocomponent or bicomponent. Monocomponent fibers are formed from a single material, whereas bicomponent fibers are synthetic fibers formed from two polymers with different chemical and / or physical structures tightly bonded to each other along the fiber length. Bicomponent fibers may be produced using processes known to those skilled in the art, such as by melt spinning.

[0050] The first porous fibrous material may consist of only one type of component, but it may also be a homogeneous mixture of different types of fibers.

[0051] In this first embodiment, the first porous fibrous material preferably has a density of 20 kg / m 3 ~100kg / m 3 , more preferably 50 kg / m 3 ~80kg / m 3 A lower density first porous fibrous material allows the sound absorbing body according to the invention to be lighter and more porous, which favours the participation of the entire volume of the sound absorbing body in the sound absorption process.

[0052] The first porous fibrous material preferably has an Air Flow Resistivity (AFR) of 10,000 Ns / m 4 ~50,000Ns / m 4 , more preferably 10000Ns / m 4 ~30,000Ns / m 4 A not too high AFR may be preferred to allow the entire volume of the object to participate effectively in the sound absorption process. Hereinafter, AFR values ​​are assumed to be measured according to ISO 9053-1:2018.

[0053] The fibers of the first porous fibrous material are preferably staple fibers and have a length of 32 mm to 76 mm. Staple fibers are fibers with a discontinuous and predefined length, as opposed to endless filaments. Furthermore, to improve sound absorption performance, the fiber fineness is preferably 0.5 denier to 8 denier, more preferably 0.5 denier to 5 denier, and even more preferably 0.5 denier to 2 denier. For a given mass of porous fibrous material, finer fibers provide better sound absorption performance.

[0054] Advantageously, the fibers of the first porous fibrous material may at least partially have a recycled nature in order to reduce the environmental impact of the manufacturing process of the sound-absorbing object according to the invention, particularly in relation to the material consumption involved. In particular, the first porous fibrous material may be in the form of shoddy natural fibers, such as shoddy cotton, or shoddy synthetic fibers, such as shoddy polyester. A shoddy-type material is defined here as comprising at least 51% by weight of recycled fibers in the material involved. Thus, for example, shoddy cotton contains at least 51% by weight of recycled cotton fibers, with the remaining 49% by weight being made up of fibers of a different material and / or virgin fibers.

[0055] Furthermore, the first porous fibrous material preferably contains a binder, preferably in an amount of 10% to 50% by weight. The binder can improve the mechanical consistency of the sound-absorbing object according to the present invention, making it easier to handle during the production process and / or the installation process on a vehicle according to the present invention. The binder may be thermosetting or thermoplastic. In both cases, some kind of heat treatment is required to activate it. Thermosetting binders preferably take the form of epoxy resins or phenolic resins, or mixtures thereof. Thermoplastic binders preferably take the form of thermoplastic binder fibers. These are fibers that contain at least one portion that melts as a result of the heat treatment, forming droplets that bind all the other fibers at their intersections / contact points. The melting temperature of the binder fiber (or the melting portion of the binder fiber) must, of course, be lower than the melting temperature of all the other fibers (and possibly the non-melting portions of the binder fiber). The binder fibers may be monocomponent or bicomponent fibers. Thermosetting binders are preferred when improved mechanical properties and structural consistency are required. On the other hand, when very complex three-dimensional shapes have to be realized, binders in the form of thermoplastic binder fibers are preferred.

[0056] In a preferred embodiment of this first aspect, the first porous fibrous material comprises bicomponent side-by-side crimped fibers, preferably in an amount of 10% to 70% by weight, and a binder.

[0057] Bicomponent side-by-side crimped fibers are bicomponent fibers formed by simultaneously spinning two fiber polymers together side-by-side, so that both polymers are in contact with the outer surface of the resulting fiber. In this case, the two polymers have different physical properties, causing the fiber to assume a curved or crimped shape during the insulation process. For example, differences in heat shrinkage properties between the two polymers may determine such fiber curvature. Due to their loft, bicomponent side-by-side crimped fibers allow for particularly efficient filling of the volume of sound-absorbing objects according to the present invention, resulting in lower weight. Furthermore, these fibers also offer excellent molding properties, making design easier and more flexible. Preferably, bicomponent side-by-side crimped fibers have an overall round cross-section, and more preferably include a hollow core; in this case, the fiber is known as a hollow bicomponent fiber. However, other cross-sections can be used as well. In bicomponent side-by-side crimped fibers, the first polymer is preferably polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and the second polymer is a copolymer of polyethylene terephthalate (coPET) or a copolymer of polybutylene terephthalate (coPBT).

[0058] In this preferred embodiment of the first aspect, the first porous fibrous material further comprises a binder, preferably in an amount of 10% to 50% by weight. The binder may be a thermosetting binder, preferably in the form of an epoxy or phenolic resin, or a thermoplastic binder, preferably in the form of a thermoplastic binder fiber, and even more preferably in the form of a thermoplastic bicomponent core-sheath binder fiber. Bicomponent core-sheath binder fibers are bicomponent fibers, with one of the two components (the sheath) surrounding the other (the core). The sheath is the portion of the fiber that melts during the heat treatment. In bicomponent core-sheath binder fibers, the first polymer is preferably polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), and the second polymer is a copolymer of polyethylene terephthalate (coPET) or a copolymer of polybutylene terephthalate (coPBT).

[0059] In this preferred embodiment of the first aspect, particularly preferred is the case where the first porous fibrous material is made entirely of polyester fibers. One example is a mixture of bicomponent PET / CoPET side-by-side crimped fibers in an amount of 10% to 70% by weight, bicomponent PET / CoPET core-sheath binder fibers in an amount of 10% to 50% by weight, and monocomponent PET fibers in an amount of 10% to 70% by weight, the percentages corresponding to the different fiber types adding up to 100%. An acoustically absorbing object made entirely of polyester allows for easier recycling of the entire acoustically absorbing object at the end of production and / or the end of the product lifecycle.

[0060] When polyester is used for the fibers that make up the first porous fibrous material, at least a portion of it can advantageously have recycled properties. For example, PET can be obtained from consumer products such as PET bottle flakes, or from PET packaging articles, or from PET marine products such as fishing nets, by melting them and forming them into pellets that can be used in a spinning process. The advantage of using recycled polyester is that it reduces the environmental impact of the manufacturing process of the trim component according to the invention, specifically its CO2 footprint. Preferably, at least 20% by weight, more preferably at least 50% by weight, and even more preferably at least 70% by weight of the polyester used for the polyester fibers contained in the sound-absorbing object according to the invention is recycled polyester.

[0061] In a second embodiment, the sound-absorbing object according to the invention comprises an object made of a first porous fibrous material at least partially covered with a layer made of a second porous fibrous material. In this embodiment, preferably at least the tread-facing surface is covered with said layer made of the second porous fibrous material. The second porous fibrous material may be identical to the first porous fibrous material. However, it is preferred that the second porous fibrous material is different from the first porous fibrous material, and this differentiation can improve both the sound-absorbing properties and the mechanical consistency.

[0062] In this second embodiment, the second porous fibrous material preferably has a significantly higher flexural modulus than the first porous fibrous material. In this second embodiment, the flexural modulus of the second porous fibrous material is at least 70 MPa, preferably 70 MPa to 1300 MPa, preferably 100 MPa to 950 MPa, preferably 150 MPa to 700 MPa, measured according to ISO 178:2019 at 23° C. and 50% relative humidity. This improves the structural properties of the sound-absorbing object according to the invention and thus favors its handling during manufacturing and installation processes. Preferably, the coverage of the layer of the second porous fibrous material is sufficient to give the sound-absorbing object according to the invention self-supporting properties. "Self-supporting properties" means that the sound-absorbing object according to the invention does not substantially deform under the load of its own weight, independently of its orientation in space. In a particularly preferred embodiment, the layer of the second porous fibrous material completely covers the object made of the first porous fibrous material.

[0063] Furthermore, the AFR of the second porous fibrous material is preferably significantly higher than that of the first porous fibrous material. This provides an impedance mismatch at the interface between the two materials. The impedance mismatch helps to improve the sound absorption properties of the sound-absorbing object according to the invention within a specific frequency range, specifically within the range of 800 Hz to 1600 Hz, where external noise emitted by tires is particularly pronounced. In this second embodiment, the AFR of the second porous fibrous material is preferably 35000 Ns / m 4 ~1200000Ns / m 4 , and even more preferably 60000Ns / m 4 ~900,000Ns / m 4 is.

[0064] In this second embodiment, the layer of second porous fibrous material is preferably significantly thinner than the dimensions of the sound absorbing body according to the invention. Preferably, the thickness of the layer of second porous fibrous material is between 2 mm and 10 mm, more preferably between 3 mm and 6 mm. The area weight of the layer of second porous fibrous material is preferably less than 600 g / m 2 ~1600g / m2 , more preferably 800 g / m 2 ~1400g / m 2 is.

[0065] The second porous fibrous material, like the first porous fibrous material, may comprise any type of natural and / or synthetic fiber common in the industry. In particular, any type of fiber and fiber mixture described in relation to the first porous fibrous material may be used for the second porous fibrous material, including the fibers and fiber mixtures described in relation to the preferred embodiment of the first embodiment of the sound-absorbing object according to the present invention. However, the second porous fibrous material preferably has a higher density than the first porous fibrous material. This means that even if the same fibers or fiber mixtures are used for the first and second porous fibrous materials, they will preferably be compressed more strongly in the second porous fibrous material than in the first porous fibrous material. Preferably, the density of the second porous fibrous material is 100 kg / m or more. 3 ~600kg / m 3 , more preferably 200 kg / m 3 ~450kg / m 3 is.

[0066] In a particularly preferred embodiment of the second embodiment, the layer of the second porous fibrous material is composed of thermoplastic bicomponent binder filaments, preferably having a core-sheath structure. The filaments, sometimes called "continuous filaments" or "endless filaments," are continuous fibers of unlimited length, i.e., not cut to a specific length like staple fibers. This confers surprisingly good mechanical properties to the layer, resulting from the synergistic effect of the endless and bicomponent nature of the filaments. On the one hand, the endless filaments extend over the entire surface of the layer. On the other hand, melting of the sheath polymer ensures the formation of junctions between the cores of the endless filaments. The junctions are uniformly distributed along the entire length of the filaments themselves. The result is a network of strongly interconnected endless filaments extending over the entire surface of the layer. Such a network has excellent mechanical properties, particularly in terms of bending stiffness.

[0067] A third embodiment of the sound-absorbing object according to the invention can be derived from the previous embodiment by inserting an air-permeable film between the object made of the first porous fibrous material and the layer made of the second porous fibrous material. The presence of the air-permeable film can further help to adjust and improve the sound absorption performance of the sound-absorbing object according to the invention within a specific frequency range, specifically within the range of 800 Hz to 1600 Hz. In this third embodiment, the airflow resistance of the air-permeable film is preferably higher than that of the layer made of the second porous fibrous material, more preferably at least 20% higher than that of the layer made of the second porous fibrous material. For a given layer of material, the airflow resistance is the product of the airflow resistivity and the thickness.

[0068] In this third embodiment, the thickness of the air permeable film is preferably between 50 micrometers and 800 micrometers, more preferably between 100 micrometers and 500 micrometers. Its area weight is preferably between 50 g / m 2 ~800g / m 2 , more preferably 100 g / m 2 ~500g / m 2Preferably, the air-permeable film is of polymeric nature, preferably comprising at least one polymer or copolymer selected from the group consisting of polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), polyamides such as polyamide 6 or polyamide 66, polyolefins such as polypropylene (PP), polyethylene (PE), thermoplastic elastomers (TPEs) such as thermoplastic polyolefins (TPO), thermoplastic polyurethanes (TPU), elastomers such as EPDM-based elastomers or butadiene-based elastomers, or silicones, high-performance polymers such as polytetrafluoroethylene (PTFE), polyetherimides, polysulfones, polyethersulfones, polyetheretherketones (PEEK), ether vinyl acetate (EVA), and biopolymers such as polylactic acid (PLA). Preferably, the materials for the air-permeable film and the materials for the first and / or second porous fibrous materials belong to the same chemical family, making recycling easier. Furthermore, the film may be mono-, bi-, or multi-layered. To favor processability, the air-permeable film preferably has a tensile strength at break of greater than 20 MPa and a strain at break of greater than 100%. If the film is anisotropic, these values ​​refer to both the machine direction and the cross direction. Stress and strain at break are measured according to the current versions of ISO 527-1:2019 and 527-3:2018.

[0069] In a variant of this third embodiment, an air-impermeable film may be provided instead of the air-permeable film. The air-impermeable film can increase the mechanical robustness of the sound-absorbing object according to the invention. In this variant, the thickness of the air-impermeable film is preferably between 50 micrometers and 800 micrometers, more preferably between 100 micrometers and 500 micrometers. Its area weight is preferably less than 50 g / m 2 ~800g / m 2 , more preferably 100 g / m 2 ~500g / m 2Since the film is extremely thin and lightweight, its air impermeability does not impair the sound absorbing properties of the sound absorbing object according to the invention.

[0070] In another variation of this third embodiment, the air-permeable film may be replaced by a thin air-permeable nonwoven known in the art as a "scrim." As with the air-permeable film, the airflow resistance of the scrim is preferably higher than that of the layer of second porous fibrous material, more preferably at least 20% higher than that of the layer of second porous fibrous material. The area weight of the scrim is preferably 400 g / m2 so as not to significantly increase the overall weight of the sound-absorbing object according to the invention. 2 or less, more preferably 200 g / m 2 Preferably, in this variation of the third embodiment, the material used for the scrim and the material used for the first and / or second porous fibrous material belong to the same chemical family (e.g., they are all composed of polyesters), making them easier to recycle.

[0071] In a fourth embodiment, the sound-absorbing object according to the invention consists of a closed hollow shell formed by a layer of a second porous fibrous material. This fourth embodiment can be considered a modification of the second embodiment. The layer of the second porous fibrous material is a closed shell, and instead of the object made of the first porous fibrous material, an air cavity is provided inside the shell. This embodiment is particularly advantageous for its light weight and simplicity of design.

[0072] In a fifth embodiment, the sound-absorbing object according to the invention comprises an object made of a first porous fibrous material that is at least partially directly covered with an air-permeable foil or scrim. The air-permeable foil or scrim has the same characteristics as those described in connection with the third embodiment and its variants. In this embodiment, the surface facing the tread is preferably covered with said air-permeable foil or scrim. This fourth embodiment can be considered a variant of the second embodiment, in which a layer made of a second porous fibrous material is provided instead of the air-permeable foil or scrim. This can make the sound-absorbing object according to the invention lighter and less expensive. Furthermore, covering the outer surface of the sound-absorbing object according to the invention with an air-permeable foil or scrim can make the sound-absorbing object more resistant to environmental factors and stone chipping.

[0073] In a variant of this fifth embodiment, an air-impermeable film may be provided instead of the air-permeable film in order to improve the aforementioned robustness against the aforementioned environmental factors and chipping by stones. In this variant, the thickness of the air-impermeable film is preferably between 50 micrometers and 800 micrometers, more preferably between 100 micrometers and 500 micrometers. Its area weight is preferably less than 50 g / m 2 ~800g / m 2 , more preferably 100 g / m 2 ~500g / m 2 Since the film is extremely thin and lightweight, its air impermeability does not impair the sound absorbing properties of the sound absorbing object according to the invention.

[0074] The embodiments of the sound-absorbing object according to the present invention listed above show exemplary embodiments in which the sound-absorbing function is mainly realized by the porous fibrous material. However, other embodiments of the sound-absorbing object according to the present invention can also be obtained by providing an open-cell foam having similar characteristics in terms of geometry and, if applicable, AFR instead of the first and / or second porous fibrous material in the above five embodiments. However, open-cell foam is typically lighter than porous fibrous material. Thus, embodiments including open-cell foam may be advantageous for forming the sound-absorbing object according to the present invention. Preferably, the open-cell foam used in the sound-absorbing object according to the present invention has a strength of 10 kg / m or more. 3 ~50kg / m 3 , more preferably 10 kg / m 3 ~35kg / m 3 Further, the open cell foam is preferably a polyurethane foam.

[0075] The embodiments described herein above for a sound-absorbing body according to the invention are merely examples of possible material arrangements for obtaining the same sound-absorbing body, and further material arrangements that may be suitable depending on the circumstances can be easily derived from these embodiments by taking into account the characteristics of the materials described herein above, in particular their properties, density, thickness, areal weight and AFR.

[0076] In addition, by combining different embodiments and examples of the invention, further embodiments of the trim component according to the invention can be derived from the description and from the description of the embodiments shown in the drawings, which are schematic and not necessarily drawn to scale. [Brief explanation of the drawings]

[0077] [Figure 1] Figure 1 shows a vehicle tire and how to define the front and rear sound radiating horns of the tire, the contents of which have already been explained and commented on in detail above. [Figure 2] FIG. 2 shows a side view of a road vehicle according to the invention. [Figure 3] 3 and 4 are side views showing the rear part of a road vehicle according to the invention, specifically the area around the rear tyres. [Figure 4] 3 and 4 are side views showing the rear part of a road vehicle according to the invention, specifically the area around the rear tyres. [Figure 5] 5a to 5c show examples of trim components according to the invention having different shapes. [Figure 6] 6a to 6e show material arrangements for sound absorbing objects according to the invention, corresponding to the five embodiments described above. [Figure 7] FIG. 7 shows a test setup for measuring the Exterior Acoustic Transfer Functions. [Figure 8] FIG. 8 shows the sound source positions corresponding to the rear tire used for measuring the exterior acoustic transfer functions as well as for measuring the interior acoustic transfer functions. [Figure 9] FIG. 9 shows a comparison between the exterior acoustic transfer functions obtained for test vehicles with different trim configurations. [Figure 10] FIG. 10 shows a comparison between interior acoustic transfer functions obtained for test vehicles with different trim configurations. DETAILED DESCRIPTION OF THE INVENTION

[0078] 2 is a side view of a vehicle 20 according to the present invention, equipped with a front tire 21 and a rear tire 22. The vehicle includes trim components 23, 24, 25, and 26 according to the present invention. Trim components 23 and 26 are mounted on a vehicle front bumper 27 and a vehicle rear bumper 28, respectively. Trim components 24 and 25 are mounted on a longitudinal rocker 29 (often referred to as a "side sill"). Trim components 23 and 24 are intended to reduce noise radiated by the front tire 21, while trim components 25 and 26 are intended to reduce noise radiated by the rear tire 22.

[0079] Figure 3 shows the same side view of the vehicle according to the invention as in Figure 2, zoomed in on the area of ​​the rear tire 22. In this view, as in Figure 1, line 13 indicates a semicircle separating the front and rear sound radiation horns 17, 18 of the same tire 22, as well as the tread 33 and the road surface 30 of the tire 22. From this view, it can be seen that trim element 25 comprises a surface 31 facing the tread 33 of tire 22, which surface 31 is arranged inside the front sound radiation horn 17 of the same tire 22. Surface 31 comprises the tread-facing surface according to the invention for trim element 25. At the same time, trim element 26 comprises a surface 32 facing the tread 33 of tire 22, which surface 32 is arranged inside the rear sound radiation horn 18 of the same tire. Surface 32 comprises the tread-facing surface according to the invention for trim element 26. Both surfaces 31 and 32 are oriented laterally. However, surface 31 is flat, whereas surface 32 is shaped like an arc of a cylinder so as to at least approximately follow the profile of the tire it faces.

[0080] FIG. 4 is similar to FIG. 3 and illustrates how to calculate the inclination of a tread-facing surface according to the present invention when the surface is flat and laterally oriented. In FIG. 4, this is illustrated for a surface 31 that is assumed to coincide with the tread-facing surface for the trim member 25; for clarity, the rear tire 22 is not shown. To calculate the inclination of the tread-facing surface 31, two directions must be considered: a normal direction 35 to the tread-facing surface 31, which is oriented outward relative to the volume of the trim member 25, and a longitudinal direction 34. The inclination angle is evaluated as the angle 36 by which the longitudinal direction 34 must be rotated to overlap the normal direction 35. The inclination angle is counted as positive if the rotation is counterclockwise and negative if the rotation is clockwise. For example, the inclination of the tread-facing surface 31 in FIG. 4 is approximately −30 degrees. It should be noted that the sign of the slope depends on whether the tread-facing surface is located within the front or rear sound radiation horn of the tire.

[0081] FIG. 5a shows an embodiment of a trim component 40 according to the present invention. For clarity, the associated road vehicle is not shown in this figure. However, the relative position of the trim component with respect to the associated road vehicle is clear based on FIGS. 2 to 4. The trim component 40 according to the present invention shown in FIG. 5a has a preferred wedge shape. It also includes a wedge-shaped sound-absorbing object 41. The base 42 of the wedge includes a surface facing the tread. The trim component further includes a plastic plate 43. The plastic plate 43 covers the upper surface of the sound-absorbing object and is materially bonded (e.g., glued) to this upper surface. A fixing clip 44 is provided on the plastic plate 43 for mounting the trim component 40 on the associated road vehicle.

[0082] Figure 5b shows another embodiment of a trim component 45 according to the present invention. Again, for clarity, the associated road vehicle is not shown in this figure. The trim component 45 according to the present invention shown in Figure 5b has a truncated wedge shape and includes a sound-absorbing body partially enclosed within a plastic shell 46 that covers all surfaces of the sound-absorbing body except for a surface 47 facing the tread. In Figure 5b, the only visible portion of the sound-absorbing body is the surface 47 facing the tread. All other surfaces of the sound-absorbing body are covered by the plastic shell 46. Furthermore, rails 49 are provided along the longitudinal edges of an upper surface 48 of the plastic shell 46 for installation on a road vehicle according to the present invention.

[0083] Figure 5c shows another embodiment of a trim component 50 according to the invention. Again, for clarity, the associated vehicle is not shown in this figure. The trim component 50 according to the invention shown in Figure 5c has the shape of a truncated semi-cone and includes a sound-absorbing body 51 having the same shape. The base 52 of the sound-absorbing body is the surface facing the tread and has a semi-circular shape. The trim component 50 also includes a plastic plate 53 covering the upper surface of the sound-absorbing body 51 and materially bonded (e.g. glued) to this upper surface, as well as a bracket 54 for mounting the trim component 50 on a road vehicle according to the invention by means of screws.

[0084] Figures 6a to 6e each show a planar cross section of a sound absorbing object according to the invention. In all cases, the shape of the sound absorbing object is the same as that of the wedge-shaped sound absorbing object 41 according to the invention shown in Figure 5a, and the cross section is taken along a plane normal to the transverse direction, indicated by the dashed line AA' in Figure 1.

[0085] The sound-absorbing object 60 according to the invention shown in Figure 6a consists of an object 61 made of a first porous fibrous material. The base 62 of the wedge-shaped sound-absorbing object 60 is the surface facing the tread. The material arrangement shown in Figure 6a corresponds to the first embodiment of the sound-absorbing object according to the invention. An alternative embodiment is one in which the object 61 consists of an open-cell foam instead of a porous fibrous material.

[0086] The sound absorbing object 63 according to the invention shown in Figure 6b consists of an object 61 made of a first porous fibrous material, which is partially covered with a layer 64 made of a second porous fibrous material. Layer 64 covers all sides of object 61 except for the top surface 66. In particular, the second porous fibrous material covers the tread-facing surface 65. The thickness of layer 64 is significantly smaller than the dimensions of sound absorbing object 63 and object 61. The material arrangement shown in Figure 6b corresponds to the second embodiment of the sound absorbing object according to the invention. In this case too, further embodiments can be obtained by providing an open-cell foam instead of the first and / or second porous fibrous material.

[0087] The sound-absorbing object 67 according to the invention shown in Figure 6c differs from that shown in Figure 6b in that an air-permeable foil 68 is inserted between the object 61 made of a first porous fibrous material and the layer 64 made of a second porous fibrous material. The material arrangement shown in Figure 6c corresponds to the third embodiment of the sound-absorbing object according to the invention. Further embodiments are obtained by providing an open-cell foam instead of the first and / or second porous fibrous material and / or by providing a thin air-permeable nonwoven, known in the art as a "scrim", instead of the air-permeable film.

[0088] The sound absorbing object 68 according to the invention shown in Figure 6d consists of a closed shell formed by a layer 69 of a second porous fibrous material enclosing an air cavity 70. The material arrangement shown in Figure 6d corresponds to the fourth embodiment of the sound absorbing object according to the invention. Also in this case, alternative embodiments can be obtained by providing an open-cell foam instead of the second porous fibrous material.

[0089] The sound absorbing object 71 according to the invention shown in Figure 6e consists of a sound absorbing object 61 made of a first porous fibrous material that is partially covered with an air-permeable film 67. In particular, the surface 71 facing the tread is covered with the air-permeable film 67. The material arrangement shown in Figure 6e corresponds to the above-mentioned fifth embodiment of the sound absorbing object according to the invention. Also in this case, further embodiments can be obtained by providing an open-cell foam instead of the first porous fibrous material and / or by providing a scrim instead of the air-permeable film.

[0090] To evaluate the effect of the invention proposed here, acoustic tests were carried out on a European F-segment road vehicle (hereinafter simply referred to as the "test vehicle") in three different configurations. The first configuration (hereinafter referred to as "Configuration 1") corresponds to the serial state of the test vehicle, where the test vehicle is equipped with a plastic underbody shield that does not have sound-absorbing properties. The second configuration (hereinafter referred to as "Configuration 2") is obtained from Configuration 1 by providing, instead of the serial plastic underbody shield, a sound-absorbing underbody of the prior art realized by a porous fibrous material layer. The layer has a thickness of approximately 4 mm and a weight of approximately 1200 g / m 2 The porous fibrous material is made of PET / CoPET bicomponent endless filaments with a fineness of approximately 7 denier. The total area of ​​the underbody shield is approximately 3 m 2 is.

[0091] A third embodiment (hereinafter referred to as "embodiment 3") was obtained from embodiment 1 by adding four trim components according to the present invention in the same manner as shown in Figure 2. All four components were installed on the right side of the vehicle in the direction of travel. All trim components according to the present invention included wedge-shaped sound-absorbing bodies based on the material arrangement described above for the second embodiment. More specifically, each sound-absorbing body according to the present invention consisted of a body made of a first porous fibrous material completely covered with a layer made of a second porous fibrous material. The first porous fibrous material had a resistance of approximately 30 kg / m 3 The second layer of porous fibrous material was made of PET staple fibers having a density of about 1200 g / m², a length of about 50 mm, and a fineness of 0.5 to 2 denier. 2 The second porous fibrous material consisted of bicomponent PET / CoPET endless filaments with a fineness of approximately 7 denier. All four sound-absorbing objects featured flat, transversely oriented tread-facing surfaces with a slope of -30 to -20 degrees on the tread-facing surface partially located within the front sound-radiating horn and a slope of +20 to +30 degrees on the tread-facing surface partially located within the rear sound-radiating horn. All trim components had longitudinal dimensions of approximately 300 mm, lateral dimensions of approximately 220 mm, and vertical dimensions of approximately 70 mm, and were secured to the test vehicle by clips. The total weight of the four trim components according to the present invention was approximately 1.2 kg. For each trim component according to the invention, the distance between the tread-facing surface and the tire tread it faced was between 70 mm and 100 mm.

[0092] To evaluate the effect of the trim component of the present invention on exterior noise, the exterior acoustic transfer function (EATF) was measured for all three configurations as follows. As shown in Figure 7, 15 microphones were positioned along a line parallel to the longitudinal axis of the test vehicle, 7.5 m from this same axis on the right side of the vehicle in the direction of travel. All microphones were positioned 1.2 m above the ground. These geometric dimensions correspond to the requirements of the test procedure under ECE 51.03. Four acoustic volume velocity sound sources were positioned at points corresponding to the leading and trailing edges of the contact patches of the front and rear tires on the right side of the test vehicle. Figure 8 shows two sound source positions 80 and 81 for the rear tire 22, as well as two positions for the front tire. For each of the four sound source positions and 15 microphones, the transfer function between the source acoustic volume velocity and the microphone sound pressure was measured. A total of 60 transfer functions were measured. The exterior acoustic transfer function is then obtained as the energy average of these 60 transfer functions.

[0093] FIG. 9 compares the EATF obtained for the three configurations over the frequency range of 400 Hz to 2000 Hz. As can be seen, for a serial car ("Configuration 1," solid line), the EATF reduction (i.e., improvement) obtained by a trim component according to the present invention ("Configuration 3," dashed line) is comparable to that obtained by a prior art sound-absorbing underbody shield ("Configuration 2," dash-dot line), which is on the order of 1 dB. This is particularly true over the frequency range of 800 Hz to 1600 Hz, which is the most critical frequency range for external tire noise. However, such comparable performance is obtained with significant savings in material and weight.

[0094] To evaluate the effect of the trim component of the present invention on interior noise, the interior acoustic transfer function (IATF) was measured for all three configurations as follows: One microphone was placed corresponding to the center of the passenger's head. Acoustic volume velocity sound sources were placed at the same four locations used for evaluating the EATF. For each source location, the transfer function between the acoustic volume velocity of the sound source and the sound pressure at the microphone was measured. A total of four transfer functions were measured. The IATF was obtained as the energy average of these four transfer functions.

[0095] 10 compares the IATFs obtained for the three configurations for the frequency range 400 Hz to 5200 Hz. As can be seen, for a serial vehicle ("Configuration 1", solid line), the IATF reduction (i.e., improvement) obtained with a trim component according to the present invention ("Configuration 3", dashed line) is significantly higher than that obtained with a prior art sound-absorbing underbody shield ("Configuration 2", dash-dot line), despite the significant savings in material and weight.

Claims

1. 1. A vehicle for moving on a road and having tires, each tire having a tread formed by an outer surface of said tire in regular contact with a road along which the vehicle moves, said tread forming, together with said road, front and rear acoustic radiating horns, and further having trim components for reducing noise radiated by said tires, 1. A vehicle, wherein the trim component includes an essentially three-dimensional sound-absorbing object, the sound-absorbing object having a maximum dimension of less than 800 mm and an aspect ratio of less than 10, at least a portion of a surface of the sound-absorbing object facing toward the tread of the tire, and the at least a portion of the surface of the sound-absorbing object being at least partially located within an acoustic radiation horn on either the front or rear side of the tire.

2. 2. The vehicle of claim 1, wherein the trim component is attached to or integrated into a longitudinal rocker, or the trim component is attached to or integrated into a bumper of the vehicle.

3. 3. The vehicle according to claim 1, wherein the minimum distance between the at least one portion of the surface of the sound absorbing object and the tread of the tire facing the at least one portion of the surface of the sound absorbing object is between 20 mm and 150 mm, preferably between 30 mm and 100 mm, more preferably between 40 mm and 70 mm.

4. A vehicle according to any one of claims 1 to 3, characterised in that the minimum distance between the trim component and the road is between 20 mm and 150 mm, preferably between 40 mm and 100 mm, more preferably between 50 mm and 80 mm.

5. 5. The vehicle of claim 1, wherein the trim component further comprises a plastic shell at least partially covering the sound absorbing object.

6. 6. An automotive trim component for use in a vehicle according to any one of claims 1 to 5 to reduce noise radiated by tyres of said vehicle, comprising:

1. A trim component for an automobile, comprising an essentially three-dimensional sound absorbing object having a dimension of less than 800 mm and an aspect ratio of less than 10, wherein at least a portion of a surface of the sound absorbing object is at least partially disposed within a front or rear noise acoustic radiating horn of the tire such that at least a portion of a surface of the sound absorbing object faces a tire tread when mounted on the vehicle.

7. 7. The automotive trim component of claim 6, wherein the trim component has the shape of a wedge, a half cylinder, a half cone, a half truncated cone, or a tapered polyhedron.

8. 8. A trim component for an automobile according to claim 6 or 7, characterized in that the lateral dimension of said at least part of the surface of the sound absorbing object is at least 120 mm, preferably at least 180 mm, more preferably at least 220 mm.

9. 9. An automotive trim component according to claim 6, wherein the at least part of the surface of the sound-absorbing object has the shape of a circular arc of a cylinder or is flat and oriented laterally at an inclination of between +60 degrees and -60 degrees.

10. 10. A motor vehicle trim component according to any one of claims 6 to 9, characterized in that the sound absorbing object comprises an object made of a first sound absorbing material.

11. 10. An automotive trim component according to any one of claims 6 to 9, characterized in that the sound-absorbing object comprises an object made of a first sound-absorbing material at least partially covered with a layer made of a second sound-absorbing material.

12. 10. An automotive trim component according to any one of claims 6 to 9, characterized in that the sound absorbing object comprises an object of a first sound absorbing material at least partially covered with an air permeable foil or scrim.

13. 13. The automotive trim component of claim 12, wherein the object of first sound-absorbing material, at least partially covered with an air-permeable foil or scrim, is at least partially covered with a layer of second sound-absorbing material.

14. 10. A trim component for an automobile according to any one of claims 6 to 9, characterized in that the sound-absorbing object comprises a closed shell made of sound-absorbing material.

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