Particle Acoustic Damper Pouch

Abstract

1. A particle acoustic damper for locally damping vibrations of and reducing noise radiated by a vehicle panel, comprising a pouch sealed to provide an enclosure and loose particles forming a filler within the enclosure, wherein the pouch comprises at least one layer of a spunbond fibrous web.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present invention relates to particle acoustic dampers, methods of making such dampers, and automotive trim components having particle acoustic dampers. [Background technology]

[0002] Vehicle noise has many sources, including powertrain, driveline, tires (road generated), brakes, and wind, among others. Powertrain and tire generated noise in particular can encompass a fairly wide frequency range, which can range from 100 Hz to 10 kHz for conventional diesel and gasoline vehicles, as well as vehicles with electric drives.

[0003] Generally, low-frequency noise can be considered to cover the frequency range from 100 Hz to 600 Hz. It is dominated by so-called "structure-borne" noise. Here, vibrations are transmitted by a source (e.g., the powertrain or tires) via various structural paths to panels around the passenger compartment, which then radiate the noise into the passenger compartment itself. Meanwhile, medium- and high-frequency noise can be considered to cover the frequency range from 600 Hz to 10 kHz. It is dominated by "air-borne noise". In this case, vibrations are transmitted by a source (e.g., the powertrain or tires) via acoustic waves to panels around the passenger compartment, which then radiate the noise into the passenger compartment itself. For passenger comfort, it is necessary that a sufficiently low interior noise level is ensured at both low and medium- and high-frequency frequencies.

[0004] For attenuation of gas-borne high frequency noise within a vehicle, the use of noise attenuating trim components such as dash inner systems or floor carpet systems is known.

[0005] Generally, noise attenuating trim components can effectively reduce mid- and high-frequency airborne radio wave noise due to their acoustic insulation and / or absorption properties. Acoustic insulation relates to the ability of a component to reflect the acoustic energy radiated by and impinging on it from a source, while acoustic absorption relates to the ability of a component to disperse the acoustic energy radiated by and impinging on it from a source.

[0006]

[0007] The acoustic insulation and absorption properties of a noise-damping trim part generally come from the materials contained therein and from their arrangement within the part itself. In particular, to obtain good insulation and / or absorption of mid- and high-frequency frequencies, the part may advantageously have a layer of material that is low-density porous and arranged on the side of the part that faces the vehicle body. This layer is placed in contact with the vehicle body when the part is introduced into the vehicle. This layer may consist of a low-density, fibrous material or a foam member. Additional layers may be necessary to obtain the desired noise attenuation in the mid- and high-frequency range. However, current noise-damping trim parts generally cannot effectively block low-frequency structure-borne noise.

[0008] For this reason, traditionally, damping pads with polymeric viscoelastic materials (e.g., asphalt-based materials) are used to block low-frequency structure-borne noise. These damping pads are laminated to the vehicle body. They are generally very effective at reducing low-frequency structure-borne noise due to their vibration damping properties.

[0009] Vibration damping relates to the ability of a component to reduce vibrations in the structure to which it is applied (eg, the body-in-white that forms the vehicle).

[0010] However, viscoelastic damping pads provide very poor noise isolation in the mid-to-high frequency range, and therefore, currently, it is generally necessary to combine two different types of components, a noise-damping trim component for mid-to-high frequencies and a vibration-damping pad for low frequencies, to achieve sufficient noise isolation over the entire frequency range.

[0011] This adds complexity and cost to the vehicle assembly process. In particular, the damping pads for damping the vibrations of the vehicle body must be laminated to it, i.e., they must adhere very strongly to the vehicle body. For this reason, the damping pads are generally first manually placed on the vehicle body along the vehicle assembly line and then cured under heat and laminated to the vehicle body. Alternatively, the damping material may be sprayed directly onto the vehicle body in predefined areas. Both of these processes are complex, time-consuming, and require significant investments, thus increasing the complexity of the vehicle assembly process and the production costs of the vehicle. Furthermore, they slow down the vehicle assembly process. On the other hand, noise-damping trim parts can be introduced into the vehicle in an easy manner by simply placing them on the vehicle body along the assembly line.

[0012] Furthermore, materials commonly used in the manufacture of vibration damping pads may present performance issues with respect to their application in the automotive industry. To reduce vehicle body vibration, damping pads (or spread damping materials) used in the automotive industry generally rely on the viscoelastic properties of the materials they comprise (e.g., asphalt-based materials), which can be very sensitive to temperature. As a result, damping pads can only function well over a narrow frequency range. However, vehicle body temperatures vary over a very wide range, from below -30°C to above +80°C. Furthermore, traditional damping materials, such as asphalt-based materials, tend to age, become brittle, and lose damping properties during the lifetime of the vehicle.

[0013]

[0014] Particle impact dampers known in the art employ particles made of granular material enclosed in cavities that can become part of existing structures or be incorporated into impact-sensitive equipment. They are used to reduce vibration stresses and associated material fatigue. Versions of this type of particle impact damper are installed, for example, in building columns in earthquake areas or in computer motherboards. This type of particle impact damper has been disclosed as a filled cavity in a rigid plate structure or as a filled rigid container, for example a metal can.

[0015] It is not excluded that these solutions could also be used to attenuate vehicle noise, but they are very large and very heavy and therefore cannot be easily integrated into vehicles.

[0016] Vibration hot spots occur on the main vehicle flooring panels, underneath the flooring trim system, on the firewall panels behind the interior dash trim components, or underneath the trunk coverage, which disrupt the balanced noise management built into the vehicle, where this balanced noise management is maintained by soft trim components that have noise absorbing and / or blocking properties. The available space is limited by the thickness of the components, and installing in a rigid enclosure can reduce the overall properties of these components. The option of using plates with cavities filled with particles would increase the weight of the vehicle as well as the space required, and is not a worthwhile proposition. Furthermore, using a rigid plate or enclosure can disrupt other properties required for the soft trim components used. For example, the step-over properties when entering the vehicle can be solved by a rigid enclosure or plate.

[0017] Attempts to create particle acoustic dampers with other structures have failed due to damage to the container and / or leakage of very fine particles, which not only destroyed the damping function but also caused contamination of the surrounding area.

[0018] It is therefore an object to provide a particle acoustic damper that can overcome the problems of known conventional systems, in particular that can reduce vibrations in localized hot spots in vehicles, and that can be used alone or integrated into trim components.

[0019] 1. A particle acoustic damper for locally damping vibrations of and reducing noise radiated by a vehicle panel, comprising a pouch sealed to provide an enclosure and loose particles forming a filler within said enclosure, wherein said pouch comprises at least one layer of a spunbond polyolefin fiber web.

[0020] Surprisingly, the pouch-shaped particle acoustic damper made of a spunbond fiber web allows for good conformance with the adjacent surface on which it is placed, thereby transmitting the vibration energy of the adjacent surface to the loose particles, while maintaining the particles sealed and being strong enough to withstand compression forces and abrasion.

[0021] Enclosure is defined as the closed space surrounded by the pouch material. Pouch may be defined as a bag or a soft pouch.

[0022] Preferably, the pouch is formed of a single layer of fibrous web material that is folded on itself and bonded around the edges to form a closed flange. Alternatively, the pouch can be formed of two layers of fibrous web material, whereby at least one layer is covered to form a cavity containing the filler and a second layer is layered on top and laminated or bonded to the other layer over the contact area.

[0023] Preferably, the loose particles are not in contact with the adhesive used or are away from the area of ​​the fibrous web that is to be bonded. Before or after closing the pouches, the pouches may be separated from the main fibrous web stock by cutting or punching. The shape from which the pouches are cut may be a basic shape such as a circle, an oval, or a shape with at least three corners, preferably a shape with three to eight corners. Angular shapes such as hexagons and honeycomb shapes have the advantage of reducing waste, while round and oval shapes are suitable for keeping the shape of the pouch in three dimensions, like a cushion.

[0024] The fibrous web material is simultaneously water repellent and waterproof so that water cannot penetrate and interfere with the loose particles, and at the same time, the pouch is flexible enough to conform to adjacent surfaces, ensuring optimal contact for the loose particles within the pouch to transmit vibrations of the adjacent surfaces, thereby dampening vibration noise.

[0025]

[0026] Preferably, the polyolefin fibrous web is formed of polyethylene, preferably high density polyethylene (HDPE), more preferably a flash-spun plexifilament HDPE fibrous web.

[0027] The term "plexifilamentary" as used herein refers to a three-dimensional, integral network or web of numerous thin, ribbon-like film fibril elements of random length. Typically, they have an average film thickness of less than about 4 micrometers and a median fibril width of less than about 25 micrometers. The average film fibril cross-sectional area, when mathematically converted to a circular area, results in an effective diameter of about 1 micrometer to about 25 micrometers. In a plexifilamentary structure, the film fibril elements intermittently bond and separate at irregular intervals at various locations throughout the length, width, and thickness of the structure to form a continuous three-dimensional network.

[0028] Nonwoven sheets made from plexifilamentary strands of polyethylene film fibrils are known. U.S. Patent No. 3,081,519 to Blades et al. discloses flash spinning of plexifilamentary strands of polyethylene film fibrils. U.S. Patent No. 3,169,899 to Steuber discloses depositing such strands on a moving receiver to form a nonwoven sheet. A method for assembling strands deposited from multiple locations is disclosed by U.S. Patent No. 3,402,227 to Knee. An improved method for depositing flash spun plexifilamentary strands and forming them into a sheet is disclosed by U.S. Patent No. 3,497,918 to Pollock et al. Adhesive sheets are disclosed by U.S. Patent No. 3,532,589 to David.

[0029] An example of a flash spun polyethylene plexifilamentary fiber web according to the present invention may be a commercially available sheet material sold as TYVEK™ spunbond olefin sheet material by EI du Pont de Nemours and Company ("DuPont") of Wilmington, Delaware. TYVEK sheet is made from flash spun polyethylene that is thermally bonded to form a lightweight sheet and is the preferred solution. TYVEK™ sheet material is made from high density polyethylene. TYVEK™ sheet as commonly available commercially has an appearance and consistency more similar to paper than cloth.

[0030]

[0031] As vehicles can be subject to large temperature changes, such as being left in the cold while operating with the heater on, or being left in full sunlight, the air trapped within the sealed material enclosure will contract or expand depending on the temperature or air pressure. Expansion in particular can cause the seals to break down, allowing particles to spill out and ultimately resulting in a loss of damping effect. Conversely, contraction of the air can impede particle movement due to the reduced space within the enclosure.

[0032] Surprisingly, it has been found that the spunbond fiber web according to the invention, preferably the HDPE spunbond fiber web, is not only able to balance the pressure due to its breathable material properties, but also that the material can take in air and return to its original shape, ensuring sufficient space to fully utilize the benefits of the particles as damping material. Moreover, the material is also flexible, so that it can adapt to small irregularities in the surface of the vehicle floor and transmit the vibrations of the floor to the loose particles.

[0033] Although the material is breathable, the microscopic perforations within the fibrous material are not only small enough to prevent particles from escaping, but the material is strong enough to prevent the escape of particles initially loaded into the fibrous material. Comparable standard nonwoven materials may initially be closed enough to retain the majority of the particles, but over time, particle loading can cause small holes in the structure.

[0034] Preferably, the fibrous web has a fiber density of 30 to 250 g / m 2 , preferably 40 to 200 g / m 2 The surface area weight may be

[0035] The thickness of the fibrous web is preferably 10 μm to 1 mm, preferably 40 μm to 500 μm, most preferably 50 μm to 200 μm. Due to the manufacturing process of the spunbond fibrous web, the thickness may vary substantially within the given range.

[0036]

[0037] The spunbond material may be partially or dot-bonded or fully bonded, preferably fully bonded materials are used to prevent delamination of the web or clogging or retention of particles within the fibrous web structure.

[0038] Surprisingly, the acoustic particle damper pouch made of the spunbond fiber web according to the invention can be compressed but returns to its original shape. This can be used to the advantage of the particle acoustic damper pouch. By forming at least one side of the pouch into a bowl-like shape during manufacture, a more effective three-dimensional enclosure can be created for the free flow of particles during vibration damping. Preferably, both sides are bowl-shaped, expanding the three-dimensional space within the pouch. Preferably, the shape is a circular or elliptical sphere, or a pyramidal sphere. All types of particle acoustic damper shapes are feasible, but at least one area of ​​the outer surface must be able to form a surface contact with the surface adjacent to the material to be damped. The combination of the fiber web pouch and the heavy loose particle filler ensures a well-operating particle acoustic damper. Preferably, the surface that contacts the damping surface is at least partially under the bag, so that gravity can improve the overall contact.

[0039] <Particle filler> For good noise attenuation, preferably at least 1500 kg / m 3 Loose particles having a material density of

[0040] The loose particles are preferably made from a material having a high material density, preferably at least 1500 kg / m 3 , preferably 3000 kg / m 3 That's it. The material may be at least one of a metal, preferably steel, zinc, nickel, or iron, or an alloy, or a mixture of high density materials. The material used may be treated to prevent degradation during use in the pouch as a particle acoustic damper.

[0041] The particles need to be free-standing (loose) within the pouch or enclosure. Preferably, the loose particles are in the form of powder, metal spheres or irregular metal clusters or nuggets. The particles may have random shapes and sizes within an average size range. Irregular shapes and sizes may improve the overall noise reduction and frequency bandwidth.

[0042]

[0043] In the noise-damping trim part of the present invention, vibration damping effect at low frequencies, e.g., 100 Hz to 600 Hz, can be achieved by transmitting the vibration energy of the vehicle body to the loose particles in the pouch, where the energy is dissipated by friction or inelastic collision.

[0044] The frequency range in which the loose particles within the pouch are most effective at dissipating vibrational energy through friction or inelastic collisions may be tailored by appropriately selecting the statistical distribution of particle sizes.

[0045] The term "particle size", when referring to individual particles, is defined as the area-equivalent circular diameter measured according to the current ISO 13322-2. Particles within one pouch may have different particle sizes. From the particle sizes of the individual particles measured according to the current ISO 13322-2, the statistical distribution of particle sizes of the particles within the pouch may be inferred, for example, as indicated in the current edition of ISO 9672-2.

[0046] Hereinafter, the term "particle size" refers to the median D of the statistical distribution of particle sizes in the pouch when referring to the aggregate of particles in the pouch. 50 This is understood to refer to the following.

[0047] Additionally, the term "particle size distribution width" or "distribution width" when referring to the collection of particles within a pouch is D 10 is the 10% size calculated from the particle size statistical distribution, D 90 is the 90% size, S=(D 90 -D 10 ) / D50 The particle size distribution width is an evaluation criterion that indicates how much the particle size statistical distribution is dispersed around the median value D50.

[0048]

[0049] Preferably, the particles in the pouch have a median particle size of 50 μm to 1250 μm, preferably 150 μm to 1000 μm, preferably 200 μm to 700 μm.

[0050] Preferably, the particles within the pouch have a particle size distribution of 2.5 or less, preferably 1.5 or less, preferably 1 or less.

[0051]

[0052] An automotive trim part having an integrated particle acoustic damper may have more than one pouch.

[0053] In different regions of a vehicle panel, such as a floor panel, the frequency content of the vibrations may be different: some regions may vibrate primarily at low frequencies, e.g., below 250 Hz, while other regions may vibrate primarily at high frequencies, e.g., 250 Hz, in some regions the vibrations may be broader and in other regions may be more concentrated in a limited frequency range.

[0054]

[0055] Surprisingly, the acoustic particle damping pouch is particularly effective at damping vibrations in areas of contact where this vibration exhibits very high levels (e.g., peaks) at high frequencies, especially when these peaks are in the low and mid frequency ranges up to 900 Hz. Hot spots with high levels of vibration (peaks) at certain unpleasant frequencies can therefore be reduced by placing a pouch in the present invention at the vibration spot.

[0056] In a preferred embodiment, a sheet having multiple individual pouches, each filled with loose particles, can be used to attenuate a relatively large area over a relatively wide frequency range.

[0057]

[0058] Preferably, the total weight of the particles in one pouch is from 5 g to 100 g, preferably from 8 g to 70 g, and more preferably from 10 g to 60 g.

[0059] Surprisingly, even with a small weight per pouch, the low frequency solid-borne vibrations of the vehicle body can be effectively reduced. Even more surprisingly, a conventional damping pad attached to a vehicle panel, weighing the same as the acoustic particle damper pouch according to the present invention, has a lower noise reduction effect than the particle damper pouch. In a comparison of three particle damper pouches of 50 g each or three conventional asphalt damper patches of 50 g each placed in the same three locations, the pouches showed a noise reduction of 2 db compared to a noise reduction of 1.2 db for the conventional damper, an increase of 0.8 db noise reduction over the conventional damper. Thus, the particle damper can replace the conventional damper with reduced weight. Furthermore, the acoustic particle damper pouch according to the present invention is easy to recycle, since the spunbond fiber web and the particles can be separated and both materials can be reused or recycled again.

[0060]

[0061] To further reduce the volume of the pouch and increase the damping performance, particles with a high material density are preferably used, preferably at least 1500 kg / m 3 More preferably, 3000kg / m 3 That's all.

[0062]

[0063] The particle acoustic damper according to the invention is most effective when installed on a horizontal surface or on an inclined surface up to 90° vertical. Preferably, the shape of the pouch is adapted to the gradient of the contact surface and its shape to optimize the surface in contact with the vibrating surface on one side and with at least a portion of the loose particles on the other side.

[0064]

[0065] Preferably, the pouch is closed, sealed and / or laminated with an adhesive, preferably an adhesive that preserves the flexibility of the laminated edges. Preferably, a heat or pressure activated adhesive is used, preferably an adhesive based on acrylamide, polyurethane, acrylate, epoxy, polyamide, ethylene vinyl acetate or branched polyethylene. More preferably, an adhesive based on polyurethane or polyamide is used.

[0066] The adhesive may be provided as a coating on the fibrous web and activated during formation of the pouch, or may be applied during manufacture of the pouch, for example, a heat or pressure sensitive adhesive film layer may be used.

[0067]

[0068] The manufacture of the pouches can be carried out in a two-stage process, whereby in a first stage a first layer of the fibrous web according to the invention is laid (draped) on a tray having one or more cavities and laid on the walls of each cavity, whereby the fibrous web is formed, optionally thermally. A predefined weight or volume of loose particles is filled into each cavity on the first fibrous web. A second fibrous web is used to cover the filled cavities. The two fibrous webs are laminated together along the edges of the cavities to form an enclosure filled with particles. During or after lamination, the pouches can be separated by a cutting blade or punch to create the damping pouches.

[0069] The material can be cut into various shapes to optimize the final surface that comes into contact with the vibrating plate. Alternatively, the pouch can be manufactured by folding the fibrous web into a pouch and laminating the contact surface while leaving open the area to be sealed for filling. The pouch is finally closed by filling and sealing the open area.

[0070]

[0071] Alternatively, the pouches can be integrated into large strips or sheets and the placement of the damping pouches optimized into a mold to create an automotive trim part with the damping pouches integrated into predefined areas.

[0072]

[0073] For example, a single pouch, preferably a strip with multiple spaced pouches, or a sheet having multiple pouches randomly or purposefully positioned on the surface of the sheet, may be placed in a mold and combined with either a foam or felt layer, preferably an injected foam layer, and laminated or materially connected to at least one surface of an adjacent layer.

[0074]

[0075] The dampening pouches may be placed or glued to vibration hot spots inside and outside the vehicle, such as around the engine or gear, on or inside the battery box, inside or outside the dash area, on the floor, inside the trunk, or in the headliner. Because the pouches are so small, they may be installed directly into new trim pieces or added later as a stand-alone solution to reduce unexpected vibration hot spots.

[0076]

[0077] Alternatively, the pouch may be mechanically or physically connected to the automotive trim part so that at least one surface is in contact with the vibrating vehicle panel surface, preferably a vibration hot spot.

[0078] Preferably, only a small area of ​​the pouch is suspended and attached to the trim portion, allowing the pouch to lie freely on the vibrating surface, with gravity on the particle encouraging contact between the pouch and the surface.

[0079] In one embodiment, the pouch has a pyramidal (FIG. 1E) or similar shape whereby the tip of the pyramid becomes integral with the surrounding material and may be pinched to hold the tip of the pyramid, for example, by mold foaming. The tip may be bent and hooked onto the foam member to act as a hanging hook for the pouch.

[0080]

[0081] Preferably, the noise attenuating trim component according to the present invention comprises multiple acoustic particle damper pouches. The number of particle acoustic damper pouches is defined based on the desired damping performance and weight, space and cost constraints. Increasing the number of particle acoustic dampers improves performance but increases weight, cost and manufacturing process complexity.

[0082] Preferably, a trim component according to the present invention may comprise up to 30 particle acoustic damper pouches, preferably between 4 and 30 particle acoustic damper pouches, more preferably between 8 and 20 particle acoustic damper pouches.

[0083] Surprisingly, with the particle acoustic dampers having a filling weight of less than 100g each, much less weight is overall required to achieve a satisfactory damping effect compared to conventional dampers used to damp the same surface, resulting in a reduction in the weight of the car and thereby a reduction in the car's energy consumption.

[0084]

[0085] By integrating the particle acoustic damper into the trim part, its position can be predefined and the correct position of the particle acoustic damper is guaranteed when the trim part is installed. The particle acoustic damper is preferably placed in the places where the vehicle body vibrates the most, so-called "vibration hot spots". Such vibration hot spots can be identified by experimental and / or simulation techniques well known in the art. A vehicle body panel may have several vibration hot spots, which are associated with different frequency ranges. The mass of the loose particles in a single particle acoustic damper may be adapted to the intensity of the vibration.

[0086] Noise-damping trim components according to the present invention are preferably mounted to a primarily horizontal vehicle body panel (e.g., a vehicle floor), but may also function mounted to vehicle body panels in other orientations (e.g., an automobile dash panel), or with the component mounted to the vehicle such that loose particles in the container are at least partially in contact with the fibrous web in areas where the fibrous web contacts the vibrating surface of the vehicle body under its gravitational load.

[0087] The particle acoustic dampers incorporated in a noise attenuating trim component according to the present invention may all have the same characteristics of size, shape, particle type and content, or they may differ when installed in a vehicle to accommodate the vibrations of the vehicle body panel and the shape of the vehicle body and / or trim component in which the component is addressed.

[0088]

[0089] In the trim component according to the present invention, a particle acoustic damper that is partially filled with loose particles is incorporated into at least one foam or felt layer.

[0090] The foam layer may be made from any type of open cell foam, preferably the layer is made from a polyurethane foam material. 3 ~120kg / m3 , preferably 35 kg / m 3 ~80kg / m 3 , preferably 45 kg / m 3 ~70kg / m 3 The foam member has a density of

[0091] The felt layer may be a fibrous layer having fibers, such as staple fibers and / or filaments, and a thermoplastic binder material.

[0092] A combination of regenerated, recycled, and / or virgin fibers, man-made, inorganic, and / or natural fibers may be used.

[0093] For example, the felt layer has recycled fibers made of at least one material selected from the group consisting of recycled cotton yarn, recycled synthetic fiber yarn, recycled polyester yarn, recycled natural fiber yarn, and a mixed recycled synthetic and natural fiber yarn.

[0094] A type of recycled yarn is defined as containing at least 51% by weight of the target material, with 49% being fibers from other sources. For example, recycled polyester contains at least 51% by weight of polyester-based fibers. Alternatively, the recycled material may be a mixture of different synthetic and natural fibers and is not limited to one type.

[0095] Preferably, the fibers or filaments are made from at least one material selected from the group consisting of polyamides (nylons), such as polyamide 6 or polyamide 66, polyesters, such as copolymers of polyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT) or polytrimethylene terephthalate (PTT), polyolefins, such as polypropylene, and polystyrenes, such as copolymers of polyethylene and mineral fibers, preferably glass fibers, recycled glass fibers, basalt fibers, carbon fibers.

[0096] Preferably, the felt layer comprises self-crimping fibers, preferably hollow self-crimping fibers.

[0097] The felt layer may comprise a thermosetting binder, such as a binder based on a phenolic resin or an epoxy resin, or a thermoplastic binder having at least one material selected from the group consisting of polyesters, such as polyethylene terephthalate (PET), copolymers of polyesters, polyolefins, such as polypropylene or polyethylene, polylactic acid (PLA), and polyamides, such as polyamide 6 or polyamide 66.

[0098] Preferably, the binder material is in the form of fibers, flakes, or powder. More preferably, the binder material is one of a monocomponent fiber or a bicomponent fiber.

[0099] The thickness of the foam or felt layer that constitutes the particle acoustic damper is generally not constant and depends mainly on the space restrictions in the vehicle. The thickness can be chosen between 2mm and 100mm, but is often between 5mm and 40mm. The average conventional thickness of the layer as part of the carpet or inner dash is usually between 10mm and 30mm, for example averaging about 20mm.

[0100] Preferably, the area weight of the felt or foam layer in which the particle acoustic dampers are embedded is less than 200 g / m 2 ~2000g / m 2 , preferably 800 g / m 2 ~1600g / m 2 It is.

[0101] The automotive noise-damping trim part according to the invention may have one or more additional layers on the surface opposite to the surface in contact with the diaphragm panel of the vehicle. The additional layer may be at least one other porous layer, preferably a foam or a felt selected from the materials defined above. Additionally or alternatively, the additional layer may be one of a film, a high density material layer known in the industry as an overlay material, a thermoplastic elastomer material with a high filler content, a decorative layer, such as a nonwoven or carpet layer, or any combination of such layers.

[0102] Alternatively, a scrim layer may be placed on the surface of the foam or felt layer that contacts the vibrating vehicle panel. The thickness of such nonwoven or scrim layer should not be so high that the contact surface of the pouch cannot contact the vibrating surface of the vehicle.

[0103] In a preferred embodiment, the trim part according to the invention is a spring mass system, formed by a soft decoupling layer of low density and a closed heavy layer of high density, whereby a particle acoustic damper, partially filled with loose particles, is contained in a foam or felt layer of a decoupler, whereby the decoupler is positioned to contact a vibrating vehicle body panel when the part is installed in the vehicle. Preferably, the mass or weight layer has a mass of 500 g / m 2 ~6500g / m 2 Finally, the trim portion may have further layers on top of the heavy layer, such as a reinforcing layer and / or a carpet layer, such as a nonwoven or tufted carpet. Such parts may be molded and used in the front or rear trunk areas, for example to form inner dash trim parts, outer dash trim parts, and / or passenger compartment floor parts of the automobile.

[0104] Preferably, the heavy layer comprises one thermoplastic material selected from the group consisting of ethylene vinyl acetate (EVA) copolymer, polyester, polyethylene terephthalate, high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, thermoplastic elastomer, thermoplastic rubber, and polyvinyl chloride (PVC), or a combination thereof. Additionally, the heavy layer may comprise up to 85% by weight of an inorganic filler to increase the density of the material.

[0105] In this embodiment, a trim component according to the present invention may include additional layers on top of the overall layers, such as, for example, a covering scrim layer, an acoustic scrim layer, a decorative top layer, a tufted or nonwoven carpet layer, etc.

[0106] In this case, the trim part can attenuate noise based on at least isolation and damping, while also attenuating noise based on sound absorption by including an additional porous layer on top of the heavy layer.

[0107] Another preferred embodiment is a trim part comprising a foam or felt layer with a particle acoustic damper according to the invention, further comprising a foam or felt layer having a higher airflow resistance than the layer with the particle acoustic damper, preferably 500 Ns·m 3 ~4000Ns·m 3 At least one distinct fibrous porous layer may be included on top of the foam or felt layer having a particle acoustic damper comprising:

[0108] Another preferred embodiment has an open cell foam layer containing particle acoustic dampers according to the present invention and further has a resistance of 500 Ns m 3 ~4000Ns·m 3and a second porous fibrous layer that is an airflow resistance of 100 nm and an intermediate film or scrim layer between the two layers. In this embodiment, when the part is introduced into the vehicle, the open cell foam layer with the particle acoustic dampers according to the present invention contacts the vehicle body, while the porous layer faces the passenger compartment. The presence of the intermediate layer or scrim enhances the damping properties of the trim part in the mid-to-high frequency range, while the porous layer on the surface layer always ensures good absorption properties at mid-to-high frequencies.

[0109] All the above embodiments can achieve good noise attenuation, isolation and / or absorption attenuation in the frequency range of 100Hz to 10kHz.

[0110]

[0111] The trim part according to the invention can be manufactured in the following manner, which is known in the prior art.

[0112] For example, the manufacture of a trim component according to the present invention may be carried out according to the steps described below.

[0113] The manufacture of the pouch may be carried out in a two-stage process, in the first stage, a first layer of the fiber web according to the invention is placed on a tray with one or more cavities, and the fiber web may be formed, optionally thermally, by resting on the walls of each cavity. A predefined weight or volume of loose particles is filled into each cavity on the first fiber web. A second fiber web is used to cover the filled cavity. The two fiber webs are sealed together along the edges of the cavity to form a particle-filled enclosure. Between or after lamination, the pouch is separated by a cutting blade or punch to produce a damped pouch. The material may be cut into various shapes to optimize the final surface in contact with the vibrating plate. The pouch may be produced by folding the fiber web into a pouch and laminating the contact surface. Filling and finally sealing the opening to close the pouch. The whole process may be carried out in a continuous process of forming, filling and closing.

[0114] The bonding step can be carried out using techniques well known in the art, such as gluing or heat sealing. The presence of a small flange around the edge of the remaining part of the cavity created in the first step can facilitate the bonding step, however, bonding is possible without this flange.

[0115] In another process, a trim part is produced having a section of its exterior surface which partially faces the vehicle body when the part is installed in the vehicle, and having a felt or foam layer in this section of its exterior surface having a recess shaped to fit the loose particle filled particle acoustic damper produced in the process described above.

[0116] The trim piece may have the recesses already formed during molding of the trim piece, or the recesses may be cut in a separate step before or after molding.

[0117] In an alternative process, the particle acoustic damper is placed in a mold and the trim part containing the particle acoustic damper is directly manufactured using, for example, an in-mold foam process or an injection fiber process.

[0118] To fit the passenger compartment space, the trim parts produced in this fourth step may have complex three-dimensional shapes.

[0119] This step may be carried out by standard manufacturing methods known in the art. For example, the barrier heavy layer may first be shaped by vacuum forming and then back-foamed, the back-foaming tool presenting protrusions that match the shape of the particle acoustic damper. After this, further layers may be added on top of the heavy layer, for example a porous felt or foam layer or a needle punched or tufted carpet.

[0120] Finally, in an additional step, the particle acoustic damper is embedded in the porous layer by inserting it into a recess in an adjacent layer.

[0121] Insertion of the particle acoustic damper into the recess is preferably performed in an automated manner, but can also be performed manually.

[0122] A flange around the edge of the pouch may facilitate the insertion process by preventing the pouch from sinking into adjacent layers, however, the pouch is not required to properly and accurately assemble into the trim piece.

[0123] Preferably, at least on a portion of its outer surface, the pouch is adhered to the adjacent layer in which it is embedded, thereby preventing it from becoming detached from the trim part during the manufacturing process of the trim part or during installation in the vehicle.

[0124] However, it is not necessary to glue the container to the trim piece in order to avoid it falling off from the trim piece, as this effect can also be achieved in other ways, for example by shaping the container in a suitable way (e.g. a barrel-shaped container or a container shaped like an inverted pyramid), by providing the container with some mechanical fastening elements (e.g. thin external projections in the form of barbs or hooks), or by a combination of at least partial gluing and a suitable shape.

[0125] Preferably, the trim part according to the present invention is a noise dampening trim part for a battery lid, enclosure, interior dash, exterior dash, or carpet system, such as a tufted carpet, needle punch carpet, carpet with a flocked surface, or a dilor carpet, where the layer embedding the particle acoustic damper partially filled with loose particles faces the vibrating vehicle body panel when the part is installed in the vehicle.

[0126]

[0127] For example, in a floor system, hot spots are identified during the design phase of the vehicle and pouches are placed in these spots, either alone or as part of the underside of the trim parts associated with these hot spots. The pouches may be attached to these dedicated areas, for example with an adhesive. Alternatively, the pouches may be laminated to the parts during molding of the underlayer or the entire part or during foaming of the underlayer attachment layer. The underlayer in contact with the pouches thereby forms dedicated void areas, preventing the pouches from becoming compressed during use. Preferably, the pouches are integrated into a two-ply fibrous web with filled cavities, so that it is easier and more economical to place the pouches in the right places.

[0128]

[0129] Surprisingly, the bi-layer fibrous web with the loose particle filled enclosure at a predetermined location of the bi-layer web has a beneficial effect on the decoupling function of the adjacent foamed or felt layer, preventing this layer from being stuck or adhering to the vehicle flooring. The spunbond fibrous web is also gas permeable, so that adjacent layers can also exchange air during compression of the layers.

[0130] Further embodiments of the invention can be derived from the description, also by combining different embodiments and examples of the invention, and also from the description of the embodiments shown in the figures, which are schematic and not necessarily to scale.

[0131]

[0132] Preferably, the particle acoustic damper according to the invention is at least partially incorporated into at least one layer of the automotive trim part in such a way that at least one outer surface of the pouch faces and contacts the vibration surface of the automobile, and the surface opposite the contact surface contacts at least a part of the loose particles inside the pouch. Preferably, at least a small part of the pouch may overhang the outside of the automotive trim part. Surprisingly, the vibration damping effect extends over a larger area than the area where the pouch is in contact with the vibration surface. Even small pouches with a filling of 10 g or less already provide a measurable damping effect.

[0133] Surprisingly, the particle acoustic damper according to the present invention can reduce vibrations at vibration hot spots as well as or better than conventional asphalt dampers, which reduces the need for larger damping patches to reduce localized vibration hot spots, while the pouch damper according to the present invention can be placed even in small spaces where conventional dampers are no longer applicable, and retrofitting of single hot spots can also be easier.

[0134] It has been shown that three damping pouches placed in three locations on a textured metal car floor can reduce the low frequency range by up to 2db. Compared to three conventional damping pads of the same weight placed at the same points, this is an increase of about 0.8db, showing that the particle acoustic damper according to the invention is superior to conventional damping materials. It has the advantage of being temperature independent and does not require full contact.

[0135] Furthermore, it has been proven that the acoustic damper pouch according to the present invention can reduce the frequency peaks in the contact range, and therefore the two-layer spunbond fiber web arranged with multiple smaller enclosures, contacted through separate arranged or laminated spunbond fiber web zones, can also act as a replacement for traditional dampers.To obtain the same damping in the low frequency range, less weight is needed, and saving the weight of a single part ultimately reduces the overall CO2 emissions of the car. [Brief description of the drawings]

[0136] 1A-E show several possible embodiments of an attenuation pouch according to the present invention.

[0137] Figures 1A, 1B and 1C show a particle acoustic damper (1) made of a first (7) and a second (6) layer of a fibrous web according to the invention. Figure 1A shows a view from above, the so-called top view, while Figures 1B and 1C show a cross section of the pouch 1. Area 2 indicates the sealed or glued area that closes the pouch and forms an internal enclosure 3 filled with rose particles 4. The lower part of the pouch, here the first layer 7, is preformed by draping to form a cavity for the loose particles. This preformation also forms a cushion-like 3D shape that allows a better contact with the substrate panel 5.

[0138] 1B shows a standalone version of the pouch on a vehicle panel 5. The interface between the pouch and the vehicle panel 5 is defined as the outer surface of the fibrous web 7 that is in contact with the vibration panel of the vehicle 5, and the opposite surface of the fibrous web is in contact with at least a portion of the loose particles, such that the vibration energy of the vehicle panel is transferred to the particles in the pouch and dissipated by the movement of the particles.

[0139] The remaining volume of the pouch that is not filled with particles is filled with air. Due to the ability of the fibrous web to exchange air with the surroundings, the compression of the pouch is decompressed after a period of time and the material surprisingly returns to its original state. Thus, the pouch always maintains a sufficient internal volume for the loose particles to move freely.

[0140]

[0141] Figures 1D and 1D' show alternative shapes to the sealed area shown in 2. In Figure 1D, the material is folded on itself, with 8 indicating the fold line. Figure 1E is an example of a pyramidal pouch, where the tip of the pyramid may be integrated into the adjacent layer to form a connection, where the pouch material is sandwiched in this area to form the remaining volume of the enclosure, but sufficient for the particles to act as a loose particle damper.

Claims

1. 1. A particle acoustic damper for locally damping vibrations of a vehicle panel and reducing noise radiated by said vehicle panel, said particle acoustic damper comprising a pouch sealed to provide an enclosure and loose particles forming a filler within said enclosure, said pouch comprising at least one layer of a spunbond polyolefin fiber web.

2. 2. The particle acoustic damper of claim 1, wherein the spunbond fibrous web is made of a polyolefin, preferably polyethylene, more preferably high density polyethylene, more preferably a flash spun plexifilamentary high density polyethylene fibrous web.

3. 10. The particle acoustic damper of claim 1, wherein the fibrous web is bonded throughout to form a paper-like material.

4. 10. The particle acoustic damper of claim 1, further comprising an adhesive layer to laminate and / or seal the at least one fibrous web at its edges into a closed pouch forming an enclosure for the particles.

5. 5. The particle acoustic damper of claim 4, wherein the adhesive layer is based on at least one of ethylene vinyl acetate, branched polyethylene, acrylate, epoxy, polyamide, and polyurethane.

6. 2. The particle acoustic damper of claim 1, wherein the pouch is formed from two layers of a spunbond polyolefin fiber web, at least one of the layers forming a cavity for at least the volume of the loose particles as filler, and the other layer covering the filled cavity and adhering to a peripheral edge to seal the cavity.

7. 2. A particle acoustic damper according to claim 1, wherein the pouch is formed in a three-dimensional shape having a base that is one of a spherical or pyramidal shape, preferably a circular, oval or a cornered shape having at least three corners, preferably a cornered shape having at least three and up to eight corners.

8. 2. A particle acoustic damper according to claim 1, wherein the loose particles are formed from a high density material, preferably a high density metal, preferably iron, nickel, zinc, steel, or an alloy, or a mixture of high density metals.

9. The particle acoustic damper of claim 1 , wherein the loose particles are formed by mixing particles based on different high density materials.

10. 10. The particle acoustic damper of claim 9, wherein the loose particles are recycled or reclaimed.

11. 2. A particle acoustic damper according to claim 1, wherein the total weight of the particles in one pouch is less than 100 grams, preferably between 5 and 100 grams, preferably between 30 and 70 grams.

12. 11. An automotive noise-damping trim part having at least one foam or felt layer, said layer comprising at least one particle acoustic damper according to any one of claims 1 to 10, wherein the particle acoustic damper pouch has a contact surface that contacts a vibrating surface of the vehicle, a surface opposite the contact surface that contacts at least some of the loose particles, whereby the fibrous web transfers vibration energy from the vibrating surface to the loose particles in the container, and a second outer surface that contacts or is connected to at least one foam or felt layer.

13. 13. An automotive noise-damping trim part according to claim 12, wherein the loose particles have a median particle size of 20 pm to 1250 pm, preferably 250 pm to 1000 pm, preferably 150 pm to 900 pm.

14. 13. The automotive noise-damping trim component of claim 12, comprising at least one layer that is a felt layer, said felt layer having fibers and / or filaments and further having a thermosetting or thermoplastic binder.

15. 13. The automotive noise-damping trim component of claim 12, further comprising one or more additional layers on a side of the foam or felt layer opposite the side that adheres to the vibrating surface of the vehicle.

16. 16. The automotive noise-damping trim component of claim 15, wherein the at least one or more additional layers are at least one of a foam or felt layer, a film layer, a foil layer, a thermoplastic elastomer layer with a pore-filler content, a decorative layer, such as a nonwoven or carpet layer, or any combination of these layers.

17. 17. Use of a noise-damping trim component comprising the particle acoustic damper of any one of claims 12 to 16 as an inner dash, outer dash, battery lid silencer, or battery insulator, as a carpet system comprising at least one of tufted carpet, needle-punched carpet, flocked surface carpet, and die-rolled carpet, or as a trunk trim component or an engine bay trim component, wherein at least one layer of the noise-damping trim component contacts a vibrating vehicle panel when the noise-damping trim component is installed in a vehicle.

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