High-performance acoustic air diffusion duct, especially for motor vehicles

Abstract

High-performance acoustic air diffusion duct, particularly for motor vehicles. The present invention relates to a high-performance acoustic air diffusion duct (C), particularly for motor vehicles, comprising two half-shells (1) (2), characterized in that each of the two half-shells (1) (2) is formed from a sheet of material (M) consisting of at least one airtight thermoplastic wall (5), itself bonded to a non-woven textile layer (4) on at least one of its faces, such that the interior of the duct is lined with the non-woven textile layer (4) on one side; and, furthermore, in that each of the two half-shells (1) (2) is airtight. The invention is advantageously intended to provide air passage, for example, by serving as a ventilation or air supply duct for a motor vehicle. Figure for the abstract: Fig 1

Description

Description Title of the invention: High-performance air diffusion duct high acoustics, particularly for motor vehicles

[0001] — The present invention relates to an air diffusion duct with high performance high acoustics, especially for motor vehicles.

[0002] It is known that the ventilation systems of motor vehicles cause undesirable noise pollution for the occupants of said vehicles.

[0003] It is also known that this acoustic disturbance is related to the group of ven- tilation, particularly to the fan, as well as to the airflow passing through the air diffusion ducts.

[0004] — In order to overcome these drawbacks, several solutions have been introduced in the literature terature.

[0005] As such, it is described in FR2822225 A1, FR2892344 A1 and in EP1403105 A1 solutions aimed at treating airflow within diffusion ducts, with the aim of to reduce noise pollution, for example by installing a duct with the mouth is roughly parallel to the airflow or by means of changes in the cross-section of the air duct cavities. FR2712851 also states That these larger cavity sections can be filled with material expanded.

[0006] — However, these solutions are not entirely satisfactory, particularly due to the geometric complexity of the product resulting from these inventions.

[0007] Also, it is described in JP2007187324 A solution for handling the noise pollution in ventilation ducts by integrating elements acoustic absorption panels positioned perpendicular to the longitudinal direction of the duct. This presents the major drawback of reducing airflow in the ventilation duct.

[0008] — EP1070843 B1 describes a suction duct whose wall is formed at starting from a non-woven fabric to improve the acoustic performance of said suction duct with air-porous walls. This presents an in- major advantage of applying the invention EP1070843B1 to conduits of air diffusion where the airtightness of the walls must be guaranteed for reasons obvious functionalities.

[0009] — Finally, a sound-absorbing hollow body used for is described in WO 2004 / 007108 A2 the air supply in motor vehicles, comprising two layers of po- closed-cell lyolefin, namely a first outer layer and a second inner needle-punched layer, and at least one additional layer located between the The inner and outer layers of this three-layer sandwich assembly are subjected to a blow molding process, as described in document EP 0 445 492 BI, to produce a hollow air duct. The manufacturing process described requires three different raw materials (closed-cell PE, needle-punched PP, and fibers). A process and product requiring fewer different types of raw materials would be preferable. One aim of the present invention is to improve upon known solutions such as those mentioned above. Another objective of the present invention is to provide an air diffusion duct with high acoustic performance and economical implementation. The present invention aims to provide an air diffusion duct in which, without modifying the geometries or orientations of the sections and without degrading the quantity of air traversed by said duct, noise pollution can be significantly reduced with a simple and inexpensive configuration. It relates to this purpose to a high acoustic performance air diffusion duct (C), in particular for motor vehicles, comprising two half-shells (1) (2), characterized in that each of the two half-shells (1) (2) is formed from a sheet of material (M) consisting of at least one layer of non-woven textile (4), itself associated on all of one of its faces with a sealed wall of thermoplastic material (5) on the one hand; and on the other hand, in that each of the two half-shells (1) (2) is airtight. The non-woven textile web (4) used for the invention contains hot-melt fibers whose melting point is lower than that of the rest of the fibers in the web. The textile layer (4) contains 5% to 50%, but not limited to, hot-melt fibers. It is noted here that below 5% hot-melt fibers in the textile layer (4), the rigidity of the product (C) of the invention after its fabrication does not appear suitable for the function of an air diffusion duct for a motor vehicle. Above 50% hot-melt fibers, the resulting air diffusion duct (C) exhibits excessive rigidity, complicating its installation on the vehicle. Furthermore, no particular advantage of the invention has been observed beyond 50% hot-melt fibers in the textile layer (4). Preferably, the non-woven textile mat contains between 20% and 50% hot-melt fibers. According to one embodiment of the invention, the non-woven textile sheet (4) is composed of polyester fibers, at least part of which contains hot-melt fibers. The textile sheet (4) has a surface mass between 350 g / m² and 1200 g / m², and advantageously between 600 g / m² and 1200 g / m². Below With a surface mass of 350 g / m², it was observed that the mechanical properties of said sheet (4), particularly its resistance to elongation, lead to mechanical weaknesses within the air diffusion duct (C) formed. Beyond 1200 g / m², no particular advantage to the invention was observed. The textile mat (4) inherently offers an advantage in the treatment of noise pollution. When a sound wave passes through it, the elasticity of the mat's fibers (4) dampens the wave through vibration mechanisms. In other words, the sound wave is dampened by the fibers of the mat (4). The waterproof thermoplastic material wall (5), associated on one side of the non-woven textile layer (4) is a barrier wall, therefore particularly airtight, watertight and dustproof. Advantageously, but without being limited to it, the thermoplastic sealing wall (5) is a thermoplastic film. According to one embodiment, the thermoplastic film is a two-component film, one of the two components having a lower melting temperature than the other, thus allowing the first to be thermally activated without influencing the second. As a non-limiting example, thermoplastic film is a two-component polyester-polyamide or polyester-polyurethane film. According to one embodiment of the invention, the thermoplastic film used has a thickness of between 15 µm and 200 µm and a density of between 900 kg / m³ and 1400 kg / m³. According to another embodiment of the invention, the thermoplastic sealing wall is described as a closed-cell polyolefin foam, for example, polyethylene or polypropylene, with a density between 20 kg / m³ and 150 kg / m³ and a thickness between 1 mm and 3 mm. It is well known that cellular materials have lower thermal conductivity characteristics than solid films. Part (C) of the invention according to this embodiment therefore offers an additional advantage. Also according to this embodiment, thicknesses greater than 3 mm are not recommended due to the space required for part (C) within the vehicle. Furthermore, the use of polyolefin foams with a density below 20 kg / m³ and a thickness less than 1 mm is not recommended due to mechanical weaknesses during the processing of such a material.Finally, the use of polyolefin foams with a density greater than 150 kg / m³ is not recommended. Such a material will offer limited benefits in terms of thermal performance. Prior to shaping the two half-shells (1) (2) for the manufacture of the air diffusion ducts (C) of the present invention, the airtight wall The thermoplastic material (5) is bonded to the textile layer using a conventional process. By way of non-limiting example, the thermoplastic membrane (5) is bonded by flame bonding or thermal lamination. The air diffusion duct (C) of the invention can be designed using a thermoforming process in which the two half-shells (1) (2) are formed from a material (M) described previously. According to this same embodiment, the processes of bonding the thermoplastic airtight wall (5) to the non-woven fabric (4) and thermoforming can be carried out successively on the same production line. Advantageously, the thermoplastic airtight wall (5) is bonded to one side of the fabric (4) using a thermal lamination process before the assembly is thermoformed. Regardless of the forming process of the two half-shells (1) (2), they have continuous weld edges (6) on both sides of each of the two half-shells (1) (2). These weld edges (6) will promote a durable and airtight assembly along all of these weld edges (6). The assembly of the two half-shells (1) (2) formed is carried out according to a conventional welding process on all weld edges (6). Regardless of the welding technology used, the latter ensures a complete and durable seal against water, air and dust on all weld edges (6). The assembly of the two half-shells (1) (2) is carried out in such a way as to obtain a hollow body (7) within the air diffusion duct (C) of the invention. Said hollow body (7) is obtained by the assembly of the two half-shells (1) (2), at least one of which has a three-dimensional geometry, obtained, for example, during a thermoforming process. The said hollow body (7) is characterized in that it fulfills an airflow passage function, in particular for a motor vehicle on the one hand; and in that the hollow body (7) comprises: -At least one end (8) dedicated to the entry of an airflow. -At least one end (9) dedicated to the outlet of an air. According to one embodiment of the present invention, the assembly of the two half-shells (1) (2) is carried out so that the airtight thermoplastic wall is positioned on the outer face of the air diffusion duct (C). According to another embodiment of the present invention, the assembly of the two half-shells (1) (2) is carried out so that the airtight thermo-plastic wall (5) is positioned on the inner face of the air diffusion duct. According to a further embodiment of the present invention, a material (M) is described as being an association of three elements carried out as follows: - A non-woven textile tablecloth (4) - A watertight wall made of thermoplastic material (5) - A non-woven textile tablecloth (4) According to this embodiment, the thermoplastic sealing wall (5) will advantageously be a three-component thermoplastic film, such as, but not limited to, a polyethylene-polyamide-polyethylene film, thus facilitating the bonding of said film with the two layers of non-woven fabric (4). The assembly of the two half-shells (1) (2) will then result in the fabrication of an air diffusion duct (C) having a visually identical internal and external surface, made of a non-woven fabric. The thermoplastic film is sandwiched between the two layers of fabric (4). The air diffusion duct (C) according to the invention can be of any shape, circular or polygonal, for example square or rectangular. Similarly, the shape and form of the hollow body (7) formed by the assembly of the two half-shells (1) (2) can be of any shape. In general, the invention applies equally well to small parts as to parts of medium or large dimensions. In order to secure the part (C) according to the invention to a support of the vehicle, fastening or retaining elements can be positioned at at least one end of the air diffusion duct. Alternatively, part (P) of the invention can be fixed to the vehicle support using clips or any other means of fastening. Other features and advantages of the present invention will become more apparent upon reading the following description of several embodiments of the invention given by way of non-limiting examples, with reference to the corresponding accompanying drawings in which: - Figure 1 is a schematic view of the high-acoustic-performance air diffusion duct (C) according to the invention, characterized in that each of the two half-shells (1) (2) is formed from a sheet of material (M) consisting of at least one layer of non-woven textile (4), itself bonded on one entire face to a thermoplastic airtight wall (5). The assembly of the two half-shells (1) (2) is carried out so that the thermoplastic airtight wall is positioned on the outer face of the air diffusion duct (C). - Fig.2 is a different configuration from that of Fig.1 in that the assembly of the two half-shells (1) (2) is carried out so that the thermoplastic sealing wall is positioned on the inner face of the air diffusion duct (C). - Figure 3 is a schematic view of the air diffusion duct (C) according to the invention, characterized in that each of the two half-shells (1) (2) is formed at starting from a sheet of material (M) consisting of two layers of non-woven textile (4), themselves associated on one of their faces with a single waterproof wall of thermoplastic material. According to an unillustrated variant, the hollow body (7) formed by the assembly of the two half-shells (1) (2) may have several ends dedicated to the air intake (8) and several ends dedicated to the air outlet (9).

Claims

Demands

1. High acoustic performance air diffusion duct (C), cn particular for motor vehicle, comprising two half-shells (1) (2), characterized in that each of the two half-shells (1) (2) is formed from a sheet of material (M) consisting of at least one non-woven textile sheet (4), itself associated over the whole of one of its faces has a sealed wall made of thermoplastic material (5) on the one hand; and on the other hand, in that each of the two half-hulls (1) {2) be airtight.

2. Part (C) according to claim 1, characterized in that the sheet of non-woven textile (4) has a surface mass of 350 g / m²? and 1200 g / m² and contains hot-melt fibers with a melting point is lower than that of the rest of the fibers in the textile web (4).

3. Part (C) according to claim 2, characterized in that the web of non-woven textile (4) contains between 5% and 50% of heat-fusible fibers, and preferably between 20% and 50%.

4. Part (C) according to claim 1, characterized in that the wall waterproof made of thermoplastic material (5), i.e., a thermoplastic film.

5. Part (C) according to claim 1, characterized in that the wall waterproof thermoplastic material (5) i.e., a polyolefin foam closed-cell structures with a density between 20 kg / m³ and 150 kg / m³ and with a thickness between 1 mm and 3 mm.

6. Part (C) according to claim 1, characterized in that each of the two half-shells (1) (2) either formed through a thermo- moformage.

7. Part (C) according to claim 1, characterized in that the assembly of the two half-shells (1) (2) is made by welding and allowing to ensure a complete and durable seal against water, air and dust on all weld edges (6).

8. Part (C) according to claim 1, characterized in that the assembly of the two half-shells (1) (2) is made so that the wall waterproof thermoplastic material (5) is positioned on the ex- face exterior of the air diffusion duct (C).

9. Part (C) according to claim 1, characterized in that the assembly of the two half-shells (1) (2) is made so that the wall waterproof thermoplastic material (5) is positioned on the in- face exterior of the air diffusion duct (C).

10. Part (C) according to claim 1, characterized in that the assembly of the two half-shells (1) (2) is made so that the wall waterproof thermoplastic material (5) either included between two layers of non-woven textile (4).

11. Part (C) according to claim 1, characterized in that the hollow body (7) formed by the assembly of the two half-hulls (1) (2) comprises: - At least one end (8) dedicated to the entry of an airflow. - At least one end (9) dedicated to the outlet of an airflow.