METHOD FOR REDUCING NONSENSE NOISE IN A VEHICLE IN OPERATION FOR THE PURPOSE OF RECYCLING THE VEHICLE AT THE END OF LIFE

Abstract

Method for attenuating unwanted noise during vehicle operation, where such unwanted noise may be generated by at least one structural component forming all or part of a chassis and / or body and / or opening of the vehicle, the structural component comprising at least one sheet metal panel, the method comprising the following steps: - identification of at least one first sheet metal region subject to a risk of vibration during operation, - formation, by local application of metallic material (3), on at least one face of the sheet metal at the location of the first region, of at least one rib, extending from one face of the sheet metal with a rib length and a rib height, the rib being intended to significantly reduce the amplitudes of possible vibrations. Figure from the abstract: Fig. 2

Description

Title of the invention: METHOD FOR REDUCING NONSENSE NOISE IN A MOTING VEHICLE FOR THE PURPOSE OF RECYCLING THE VEHICLE AT THE END OF LIFE

[0001] The invention applies to the general field of manufacturing mechanical parts that make up the body of a motor vehicle, and more generally the structural parts of a motor vehicle.

[0002] The invention relates in particular to a method of attenuating parasitic noises in a motor vehicle subjected to driving, this method making it easier to recycle the vehicle at the end of its life.

[0003] The structure of a motor vehicle comprises a plurality of sheet metal parts shaped by stamping and then assembled together by welding.

[0004] The term "vehicle structure" includes the chassis, body, doors or openings. In this context, the chassis includes the suspension components and the powertrain cradle.

[0005] Many structural elements of a motor vehicle are made from sheet metal. Here, "sheet metal" is understood to mean a thin piece that extends locally in a plane, with a thickness substantially less than its dimensions in the other two directions (parallel to the local plane if the sheet metal is flat). The sheet metal is not necessarily flat; it may have been formed in three dimensions by stamping.

[0006] The sheet metal thickness is chosen according to the stresses to be borne by the different parts of the structural piece.

[0007] It turns out that in practice, certain sheet metal parts, when subjected to vibratory stresses induced by the rolling of the vehicle, are subject to vibrations or vibratory modes.

[0008] These vibrations can cause undesirable noise. Furthermore, these vibrations can contribute to premature damage to the structure (e.g., corrosion under alternating stresses).

[0009] To remedy these vibration phenomena, in the known art, inserts made of polymeric material are used, which are placed in suitable locations and which are expanded by the heat undergone in the cataphoresis operations.

[0010] However, in many configurations, it is not possible, at the end of the vehicle's life, to remove the polymer inserts; they are difficult to access, or even in some cases they are located in a hollow body.

[0011] The need to be able to recycle the different parts and components of a motor vehicle is becoming increasingly important, and it is becoming increasingly important to avoid cross-pollution between different materials.

[0012] The presence of polymer inserts in the metallic structure is therefore a problem.

[0013] In this context, the inventors sought to propose a solution to improve the recycling conditions of the metallic structure of motor vehicles, while solving the problem of undesirable vibration modes.

[0014] In this context, the invention proposes a method for attenuating unwanted noise during the operation of a vehicle, the unwanted noise being generated by at least one structural part forming all or part of a chassis and / or bodywork and / or an opening of the vehicle, the structural part comprising at least one sheet metal, the method comprising the following steps: - identification of at least one initial area of ​​sheet metal subject to a risk of vibration during rolling, - formation, by a local supply of metallic material, on at least one face of the sheet at the location or in the vicinity of the first region, of at least one rib, extending from one face of the sheet along a rib length and a rib height, the rib being intended to reduce the amplitudes of possible vibrations.

[0015] It should be noted that the rib length is taken along the face of the sheet metal and the rib height is taken perpendicular to the face of the sheet metal.

[0016] Thanks to these arrangements, the presence of the local metallic material in the form of a rib makes it possible to substantially reduce the effect of vibrational stresses. In practice, the vibrational natural modes are pushed to much higher frequencies and the amplitudes are greatly reduced.

[0017] Advantageously, the structure is entirely metallic, which allows for a homogeneous cataphoresis treatment process over the entire structure. In practice, the structural part is devoid of a polymer insert, thus facilitating the recycling of the structural part at the end of its life.

[0018] The absence of a polymer or plastic part makes recycling easier at the end of the vehicle's life. This is all the more important because if the anti-vibration treatment is located in a hollow body, it is practically impossible to remove the polymer insert from the previous solution.

[0019] In one embodiment, the structural component is made of aluminum or steel. This results in a vehicle structure with good robustness. Furthermore, well-established recycling channels exist for both steel and aluminum.

[0020] Generally regarding terminology, it should be noted that "additive manufacturing" is also called "3D printing", and it should be noted that "local material supply" is also called "deposition".

[0021] It is noted that the vehicle structure may also incorporate composite elements, made for example of fibers and resin, as is known per se. These composite elements may be found for opening parts or for certain aesthetic components.

[0022] According to one embodiment, the structural part is made of aluminium and the local material input is made of aluminium.

[0023] According to one embodiment, the structural part is made of steel and the local material added is also made of steel. This results in good cohesion of the added rib with respect to the sheet metal forming the substrate.

[0024] According to one embodiment, the local material is added in the form of several parallel ribs. Here too, good cohesion of the added rib with respect to the sheet metal forming the substrate is obtained.

[0025] The anti-vibration device provided by these ribs can thus be adapted to deal with the risk that has been evaluated in digital design or in feedback from physical prototype testing.

[0026] A series of cords or ribs can be formed oriented in the relevant direction with respect to the vibration risk which has been evaluated beforehand in digital design or in feedback from physical prototype testing.

[0027] According to one embodiment, the local material supply is achieved with molten metal powder using a plasma torch. This is a solution that is now well-established technically and affordably priced.

[0028] According to one embodiment, the local material is supplied using a molten metal wire and a laser beam. This solution is now also well-established technically and affordably priced.

[0029] According to one embodiment, the local supply of material can be carried out in successive layers of 0.1 mm to 0.4 mm thickness.

[0030] The thickness of the deposit layer is adjusted in relation to the thermal resistance capacity of the sheet forming the substrate and the number of passes is adjusted to the desired height for the total contribution, i.e. to the height of the rib to be formed.

[0031] According to one embodiment, the sheet metal has a sheet metal thickness of between 0.7 mm and 2.5 mm

[0032] It is possible to carry out the local deposition or supply of molten metal material according to one of the methods previously mentioned without substantially damaging the substrate formed by the sheet metal.

[0033] According to one embodiment, the sheet metal thickness can go up to 4 mm.

[0034] It is thus possible to treat structural or reinforcement parts forming, for example, longitudinal members, cross members or crash protection beams.

[0035] According to one embodiment, the rib height is between 1 mm and 6 mm.

[0036] By this means, the appropriate height can be chosen to form a wall that will prevent the onset of undesirable vibration modes. It should be noted that the height of the rib can be greater than the thickness of the sheet metal to which it is attached.

[0037] According to one embodiment, the rib has a width between 0.5 mm and 3 mm. The length of the rib can be arbitrary, consistent with the need for anti-vibration function.

[0038] According to one embodiment, the step of identifying at least one first region of sheet metal subject to risk of vibration includes a numerical simulation launched on the basis of a numerical definition of the structural part of the vehicle.

[0039] According to an alternative or complementary embodiment, the step of identifying at least one first region of sheet metal subject to risk of vibration includes one or more tests carried out on a vibration bench on which a prototype of the structural part or a prototype of the complete vehicle structure is installed.

[0040] According to an alternative or complementary embodiment, the step of identifying at least one first region of sheet metal subject to risk of vibration is based on empirical rules derived from previous experience.

[0041] The present invention also relates to a motor vehicle obtained by implementing the use as defined above.

[0042] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which: [Fig.l] schematically illustrates in profile view a motor vehicle in which the present invention can be implemented; [Fig.2] shows a portion of sheet metal with added material by additive manufacturing, in the form of three parallel ribs in the illustrated example; [Fig.3] represents in cross-sectional view an example of a material application process; [Fig.4] represents in sectional view a rib formed by the addition of metallic material.

[0043] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0044] In [Fig.1], a vehicle 1 is represented schematically, in side view.

[0045] With regard to the location of the vehicle in space, the X direction corresponds to the longitudinal direction of the vehicle, and the Z direction corresponds to the vertical direction relative to the local ground and the Y direction perpendicular to the two previous ones and corresponds to the transverse direction of the vehicle.

[0046] The vehicle in question may be a passenger vehicle, a utility vehicle, a van, a recreational vehicle, a minibus, a coach, a truck, etc.

[0047] The vehicle comprises a main structure, also called the body, with the openings included, and complementary structural elements, such as certain ground connection elements, e.g. suspension triangles, and such as seat frames, or the cabin partition frame in the case of vans.

[0048] As is known in the bodywork trade, the main structure and complementary structural elements comprise sheet metal parts shaped by stamping and then assembled together by welding. Anti-corrosion protection and painting are then carried out.

[0049] In the vehicle's body-in-white, the metal structural elements concerned by the present invention cover chassis frame elements, as well as skin parts and associated linings.

[0050] The vehicle structure can typically be made of aluminum or steel. It is not excluded to have some parts formed from steel and other parts formed from aluminum.

[0051] The vehicle structure may include parts such as body sides, longitudinal members, floor cross members, mud flaps, windshield bay pillars, roof, stretcher, spare wheel housing, without this list being exhaustive.

[0052] As presented in the introductory part, when the vehicle is subjected to certain vibratory stresses, in particular when driving the vehicle on different road surfaces, certain areas of sheet metal are subject to vibratory modes.

[0053] In particular, certain road surfaces, such as paving stones or granular asphalt, provide a very wide spectrum of excitation frequencies.

[0054] Vibrational stresses transmitted from the road surface, notwithstanding the filtering provided by the suspension, are transmitted to the vehicle body and more generally to the entire structure and its attached accessories. The spectral content is highly variable and generally very rich. The vehicle can be considered to be subjected to a vibrational stress of the white noise type.

[0055] Areas subject to vibration risk can be identified during numerical simulations launched based on the digital definition ('CAD') of the vehicle structure. The digital definition ('CAD') of the vehicle structure uses the finite element decomposition technique. Additional numerical simulations with the presence of anti-vibration ribs... can be used to determine the number, position and orientation of ribs needed to prevent the risk of vibrational modes.

[0056] In addition or as an alternative, areas subject to vibration risk can be identified during vibration bench tests, using acoustic sensors or video cameras.

[0057] In addition or as an alternative, areas subject to vibration risk can be identified from business rules which make it possible to know, for example, that a portion of unsupported sheet metal with a surface area greater than a threshold surface area will be subject to vibrations.

[0058] In addition or as an alternative, areas subject to vibration risk can be identified from empirical rules derived from previous experience.

[0059] Advantageously, according to the present invention, the definition of the structural parts is modified to add in places subjected to vibratory modes a metallic deposit formed as a bead, a groove or even a wall.

[0060] As illustrated in [Fig. 2], a sheet metal element 2 comprises a first vertical portion 4, a horizontal extension 5, and another downward vertical extension 6. Of course, this solution can be applied to any other shape of sheet metal part.

[0061] The ribs identified as 3 were added by additive manufacturing process or 3D printing.

[0062] In other words, the additive manufacturing process includes a local supply of metallic material on one face of the sheet at the location of the first region, the local supply of material being intended to reduce the amplitudes of possible vibrations.

[0063] Locally, metallic material is added to at least one face of the sheet metal at or near the area identified as being subject to vibration risks. The ribs 3 project from the surface of the sheet metal. The surface of the sheet metal extends along the directions marked U and V in Figures 2, 3, and 4. The ribs 3 project from the surface of the sheet metal along the direction marked W in Figures 2, 3, and 4.

[0064] It is not excluded to apply a material supply to both faces of the sheet metal, in the same place or in offset places.

[0065] In the illustrated example, the deposit is made in the form of several beads of material, here three in the example. In the illustrated example, the beads are parallel to each other, but other configurations are possible, for example two beads perpendicular to each other, several beads arranged in a grid pattern, beads of different heights.

[0066] According to a first example, the structural part is made of steel and the local material input is also steel. According to a second example, the structural part is made of aluminum and the local material input is also aluminum.

[0067] On figure 3, a multi-pass deposition process has been illustrated.

[0068] A metal wire 7 is positioned at the point of action 9 by a reel which advances The wire melts as it is subjected to localized heating by the laser beam 8. The material then solidifies in place. The action point 9 moves as the feed material is deposited.

[0069] A first layer 31 is applied to the sheet 2 forming the deposition substrate. Then, a second layer 32 is applied over the first layer 31. [Fig. 3] shows the application phase of a third layer 33 being applied over the second layer 32.

[0070] The number of layers applied can be arbitrary. There can even be only one layer.

[0071] Two (or more) deposition cords can be provided side-by-side to obtain the desired width L2 for the rib to be formed.

[0072] It is noted that the thickness of sheet metal E2 is between 0.7 mm and 2.5 mm. The sheet metal thickness can reach up to 4 mm for certain structural parts.

[0073] The thickness of each successive layer can range from 0.1 mm to 0.4 mm thick, depending on the diameter of the metal filler wire.

[0074] According to an alternative implementation not shown, the metal input results from an input of material in the form of a stream of metal powder which is melted by a plasma torch.

[0075] Of course, any other method of metal deposition may be used within the framework of the present invention.

[0076] With reference to [Fig.4], the metallic material deposit forms a rib having a height H2 along W between 1 mm and 6 mm, and a width L2 along V between 0.5 mm and 3 mm.

[0077] The length of the rib, denoted L1 according to U, can be arbitrary.

[0078] Thus, thanks to the metal addition technique in areas subject to risk of vibration, the structural part is devoid of polymer insert, thus facilitating the recycling of the structural part at the end of its life.

Claims

Demands

1. Method for attenuating unwanted noise during the movement of a vehicle, unwanted noise being generated by at least one structural part forming all or part of a chassis and / or body and / or opening of the vehicle, the structural part comprising at least one sheet metal, the method comprising the following steps: - identification of at least one first region of sheet metal subject to a risk of vibration during movement, - formation, by a local supply of metallic material, on at least one face of the sheet metal at the location or in the vicinity of the first region, of at least one rib (3), extending from one face of the sheet metal along a rib length (L2) and a rib height (H2), the rib being intended to reduce the amplitudes of possible vibrations.

2. Method according to claim 1, wherein the structural part is made of aluminium and the local material supply is made of aluminium.

3. Method according to claim 1, wherein the structural part is made of steel and the local material supply is made of steel.

4. A method according to any one of claims 1 to 3, characterized in that the local supply of material is carried out in the form of several parallel ribs.

5. A method according to any one of claims 1 to 4, characterized in that the local supply of material is carried out with a molten metal powder by means of a plasma torch.

6. A method according to any one of claims 1 to 5, characterized in that the local supply of material is made with a metal wire (7) melted by means of a laser beam.

7. A method according to any one of claims 1 to 6, characterized in that the sheet metal has a sheet metal thickness (E2) between 0.7 mm and 2.5 mm.

8. A method according to any one of claims 1 to 7, characterized in that the rib height (H2) is between 1 mm and 6 mm.

9. A method according to any one of claims 1 to 8, characterized in that the step of identifying at least one first region of sheet metal subject to vibration risk comprises a simulation 9 digital launched on the basis of a digital definition of the vehicle's structural part.

10. Motor vehicle, obtained by implementing the process according to any one of claims 1 to 9.

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