Body component of a motor vehicle comprising an area arranged opposite a radar

Abstract

The invention relates to a body part (1) of a motor vehicle, comprising a region (11) intended to be arranged opposite a radar, wherein the region (11) is thicker than a peripheral region (13) of the region (11), the thickness of the region (11) being such that the attenuation of radar waves in the region (11) is less than the attenuation of radar waves in the peripheral region (13).

Description

Technical Field

[0001] The invention relates to a body component of a motor vehicle, comprising a region arranged opposite a radar. Background Art

[0002] It is known in the prior art that the body parts of motor vehicles include parts intended to be arranged in front of a radar, or parts that have the function of a radome. Therefore, it is crucial that the parts of the body parts intended to be arranged in front of a radar must be able to transmit the radar waves passing through them well. However, due to their manufacturing process, the thickness of the body parts is minimal. Therefore, a known solution for improving the transparency (penetration) to radar waves is to locally reduce the thickness of the part forming the hood, so as to achieve a minimum thickness that optimizes the attenuation of the waves. However, this solution has several disadvantages, including the risk of cosmetic defects in the body parts, the need for more complex injection molding methods and processes, and the risk of brittleness in the areas of reduced thickness. Summary of the Invention

[0003] The present invention aims to provide a body component for a motor vehicle, which includes a region arranged opposite a radar, wherein the region has good transparency (penetration) for radar waves and is easy to manufacture and has no appearance defects.

[0004] To this end, the present invention relates to a body component of a motor vehicle, comprising a region intended to be arranged opposite a radar, wherein the region is thicker than regions surrounding it, the thickness of the region being such that the attenuation of radar waves in the region is less than the attenuation of radar waves in the peripheral regions.

[0005] Unexpectedly, the inventors discovered that the radar wave transmission of a body component in the area facing the radar can be improved by increasing its thickness. However, it is desirable for body components to have a substantially constant thickness to facilitate injection molding of the component while achieving a good surface appearance. Furthermore, it is desirable for body components to be of low thickness, particularly for reasons of vehicle weight, aesthetics, and ease of implementation. Therefore, to achieve optimal radar wave transmission in the area of ​​the body component intended for placement in front of the radar while maintaining a low body component thickness, the thickness of the component is locally increased in the area intended for placement in front of the radar. This contrasts with prior art solutions, which rely on reducing the thickness of this area.

[0006] In the sense of the present invention, the area intended to be arranged opposite the radar is the area of ​​the body part that can be penetrated by the radar waves on the vehicle. Therefore, this area essentially corresponds to the cone projection formed by the radar waves on the body part.

[0007] It will be understood that a "peripheral area" of an area intended to be arranged opposite the radar is formed by parts of the vehicle body component that are located around and in the vicinity of this area.

[0008] In one embodiment, the thickness of the area intended to be positioned in front of the radar is selected from a set of pairs of values: radar wave attenuation and reflection / thickness of the area. This set of pairs is obtained, for example, by measuring and calculating the attenuation and reflection of the wave as a function of thickness. These attenuation and reflection also depend on other parameters, such as the dielectric properties of the material used to manufacture the component, or the paint applied to the component surface, particularly the different paint layers and their varying thicknesses. These paints can be used to form paint layers for motor vehicles, such as primer, basecoat, and clearcoat. Therefore, the thickness of the area is simple to select, as it is selected from a set of predetermined pairs of values.

[0009] In another embodiment, a body component comprises a main body and at least one membrane, the main body including an area intended to be positioned opposite a radar, the membrane being attached to this area. This makes the main body easy to manufacture, and in particular, allows for a consistent geometry. In particular, when the main body is injection molded, the mold shape is also simple. Furthermore, when replacing a body component at a dealership, the dealer has a standard main body, and thanks to the use of a membrane of the appropriate thickness, the thickness of the area intended to be positioned in front of the radar can be easily selected and fixed. More specifically, when the component is painted, the optimal thickness of this area varies depending on the paint applied.

[0010] The vehicle body component according to the present invention may further include the following optional features, either alone or in combination:

[0011] - said body comprises a receiving area for said membrane situated in said region, said receiving area for said membrane having a thickness substantially the same as that of said peripheral area.

[0012] The film includes heating wires. This allows, in particular, defrosting of the area of ​​the vehicle body component that is located in front of the radar. The heating wires are arranged so that the transparency of this area to radar waves is maintained.

[0013] The film is held on the body by means of an adhesive. Therefore, the installation of the film on the body is easy and can be easily performed in a car dealership, for example during the replacement or repair of a body part.

[0014] The film is held on the body by overmolding. Overmolding is particularly advantageous when the body parts are manufactured in a factory and avoids the use of adhesives that may not be very stable over time.

[0015] The body comprises a receiving area of ​​the membrane, identified by a texturing on the receiving area, or a slight increase in thickness, or texturing only on the edge of the receiving area.

[0016] -The material of the body is selected from polypropylene, polycarbonate, polymethyl methacrylate, polyamide, polyethylene terephthalate (PET), copolyester, acrylonitrile butadiene styrene, a mixture of acrylonitrile butadiene styrene and polycarbonate (ABS / PC), acrylonitrile styrene acrylate (ASA), styrene acrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, a mixture of polypropylene and EPDM; the membrane includes a material selected from polycarbonate, ABS / PC, PET, polyurethane, and polyamide.

[0017] The surface of the body part intended to be arranged outside the vehicle is coated with paint.

[0018] The invention also relates to a method for producing a body part for a motor vehicle by molding a plastic material, the body part comprising a region intended to be arranged opposite a radar, the region being thicker than regions surrounding the region, wherein the thickness increase is implemented in the region, the thickness of the region being such that the attenuation of radar waves in the region is less than the attenuation of radar waves in the peripheral regions.

[0019] The method for manufacturing a body part for a motor vehicle according to the present invention may further adopt the following optional features, alone or in combination:

[0020] A method for manufacturing a body part for a motor vehicle comprises the following steps:

[0021] a) manufacturing the main body of the vehicle body component by molding,

[0022] b) selecting a film of appropriate thickness from a group of films, or selecting multiple films of appropriate thickness,

[0023] c) fixing the selected film or films in said region of said body intended to be arranged opposite the radar.

[0024] Thus, only a single mould is required for the manufacture of the body, since the same part is always injected, and then a film of the required thickness is added to obtain an overall thickness enabling minimum damping.

[0025] Between steps a) and b) a paint is applied to the surface of the vehicle body part intended to be placed on the outside of the vehicle. The paint generally comprises several components of different thicknesses, such as a primer, a basecoat and a clearcoat, to form a coating of the thickness to be applied to the motor vehicle.

[0026] The thickness of the region is selected from a set of pairs of values ​​of attenuation and reflection of radar waves / thickness of the region.

[0027] - In step b), the thickness of the membrane is chosen taking into account at least one of the following parameters: the material of the body, the thickness of the area, the material of the membrane,

[0028] The paint applied on the main body

[0029] In practice, the inventors have discovered that the attenuation of radar waves depends on the type of plastic material constituting the body and the film, respectively, and also on the type of lacquer applied, for example a lacquer with a matte, pearlescent or metallic appearance. These parameters are therefore preferably taken into account when selecting the film to be applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention will be better understood from a reading of the accompanying drawings, which are provided by way of example and not limitation, in which:

[0031] - Figure 1 is a schematic perspective view of a body component of a motor vehicle according to a first embodiment of the present invention;

[0032] - Figure 2 is based on Figure 1 a rear view of a portion of a body member of an embodiment;

[0033] - Figure 3 is a rear view of a portion of a vehicle body component according to another embodiment;

[0034] - Figure 4 Graph showing the attenuation and reflection of radar waves as a function of plastic material thickness. DETAILED DESCRIPTION

[0035] exist Figure 1 and Figure 2 Detailed Description of the Invention A body portion of a motor vehicle according to one embodiment of the invention is shown and is indicated by the general reference numeral 1 .

[0036] Figure 1 A body part of a motor vehicle is shown, which in this embodiment is a bumper 1, comprising an area 11 intended to face the radar arrangement and a main body 10. It should be understood that the vehicle body part according to the present invention is not limited to a bumper, but may be another body part, such as a door, a roof, a tailgate, or a fender.

[0037] Radars placed behind vehicle body components can be of different types, such as short-range radar (SRR) for detecting nearby obstacles, mid-range radar (MRR), and long-range radar (LRR) for assisting driving. These radars typically operate in the 76-77 GHz and 77-81 GHz frequency bands.

[0038] Figure 2 1 is a partial view of a body part of a motor vehicle, showing an area 11 intended to be arranged opposite a radar and an area 13 surrounding this area 11. Area 11 is thicker than area 13 surrounding this area 11, and the thickness of this area is set so that the attenuation of radar waves in this area is less than the attenuation of radar waves in the peripheral area 13.

[0039] More specifically, the thickness of the region 11 is selected from a set of coupled radar wave attenuation and reflection / thickness value pairs, which are obtained by measuring and calculating the attenuation and reflection of radar waves, or by simulation.

[0040] This set of value pairs is obtained, for example, by measuring and calculating the thickness-dependent attenuation and reflection of the wave, which also depend on other parameters, such as the dielectric properties of the material used to make the component, or the paint applied to the surface of the component, in particular the different paint layers and their varying thicknesses. These paints can be used to obtain paint layers for motor vehicles, such as primer, basecoat, and clearcoat.

[0041] In one advantageous embodiment, the body part 1 comprises a body 10 comprising a region 11 intended to be arranged opposite the radar, and at least one membrane 12 added on said region 11 with increased thickness.

[0042] This embodiment is particularly advantageous because it simplifies the production of the body part, since the increased thickness of the region 11 can be formed very easily by arranging a film 12 of predetermined thickness. Consequently, the shape of the body part 10 does not have to be adjusted, for example, to the paint to be applied subsequently.

[0043] For example, attenuation and reflection measurements are performed in the following manner to obtain a transmittance pair for radar wave-thickness:

[0044] - obtaining the body part or a representative sample of the body part (that is to say a sample made of the same material by the same process and having a thickness corresponding to that of the peripheral zone 13 and possibly painted);

[0045] - fixing a film taken from the set of films to be tested on a component or a sample of a component so as to obtain an area 11;

[0046] - measuring the transmission and reflection of radar waves passing through the area 11;

[0047] -Selection of a film with satisfactory radar wave transmittance;

[0048] - Repeat the measurement as many times as necessary, especially for components or samples of components sprayed with different paints.

[0049] For example, in Figure 4 The graphs in Figure 1 show the attenuation of the radar wave (in dB as a function of the thickness it passes through) and the reflection of the radar wave (as a function of the thickness it passes through). It can be seen that the attenuation curve has a minimum attenuation value for a given thickness, and that the reflection value is also minimum for the same thickness. This makes it possible to determine the optimal thickness of region 11.

[0050] exist Figure 3 In the particular embodiment shown, the membrane 12 includes heating wires 16. These heating wires can defrost the area 11 so that the radar can function properly. In fact, the presence of frost, snow, or ice formed on the area 11 greatly reduces the transparency of the radar waves.

[0051] The position of the heating wires is chosen so as not to hinder the transmission of the radar waves, in particular their spacing. Figure 3 As shown, the bent portion of the heating wire, which may hinder the transmission of radar waves, is located outside the portion indicated by the dashed rectangle 17 , which is located exactly in front of the radar sensor.

[0052] In one embodiment, the membrane 12 is retained on the body 10 by overmolding. This embodiment is preferably used in the factory during the manufacture of the body part, since it enables a part to be obtained that has good stability over time and a simple manufacturing process.

[0053] In another embodiment, the film 12 is secured to the body by an adhesive. This embodiment is particularly useful when modifying or repairing a vehicle body component at a car dealership. In this case, the dealership has a standard body 10, identical for all vehicles of the same model, and a set of films 12. During the manufacture of the vehicle body component 1, the film 12 is selected based on the following specific but non-limiting factors: the thickness of the body 10, specifically the thickness of the peripheral region 13; the nature of the material comprising the body 10; the paint (colored, metallic, matte, pearlescent, or other) applied to the outer surface of the body 10; and the nature of the material of the film 12. The film is then easily secured to the body 10 using a suitable adhesive. The film is preferably selected from a predetermined list by the manufacturer of the motor vehicle component. After the component is manufactured and before it is installed in the vehicle, it can be checked, if necessary, using specially provided equipment to ensure proper transmission and reflection of radar waves.

[0054] In one embodiment, body 10 is made of polypropylene. This is typically the case when vehicle body component 1 is a bumper skin. Film 12 comprises a material selected from polycarbonate, ABS / PC, PET, polyurethane, and polyamide. These materials are readily available in film form and are suitable for attachment to polypropylene by overmolding or bonding.

[0055] In other embodiments, the material of the main body 10 is selected from polypropylene, polycarbonate, polymethyl methacrylate, polyamide, polyethylene terephthalate (PET), copolyester, acrylonitrile butadiene styrene, a mixture of acrylonitrile butadiene styrene and polycarbonate (ABS / PC), acrylonitrile styrene acrylate (ASA), styrene acrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, and a mixture of polypropylene and EPDM.

[0056] Advantageously, body 10 includes a receiving area for receiving film 12, identified by a surface texture or a slightly increased thickness at its edge 14. This allows film 12 to be positioned correctly on body 10 when the body part is removed from the vehicle. In practice, the position of area 11 is difficult to determine when the body part is removed from the vehicle, as the radar is not fixed to the body part. If the receiving area of ​​film 12 is not identified, the film must be larger to ensure full coverage, resulting in positioning uncertainty.

[0057] In another embodiment, the body 10 includes a receiving area for the membrane 12, which includes an indexation 18. The membrane 12 includes an indexation corresponding to the indexation 18 of the receiving area. This indexation 18 enables the membrane 12 to be positioned very precisely on the receiving area. This is particularly useful for membranes with heating wires, since the degree of transparency to radar waves depends on the position of the heating wires. The indexation can be in the form of Figure 2 and Figure 3 The shape of an "ear" is shown, but the shape of an indentation in the membrane 12 and a shape corresponding to the indentation on the receiving area may also be used.

[0058] We will now describe the method according to the invention for producing a body component 1 of a motor vehicle.

[0059] Preferably, the method for manufacturing a component includes a step of molding a plastic material. The method includes implementing an increased thickness in a region 11 of the component intended for placement in front of a radar. This increased thickness is achieved in addition to the thickness of a region 13 surrounding region 11. The thickness of region 11 is selected such that radar wave attenuation in region 11 is less than radar wave attenuation in peripheral region 13. Minimum attenuation is achieved by selecting the thickness of region 11 from a pair of values: radar wave attenuation / thickness of region 11, these value pairs being predetermined, for example, using the method described above.

[0060] In a particular embodiment, the method for manufacturing a body component 1 for a motor vehicle comprises the following steps:

[0061] a) providing a main body 10,

[0062] b) selecting a film 12 of appropriate thickness from a group of films, or selecting a plurality of films 12 of appropriate thickness,

[0063] c) Fixing the selected film or films 12 in the area 11 of the body 10 intended to be arranged opposite the radar.

[0064] Between step a) and step b), a surface of the vehicle body intended to be arranged on the outside of the vehicle is usually sprayed with paint.

[0065] Therefore, for all vehicles of the same model, the body is identical and only a single mold is required for the body, since the same part is always injected, and then one or more films of the desired thickness are added to obtain an overall thickness that minimizes attenuation and reflection of radar waves.

[0066] Furthermore, in step b) above, the thickness of film 12 is selected taking into account at least one of the following parameters: the material of body 10, the thickness of region 11, the material of film 12, and the paint applied to body 10. In practice, the inventors have discovered that the transmission of radar waves necessarily depends on the thickness of the components of the paint applied to the motor vehicle (thickness of primer, basecoat, and clearcoat), as well as on the color of the paint used and whether the paint has a metallic, matte, pearlescent, or other finish. Therefore, the paint is an important parameter when selecting the film or films to be applied in region 11.

[0067] Glossary

[0068] 1 Body parts

[0069] 10 Main Body

[0070] 11 Areas intended to be located opposite to radars

[0071] 12 Film (increases the thickness of area 11)

[0072] 13. Outer area of ​​area 11

[0073] 14 The edge of the receiving area of ​​the film 12 on the body 10

[0074] 15 Edge of membrane 12

[0075] 16 Heating wire

[0076] 17 Area in front of the radar sensor

[0077] 18 Index mark of the receiving area of ​​the membrane.

Claims

1. A body part (1) of a motor vehicle comprising an area (11) intended to be arranged opposite a radar, characterized in that The area (11) is thicker than a peripheral area (13) of the area (11), the thickness of the area (11) being set so that the attenuation of radar waves in the area (11) is less than the attenuation of radar waves in the peripheral area (13), the body part (1) comprising a body (10) and at least one film (12), the body (10) comprising the area (11) intended to be arranged opposite the radar, the film being attached to the area (11), the body (10) comprising a receiving area of ​​the film (12), the receiving area of ​​the film being identified by texturing on the receiving area, or a slightly thin increase in thickness, or texturing only on the edge (14) of the receiving area.

2. The vehicle body component (1) according to claim 1, wherein The thickness of the region (11) is selected from a set of value pairs of attenuation and reflection of radar waves / thickness of the region (11).

3. The body component (1) according to claim 1 or 2, wherein The body comprises a receiving area for the membrane (12) in the region (11), the thickness of the receiving area for the membrane (12) being substantially the same as the thickness of the peripheral region (13).

4. The body component (1) according to claim 1 or 2, wherein The membrane (12) includes a heating wire (16).

5. The body component (1) according to claim 1 or 2, wherein The film (12) is held on the body (10) by an adhesive.

6. The vehicle body component (1) according to claim 1 or 2, wherein The membrane (12) is held on the body (10) by overmolding.

7. The body component (1) according to claim 1 or 2, wherein The body (10) has a receiving area for the membrane (12), the receiving area for the membrane (12) including an index mark (18).

8. The body component (1) according to claim 1 or 2, wherein The material of the main body (10) is selected from polypropylene, polycarbonate, polymethyl methacrylate, polyamide, polyethylene terephthalate (PET), copolyester, acrylonitrile butadiene styrene, a mixture of acrylonitrile butadiene styrene and polycarbonate (ABS / PC), acrylonitrile styrene acrylate (ASA), styrene acrylonitrile, a mixture of acrylonitrile styrene acrylate and polycarbonate, a mixture of polycarbonate and polyethylene terephthalate, and a mixture of polypropylene and EPDM; the membrane (12) includes a material selected from polycarbonate, ABS / PC, PET, polyurethane, and polyamide.

9. The body component (1) according to claim 1 or 2, wherein A surface of the vehicle body component that is intended to be provided outside the vehicle is coated with paint.

10. Method for manufacturing a body part (1) for a motor vehicle by molding a plastic material, said body part (1) comprising a region (11) intended to be arranged opposite a radar, said region (11) being thicker than a peripheral region (13) of said region (11), characterized in that The thickness increase is implemented at the region (11), and the thickness of the region (11) is set so that the attenuation of radar waves at the region (11) is smaller than the attenuation of radar waves at the peripheral region (13).

11. The manufacturing method according to claim 10, wherein: a) manufacturing the body (10) of the vehicle body component by molding, b) selecting a film (12) of appropriate thickness from a group of films, or selecting a plurality of films of appropriate thickness, c) fixing the selected film or films (12) in said area (11) of said body (10) intended to be arranged opposite to the radar.

12. The manufacturing method according to claim 11, wherein: Between step a) and step b), a surface of a vehicle body component (1) to be arranged outside the vehicle is coated with paint.

13. The manufacturing method according to one of claims 10 to 12, wherein: The thickness of the region (11) is selected from a set of value pairs of attenuation and reflection of radar waves / thickness of the region (11).

14. The manufacturing method according to claim 11 or 12, wherein: In step b), the thickness of the film (12) is selected taking into account at least one of the following parameters: the material of the body (10), the thickness of the region (11), the material of the film (12), the paint applied to the body (10).

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