Method for manufacturing a covering element, covering element and radar sensor unit having a covering element

Abstract

The invention relates to a method for manufacturing a covering element, a covering element and a radar sensor unit having a covering element, wherein a substrate (3) of the covering element (1) is provided and a wave passage region (4) for a radar sensor (5) is determined at the substrate (3); a primer layer (7) is applied to the substrate (3) on the outer side and a topcoat layer (10) is applied to the primer layer (7) on the outer side. According to the invention, before applying the topcoat layer (10), an initial radar reflection value (R0) of the substrate (3) coated with the primer layer (7) in the wave passage region (3) is determined, and the topcoat thickness of the topcoat layer (10) is determined based on the initial radar reflection value (R0) so that the initial radar reflection value (R0) of the substrate (3) coated with the primer layer (7) is compensated to a preset target radar reflection value (R1) of the covering element (1) by applying the topcoat layer (10).

Description

Technical Field

[0001] According to a first aspect, the present invention relates to a method for manufacturing a covering element for a radar sensor unit, in particular for a radar sensor unit of a motor vehicle. Furthermore, according to a second aspect, the present invention relates to a covering element for a radar sensor unit. Furthermore, in a third aspect, the present invention relates to a radar sensor unit for a motor vehicle, wherein the radar sensor unit has a covering element. Background Art

[0002] Due to the ongoing development of the automation of the driving operation of motor vehicles, the number of sensors, such as radar sensors, has increased today, and these sensors are especially mounted on the outside of the motor vehicle. Such radar sensors are used, for example, for autonomous driving operation modes, distance-related speed control devices, parking steering assist devices, etc. In order to nevertheless ensure a particularly appealing appearance of the corresponding motor vehicle, there is also a need to cover the sensors of the corresponding motor vehicle outwardly, that is, for example, to arrange the sensors under the outer skin of the motor vehicle. Furthermore, it is known and common that the outer skin of a motor vehicle is provided with a color layer, especially painted with a color layer, and nowadays metallic paints are used, that is, paints into which effect particles are incorporated. Since these effect particles are often metallic, for example, made of a metallic material, when the area of the outer skin behind which a radar sensor is arranged is coated or painted with such a paint layer, this results in a reduction in the working ability of the radar sensor. Currently, this problem is faced, and only certain paints are used for painting the outer skin of a motor vehicle, and other such painting process paints are excluded.

[0003] The corresponding solutions completely abandon painting the outer skin of the motor vehicle at least in the area interacting with the radar sensor or installing the radar sensor only in the area of the motor vehicle that remains unpainted anyway. But this can lead to a decrease in the acceptance by customers of the corresponding motor vehicle and furthermore lead to a deterioration of traffic safety because sensing devices, especially radar sensing devices, are required for operating modern driving assistance systems and / or motor vehicle safety systems. Another possible solution is to adapt the material thickness to the thickness of the paint layer to be applied later when designing or planning the corresponding outer skin component. But this is on the one hand also particularly time-consuming and on the other hand particularly economically disadvantageous, especially when the corresponding motor vehicle only optionally, that is, as an optional equipment, has a radar sensor. Yet another solution is to use an inductive grid, a thin metal layer, and / or a coated film on the inner side of the outer skin of the motor vehicle, by means of which the corresponding outer skin component is coordinated with the sensor operation of the radar sensor. But this is also particularly time-consuming because these elements have to be arranged and fixed correspondingly on the inner side of the outer skin element.

[0004] US 9812787 B2 discloses a system consisting of a radar sensor and an external covering component through which the microwaves of the radar sensor can pass. Here, the covering component has a substrate which is clad with an outer layer on the outer side. In addition, in this conventional system, an additional layer is provided on the inner side at the substrate, and the additional layer is configured, through its thickness and material-related dielectric constant, to reduce a certain proportion of the reflection of microwaves. However, the application of the additional layer on the inner side at the substrate of the covering component and the selection of the material for the additional layer are particularly time-consuming.

[0005] WO 2018101165 A1 and JP 2006287500 A respectively disclose covering elements for radar sensing devices, wherein a decorative element, such as a logo, is formed by or covered by means of the covering element. Summary of the Invention

[0006] The object of the present invention is to provide a covering element and a radar sensor unit, wherein the radar waves are particularly little affected by the covering element.

[0007] This object is solved according to the first aspect of the present invention by a method for manufacturing a covering element for a radar sensor unit of a motor vehicle, wherein a substrate of the covering element is provided and a wave passage area for the radar sensor is determined at the substrate; a primer layer is applied to the substrate on the outer side, and a topcoat layer is applied to the primer layer on the outer side; it is characterized in that, before applying the topcoat layer, an initial radar reflection value in the wave passage area of the substrate clad with the primer layer is determined, and a topcoat thickness of the topcoat layer is determined based on the initial radar reflection value, so as to compensate the initial radar reflection value of the substrate clad with the primer layer to a preset radar reflection target value of the covering element by applying the topcoat layer.

[0008] Furthermore, this object is solved according to the second aspect of the present invention by a covering element for a radar sensor unit of a motor vehicle.

[0009] Furthermore, this object is solved by a radar sensor unit for a motor vehicle.

[0010] The features, advantages, and advantageous designs of the covering element according to the invention can be regarded as the features, advantages, and advantageous designs of the radar sensor unit according to the invention and vice versa. If the advantages, features, and advantageous designs of the radar sensor unit or the covering element are described in connection with a method for manufacturing the covering element, then the advantages, features, and advantageous designs of the radar sensor unit or the covering element shall be regarded as the advantages, features, and advantageous designs of such a method for manufacturing the covering element. If the advantages, features, and advantageous designs of the method for manufacturing the covering element according to the invention are described in connection with the covering element and / or the radar sensor unit, then the advantages, features, and advantageous designs of the method for manufacturing the covering element shall be regarded as the advantages, features, and advantageous designs of such a covering element and / or radar sensor unit.

[0011] According to a first aspect of the invention, a method for manufacturing a covering element is provided. Here, the covering element is provided for a radar sensor unit, in particular for a radar sensor unit of a motor vehicle, such as a passenger car and / or a truck. The radar sensor unit is, for example, part of a driving assistance system and / or a safety system of a motor vehicle. As already explained above, - especially for visual reasons and / or to protect the radar sensor from environmental influences, etc. - there is a need to cover or shield the radar sensor of the radar sensor unit. For this purpose, a covering element is provided which can be manufactured or is manufactured by means of the manufacturing method described here.

[0012] In the method for manufacturing the covering element, a base body of the covering element is provided. In particular, the material of the base body has plastic or the base body consists entirely of plastic, i.e., of thermoplastic, thermosetting plastic, and / or elastomer. In addition, it is conceivable that the base body has a fiber-reinforced material.

[0013] At the base body, a wave passage region for the radar sensor is determined. This means identifying or providing a region of the base body in which the radar waves of the radar sensor pass through the material of the base body or the covering element. In other words, the wave passage region is provided to be passed through by the radar waves which are generated by the radar sensor in the operating mode of the radar sensor. For a completed or assembled radar sensor unit, this means that the radar sensor is arranged at or close to the wave passage region on the inner side of the base body or the covering element. Here, in particular, the transmitting unit and the receiving unit of the radar sensor face the wave passage region on the inner side of the base body. In other words, the radar sensor points towards the wave passage region on the inner side of the base body. Thereby, a wave vector is penetrated, i.e., the wave vector has the wave passage region for its origin at the transmitting unit of the radar sensor. Along the direction of the wave vector, the radar waves are sent from the radar sensor towards the wave passage region, pass through the wave passage region, and move away from the wave passage region on the outer side of the base body or the covering element.

[0014] In this method, further, a primer layer is applied to the substrate on the outside. Here, the primer layer has, for example, a colored paint and / or a pigmented paint, for example a metallic paint. When applying the primer layer to the substrate, in particular a primer with a primer thickness of one or up to a preset or presettable primer thickness is applied. Painting in particular includes pre-processing, by means of which a particularly favorable painting result is achieved or facilitated. The pre-processing in particular includes grinding of the substrate and cladding of the substrate with a filler in order to compensate for unevenness in the material of the substrate, so that a particularly smooth surface is produced when applying the primer layer. Alternatively or additionally, within the scope of the pre-processing, the substrate is provided with a primer (sometimes also called an undercoat) before applying the primer layer, whereby the primer adheres particularly strongly to the substrate by means of the primer. Since the aforementioned and possibly additional pre-processing is well known, it will not be discussed further here.

[0015] Further, in the method for manufacturing a covering element, a topcoat layer is applied to the primer layer on the outside. In particular, the topcoat layer is a colorless varnish, which serves as a protective layer for the primer layer. In addition, such a topcoat layer or varnish layer results in a particularly smooth surface of the covering element, thereby giving the covering element a particularly appealing appearance.

[0016] In order to now construct the covering element by means of the method such that the radar waves of the radar sensor are affected particularly little by the covering element, according to the invention, before applying the topcoat layer, the initial radar reflection value in the wave passage region of the substrate clad with the primer layer (and if possible with a filler and / or a primer) is determined. In addition, based on the initial radar reflection value, the topcoat thickness of the topcoat layer to be applied is determined in order to compensate the initial radar reflection value of the substrate clad with the primer layer to a preset radar reflection target value of the covering element by applying the topcoat layer to the substrate or to the primer layer. In other words, the first radar reflection value (initial radar reflection value) of the substrate clad with the primer layer, but still without the topcoat layer, is changed into the second radar reflection value (radar reflection target value) of the substrate or covering element then clad with the primer layer and with the topcoat layer by applying a topcoat layer with a previously determined topcoat thickness or up to a previously determined topcoat thickness to the substrate or to the primer layer.

[0017] Furthermore, it is conceivable to determine a corresponding radar transmission value (Radartransmissionswert) alternatively or in addition to the determination of the corresponding radar reflection value. In other words, it is possible to determine the initial radar transmission value in the wave passage area of a substrate coated with a primer layer (and, if possible, with a filler and / or an undercoat) before applying the topcoat. Then, based on the initial radar transmission value, the topcoat thickness is determined in order to compensate the initial radar transmission value of the substrate coated with the primer layer to a preset radar transmission target value of the covering element by applying the topcoat layer to the substrate or to the primer layer. The corresponding radar transmission value is determined here according to the operating frequency of the radar sensor, in particular the operating frequency range.

[0018] In order to determine the first radar reflection value or the initial radar reflection value, for example, it is conceivable to radiate the substrate coated with the primer layer with radar waves from the inside by means of the radar sensor of the radar sensor unit and / or by means of an additional radar sensor in such a way that the radar waves strike the substrate in the wave passage area on the inside and pass through the substrate in the wave passage area, so that the radar waves propagate further from the wave passage area on the outside of the substrate. The radar sensor and / or the additional radar sensor are operated here in such a way that the substrate is radiated with radar waves of a plurality of radar wave frequencies in order to determine the radar reflection value according to the respective radar wave frequency. Thereby, the minimum value of the radar reflection value of the substrate corresponding to one of the radar wave frequencies is emphasized, where the minimum value related to the respective radar wave frequency is the initial radar reflection value. Thus, the initial radar reflection value is the minimum value of the reflectivity of the substrate at a determined radar wave frequency.

[0019] At least a part of the radar waves generated by the radar sensor is reflected at the wave passage area on the inside of the substrate, and the reflected radar waves (reflected radar waves) are received by the receiving unit of the radar sensor. Briefly, the initial radar reflection value is measured by detecting the fraction of the radar waves generated by the respective radar sensor at one of the radar wave frequencies that are - instead of passing through the substrate - reflected on the inside of the substrate. For the measurement of the initial radar transmission value, the fraction of the radar waves generated by the respective radar sensor at one of the radar wave frequencies that - instead of being reflected on the inside of the substrate - penetrate the substrate is detected.

[0020] The radar reflection value or radar transmission value of a material or a material layer is related to the thickness and dielectric constant of the corresponding material. In addition, the dielectric constant of the topcoat and the initial radar reflection value or initial radar transmission value (i.e., the radar reflection value / radar transmission value of the substrate coated with the primer layer without the topcoat) are known. In addition, the operating frequency of the radar sensor, which should be arranged inside the substrate or the covering element, is known. The aim of the method is to manufacture the covering element by applying the topcoat layer in such a way that the covering element has a minimum value for the reflectivity of radar waves with the operating frequency. In other words, by means of the method, it is achieved that the radar reflection target value has a minimum value for the reflectivity of the covering element in the operating frequency, especially in the operating frequency range. In other words, by means of the method, the minimum value of the radar reflectivity is "shifted into the operating frequency range". Thus, if the covering element is irradiated with radar waves having the operating frequency, there is a minimum value corresponding to the operating frequency of the radar reflection value of the covering element.

[0021] It is possible to determine the desired thickness of the topcoat layer to be applied based on the radar reflection target value or radar transmission target value (i.e., the desired radar reflection value / radar transmission value of the substrate or covering element coated not only with the primer layer but also with the topcoat layer) and based on the operating frequency, for example by means of extreme value calculation, computer-aided simulation, etc. In particular, for this purpose, the operating frequency of the radar sensor to be arranged inside the covering element is used as a boundary condition. By applying the topcoat layer with the previously determined topcoat thickness, the initial radar reflection value and / or initial radar transmission value of the substrate coated with the primer layer is thus at least partially compensated - especially by applying the topcoat layer in such a way that the reflectivity or the desired measure of reflection, especially the minimum value, of the substrate coated with the primer layer is shifted into a preset or presettable frequency range. Alternatively or additionally, by applying the topcoat layer, the desired measure of the transmittance ("transmission rate") of the substrate coated with the primer layer, for example the minimum value, is shifted into a preset or presettable frequency range. The preset / presettable frequency range is especially the operating frequency range of the radar sensor, where the operating frequency range includes the operating frequency or more than one operating frequency.

[0022] For this purpose, the application of a topcoat layer with the desired topcoat thickness is advantageously used to produce the desired reflection behavior or transmission behavior of the covering element. Thereby, the desired radar reflection target value and / or radar transmission target value of the covering element can be reliably established, wherein even manufacturing-related tolerances of the substrate and / or the primer layer are compensated for by the appropriately selected or adapted topcoat thickness. Thereby, the radar transmissivity or radar reflectivity of the covering element can be adjusted particularly efficiently when manufacturing the covering element, namely individually, i.e., according to the respective operating frequency of the radar sensor used, according to the respective thickness and dielectric constant of the primer, and / or according to the thickness and dielectric constant of the substrate. In particular, the radar transmissivity or radar reflectivity in the wave passage region is adjusted particularly efficiently by manufacturing the covering element or during the manufacturing of the covering element. Furthermore, it is conceivable that - i.e., not only in the wave passage region but also outside the wave passage region - the entire covering element is manufactured accordingly, such that the entire covering element has a unique radar reflection value or radar transmission value. Herein, the primer layer forms the first coating layer of the covering element, and the topcoat layer forms the second coating layer of the covering element.

[0023] An important concept of the present invention is to change as few, in particular only a single, process parameter when manufacturing the covering element in order to, in particular, produce the desired radar reflection target value when manufacturing the covering element. This is currently achieved by a method for manufacturing the covering element. Other measures or means for influencing the radar reflection value of the covering element are suitably dispensed with. Thereby, for example, the application of additional (third) coating layers, such as induction grids, metal films, etc., is dispensed with. It follows therefrom that the covering element is manufactured particularly efficiently and material-efficiently by means of the proposed method. Furthermore, the covering element has particularly few components. In particular, the covering element has exactly those components that it would have if it were not optimized with respect to radar transmissivity. The acquisition and maintenance of additional tools are dispensed with, and the compensation of the initial radar reflection value or the shift of the reflectivity or the desired minimum value of the reflection into a preset or presettable frequency range is achieved particularly precisely by applying the topcoat layer.

[0024] Herein, the determination or acquisition of the topcoat thickness is described with reference to the radar reflection characteristics at the inner side of the covering element. It is to be understood that, alternatively or additionally, the radar reflection characteristics at the outer side of the covering element can be considered in a similar manner or can be taken into account in the method for determining the topcoat thickness.

[0025] In a further design of the method, the determination of the topcoat thickness is carried out by means of a computing unit. The computing unit is a non-human computing unit, for example a calculator unit. The (non-human) computing unit then - after the computing unit has determined or obtained the desired topcoat thickness - provides the painting device directly or indirectly with a control data record for applying a topcoat layer having the topcoat thickness. In other words, the computing unit generates a control data record, wherein the painting device is configured to receive the control data record as control data. This means that the painting device applies the topcoat layer to the primer layer according to the control data record (especially automatically). For this purpose, the computing unit and the painting device are interconnected or at least connectable to each other for transmitting the control data record. The provision of the control data record can be carried out directly or indirectly here. The indirect provision of the control data record should be understood, for example, as the computing unit generating a control data record, for example writing it to a data carrier. This data carrier is then brought to the painting device, for example by a human worker, and connected to the painting device, so that the painting device then calls the control data stored on the data carrier. The direct provision of the control data record is, for example, a direct data connection between the computing unit and the painting device, so that the control data record generated by the computing unit is directly provided to the painting device via the data connection. For example, the computing unit and the painting device can be interconnected wirelessly and / or wired for data communication.

[0026] By determining the topcoat thickness by means of a computing unit or a calculator unit and providing the topcoat thickness to the painting device directly or indirectly in the form of a control data record, the method is particularly reliable because, in particular, human error sources are excluded. Since advantageously the painting device is a non-human painting device, for example a painting robot, a painting line (Lackierstraße), etc., the desired topcoat thickness of the covering element and thus the desired radar reflection target value are particularly precisely and reliably achieved when applying the topcoat layer.

[0027] According to another design of the method, it is advantageously arranged that when providing the substrate, different material properties are produced in the wave-passing region than outside the wave-passing region. For example, the substrate has been at least roughly adapted to the desired or to-be-achieved radar reflection target value in the wave-passing region during the manufacture of the substrate. For example, the substrate can be provided or manufactured such that the substrate has a different material in the wave-passing region than outside the wave-passing region. Furthermore, it is conceivable that when providing or manufacturing the substrate, the substrate has a different material thickness in the wave-passing region than outside the wave-passing region. Here, when providing the substrate, it is not particularly necessary to maintain very precise tolerances, because - as already mentioned - possible tolerances are compensated for by applying the topcoat layer when providing or manufacturing the substrate. By at least roughly adapting the wave-passing region to the to-be-achieved reflection target value and then applying the topcoat layer, a more precise implementation or adjustment of the radar transmissivity characteristics of the covering element is thus obtained, i.e., a more precise adjustment of the minimum value of the radar reflectivity of the covering element.

[0028] In order to continuously achieve the best possible results in terms of the radar reflection target value in the covering element during mass production of the covering element, especially within the scope of mass vehicle manufacturing, according to another advantageous design of the method, it is arranged that for manufacturing a batch of such covering elements, the determination of the topcoat thickness is carried out at each substrate of the substrates of the batch coated with the primer layer. Correspondingly, at the first substrate of the batch coated with the primer layer, the initial radar reflection value is determined or measured before applying the topcoat layer and the topcoat thickness determined accordingly is taken into account in order to correspondingly provide the first substrate of the batch with the topcoat layer. This process is then repeated for all the other covering elements of the batch. Thus, in each covering element of the batch, the initial radar reflection value is first measured, then the required or desired topcoat thickness is determined and then the corresponding substrate coated with the primer layer is coated with the topcoat layer. Thus, a 100%-check is produced, thereby ensuring a constant quality during mass production of the covering element.

[0029] Regarding mass production of the covering element, according to an alternative embodiment of the method, it is conceivable that for manufacturing a batch of such covering elements, the determination of the topcoat thickness is carried out at one substrate of the substrates of the batch coated with the primer layer, especially at a single substrate. In particular, at the first substrate of the batch coated with the primer layer, the initial radar reflection value is first measured, then the required or desired topcoat thickness is determined and then the substrate is provided with the topcoat layer, where in this case the desired or required topcoat thickness is stored and used for the remaining batches. This means that the determination or measurement of the corresponding initial radar reflection value of another substrate of the batch is dispensed with, whereby the cycle time of the mass manufacturing process of the corresponding covering elements is advantageously particularly small.

[0030] According to a second aspect of the present invention, a covering element for a radar sensor unit of a motor vehicle is proposed. Here, the covering element is manufactured by means of the method described in the above specification. The covering element is furthermore arranged to cover or enclose the radar sensor of the radar sensor unit, such that due to the covering element, an observer arranged in the surroundings of the radar sensor unit is prevented from directly seeing the radar sensor.

[0031] According to an advantageous design of the covering element, the covering element is an outer skin component for a motor vehicle. In other words, the outer skin component for the motor vehicle is formed by the covering element. For example, the covering element or the outer skin component is a fender, a bumper, a cover element (such as a trunk lid, an engine hood), a transmissive surface of an external lighting device of the motor vehicle, etc. By forming the outer skin component for the motor vehicle by means of the covering element, a particularly efficient and material-efficient manufacture of the motor vehicle is achieved. Furthermore, the radar sensor unit or the radar sensor to be covered by means of the covering element can be integrated into the motor vehicle particularly unobtrusively, thereby ensuring a particularly appealing visual appearance of the motor vehicle or the radar sensor unit. Thereby, the acceptance on the part of the customer of the radar sensor unit or the motor vehicle is advantageously increased. This in turn leads to increased traffic safety, since such a radar sensor unit with such a covering element is in particular part of a driving assistance system and / or a motor vehicle safety system, which contributes to a particularly reliable driving operation of the motor vehicle.

[0032] It has furthermore proven to be advantageous in the covering element that a marking for the motor vehicle is arranged on the outside of the covering element at the wave passage region of the covering element. The marking can be, for example, a model of the respective motor vehicle and / or a nameplate of the motor vehicle manufacturer. Thereby, a synergistic effect is obtained during the manufacture of the covering element, since on the one hand, markings of motor vehicles are nowadays usually three-dimensionally structured, i.e., protrude from the outer surface of the motor vehicle. This protrusion from the outer surface of the motor vehicle can then advantageously be used as a radome for the underlying radar sensor, wherein the marking or the radome is coated with a topcoat layer by means of the method for manufacturing the covering element or the outer skin component, and the preset or determined topcoat thickness is maintained. Thus, if the covering element has a marking of the motor vehicle, the covering element fulfills a dual function, namely - firstly - the radar sensor can be covered or shielded particularly efficiently by means of the covering element, and - secondly - a radome for the radar sensor is formed by the covering element.

[0033] The invention also includes the following improvement of the covering element according to the invention, which improvement has the features already described in connection with the improvement of the method according to the invention. For this reason, the corresponding improvements of the covering element according to the invention are not described again here.

[0034] According to a third aspect of the present invention, a radar sensor unit for a motor vehicle is provided. The radar sensor unit has a radar sensor and a covering element constructed according to the above description. The covering element has a substrate, and a topcoat layer of an outer primer layer and a covering primer layer is applied to the substrate, and a wave passing region for the radar sensor is constructed at the substrate. The radar sensor is arranged inside the wave passing region such that, in the operating mode of the radar sensor, the radar waves emitted by the radar sensor radiate through the wave passing region of the covering element. Here, it is conceivable that the radar sensor is directly fixed to the substrate, especially in the wave passing region. Alternatively, it is conceivable that the radar sensor is spaced apart from the substrate by a distance on the inside.

[0035] Furthermore, in the radar sensor unit according to the third aspect of the present invention, it is proposed that, before applying the topcoat layer, the initial radar reflection value of the substrate coated with the primer layer in the wave passing region is determined and the topcoat thickness of the topcoat layer to be applied is determined based on the initial radar reflection value, so that the initial radar reflection value of the substrate coated with the primer layer is compensated to a preset radar reflection target value of the covering element by applying the topcoat layer. This means that the radar reflection target value is achieved by applying the topcoat layer with the previously determined topcoat thickness.

[0036] The present invention also includes the following improvement schemes of the radar sensor unit according to the present invention, and the improvement schemes have the features already described in connection with the improvement schemes of the method for manufacturing the covering element according to the present invention or in connection with the improvement schemes of the covering element according to the present invention. For this reason, the corresponding improvement schemes of the radar sensor unit according to the present invention are not elaborated once again here.

[0037] The present invention also includes combinations of the features of the described embodiments. Description of the Drawings

[0038] The embodiments of the present invention are described below. For this purpose:

[0039] Figure 1 A flowchart is shown to illustrate the method for manufacturing the covering element;

[0040] Figure 2 A schematic and sectional view of the substrate of the covering element is shown, where the substrate is coated with the primer layer; and

[0041] Figure 3 A schematic and sectional view of the substrate or the covering element is shown, where the topcoat layer is applied to the primer layer. Detailed Description of the Embodiment

[0042] The embodiments described below are preferred embodiments of the present invention. In this embodiment, the components described in the embodiment respectively constitute individual features of the present invention that should be considered independently of each other. These features respectively improve the present invention independently of each other and should thus be regarded as components of the present invention individually or in combinations different from those shown. In addition, the described embodiments can also be supplemented by additional features of the features of the present invention that have already been described.

[0043] Elements having the same function are respectively provided with the same reference signs in the drawings.

[0044] The method for manufacturing the covering element 1, the covering element 1 itself, and the radar sensor unit 2 are described together below.

[0045] Figure 1 In order to clarify the method for manufacturing the covering element 1 (see Figure 3 ), a flow chart is shown. In the method for manufacturing the covering element 1, in a first method step S1, a substrate 3 of the covering element 1 is provided (see Figure 2 ). This means that in the first method step S1, the substrate 3 is, for example, manufactured or otherwise supplied to the method for manufacturing the covering element 1. The substrate 3 is provided as a substrate 3 having plastic in the present example. The substrate 3 is manufactured or provided, for example, by shaping a plastic material (e.g., by casting) into the substrate 3. In addition, it is conceivable that the material of the substrate 3 has reinforcing fibers for achieving particularly advantageous mechanical properties of the substrate 3. The substrate 3 is particularly provided for a motor vehicle, for example, as a buffer ("bumper") for a motor vehicle and / or (additional) outer skin member. In particular, the motor vehicle is a passenger car and / or a truck.

[0046] After providing the substrate 3, for example, in a further method step S2, a wave passage region 4 for the radar sensor 5 is determined at the substrate 3, wherein the wave passage region 4 and the radar sensor 5 are first shown in Figure 2 . As can be seen in Figure 2 , the wave passage region 4 is a defined, for example, preset region of the substrate 3, wherein this defined region - namely the wave passage region 4 - and the radar sensor 5 are assigned to each other. The radar sensor 5 is arranged at or on the inner side 6 of the substrate 3. In other words, the radar sensor 5 is arranged inside the substrate 3. Here, it is conceivable that the radar sensor 5 is directly fixed to the substrate 3 in the wave passage region 4. In the following example, the radar sensor 5 is spaced apart from the substrate 3 by a distance.

[0047] In a further method step S3, a primer layer 7 is applied to the outer side 8 of the substrate 3. In other words, the substrate 3 is coated on the outer side with a primer so that the primer layer 7 is formed at the outer side 8 of the substrate 3. This means that the covering element 1 has a first applied layer which is formed by the primer layer 7 or which is the primer layer. The primer of the primer layer 7 in particular has a colored paint, wherein the colored paint and thus the primer layer 7 have effect particles for achieving a visually particularly appealing effect. In other words, the colored paint used to form the primer layer can be a metallic paint.

[0048] For a further method step S4, there is thus a substrate 3 coated with the primer layer 7. In method step S4, the radar-related initial value of the substrate 3 coated with the primer layer is now determined in the wave passage region 4. The radar-related initial value of the substrate 3 is, for example, a radar transmission value, i.e., a value by means of which it is characterized to what extent the substrate 3 can allow radar waves to pass through its material. In the present example, the radar-related initial value is a radar reflection initial value denoted by R0.

[0049] The substrate 3 coated with the primer layer 7 is irradiated, for example, by means of a radar sensor 5 with radar waves of a plurality of radar wave frequencies in order to determine the radar reflection initial value R0 related to the respective radar wave frequency. The first portion of the radar waves penetrates the substrate 3 coated with the primer layer 7 in the wave passage region 4, wherein the further portion of the radar waves is reflected on the inner side of the substrate, i.e., on the inner side 6 of the substrate 3, in the wave passage region 4. Thereby, the radar reflection initial value R0 is determined as the minimum value of the reflectivity of the substrate 3 at a determined radar wave frequency.

[0050] However, for the particularly efficient operation of the radar sensor 5 arranged inside the covering element 1, in particular inside the substrate 3, it can be aimed to ensure that the portion of the radar waves reflected at the inner side 6 of the substrate 3 is particularly small at the operating frequency of the radar sensor 5. In other words, for the covering element 1, a radar reflection target value R1 can be aimed for which is different from the radar reflection initial value R0. The radar reflection target value R1 is here the minimum value of the reflectivity of the covering element 1 which is irradiated with radar waves having the operating frequency.

[0051] In order to achieve the minimum radar reflection target value R1, in the present example, it is set in method step S2 that the wave passing region 4 is configured such that only a particularly small fraction of the radar waves emitted by the radar sensor 5 is reflected at the wave passing region 4. This can be achieved, for example, by the fact that the substrate 3 has different material properties in the wave passing region 4 than outside the wave passing region 4. For example, the substrate 3 has a smaller material thickness in the wave passing region 4 than outside the wave passing region 4. Additionally, it is conceivable that the substrate 3 has a different material in the wave passing region 4 - and thus has a different material-related dielectric constant. In this method, it is especially set that, by prescribing or determining the wave passing region 4, the substrate 3 has particularly favorable radar transmissibility in the wave passing region 4 or at the wave passing region 4. In other words, the substrate 3 then has such material properties in the wave passing region / at the wave passing region 4 that the fraction of the radar waves reflected at the inner side 6 of the substrate 3 is particularly small.

[0052] The radar reflection target value R1 that the finished covering element 1 should have is determined by calculation, since the dimensions or parameters of the substrate 3 coated with the primer layer 7 and the operating frequency range 9 of the radar sensor 5 are known. This means that the material thickness of the substrate 3, the material-related dielectric constant of the substrate 3, the thickness of the primer layer 7, and the material-related dielectric constant of the primer - especially the dielectric constant in the wave passing region 4 respectively - are known. Since the minimum value of the reflection behavior of the substrate 3 coated with the primer layer 7 is related to the operating frequency range 9 of the radar sensor 5, the radar reflection target value R1 is calculated according to the operating frequency range 9 of the radar sensor 5, especially according to the operating frequency. This means that there are different radar reflection target values R1 for each operating frequency range 9 of the radar sensor 5. In this regard, the operating frequency range 9 or the operating frequency affects the calculation / determination of the radar reflection target value R1 as a boundary condition in the form of data or as a data record. The operating frequency range 9 has the operating frequency or multiple operating frequencies of the radar sensor 5.

[0053] Therefore, in order to manufacture the covering element 1 such that it has a radar reflection target value R1 after its manufacture, which means that the covering element 1 is then optimally adapted to the operating frequency range 9 of the radar sensor 5, the initial radar reflection value R0 is changed or compensated by applying the topcoat layer 10 on the outside, i.e., at the outside 8, to the primer layer 7. Here, the initial radar reflection value R0 is influenced by the topcoat thickness of the topcoat layer 10 to be applied such that, in the case of the manufactured covering element 1, instead of the initial radar reflection value R0, there is a radar reflection target value R1 for the operating frequency. Since (as already described) all the decisive parameters or dimensions of the substrate 3 coated with the primer layer 7 and the operating frequency range 9 of the radar sensor 5 are known, and furthermore the material-related dielectric constant of the topcoat is known, the topcoat thickness is now determined.

[0054] Therefore, if the topcoat layer 10 with the said or until determined or determined topcoat thickness is coated on the primer layer 7, the initial radar reflection value R0 of the substrate 3 coated with the primer layer 7 is changed to the radar reflection target value R1 of the covering element 1. Because the manufacture of the covering element 1 includes the application of the topcoat layer 10 on the primer layer 7. In other words, the covering element 1 is manufactured in the case of applying the topcoat layer 10 on the primer layer 7. Due to the topcoat layer 10 with a completely specific topcoat thickness, the initial radar reflection value R0 is compensated to a preset or presettable radar reflection target value R1. Here, the application of the topcoat layer 10 takes place in a further method step S6. Thereby, the covering element 1 has a second coating layer, which is formed by the topcoat layer 10 or which is the topcoat layer.

[0055] Furthermore, in the method for manufacturing the covering element 1, it is conceivable to take into account the radar reflection target value R1 and / or the operating frequency range 9 when providing the wave passage region 4. In other words, it can be arranged that a substrate 3 with a wave passage region 4 is provided, where the radar reflection target value R1 and / or the operating frequency range 9 are already taken into account when constructing or providing the wave passage region 4 in order to endow the substrate 3, especially in the wave passage region 4, with particularly advantageous properties, thus achieving an optimal reflection behavior at the inside 6 of the substrate 3.

[0056] Furthermore, in this example, it is set that the determination of the topcoat thickness (by means of which the initial radar reflection value R0 is compensated to the target radar reflection value R1 during the manufacture of the covering element 1) is carried out by means of a computing unit (not shown). In particular, the computing unit is thus a calculator unit. The topcoat thickness determined by means of the computing unit is then provided in the form of data of a painting device (not shown), for example in the form of a control data record, wherein the painting device is configured to convert the control data record as a control instruction. Furthermore, the painting device is configured to apply a topcoat layer 10 with the provided topcoat thickness to the outer side 8 of the primer layer 7 or the substrate 3. This means that the painting device is, for example, a painting line, a painting robot, etc.

[0057] In the mass production of the covering element 1, in this method it is in particular set that the method steps S4, S5 are carried out again for each individual covering element 1 of a common batch. This means that for each individual substrate 3 coated with the primer layer 7, the initial radar reflection value R0 is measured or determined individually or separately and - also individually or separately for each - the corresponding topcoat thickness is determined. In an alternative design of the mass production of the covering element, it is conceivable that, in order to manufacture a batch of covering elements 1, the determination of the topcoat thickness is carried out at only one single substrate 3 coated with the primer layer 7, in particular at the first substrate 3 coated with the primer layer 7. In other words, in the first substrate 3 coated with the primer layer 7 and without the topcoat layer 10, the initial radar reflection value R0 is determined or measured and the topcoat thickness is determined. The topcoat thickness determined from the first substrate 3 of the batch is then used for the remaining substrates 3 of the batch coated with the corresponding primer layer 7 in order to apply the topcoat layer 10.

[0058] Figure 2 The substrate 3 of the covering element 1 is shown in a schematic and sectional view, wherein the substrate 3 is coated with the primer layer 7 but (still) does not have the topcoat layer 10. In this regard Figure 2 the following state is depicted, in which the substrate 3 coated with the primer layer 7 is irradiated with radar waves on the inner side, i.e. on the inner side 6 of the substrate 3, by means of the radar sensor 5 and / or by means of a further radar sensor for measuring or determining the initial radar reflection value R0. The covering element 1 is then manufactured by applying the topcoat layer 10, for example by means of a painting unit, on the outer side, i.e. on the outer side 8 of the substrate 3, which covering element is shown in Figure 3 this.

[0059] Accordingly, Figure 3 the covering element 1, i.e. the substrate 3, is shown in a schematic and sectional view, wherein the topcoat layer 10 is applied to the primer layer 7. Furthermore, in Figure 3Figure 2 shows a radar sensor unit 2, which has a covering element 1 and a radar sensor 5. Here, for example, it is arranged that the radar sensor unit 2 - if the radar sensor unit is installed in a motor vehicle or car not shown - is located on the inner side of the outer skin member of the motor vehicle. In an advantageous design, the covering element 1 forms the corresponding outer skin member of the motor vehicle. Alternatively or additionally, a logo of the motor vehicle is arranged on the covering element 1 and / or the logo of the motor vehicle is at least partially formed by the covering element 1 of the motor vehicle. In particular, the covering element 1 is a logo. Thus, for example, the covering element 1 can be a radome or an antenna cover, and the radar sensor 5 transmits radar waves through the radome or the antenna cover in the operating mode.

[0060] Overall, the present invention shows the following feasible solution. In this feasible solution, depending on the topcoat, a unique total thickness of the covering element 1 can be produced during the manufacture of the covering element. Then, the covering element 1 has particularly advantageous characteristics in terms of radar transmissivity. Correspondingly, the radar waves emitted by the radar sensor 5 are obstructed particularly little by the covering element 1 because the covering element 1 can only reflect a minimum portion of the radar waves emitted by the radar sensor 5 on the inner side, that is, at the inner side 6 of the covering element 1. This corresponds to the manufacture of the covering element 1, in which the covering element is adjusted to the radar reflection target value R1 by applying a topcoat layer 10 with a previously determined or obtained topcoat thickness onto a primer layer 7. Here, in particular, it should be understood that the covering element 1 has a total of three layers. The first layer is formed by the substrate 3, the second layer is formed by the first coating layer or by the primer layer 7, and the third layer (which is the second coating layer) is formed by the topcoat or by the topcoat layer 10. The second layer may include fillers and / or undercoats if possible. In the covering element 1, other layers are appropriately omitted, and nevertheless, particularly advantageous radar transmissivity, that is, the desired radar reflection target value R1, is produced.

[0061] List of reference numerals

[0062] 1 Covering element

[0063] 2 Radar sensor unit

[0064] 3 Substrate

[0065] 4 Wave passing region

[0066] 5 Radar sensor

[0067] 6 Inner side

[0068] 7 Primer layer

[0069] 8 Outer side

[0070] 9 Operating frequency range

[0071] 10 Topcoat layer

[0072] Initial value of R0 radar reflection

[0073] Target value of R1 radar reflection

[0074] Steps of method S1

[0075] Steps of method S2

[0076] Steps of method S3

[0077] Steps of method S4

[0078] Steps of method S5

[0079] Steps of method S6.

Claims

1. A method for manufacturing a covering element (1) for a radar sensor unit (2) of a motor vehicle, wherein, Provide a substrate (3) of the covering element (1), and define a wave passage region (4) for the radar sensor (5) at the substrate (3); apply a primer layer (7) on the outside of the substrate (3), and apply a topcoat layer (10) on the outside of the primer layer (7); It is characterized in that Before applying the topcoat layer (10), determine the initial radar reflection value (R0) of the substrate (3) covered with the primer layer (7) in the wave passage region (3), and determine the topcoat thickness of the topcoat layer (10) based on the initial radar reflection value (R0), so that the initial radar reflection value (R0) of the substrate (3) covered with the primer layer (7) is compensated to a preset radar reflection target value (R1) of the covering element (1) by applying the topcoat layer (10).

2. The method according to claim 1, wherein The determination of the topcoat thickness is carried out by means of a calculation unit, and the calculation unit provides a control data record to the painting device for applying a topcoat layer (10) with the topcoat thickness.

3. The method according to claim 1 or 2, characterized in that, When providing the substrate (3), generate material properties different from those outside the wave passage region (4) in the wave passage region (4).

4. The method according to claim 1 or 2, characterized in that, To manufacture a batch of such covering elements (1), the determination of the topcoat thickness is carried out at each substrate of the substrates (3) of the batch covered with the primer layer (7).

5. The method according to claim 1 or 2, characterized in that, To manufacture a batch of such covering elements (1), the determination of the topcoat thickness is carried out at one substrate of the substrates (3) of the batch covered with the primer layer (7).

6. A covering element (1) for a radar sensor unit (2) of a motor vehicle, wherein, The covering element (1) is manufactured by means of the method according to any one of claims 1 to 5.

7. The covering element (1) according to claim 6, characterized in that, The covering element (1) is an outer skin member for the motor vehicle.

8. The covering element (1) according to claim 6 or 7, characterized in that, A sign for the motor vehicle is arranged at the wave passage region (4) on the outside of the covering element (1).

9. A radar sensor unit (2) for a motor vehicle, the radar sensor unit having a radar sensor (5) and a covering element (1) according to claim 6, 7 or 8, the covering element including a substrate (3), applying a primer layer (7) and a topcoat layer (10) covering the primer layer (7) on the outside of the substrate, and constructing a wave passage region (4) for the radar sensor (5) at the substrate, and arranging the radar sensor (5) inside the wave passage region (4) such that in the operating mode of the radar sensor (5), the radar waves emitted by the radar sensor (5) radiate through the wave passage region (4) of the covering element, It is characterized in that Before applying the topcoat layer (10), determine the initial radar reflection value (R0) of the substrate (3) coated with the primer layer (7) in the wave passage region (4), and determine the topcoat thickness of the topcoat layer (10) based on the initial radar reflection value (R0), so that by applying the topcoat layer (10), the initial radar reflection value (R0) of the substrate (3) coated with the primer layer (7) is compensated to a preset radar reflection target value (R1) of the covering element (1).

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