Automotive parts including de-icing devices intended to be installed opposite the radar sensor radiation cone of a vehicle.

Abstract

The invention relates to an automotive part (2) intended to be placed against the radiation cone of a radar sensor (4), the radar sensor (4) being configured to radiate electromagnetic waves (6) whose electric field comprises a component (E1) oscillating in a direction of interest (P1), said part (2) comprising a device (12) for de-icing the part (2). According to the invention, the de-icing device (12) comprises a set (13) of elongated heatable elements (14), at least a subset of the set of elongated heatable elements (14) being arranged to be placed in the radiation cone of the radar sensor (4) when the part (2) is placed against the radar sensor (4) and configured to be placed on the part (2) such that each of the elongated heating elements (14) of the subset extends in a direction substantially perpendicular to the main polarization direction (P1) of the radar sensor.

Description

Technical Field

[0001] The present invention belongs to the field of integration of radar sensors in automobiles, and more particularly to the field of de-icing devices for automobiles that enable the maintenance of the reliability of detection by such radar sensors. The present invention relates to automotive parts including such de-icing devices, particularly intended to be installed facing the radiation cone of the radar sensor of a vehicle.

Background Art

[0002] Autonomous or semi-autonomous vehicles require a number of sensors to receive an abundance of data from around the vehicle to prevent collisions and ensure the vehicle arrives safely at its destination. Many of these sensors are radar sensors, which are installed at predetermined locations on the vehicle to capture as much data as possible. Vehicle lighting devices (such as headlights and taillights) are generally in advantageous locations for such radar sensors, even though other locations on the vehicle are possible.

[0003] The electromagnetic waves emitted by such radar sensors are generally linearly polarized. By convention, the polarization of an electromagnetic wave describes the vibration of the electric field. When an electromagnetic wave is linearly polarized, its electric field vibrates in only one direction, which is the main polarization direction, usually the horizontal polarization direction or the vertical polarization direction.

[0004] One problem associated with integrating such radar sensors in automobiles is the need for a radar sensor that can detect external objects regardless of the weather conditions under which the vehicle is operating. However, at temperatures below the threshold of 0°C, there is a high possibility of a frost layer forming at the radiation / reception location of the vehicle's radar sensor. Such a frost layer reflects and absorbs most of the radar waves emitted due to the very high refractive index of water. As a result, the radar range may be significantly reduced, and the detection function of the radar sensor may no longer be usable within the vehicle.

[0005] To address this problem, there are known cases where de-icing devices that allow the radar sensor's detection function to be maintained are used at the vehicle's radar sensor's receiving location.

[0006] For example, the publicly available International Publication No. 2020 / 239380 discloses such a de-icing device for vehicle components prone to icing problems (e.g., such as radar sensors). The de-icing device is installed outside the radar sensor's radiation cone at the end of the radar sensor housing. Heat for de-icing is transferred to the de-icing device using a conductive elastomer material. The electricity applied to the elastomer material generates the heat necessary for de-icing.

[0007] However, such de-icing devices cannot be installed inside the radar sensor's radiation cone without affecting the electromagnetic waves emitted by the radar sensor. As a result, the space available for the de-icing device within the radar sensor housing on the vehicle is relatively limited, as it is confined to the edges of the housing. This limits the size of the de-icing device and considerably restricts the de-icing speed. Furthermore, this de-icing speed depends on the electrical conductivity of the elastomer material used. [Overview of the project] [Problems that the invention aims to solve]

[0008] This invention improves this situation.

[0009] One of the objects of the present invention is to provide an automotive component including a de-icing device intended to be installed opposite the radiation cone of a vehicle's radar sensor, which can be installed inside the radar sensor's radiation cone without affecting the electromagnetic waves emitted by the radar sensor and therefore without impairing the efficiency of the radar sensor while having a high de-icing speed. [Means for solving the problem]

[0010] For this purpose, a first aspect of the present invention relates to an automotive component intended to be installed opposite the radiating cone of a radar sensor of a vehicle, wherein the radar sensor is configured to radiate electromagnetic waves within the radiating cone, the electric field of the electromagnetic waves radiated by the radar sensor includes a component that oscillates in the direction of interest, the electromagnetic waves propagate in the principal propagation direction, and the automotive component has a device on one of its surfaces for de-icing itself. The radiating cone of the radar sensor corresponds to the angular region radiated by the radar sensor. This angular region has a principal direction that corresponds to the principal propagation direction of the electromagnetic waves where the amplitude of the electromagnetic waves is maximum. The direction of interest of the electric field of the electromagnetic waves corresponds to a preferred direction perpendicular to the principal propagation direction of the electromagnetic waves. The electric field of the electromagnetic waves radiated by the radar sensor can be unpolarized or linearly polarized (typically vertical or horizontal, or any linear direction other than vertical or horizontal). If the radar sensor is linearly polarized in the principal polarization direction (e.g., horizontal or vertical), the direction of interest corresponds to this principal polarization direction. In this case, the electric field of the electromagnetic waves includes only the component of interest.

[0011] According to the present invention, the de-icing device includes a set of elongated heating elements, at least one subset of the set of elongated heating elements being positioned within the radiation cone of the radar sensor when the automotive part is installed facing the radar sensor, and each of the elongated heating elements of the subset being positioned on the automotive part is positioned such that it extends in a direction substantially perpendicular to the direction of interest of the electric field of the electromagnetic waves radiated by the radar sensor when the automotive part is installed facing the radar sensor.

[0012] Therefore, due to the orientation of the elongated heating element positioned within the radar sensor's radiation cone, which is placed on the automotive part so as to extend in a direction substantially perpendicular to the direction of interest of the electric field of the electromagnetic waves emitted by the radar sensor, the de-icing device allows the component of interest of the electromagnetic waves to pass through. This component of interest is hardly reflected by the elongated heating element and is transmitted almost completely to the opposite side of the de-icing device. The device for de-icing automotive parts according to the present invention can therefore be installed inside the radar sensor's radiation cone without affecting the electromagnetic waves emitted by the radar sensor and thus without impairing the efficiency of the radar sensor. Furthermore, by changing the number and density of the elongated heating elements, the de-icing speed can be advantageously increased compared to prior art devices.

[0013] According to a preferred embodiment of the present invention, the elongated heating element extends within the same plane, and the plane extends perpendicular to the main propagation direction of the electromagnetic waves radiated by the radar sensor.

[0014] According to one embodiment of the present invention, elongated heating elements extend parallel to each other in the plane, and the set of elongated heating elements forms a grid polarization.

[0015] According to the first embodiment of the present invention, the elongated heating elements are arranged such that the distance between two adjacent elongated heating elements is constant.

[0016] According to one embodiment of the present invention, the distance separating two adjacent elongated heating elements is smaller than the wavelength of electromagnetic waves emitted by the radar sensor.

[0017] According to one embodiment of the present invention, the distance separating two adjacent elongated heating elements is less than 5 mm, preferably 1 mm to 5 mm, and more preferably 2 mm to 4 mm.

[0018] According to one embodiment of the present invention, the ratio of the width of each elongated heating element to the wavelength of the electromagnetic waves emitted by the radar sensor is less than 1 / 10.

[0019] According to one embodiment of the present invention, the width of each elongated heating element is less than 0.5 mm, and preferably approximately equal to 0.4 mm.

[0020] According to a second embodiment of the present invention, a first subset of elongated heating elements is arranged inside the radiation cone of the radar sensor when the automotive component is installed facing the radar sensor, and a second subset of elongated heating elements is arranged outside the radiation cone of the radar sensor when the automotive component is installed facing the radar sensor. The elongated heating elements of the first and second subsets are arranged such that the distance separating two adjacent elongated heating elements is not constant but increases, considering the direction of propagation from the second subset to the first subset and from the outside of the radiation cone of the radar sensor to the center of the radiation cone, which are perpendicular to the main propagation direction of electromagnetic waves emitted by the radar sensor. The second embodiment of the present invention allows for a further increase in de-icing speed compared to the first embodiment of the present invention, in which the elongated heating elements extend parallel to each other to form a grid polarization, and the distance between two adjacent elongated heating elements is constant. Specifically, in this second embodiment, the density of the elongated heating elements of the second subset is maximized outside the radiation cone of the radar sensor to maximize electrical conductivity and, consequently, the de-icing speed. Conversely, inside the radar sensor's radiation cone, the distance between two adjacent elongated heating elements in the first subset is greater than the distance between two adjacent elongated heating elements in the second subset. This minimizes signal attenuation from the radar sensor, regardless of the electromagnetic wave components in question. According to a first variation of this second embodiment, inside the radar sensor's radiation cone, the elongated heating elements of the first subset are arranged such that the distance between two adjacent elongated heating elements increases as these elements move laterally closer to the center of the cone. According to another variation of this second embodiment, the distance separating two adjacent elongated heating elements in the first subset is constant.

[0021] According to one embodiment of the present invention, the profile function for which the distance increases is a linear function or a piecewise linear function, for example, a step function.

[0022] According to one embodiment of the present invention, the minimum distance separating two adjacent elongated heating elements in a first subset of elongated heating elements is greater than 2 mm, preferably greater than 3 mm.

[0023] According to one embodiment of the present invention, the width of each elongated heating element in the first subset of elongated heating elements is less than 0.5 mm.

[0024] According to one embodiment of the present invention, the elongated heating element is a heated metal piece or heated metal wire. The heated metal piece or heated metal wire is powered, for example, by a common power supply unit configured to conduct an electric current through each of the metal pieces or wires. The heat required for de-icing is then generated by the Joule effect in the metal pieces or wires. The power supply unit is connected to the heated metal piece or heated metal wire, for example, via one or more electrical connection elements (e.g., current distribution bars, electrical cables, and / or power supply ribbon cables). These electrical connection elements are generally made of an opaque conductive material and are located inside the automotive component outside the radar sensor's radiation cone.

[0025] According to one embodiment of the present invention, each heating metal piece or heating metal wire is covered with a layer of dielectric material or placed within a dielectric protective and insulating element.

[0026] According to an embodiment of the present invention, the dielectric material has a refractive index and a thickness that is 0.8 to 1.2 times the ideal thickness. The ideal thickness, for an electromagnetic wave with an incident angle of zero (a normal electromagnetic wave), is equal to the wavelength of the electromagnetic wave emitted by the radar sensor multiplied by a natural number and divided by twice the refractive index of the dielectric material. This ideal thickness is such that the electromagnetic wave reflected by the electrothermal metal piece or electrothermal metal wire undergoes destructive interference, thus minimizing or even preventing attenuation of the signal from the radar sensor. Transmission of the signal through the metal piece or metal wire is thus maximized regardless of the component of the electromagnetic wave in question. In certain cases, the thickness of the dielectric material is 0.8 to 1.2 times the wavelength divided by twice the refractive index. This thickness corresponds to the minimum value achievable in this embodiment of the present invention, but enables prevention of other interference.

[0027] According to an embodiment of the present invention, the automotive part is a styling part for hiding the radar sensor.

[0028] For example, the styling part may be a logo.

[0029] According to an embodiment of the present invention, the automotive part is an outer lens that closes an element for lighting and / or signal transmission in which the radar sensor is integrated.

[0030] A further subject of the present invention relates to an assembly that includes a vehicle radar sensor and an automotive part according to the present invention. The radar sensor is configured to emit electromagnetic waves within a radiation cone. The electric field of the electromagnetic wave emitted by the radar sensor includes a component that vibrates in the direction of interest. The electromagnetic wave propagates in the main propagation direction. The automotive part is installed facing the radiation cone of the radar sensor.

[0031] According to one embodiment of the present invention, the radar sensor is a millimeter-wave radar sensor polarized in a horizontal or vertical polarization direction. The vibration of the electromagnetic field spreads horizontally or vertically. The wavelength of the radar sensor is typically 3.70 mm to 3.94 mm. This type of radar sensor is typically suitable for autonomous driving applications, as such wavelengths are advantageously suited for detecting objects without excessive power consumption or delayed response.

[0032] According to one embodiment of the present invention, the radar sensor has an operating frequency of 76 GHz to 81 GHz.

[0033] According to one embodiment of the present invention, the assembly is an element for illuminating and / or transmitting signals in a vehicle, in particular a vehicle headlight. For example, the automotive part may be an outer lens that forms the outer surface of the element, closing the element for illuminating and / or transmitting signals. Such an element for illuminating and / or transmitting signals may house a radar sensor.

[0034] In this specification, “vehicle” means any type of vehicle capable of carrying at least one occupant or intended for transporting people or objects, such as automobiles, mopeds, motorcycles, warehouse robots, or any other machine.

[0035] An "electrical cable" means one or more elongated conductive elements surrounded by at least one electrical insulating layer, the electrical insulating layer being in direct physical contact with the elongated conductive elements in some cases.

[0036] Furthermore, "power supply ribbon cable" refers to a power supply element whose thickness is small relative to its length and width. The power supply ribbon cable may be curved or have a given contour. Thus, the ribbon cable has two broad surfaces separated by a periphery, which defines the thickness of the ribbon cable, and the thickness may be variable, for example, decreasing from one end to the other. [Brief explanation of the drawing]

[0037] Other features and advantages of the present invention will become clear upon closer examination of the following detailed description and accompanying drawings.

[0038] [Figure 1] This is a schematic perspective view of an assembly including a radar sensor and an automotive part according to the first embodiment of the present invention.

[0039] [Figure 2] Figure 1 is a schematic front view of an automobile part.

[0040] [Figure 3] Figure 1 is a schematic side view of an automobile part.

[0041] [Figure 4] This is a schematic front view of an automotive part according to a second embodiment of the present invention.

[0042] [Figure 5] This diagram schematically depicts an electrical circuit corresponding to the configuration shown in Figure 3.

[0043] In this specification, unless otherwise specified, the terms “upstream” and “downstream” refer to the direction of propagation of an electromagnetic beam within the object in question, and the direction of radiation of electromagnetic waves outside the object.

[0044] Furthermore, everything referred to as "rear" is located upstream, and everything referred to as "front" is located downstream.

[0045] The terms “horizontal,” “vertical,” “lateral,” “downward,” “upward,” “high,” “low,” and “lateral” are defined in relation to the orientation of part 2 according to the present invention, which is intended to be fitted to a vehicle. In particular, in this application, the term “vertical” refers to an orientation perpendicular to the horizontal line, and the term “horizontal” refers to an orientation parallel to the horizontal line.

[0046] The orthogonal reference coordinate system related to the automotive part 2 is shown in Figures 1 to 4. This reference coordinate system consists of three axes, namely X, Y, and Z, which are called the longitudinal axis X, the transverse axis Y, and the vertical axis Z, respectively. [Modes for carrying out the invention]

[0047] Figure 1 is a schematic perspective view showing an assembly 1 including an automotive part 2 according to the present invention and its operating principle. The assembly 1 further includes a radar sensor 4. For clarity, only a portion of part 2 is shown in this figure. Without implying any limitations in the context of the present invention, assembly 1 is, for example, an element for vehicle illumination and / or signal transmission, particularly a vehicle headlight. In this case, part 2 is typically an outer lens that encloses the illumination and / or signal transmission element 1, and the outer lens 2 constitutes the outer surface of this element 1. Alternatively, part 2 may be a stylistic part such as a logo to conceal the radar sensor 4. In this case, assembly 1 may be an element for vehicle illumination and / or signal transmission, or any other element of the vehicle.

[0048] The radar sensor 4 is configured to radiate electromagnetic waves 6 within a radiating cone 7 (such a radiating cone 7 is not shown in Figure 1, but is visible in Figures 2 and 4). The electric field of the electromagnetic waves 6 radiated by the radar sensor 4 includes a component E1 that oscillates in a direction of interest P1. More specifically, this means that this component E1 of the electric field of the electromagnetic wave 6 extends in a direction of interest P1 when projected into a plane S defined by the radiating surface of the radar sensor 4. The direction of interest P1 of the electric field of the electromagnetic wave 6 corresponds to a preferred direction perpendicular to the principal propagation direction D1 of the electromagnetic wave 6, and the component E1 of interest of the electric field of the electromagnetic wave 6 oscillates in this direction. If the radar sensor 4 is linearly polarized in the principal polarization direction (e.g., horizontal or vertical), the direction of interest P1 corresponds to this principal polarization direction. In the exemplary embodiment shown in Figure 1, the direction of interest of the electromagnetic wave 6 is the vertical direction corresponding to the vertical axis Z. According to this exemplary embodiment, the electric field of the electromagnetic waves 6 radiated by the radar sensor 4 is unpolarized. In variations not shown, the electric field of electromagnetic waves emitted by the radar sensor may be polarized vertically or horizontally, or in any linear direction other than vertically or horizontally.

[0049] The electromagnetic wave 6 propagates in the main propagation direction D1. The radiation cone 7 of the radar sensor 4 corresponds to the angular region radiated by the radar sensor 4. This angular region has a main direction that corresponds to the main propagation direction D1 of the electromagnetic wave where the amplitude of the electromagnetic wave 6 is maximum. In this case, the main propagation direction D1 corresponds to the optical axis of the radar sensor 4. In the shown embodiment, the main propagation direction D1 is the front-to-back direction, and in the figure it corresponds to the front-to-back axis X.

[0050] The radar sensor 4 is typically a frequency-modulated continuous-wave millimeter-wave radar sensor, with an operating frequency typically between 76 GHz and 81 GHz. The radar sensor 4 can be, for example, a long-range radar sensor (and therefore with a small field of view) or a medium-range radar sensor (and therefore with a medium field of view). The wavelength of the radar sensor 4 is typically between 3.70 mm and 3.94 mm. This type of radar sensor is typically suitable for autonomous driving applications, as such wavelengths are advantageously suited for detecting objects without excessive power consumption or delayed response.

[0051] As shown in Figures 1, 2, and 4, component 2 is positioned in front of the radar sensor 4, facing the radiation cone 7 of the radar sensor 4. Component 2 has a de-icing device 12 on one of its surfaces 10.

[0052] The de-icing device 12 includes a set 13 of elongated heating elements 14. The de-icing device 12 further includes a power supply unit (not shown), which is connected to the elongated heating elements 14 via one or more electrical connection elements (e.g., current distribution bars, electrical cables, and / or power supply ribbon cables). These electrical connection elements are generally made of an opaque conductive material and are located inside the outer component 2 of the radiation cone 7 of the radar sensor 4. The power supply unit is configured to supply current to each elongated heating element 14. Each elongated heating element 14 is typically a heated metal piece or heated metal wire. The heat required for de-icing is generated by the Joule effect in the heated metal piece or heated metal wire 14.

[0053] Preferably, each heating metal piece or heating metal wire 14 is covered with a layer of dielectric material or placed within a dielectric protective / insulating element (such dielectric material or element is not shown in the figure for clarity). The dielectric material has a refractive index and thickness. The thickness of the dielectric material is advantageously 0.8 to 1.2 times the ideal thickness, which is equal to a natural number multiplied by the wavelength of the electromagnetic wave 6 emitted by the radar sensor 4 and divided by twice the refractive index of the dielectric material for electromagnetic waves 6 at an incident angle of zero (normal electromagnetic waves). According to a particular exemplary embodiment, the thickness of the dielectric material is 0.8 to 1.2 times the wavelength divided by twice the refractive index. This thickness corresponds to the minimum value that can be taken in this particular feature of the present invention, but allows for the prevention of other interferences.

[0054] All or part of the elongated heating elements 14 are positioned within the radiating cone 7 of the radar sensor 4, as will be described in more detail below. Each elongated heating element 14 positioned within the radiating cone 7 of the radar sensor 4 is positioned in component 2 such that it extends in a direction substantially perpendicular to the direction of interest P1 of the electric field of the electromagnetic wave 6 radiated by the radar sensor 4. In the embodiment shown, this extension direction of the elongated heating elements 14 is transverse, corresponding to the front-to-back axis Y in the figure. In this way, the component of interest E1 of the electromagnetic wave 6 extends perpendicular to the extension direction of the elongated heating elements 14, but is hardly reflected by these heating elements 14 and is transmitted almost completely to the opposite side of the de-icing device 12. In addition to the component of interest E1, the electric field of the electromagnetic wave 6 radiated by the radar sensor 4 in Figure 1 includes other components 9a, 9b, and 9c, each extending in directions other than the direction of interest P1 when projected into the plane S defined by the radiating surface of the radar sensor 4. As shown in Figure 1, these other components 9a, 9b, and 9c of the electromagnetic wave 6 are reflected by the elongated heating element 14 and are not transmitted to the other side of the de-icing device 12. In a variation not previously shown, when the radar sensor is linearly polarized, the electric field of the electromagnetic wave 6 emitted by the radar sensor 4 consists of component E1.

[0055] As shown in Figures 1 to 4, the elongated heating elements 14 extend within the same plane T. This plane extends perpendicular to the main propagation direction D1 of the electromagnetic waves 6 emitted by the radar sensor 4. In other words, the plane T on which the elongated heating elements 14 are located extends substantially parallel to the plane S defined by the radiating surface of the radar sensor 4 and lies in front of plane S. In the specific exemplary embodiments shown in Figures 1 to 4, the elongated heating elements 14 extend parallel to each other within plane T. The set 13 of elongated heating elements 14 forms a grid polarization.

[0056] According to the first embodiment of the present invention shown in Figures 1 to 3, a set 13 of elongated heating elements 14 is arranged inside the radiation cone 7 of the radar sensor 4. The elongated heating elements 14 are arranged such that the distance d2 separating two adjacent elongated heating elements 14 is constant (such a distance d2 is visible in Figure 2 and is measured in the direction perpendicular to axis Z).

[0057] Preferably, the distance d2 separating two adjacent elongated heating elements 14 is smaller than the wavelength of the electromagnetic waves 6 emitted by the radar sensor 4. The distance d2 separating two adjacent elongated heating elements 14 is typically less than 4 mm, and preferably 2 mm to 4 mm.

[0058] More preferably, the ratio of the width l2 of each elongated heating element 14 to the wavelength of the electromagnetic wave 6 emitted by the radar sensor 4 is less than 1 / 10, and preferably approximately equal to 1 / 10 (in this case, the width is measured perpendicular to axis Z). The width l2 of each elongated heating element 14 (visible in Figure 2) is typically less than 0.5 mm, and preferably approximately equal to 0.4 mm. Note that in Figure 2, the distance d2 and width l2 are not shown to scale.

[0059] According to a second embodiment of the present invention shown in Figure 4, a first subset 16 of elongated heating elements 14 is arranged inside the radiation cone 7 of the radar sensor 4, and a second subset 18 of elongated heating elements 14 is arranged outside the radiation cone 7 of the radar sensor 4. The elongated heating elements 14 of the second subset 18 extend to the periphery of the radiation cone 7 of the radar sensor 4. The elongated heating elements 14 of the first subset 16 and the second subset 18 are arranged such that the distance separating two adjacent elongated heating elements 14 is not constant but follows a profile function that increases in distance, considering the direction of propagation from the second subset 18 to the first subset 16 (and therefore in the plane YZ), which is perpendicular to the main propagation direction D1 of the electromagnetic waves 6 radiated by the radar sensor 4, and from the outside of the radiation cone 7 of the radar sensor 4 to the center of the radiation cone 7. The profile function that increases in distance is, for example, a linear function or a piecewise linear function, for example, a step function. According to a first variation of the second embodiment of the present invention, inside the radiation cone 7 of the radar sensor 4, the elongated heating elements 14 of the first subset 16 are arranged such that the distance between two adjacent elongated heating elements 14 increases as these elongated heating elements are closer to the center of the cone in the lateral direction. According to another variation of the second embodiment shown in Figure 4, the distance separating two adjacent elongated heating elements 14 of the first subset 16 is constant inside the radiation cone 7 of the radar sensor 4.

[0060] Preferably, the minimum distance separating two adjacent elongated heating elements 14 in the first subset 16 is greater than 2 mm, and preferably greater than 3 mm (in this case, the distance is measured perpendicular to axis Z).

[0061] More preferably, the maximum distance separating two adjacent elongated heating elements 14 in the first subset 16 is smaller than the wavelength of the electromagnetic wave 6 emitted by the radar sensor 4.

[0062] More preferably, the width of each elongated heating element 14 in the first subset 16 is less than 0.5 mm (in this case, the width is measured perpendicular to axis Z). This width can be variable for each adjacent elongated heating element in the first subset 16. Note that in Figure 4, the distance between two adjacent elongated heating elements 14 and the width of each elongated heating element 14 are not shown to scale.

[0063] In the two embodiments of component 2 described above, the distance between two adjacent elongated heating elements and the width of each elongated heating element are calculated to minimize the reflection of electromagnetic waves 6 from the elongated heating elements and, consequently, maximize the transmission of these electromagnetic waves 6 to the opposite side of the heating elements. The calculation of these two parameters depends on the polarization type and wavelength of the radar sensor 4 and the incident angle of the electromagnetic waves 6, which will be described in detail later.

[0064] More specifically, the configuration of component 2 shown in Figure 3 is schematically depicted in Figure 5 by an equivalent electrical circuit. In this equivalent electrical circuit, where the radar sensor 4 is vertically polarized in a direction P1 perpendicular to the extension direction of the elongated heating element 14, the parameters Y0 and B are given by the following equation (1).

[0065]

number

number

[0066] When the incident angle θ of electromagnetic wave 6 is 0 degrees, equation (1) becomes as follows:

[0067]

number

[0068] From the electrical circuit diagram in Figure 5, the reflectance R of electromagnetic wave 6 is shown. v is a complex number and is given by equation (2) below.

[0069]

number

[0070] The distance d between two adjacent elongated heating elements 14 and the width ad of each elongated heating element 14 are given by this reflectance R v It is calculated to minimize the coefficient of .

[0071] The present invention is not limited to the embodiments described above as an example, and other variations are possible, in particular, in which at least one subset of the set of elongated heating elements 14 is arranged inside the radiation cone 7 of the radar sensor 4, and each of the elongated heating elements 14 of this subset is arranged in the component 2 such that it extends in a direction substantially perpendicular to the direction of interest P1 of the electric field of the electromagnetic wave 6 radiated by the radar sensor 4.

Claims

1. An automotive part (2) intended to be installed opposite the radiation cone (7) of a vehicle's radar sensor (4), wherein the radar sensor (4) is configured to radiate electromagnetic waves (6) within the radiation cone (7), the electric field of the electromagnetic waves (6) radiated by the radar sensor (4) includes a component (E1) that oscillates in the direction of interest (P1), the electromagnetic waves (6) propagate in the main propagation direction (D1), and the automotive part (2) has a de-icing device (12) on one of its surfaces (10). The device (12) includes a set (13) of elongated heating elements (14), wherein at least one subset (16) of the set of elongated heating elements (14) is positioned within the radiation cone (7) of the radar sensor (4) when the automobile part (2) is installed facing the radar sensor (4), and each of the elongated heating elements (14) of the subset (16) is positioned on the automobile part (2) such that it extends in a direction substantially perpendicular to the direction of interest (P1) of the electric field of the electromagnetic wave (6) radiated by the radar sensor (4). The elongated heating element (14) extends within the same plane (T), and the plane (T) extends perpendicular to the main propagation direction (D1) of the electromagnetic wave (6) radiated by the radar sensor (4). The elongated heating elements (14) extend parallel to each other in the plane (T), and the set (13) of the elongated heating elements (14) forms a grid polarization. The elongated heating elements (14) are arranged such that the distance (d2) separating two adjacent elongated heating elements (14) is constant. The automobile part (2) is characterized in that a first subset (16) of the elongated heating element (14) is placed inside the radiating cone (7) of the radar sensor (4) when the automobile part (2) is installed facing the radar sensor (4), and a second subset (18) of the elongated heating element (14) is placed outside the radiating cone (7) of the radar sensor (4) when the automobile part (2) is installed facing the radar sensor (4).

2. The automobile part (2) according to claim 1, wherein the distance (d2) separating two adjacent elongated heating elements (14) is smaller than the wavelength of the electromagnetic wave (6) emitted by the radar sensor (4).

3. The automobile part (2) according to claim 1, wherein the distance (d2) separating two adjacent elongated heating elements (14) is less than 5 mm.

4. The automobile part (2) according to claim 2, wherein the ratio of the width (l2) of each of the elongated heating elements (14) to the wavelength of the electromagnetic waves (6) emitted by the radar sensor (4) is less than 1 / 10.

5. The automobile part (2) according to claim 4, wherein the width (l2) of each of the elongated heating elements (14) is less than 0.5 mm.

6. The automotive part (2) according to claim 1, wherein the elongated heating elements (14) of the first subset (16) and the second subset (18) are arranged such that the distance separating two adjacent elongated heating elements (14) is not constant but follows a profile function in which the distance increases, taking into account the direction of propagation from the second subset (18) to the first subset (16), and from the outside of the radiation cone (7) of the radar sensor (4) to the center of the radiation cone (7), which is perpendicular to the main propagation direction (D1) of the electromagnetic waves (6) radiated by the radar sensor (4).

7. The automobile part (2) according to claim 6, wherein the profile function for which the distance increases is a linear function or a piecewise linear function.

8. The automobile part (2) according to claim 6, wherein the minimum distance separating two adjacent elongated heating elements (14) of the first subset (16) of the elongated heating elements (14) is greater than 2 mm.

9. The automobile part (2) according to claim 6, wherein the width of each of the elongated heating elements (14) in the first subset (16) of the elongated heating elements (14) is less than 0.5 mm.

10. The automobile part (2) according to claim 2, wherein the elongated heating element (14) is a heated metal piece or a heated metal wire.

11. The automobile part (2) according to claim 10, wherein each of the electric heating metal pieces or electric heating metal wires (14) is covered with a layer of dielectric material or is placed in a dielectric protective / insulating element.

12. The dielectric material has a refractive index and a thickness of 0.8 to 1.2 times the ideal thickness, wherein the ideal thickness is equal to the result of multiplying a natural number by the wavelength of the electromagnetic wave (6) emitted by the radar sensor (4) and dividing by twice the refractive index of the dielectric material, for the electromagnetic wave (6) with an incident angle of zero.

13. The automotive part (2) according to claim 1, wherein the automotive part (2) is a styling part for concealing the radar sensor (4).

14. The automotive part (2) according to claim 13, wherein the stylistic component is a logo.

15. The automotive part (2) according to claim 1, wherein the automotive part (2) is an outer lens that closes off an element (1) for illumination and / or signal transmission into which the radar sensor (4) is integrated.

16. An assembly (1) comprising a vehicle radar sensor (4) and an automobile part (2) as described in claim 1, wherein the radar sensor (4) is configured to radiate electromagnetic waves (6) within a radiating cone (7), the electric field of the electromagnetic waves (6) radiated by the radar sensor (4) includes a component (E1) that oscillates in the direction of interest (P1), the electromagnetic waves (6) propagate in the main propagation direction (D1), and the automobile part (2) is installed facing the radiating cone (7) of the radar sensor (4).

17. The assembly (1) according to claim 16, wherein the radar sensor (4) is a millimeter-wave radar sensor polarized in a horizontal or vertical polarization direction.

18. The assembly (1) according to claim 17, wherein the radar sensor (4) has an operating frequency of 76 GHz to 81 GHz.

19. The assembly (1) according to claim 16, wherein the assembly (1) is an element for lighting and / or transmitting signals for a vehicle, in particular a vehicle headlight.

20. The assembly (1) according to claim 19, wherein the automotive part (2) is an outer lens that forms the outer surface of the element (1) and closes the element (1) for illumination and / or signal transmission.

Images