Vehicle assembly comprising a group of radar sensors and layers

Abstract

The invention relates to a vehicle assembly (1) for a vehicle (2), said vehicle assembly (1) comprising: - a radar sensor (10) configured to emit / receive radar waves (R1), said radar sensor (10) being placed facing a set of layers (C); and - said set of layers (C) comprising at least two dielectric layers (11, 12), i.e. a primary layer (11) and a secondary layer (12) separated by an air layer (13), - characterized in that said air layer (13) has a thickness (e3) equal to (m3 x (λ / 2)) / cos(θ3), with θ3 being the angle of incidence of an outgoing reflected wave (R20) hitting said secondary layer (12), and m3 = 1, … N, N being an integer, said outgoing reflected wave (R20) resulting from a radar wave (R1) emitted by said radar sensor (10).

Description

Technical Field

[0001] This invention relates to a vehicle component. It is particularly, but not limited to, applicable to motor vehicles. Background Technology

[0002] Vehicle components known to those skilled in the art include:

[0003] - A radar sensor configured to transmit / receive radar waves, and

[0004] - A layer assembly comprising at least two dielectric layers, the dielectric layers including a primary layer and a secondary layer separated by an air layer.

[0005] The vehicle component is placed at the front or rear of the vehicle to meet the need for detection of objects in the external environment of the vehicle.

[0006] One drawback of this prior art is that the radar sensor is placed behind the layer assembly. Therefore, radar waves must travel through the dielectric layer to detect objects in the environment outside the vehicle. Some of these radar waves are reflected by the dielectric layer and then within the air layer between the dielectric layers. Consequently, the power of the radar waves emitted from this layer assembly is lower than the power of the radar waves initially emitted by the radar sensor and entering the layer assembly. This reduces the detection range of the radar sensor. Therefore, detection errors or failure to detect objects may occur, even if the object is present in the environment outside the vehicle. Summary of the Invention

[0007] In this context, the present invention aims to provide a vehicle component that allows for the resolution of the mentioned drawbacks.

[0008] Therefore, the present invention provides a vehicle component for a vehicle, the vehicle component comprising:

[0009] - A radar sensor configured to transmit / receive radar waves, the radar sensor being positioned facing the layer assembly; and

[0010] - The layer assembly includes at least two dielectric layers, which include a primary layer and a secondary layer separated by an air layer.

[0011] The air layer is characterized in that it has a thickness equal to (m3 x (λ / 2)) / cos(θ3), where θ3 is the incident angle of the outgoing reflected wave striking the secondary layer, and m3 = 1, ... to N, where N is an integer, and the outgoing reflected wave originates from the radar wave emitted by the radar sensor.

[0012] Therefore, as detailed below, defining the thickness of the air layer in this way allows for the addition of second-order emitted radar waves, resulting in virtually no power loss between the radar wave emitted from the layer assembly opposite the radar sensor and the initial radar wave emitted by the sensor. Consequently, during the propagation of the initially emitted radar wave through the primary layer, air layer, and secondary layer, power loss is minimal, except for some absorption of the radar wave by the layer materials. Therefore, the detection of objects by the radar sensor will be accurate.

[0013] According to a non-limiting embodiment, the vehicle component may include, individually or in any technically possible combination, one or more additional features selected from the following features.

[0014] According to a non-limiting embodiment, the outgoing reflected wave is a wave emitted from the primary layer on the side opposite to the radar sensor.

[0015] According to a non-limiting embodiment, the radar sensor is a radar sensor that employs millimeter waves (waves between 24 GHz and 300 GHz), submicrowaves (waves between 300 MHz and 81 GHz), or microwaves (waves between 1 GHz and 300 GHz).

[0016] According to a non-limiting embodiment, the radar waves are transmitted in a frequency band between 100 MHz and 3 GHz.

[0017] According to a non-limiting embodiment, the primary layer has a thickness equal to (λ / (2n1cosβ1))+(m1 x λ), where β1 is the refraction angle corresponding to the incident angle θ1 of the emitted radar wave, n1 is the refractive index of the primary layer, and m1=1, ... to N, where N is an integer.

[0018] According to a non-limiting embodiment, the thickness of the primary layer is defined by an incident angle θ1 equal to arctan(d1 / (2e4)), where e4 is the distance between the radar sensor and the primary layer.

[0019] According to a non-limiting embodiment, the secondary layer has a thickness equal to (λ / (2n2cosβ2))+(m2 x λ), where β2 is the refraction angle corresponding to the incident angle θ2 of the radar wave emitted from the primary layer, and n2 is the refractive index of the secondary layer, and m2=1, ... to N, where N is an integer.

[0020] According to a non-limiting embodiment, the primary layer is a decorative portion, and the secondary layer is an exiting lens of the vehicle's light-emitting device.

[0021] According to a non-limiting embodiment, the light-emitting device is a headlight or a taillight.

[0022] According to a non-limiting embodiment, the primary layer is a light-emitting element of the logo, and the secondary layer is an exiting lens of the logo of the vehicle.

[0023] According to a non-limiting embodiment, the primary layer is an antenna radome, and the secondary layer is a logo.

[0024] According to a non-limiting embodiment, the layer assembly includes more than two dielectric layers, which include a primary layer and a secondary layer separated by an air layer.

[0025] According to a non-limiting embodiment, the incident angle θ3 is equal to the incident angle θ1.

[0026] According to a non-limiting embodiment, the incident angle θ3 is equal to the incident angle θ2.

[0027] According to a non-limiting embodiment, the incident angle θ2 is equal to the incident angle θ1.

[0028] A layer assembly for a vehicle is also provided, the layer assembly being configured to face a radar sensor configured to transmit / receive radar waves, and the layer assembly comprising at least two dielectric layers, the dielectric layers including a primary layer and a secondary layer separated by an air layer.

[0029] The air layer is characterized in that it has a thickness equal to (m3 x (λ / 2)) / cos (θ3), where θ3 is the incident angle of the outgoing reflected wave striking the secondary layer, and m3 = 1, ... to N, where N is an integer, and the outgoing reflected wave originates from the radar wave emitted by the radar sensor.

[0030] According to a non-limiting embodiment, the layer assembly includes more than two dielectric layers, which include a primary layer and a secondary layer separated by an air layer. Attached Figure Description

[0031] A better understanding of the invention and its various applications will be achieved after reading the following description and reviewing the accompanying drawings, in which:

[0032] [ Figure 1 [Illustration of a vehicle assembly according to a first non-limiting embodiment of the present invention, the vehicle assembly including a radar sensor and a layer assembly having at least two dielectric layers including a primary layer and a secondary layer separated by an air layer;]

[0033] [ Figure 2 [This is based on a non-limiting embodiment.] Figure 1A schematic diagram of the propagation of radar waves emitted by the radar sensor of the vehicle component and their reflection from the two dielectric layers.

[0034] [ Figure 3 [Illustration of a vehicle assembly according to a second non-limiting embodiment of the present invention, the vehicle assembly including a radar sensor and a layer assembly having more than two dielectric layers including two primary layers and two secondary layers, each primary-secondary layer assembly being separated by an air layer.] Detailed Implementation

[0035] Unless otherwise specified, elements that are consistent in structure or function in various drawings retain the same reference numerals.

[0036] refer to Figures 1 to 3 To describe the vehicle component 1 for a vehicle 2 according to the present invention. In a non-limiting embodiment, the vehicle 2 is a motor vehicle. A motor vehicle refers to any type of motorized vehicle. This embodiment is considered by way of non-limiting example in the remainder of the specification. Therefore, in the remainder of this specification, the vehicle 2 is also referred to as a motor vehicle 2.

[0037] like Figure 1 and Figure 3 As illustrated, vehicle component 1 (also referred to as vehicle arrangement 1) includes:

[0038] - Radar sensor 10, which is configured to transmit / receive radar waves R1, and

[0039] A layer assembly C, also known as a layer arrangement C, includes at least two dielectric layers 11, 12, which include a primary layer 11 and a secondary layer 12 separated by an air layer 13.

[0040] These components are described below. Radar sensor 10 is described below.

[0041] Radar sensor 10 is positioned facing primary layer 11. In a non-limiting embodiment, radar sensor 10 is a millimeter-wave (waves between 24 GHz and 300 GHz) or submicrowave (waves between 300 MHz and 81 GHz) or microwave (waves between 1 GHz and 300 GHz) radar sensor. In a non-limiting variation of the embodiment, radar sensor 10 operates at radar frequencies including those between 76 GHz and 81 GHz. In a non-limiting embodiment, radar wave R1 is transmitted over a frequency band including those between 100 MHz and 3 GHz. Therefore, in a non-limiting example, if the sensor operates at a radar frequency of 77 GHz and has a 1 GHz frequency band, then radar sensor 10 will operate in a frequency band from 76.5 GHz to 77.5 GHz.

[0042] Radar sensor 10 is configured to scan the external environment of the motor vehicle 2 by means of the emission of radar waves R1. Figure 1 As illustrated, the radar sensor 10 therefore includes:

[0043] - At least one transmitting antenna 100, which is configured to transmit primary radar wave R1;

[0044] - At least two receiving antennas 101 are configured to receive secondary radar waves R2.

[0045] The radar sensor 10 also includes at least one transmitter 103 and at least one receiver 104, the at least one transmitter 103 being configured to generate a primary radar wave R1, and the at least one receiver 104 being configured to process a secondary radar wave R2 received as a return (wave). In a non-limiting embodiment, a single electronic component may be used for both the transmitting and receiving functions. Thus, one or more transceivers will be present. The transmitter 103 generates the primary radar wave R1, which is then transmitted by the transmitting antenna 100, and when the primary radar wave R1 encounters an object 3 in the external environment of the motor vehicle 2 (here, a pedestrian in the non-limiting example illustrated), the primary radar wave R1 is reflected from the object 3. The radar wave thus reflected is the wave that is transmitted back to the radar sensor 10. These waves are the secondary radar waves R2 received by the receiving antenna 101. These waves are radar waves that are transmitted again in the direction of the radar sensor 10. In a non-limiting embodiment, the primary radar wave R1 and the secondary radar wave R2 are radio frequency waves. In one non-limiting embodiment, the radar sensor 10 includes a plurality of transmitters 103 and a plurality of receivers 104.

[0046] A transmitting antenna 100 (also referred to as antenna 100) is configured to transmit a primary radar wave R1 generated by a transmitter 103. A receiving antenna 101 (also referred to as antenna 101) is configured to receive a secondary radar wave R2 and transmit it to a receiver 104, which then processes the secondary radar wave R2. A phase shift exists between the secondary radar wave R2 received by the receiving antenna 101, which allows inference of the position of an object 3 relative to a motor vehicle 2 located in an environment outside the motor vehicle 2. In a non-limiting embodiment, antennas 100 and 101 are patch antennas or slot antennas.

[0047] In one non-limiting embodiment, antennas 100, 101, transmitter 103, and receiver 104 are placed on a printed circuit board 105. In one non-limiting embodiment, the printed circuit board is a rigid printed circuit board (also referred to as a printed circuit board assembly or PCBA) or a flexible printed circuit board (also referred to as a flexible board).

[0048] The radar sensor 10 also includes an electronic control unit 106 configured to control the transmitter 103 and the receiver 104. Since such radar sensors are known to those skilled in the art, they will not be described in further detail here.

[0049] The following describes layer component C.

[0050] In one non-limiting embodiment, the primary layer 11 is a decorative portion (also referred to as a border), and the secondary layer 12 is an exiting lens of the light-emitting device 20 of the motor vehicle. In one non-limiting embodiment, the light-emitting device 20 is a headlight or taillight of the vehicle 2. In another non-limiting embodiment, the primary layer 11 is a light-emitting element of an illuminated emblem, and the secondary layer 12 is an exiting lens of the illuminated emblem. In one non-limiting example, the light-emitting element is a light guide. In another non-limiting embodiment, the primary layer 11 is a radome, and the secondary layer 12 is an emblem, optionally an illuminated emblem. In another non-limiting embodiment, the primary layer 11 is a radome, and the secondary layer 12 is an exiting lens of the light-emitting device 20. In one non-limiting embodiment, the light-emitting device 20 is a headlight or taillight of the vehicle 2.

[0051] The primary layer 11 and the secondary layer 12 are made of a dielectric. In a non-limiting embodiment, the dielectric is plastic, glass, or ceramic. In one non-limiting example, the plastic is polycarbonate. It can be recalled that the dielectric is non-conductive and therefore allows radar waves R1 to pass through, unlike a conductor.

[0052] exist Figure 1 In the first non-limiting embodiment illustrated, the layer assembly C includes a single primary layer 11 and a single secondary layer 12 separated by an air layer 13.

[0053] like Figure 2 As illustrated, the primary layer 11 has a thickness e1 (also referred to as primary thickness e1) and two surfaces V1 and V2 serving as transition surfaces from one medium to another; these surfaces are also referred to as refractive interfaces V1 and V2. Figure 2 As illustrated, at the refractive interface V1, the wave travels from the air (indicated by reference numeral 8) to the dielectric of the primary layer 11. At the refractive interface V2, the wave travels from the dielectric of the primary layer 11 to the air 8. The primary layer 11 has a refractive index n1.

[0054] The secondary layer 12 has a thickness e2 (also referred to as secondary thickness e2) and two surfaces V3 and V4, which serve as transition surfaces from one medium to another; these surfaces are also referred to as refractive interfaces V3 and V4. Figure 2As illustrated, at the refractive interface V3, the wave travels from the air layer 13 to the dielectric of the secondary layer 12. At the refractive interface V4, the wave travels from the dielectric of the secondary layer 12 back to the air (already indicated by reference numeral 8 in the figure). The secondary layer 12 has a refractive index n2.

[0055] Air layer 13 has a thickness e3, also known as tertiary thickness e3. Air layer 13 has a refractive index n3 equal to 1.

[0056] like Figure 2 As illustrated, when radar wave R1 is emitted, a portion of radar wave R1 travels through the primary layer 11, the air layer 13, and the secondary layer 12.

[0057] When the emitted radar wave R1 travels through the primary layer 11, a portion of R1' travels through the air layer 13. This radar wave... Figure 2 The portion of the radar wave R1' is indicated by the reference numeral R1' and is referred to as the emitted radar wave R1'; another portion will be reflected in the primary layer 11. The portion R1' of the emitted radar wave, after traveling through the air layer 13, will directly enter the secondary layer 12 and exit directly from the secondary layer 12. This emitted radar wave is indicated by the reference numeral R1'' and is referred to as the emitted radar wave R1''. It should be noted that once the emitted radar wave R1' enters and exits the secondary layer 12, it becomes the emitted radar wave R1'', which has a lower power than the emitted radar wave R1', and therefore a lower power than the radar wave R1 initially emitted by the radar sensor 10. Because of the lower power, this reduces the detection range of the radar sensor.

[0058] When radar wave R1 is emitted, another portion is reflected from surfaces V1 and V2, generating reflected waves R11 and R12, respectively referred to as order 1. Therefore, the emitted radar wave R1 is reflected directly from surface V1 out of the primary layer 11, generating reflected wave R11, and also reflected from surface V2 back into the primary layer 11, generating reflected wave R12. Reflected waves R11 and R12, also referred to as waves R11 and R12, are parasitic reflections that return to radar sensor 10 and reduce its signal-to-noise ratio because they are reflected back in the direction of radar sensor 10. Therefore, since the reflected waves R11 and R12 will cause interference at the receiving antenna 101, this also leads to a reduction in the detection range of the radar sensor. Accordingly, detection errors or failure to detect objects may occur, even if the object exists in the environment outside the vehicle. As described below, they are eliminated to prevent a decrease in the signal-to-noise ratio of radar sensor 10.

[0059] like Figure 2As illustrated, the emitted radar wave R1 strikes the primary layer 11 at an incident angle θ1. When the incident angle θ1 is different from 0°, the corresponding refraction angle ( Figure 2 The angle β1 (represented by the reference numeral β1 in the attached figure) is also different from 0°. The path δ1 of the reflected wave in the primary layer 11 is equal to 2e1 / cos(β1). Therefore, the phase shift Δφ1 between the reflected waves R11 and R12 depends on the cosine of the refraction angle β1 (and therefore also on the cosine of the incident angle θ1) and the thickness e1 of the primary layer 11. It can be shown that Δφ1 = (2π(n1δ1 - 2e1tan(β1)sin(θ1)) / λ) + π, where λ is the wavelength of the emitted radar wave R1, and n3 <n1。

[0060] In a non-limiting embodiment, the primary layer 11 has a thickness e1 such that the first-order reflected waves R11 and R12 corresponding to the transmitted radar wave R1 are out of phase. Therefore, their phase shift Δφ1 is π modulo 2π. This forms destructive interference. For the first order, the reflected waves R11 and R12 are thus eliminated by partially canceling each other out. Therefore, they reduce the signal-to-noise ratio less. It should be noted that since the amplitude of wave R12 is necessarily lower than that of wave R11, waves R11 and R12 do not strictly cancel each other out. A very weak third-order residual typically exists. It will be recalled that the second-order reflected wave has lower power than the first-order reflected wave, and the third-order wave has lower power than the second-order reflected wave.

[0061] Therefore, it can be shown that since sin(θ1) = n1sin(β1), Δϕ1 = (2π x n1 x (2e1 x cosβ1) / λ) + π. However, since Δϕ1 = π modulo 2π is necessary, e1 = (λ / (2n1cosβ1)) + (m1 x λ) is necessary regardless of the value of the incident angle θ1, where m1 = 1, ..., N, and N are integers. It should be noted that the value of the incident angle θ1 is included within the possible transmission angles of the radar sensor 10. The possible values ​​of the incident angle θ1 are defined in the technical specifications of the radar sensor 10. Conventionally, the incident angle θ1 is included between 0° and 30°. It should be noted that there are values ​​of incident angle θ1 that cause the maximum interference at the receiving antenna 101 of the radar sensor 10 due to parasitic reflections R11 and R12. In a non-limiting embodiment, this value is equal to θ1 = arctan(d1 / (2e4)), where d1 is the distance between the transmitting antenna 100 and the receiving antenna 101, and e4 is the distance between the radar sensor 10 and the primary layer 11, as shown below. Figure 2As illustrated. Therefore, based on the value of the refractive index n1 and the wavelength λ used within the operating frequency range of the radar sensor 10 (between 76 GHz and 81 GHz in the given non-limiting example), the value of thickness e1 for the first-order reflected waves R11 and R12 to partially cancel each other out can be determined. In a non-limiting embodiment, thickness e1 is contained between 2 mm and 3 mm. In a non-limiting embodiment, if n1 = 1.66 for polycarbonate and wavelength λ corresponds to a frequency of 76 GHz, then for θ1 = 0° and m1 = 2, e1 = 2.36 mm. In a non-limiting embodiment, the value of thickness e1 is defined for the incident angle θ1 = arctan(d1 / (2e4)). This ensures that the interference generated by the reflected waves R11 and R12 is eliminated at their maximum.

[0062] As described above, when radar wave R1 is emitted from the primary layer 11, it becomes an emitted radar wave R1' with lower power than the emitted radar wave R1. As the emitted radar wave R1' travels through the secondary layer 12, it is reflected from surfaces V3 and V4, resulting in reflected waves R13 and R14, each of order 1. Therefore, the emitted radar wave R1' is reflected directly from surface V3 into the secondary layer 12, generating reflected wave R13, and also reflected from surface V4 into the secondary layer 12, generating reflected wave R14. Reflected waves R13 and R14, also referred to as waves R13 and R14, are parasitic reflections that return to the radar sensor 10 and reduce its signal-to-noise ratio because they are reflected back in the direction of the radar sensor 10. This also reduces the detection range of the radar sensor. Consequently, detection errors or failure to detect objects may occur, even if the object exists in the environment outside the vehicle. As described below, they are eliminated to prevent a decrease in the signal-to-noise ratio of the radar sensor 10.

[0063] The outgoing radar wave R1' impinges on the secondary layer 12 at an incident angle θ2. When the incident angle θ2 is different from 0°, the corresponding refraction angle (denoted by reference sign β2 in the figure) is also different from 0°. The path δ2 traveled by the reflected wave R14 is equal to 2e2 / cos(β2). Therefore, the phase shift Δφ1 between the reflected waves R13 and R14 depends on the cosine of the refraction angle β2 (and thus also on the cosine of the incident angle θ2) and the thickness e2 of the secondary layer 12. It can be shown that Δϕ2 = (2π(n2δ2-2e2tan(β2)sin(θ2)) / λ)+ π. Therefore, Δϕ2 = (2π × (2n2e2cos(β2)) / λ)+π, where n3<n2. It should be noted that θ2=θ1, because the outgoing radar wave R1' exits the primary layer 11 at the same incident angle as the radar wave R1 that entered the primary layer 11. Therefore, the outgoing radar wave R1' enters the secondary layer 12 at the same incident angle.

[0064] In one non-limiting embodiment, the secondary layer 12 has a thickness e2 such that the first-order reflected waves R13, R14 corresponding to the emitted radar wave R1 are in opposite phases. Therefore, their phase shift Δφ2 is π modulo 2π. This creates destructive interference. In the same manner as the reflected waves R11 and R12, the reflected waves R13 and R14 partially cancel each other out. The reflected waves R13 and R14 are thus eliminated by being partially canceled out with each other. Therefore, they reduce the signal-to-noise ratio to a smaller extent. It should be noted that since the amplitude of wave R14 is necessarily lower than that of wave R13, waves R13 and R14 do not strictly cancel each other out. There is usually a very weak third-order residual.

[0065] In other words, Δϕ2 = π modulo 2π = π+m2 × 2π, where m2=1, ... N, and N is an integer. Regardless of the value of the incident angle θ2, e2 = (λ / (2n2cosβ2))+(m2 × λ). Therefore, according to the value of the refractive index n2 and the wavelength λ used within the operating frequency range of the radar sensor 10, the value that the thickness e2 must have for the first-order reflected waves R13 and R14 to cancel each other out can be determined. In one non-limiting embodiment, the thickness e2 is comprised between 2 millimeters and 3 millimeters (mm). In one non-limiting example, if n2=1.66 for polycarbonate and the wavelength λ corresponds to a frequency of 76GHz, then for θ2=0° and m2=2, e2=2.36mm.

[0066] As Figure 2As illustrated, when the emitted radar wave R1 travels through the primary layer 11, it may be reflected multiple times from surfaces V1 and V2 within the primary layer 11. This reflection of R1 from surfaces V1 and V2 generates additional reflected waves (shown in gray in the figure). Some of these reflected waves exit along the direction of the secondary layer 12 to travel through the air layer 13. These reflected waves are reflections emitted from the primary layer 11, and... Figure 2 The reference numeral R20 is used to indicate this. Therefore, the emitted reflected wave 20 is derived from the radar wave R1 emitted by the radar sensor 10; in other words, it originates from the radar wave R1 emitted by the radar sensor 10. These waves strike the secondary layer 12 at an incident angle θ3.

[0067] Some of the reflected waves R20 emitted from the primary layer 11 travel through the air layer 13 and directly through the secondary layer 12. They strike the secondary layer 12 at an incident angle θ3. While traveling through the secondary layer 12, some of these reflected waves are emitted directly from the secondary layer 12. These reflected waves are indicated by the reference numeral R15. Because they originate from other reflected waves, their order is 2. Therefore, the second-order reflected wave R15 originates from a wave that has been reflected by the surface V1 inside the primary layer 11 and has traveled directly through the air layer 13 and the secondary layer 13.

[0068] The remaining portion R20 of the reflected waves exiting the primary layer 11 travels through the air layer 13 and is alternately reflected from the surface V2 of the primary layer 11 and the surface V3 of the secondary layer 12, then travels through the secondary layer 12 and exits from it. They also strike the secondary layer 12 at an incident angle θ3. These are the reflected waves indicated by the reference numeral R16. Because they originate from other reflected waves, their order is 2. Therefore, the second-order reflected wave R16 originates from a wave that has been reflected into the air layer 13 by the outer surface V2 of the primary layer 11 and has primarily traveled through the secondary layer 12.

[0069] These second-order reflected waves R15 and R16 are emitted from the secondary layer 12 in the direction that guides them away from the radar sensor 10. Because these second-order reflected waves R15 and R16 have lower power than the emitted radar wave R1, they are residual reflected waves that affect the range of the radar sensor 10 in detecting objects 3 in the environment outside the vehicle 2. To recap, second-order waves have lower power than first-order reflected waves.

[0070] The difference δ3 between the paths traveled by reflected wave R16 and R15 is equal to 2e3 / cos(θ3) - 2e3tan(θ3)sin(θ3). Therefore, the phase shift Δφ3 between reflected waves R16 and R15 depends on the cosine of the incident angle θ3 and the thickness e3 of the air layer 13. It can be shown that Δφ3 = 2πn3δ3 / λ = 2πδ3 / λ, where n3 = 1 (air). Therefore, Δφ3 = 4π x (e3 x cos(θ3)) / λ.

[0071] To achieve higher power by adding these residual reflected waves R15 and R16 together, the air layer 13 has a thickness e3, such that the two second-order reflected waves R15 and R16, emitted from the secondary layer 12 and corresponding to the transmitted radar wave R1, have a phase shift Δϕ3 = 0 modulus 2π. Therefore, the reflected waves R15 and R16 are in phase. This 0 modulus 2π phase shift allows the reflected waves R15 and R16 to be added together, resulting in a higher-powered reflected wave R17. That is, Δϕ3 = 4π x (e3cos(θ3)) / λ = 2πm3 is necessary, where m3 = 1, ..., N, where N is an integer. Specifically, regardless of the value of the incident angle θ3, e3 = (m3 x (λ / 2)) / cos(θ3), where λ is the wavelength of the transmitted radar wave R1, and θ3 is the incident angle of the reflected wave R20 entering the secondary layer 12. Therefore, based on the wavelength λ corresponding to the operating frequency range of the radar sensor 10, the value that the thickness e3 must have to make the reflected waves R15 and R16 of level 2 add together can be determined. In a non-limiting example, if the wavelength λ corresponds to a frequency of 76 GHz and θ3 = 0°, e3 = 1.98 mm in the case of m = 1, and for θ3 > 0°, e3 > 1.98 mm in the case of m3 = 1.

[0072] As mentioned above, in a non-limiting embodiment, the primary layer 11 and the secondary layer 12 will preferably be optimized for an angle equal to θ1 = arctan(d1 / (2e4)), where d1 is the distance between the transmitting antenna 100 and the receiving antenna 101, and e4 is the distance between the radar sensor 10 and the primary layer 11. Figure 2 As illustrated. In a non-limiting embodiment, thickness e3 will be preferentially optimized for angles different from θ1. During production, thickness e3 and radar operating frequency may differ from their respective nominal values. To account for these variations, the coefficient ɛ ∊ [-0.25; +0.25] is inserted into the equation for e3: e3 = ((m3+ɛ) x (λ / 2)) / cos(θ3). Therefore, e3 will be included within this value range.

[0073] Therefore, the reflected wave R17 generated by the addition of reflected waves R15 and R16 will allow radar sensor 10 to perform accurate detection. Specifically, its power will be added to the power of the radar wave R1'' directly emitted from secondary layer 12, and the choice of e1 ensures that R15 and R1'' are in phase. The reflected wave R17 and the radar wave R1'' form the overall emitted radar wave, in Figure 2 The total power of the radar wave R3 emitted from the secondary layer 12 (which will thus be used to detect object 3) is very close to the total power of the radar wave R1 initially emitted by the radar sensor 10.

[0074] In a non-limiting embodiment, θ3 = θ1 = θ2. This is the case if the primary layer 11 and the secondary layer 12 are placed parallel to each other and have planar surfaces V1, V2, V3, and V4. In this case, e3 = (m3 / cos(θ1)) x λ / 2.

[0075] It should be noted that the radar sensor 10 operates in a band (between 100 MHz and 3 GHz in one non-limiting embodiment) rather than at a single frequency. Since there are multiple layers of thickness e1, e2, e3 in the layer assembly C, these thicknesses can be adjusted to create an anti-reflection bandpass filter. Therefore, in one non-limiting embodiment, since each thickness e1, e2, e3 depends on the wavelength λ, each thickness e1, e2, e3 can be defined according to different wavelengths λ1, λ2, λ3, the three selected wavelengths being located in the band (here between 100 MHz and 3 GHz). Thus, in a non-limiting example, if the band is 1 GHz and the radar sensor 10 operates at a frequency of 76 GHz, then wavelength λ1 corresponding to a frequency of 75 GHz is selected to define thickness e1, wavelength λ2 corresponding to a frequency of 77 GHz is selected to define thickness e2, and wavelength λ3 corresponding to a frequency of 76 GHz is selected to define thickness e3. Therefore, the detection by radar sensor 10 is very accurate in the frequency bands of 75 GHz, 76 GHz, and 77 GHz because there is no longer any superposition of parasitic reflections R11, R12, R13, R14 and radar waves R15, R16, and thus the loss in the power output of the layer component C is very small. Parasitic reflections will exist, but these parasitic reflections will be attenuated very strongly over the entire operating frequency range of radar sensor 10. Therefore, the (long-range) detection resolution of radar sensor 10 will be better. In another non-limiting example, the detection resolution will be 0.4 cm for a frequency of 350 MHz and 0.2 cm for a frequency of 750 MHz. Thus, for example, radar sensor 10 will be able to detect objects 3 in the external environment of motor vehicle 2 within 0.4 cm or 0.2 cm at a given distance. In another non-limiting embodiment, each thickness e1, e2, e3 can be defined according to the same wavelength λ.

[0076] It should be noted that the description given is for a single radar wave R1, but it certainly applies to all radar waves R1 emitted by radar sensor 10.

[0077] It should be noted that the above description of a layer assembly C comprising a single primary layer 11 and a single secondary layer 12 separated by an air layer 13 applies to a layer assembly C comprising multiple sub-assemblies cs comprising a primary layer 11 and a secondary layer 12, each primary layer 11 and secondary layer 12 of the sub-assemblies cs being separated by an air layer 13 in the same manner. Therefore, in a non-limiting embodiment, the layer assembly C comprises more than two dielectric layers 11, 12, which include a primary layer 11 and a secondary layer 12 separated by an air layer 13. Therefore, multiple air layers 13 are present. Therefore, the vehicle assembly 1 comprises more than two dielectric layers 11, 12 separated by air layers 13.

[0078] Therefore, in Figure 3 In the non-limiting example illustrated, layer component C includes:

[0079] - First layer sub-component cs1, which includes a first primary layer 111 with a thickness e11 and a first secondary layer 121 with a thickness e21 separated by an air layer 131;

[0080] - Second layer sub-component CS2, which includes a second primary layer 112 with a thickness e12 and a second secondary layer 122 with a thickness e22 separated by an air layer 132.

[0081] like Figure 3 As illustrated, the first primary layer 121 of the first sub-component CS1 is also the second primary layer 112 of the second sub-component CS2. Therefore, in a first non-limiting embodiment, the first sub-component CS1 includes a first primary layer 111 (which is the radome of the radar sensor 10) and a first primary layer 121 (which is the decorative portion) separated by a first air layer 131; and the second sub-component CS2 includes a second primary layer 112 (which is the decorative portion) and a second primary layer 122 (which is the emitting lens of the light-emitting device 20 of the motor vehicle 2) separated by a second air layer 132. In a second non-limiting embodiment, the first layer sub-assembly CS1 includes a first primary layer 111 (which is the radome of the radar sensor 10) and a first secondary layer 121 (which is the light-emitting element) separated by a first air layer 131; and the second layer sub-assembly CS2 includes a second primary layer 112 (which is the light-emitting element) and a second secondary layer 122 (which is the exit lens of the light-emitting device 20 of the motor vehicle 2) separated by a second air layer 132.

[0082] In other words, vehicle assembly 1 may also include an antenna radome separated from the decorative portion 11 by an air layer 13, the decorative portion 11 itself being separated from the exiting lens by the air layer 13. The decorative portion may be replaced by a light-emitting element. It should be noted that the more layers in the layer assembly C, the greater the space for enhancing the anti-reflection bandpass filter by adjusting the thickness of each layer; in a non-limiting embodiment, this is achieved by selecting various wavelengths λ for each thickness.

[0083] Therefore, the layer assembly C includes more than two dielectric layers, which include primary layers 111 and 112 and secondary layers 121 and 122 separated in pairs by air layers 131 and 132. That is, the first primary layer 111 is separated from the first secondary layer 121 by the first air layer 131, and the second primary layer 112 is separated from the second secondary layer 122 by the second air layer 132. Thus, as described above, there exists: a layer 111 having a thickness e11 as an antenna radome; a layer 121 having a thickness e21 as a decorative part; and an additional layer 122 having a thickness e22 as an emitting lens of a light-emitting device. Layer 111 is separated from layer 121 by an air layer 131 having a thickness e31. Layer 122 is separated from layer 121 by an air layer 132 having a thickness e32. Therefore, in the first layer sub-component CS1 (including layers 111 and 121), layer 111 is the primary layer as described above, and layer 121 is the secondary layer as described above. Conversely, in the second layer sub-component CS2 (including layers 121 and 122), the same layer 121 is, this time, the primary layer as described above and also indicated by reference numeral 112, and layer 122 is the secondary layer as described above.

[0084] Of course, the invention described is not limited to the embodiments and fields described above. Therefore, in another non-limiting embodiment, the radar sensor 10 includes more than one transmitting antenna 100 and more than two receiving antennas 101.

[0085] Therefore, the described invention has the following advantages in particular:

[0086] - This invention allows the superposition of second-order outgoing and reflected waves R15 and R16 to obtain higher power for detection by radar sensor 10;

[0087] - This invention allows for the elimination of first-order reflected waves R11, R12, R13, and R14 reflected along the direction of radar sensor 10. Therefore, the signal-to-noise ratio of the radar sensor 10 no longer decreases;

[0088] - This invention allows for the creation of an anti-reflection bandpass filter. It allows for the elimination of most reflections across the entire operating frequency range of the radar sensor 10, regardless of the incident angles θ1, θ2, θ3;

[0089] -This invention allows for better detection resolution using radar sensor 10;

[0090] - This invention is easy to implement.

Claims

1. A vehicle component (1) for a vehicle (2), the vehicle component (1) comprising: - Radar sensor (10), the radar sensor is configured to transmit / receive radar waves (R1), the radar sensor (10) is placed facing the layer assembly (C); and - The layer assembly (C) includes at least two dielectric layers (11, 12), which include a primary layer (11) and a secondary layer (12) separated by an air layer (13). - Characterized by the fact that the air layer (13) has a thickness (e3) equal to ((m3+ɛ)x(λ / 2)) / cos(θ3), where ɛ is contained between -0.25 and +0.25, θ3 is the incident angle of the outgoing reflected wave (R20) striking the secondary layer (12), and m3 = 1, ... to N, where N is an integer, the outgoing reflected wave (R20) originates from the radar wave (R1) emitted by the radar sensor (10), and λ is the wavelength of the emitted radar wave R1. The primary layer (11) has a thickness (e1) equal to (λ / (2n1cosβ1))+(m1xλ), where β1 is the refraction angle corresponding to the incident angle θ1 of the emitted radar wave (R1), n1 is the refractive index of the primary layer (11), and m1=1, ... to N, where N is an integer.

2. The vehicle component (1) according to claim 1, wherein, The radar sensor (10) is a radar sensor that uses millimeter waves between 24 GHz and 300 GHz, or sub-microwaves between 300 MHz and 81 GHz, or microwaves between 1 GHz and 300 GHz.

3. The vehicle component (1) according to claim 2, wherein, The radar wave (R1) is transmitted in a frequency band between 100MHz and 3GHz.

4. The vehicle component (1) according to claim 1, wherein, The thickness (e1) of the primary layer (11) is defined by an incident angle θ1 equal to arctan(d1 / (2e4)), where e4 is the distance between the radar sensor (10) and the primary layer (11), and d1 is the distance between the transmitting antenna and the receiving antenna.

5. The vehicle component (1) according to any one of claims 1-4, wherein, The secondary layer (12) has a thickness (e2) equal to (λ / (2n2cosβ2))+(m2xλ), where β2 is the refraction angle corresponding to the incident angle θ2 of the radar wave (R1') emitted from the primary layer (11), n2 is the refractive index of the secondary layer (12), and m2=1, ... to N, where N is an integer.

6. The vehicle component (1) according to any one of claims 1-4, wherein, The primary layer (11) is a decorative part, and the secondary layer (12) is the outgoing lens of the light-emitting device (20) of the vehicle (2).

7. The vehicle component (1) according to claim 6, wherein, The light-emitting device (20) is a headlight or a taillight.

8. The vehicle component (1) according to any one of claims 1 to 4, wherein, The primary layer (11) is the light-emitting element of the logo, and the secondary layer (12) is the outgoing lens of the logo of the vehicle (2).

9. The vehicle component (1) according to any one of claims 1 to 4, wherein, The primary layer (11) is an antenna radome, and the secondary layer (12) is a logo.

10. The vehicle component (1) according to any one of claims 1 to 4, wherein, The layer assembly (C) includes more than two dielectric layers, which include a primary layer and a secondary layer separated by an air layer.

11. The vehicle component (1) according to claim 10, wherein, The layer assembly (C) includes a layer (111) serving as an antenna radome, layers (112, 121) serving as decorative parts, and a layer (121) serving as an outgoing lens for a light-emitting device.

12. A layer assembly (C) for a vehicle (2), the layer assembly (C) being configured to face a radar sensor (10) configured to transmit / receive radar waves (R1), and the layer assembly comprising at least two dielectric layers (11, 12) comprising a primary layer (11) and a secondary layer (12) separated by an air layer (13). Its features are, The air layer (13) has a thickness (e3) equal to (m3x(λ / 2)) / cos(θ3), where θ3 is the incident angle of the outgoing reflected wave (R20) striking the secondary layer (12), and m3 = 1, ... to N, where N is an integer. The outgoing reflected wave (R20) originates from the radar wave (R1) emitted by the radar sensor (10), where λ is the wavelength of the emitted radar wave R1. The primary layer (11) has a thickness (e1) equal to (λ / (2n1cosβ1))+(m1xλ), where β1 is the refraction angle corresponding to the incident angle θ1 of the emitted radar wave (R1), n1 is the refractive index of the primary layer (11), and m1=1, ... to N, where N is an integer.

13. The layer component (C) according to claim 12, wherein, The layer assembly (C) includes more than two dielectric layers, which include a primary layer and a secondary layer separated by an air layer.

Images