Cover member and method for manufacturing the same

Abstract

To provide a cover member that has the same degree of transmission and attenuation amount regardless of a paint color.SOLUTION: A cover member 10 arranged on a radio emission side of a radar instrument 20 is formed to include three layers of a base material layer 11, a painted layer 12 arranged on the base material layer on the opposite side of the radar instrument, and an addition layer 13. The addition layer is adjusted in its dielectric constant or thickness according to the type of the coated layer so that the amount of transmission and attenuation of radio waves radiated from the radar instrument performed by the cover member falls within a predetermined fixed range.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a cover member and a method for manufacturing the same.

Background Art

[0002] Conventionally, a radar system is known that includes a millimeter-wave radar device and a housing that protects the millimeter-wave radar device, and a part of the housing is formed of a resin sheet (Patent Document 1). In particular, in Patent Document 1, the resin sheet is formed so as to gradually increase or decrease from both ends toward the center in the thickness direction in order to suppress reflection of millimeter waves on the resin sheet and increase the transmittance of millimeter waves.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, a cover member for protecting a radar device may be painted. In such painting, since the relative dielectric constant varies depending on the paint color, the amount of transmission attenuation by the cover member may vary depending on the paint color.

[0005] However, even if the paint colors are different, basically the same type of radar device is provided in the same type of vehicle. Therefore, in order to perform accurate measurement by the radar device and eliminate the need to change the design for each paint color, it is preferable that the cover member has approximately the same amount of transmission attenuation regardless of the paint color.

[0006] In view of the above problems, an object of the present disclosure is to provide a cover member having approximately the same amount of transmission attenuation regardless of the paint color and a method for manufacturing the same.

Means for Solving the Problems

[0007] The gist of this disclosure is as follows:

[0008] (1) A cover member positioned on the radio wave emission side of radar equipment, It is formed to include three layers: a base layer, a coating layer located on the opposite side of the base layer from the radar equipment side, and an additional layer. The aforementioned additional layer is a cover member in which the relative permittivity or thickness is adjusted according to the type of coating layer so that the amount of transmission attenuation of radio waves emitted from the radar equipment by the cover member falls within a predetermined range. (2) The cover member described in (1) above, wherein the additional layer is positioned on the side of the coating layer opposite to the base material layer. (3) The additional layer is the cover member described in (1) or (2) above, which is formed as a resin sheet. (4) The cover member according to any one of (1) to (3) above, wherein the radar equipment is installed on the vehicle, and the certain range is the same for each type of vehicle, regardless of the type of paint layer. (5) A method for manufacturing a cover member that is placed on the radio wave transmitting side of radar equipment, The cover member is formed to include three layers: a base layer, a coating layer located on the side of the base layer opposite to the radar equipment side, and an additional layer. A manufacturing method in which the dielectric constant or thickness of the additional layer is adjusted according to the type of coating layer such that the transmission attenuation of radio waves of the radar equipment falls within a predetermined range due to the cover member. [Effects of the Invention]

[0009] According to this disclosure, a cover member having a similar amount of transmission attenuation regardless of the paint color, and a method for manufacturing the same are provided. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram of the vehicle. [Figure 2]Figure 2 is a cross-sectional view of the area around the front grille, taken along line II-II in Figure 1. [Figure 3] Figure 3 shows the changes in amplitude and wavelength of radio waves emitted from radar equipment. [Figure 4] Figure 4 shows an example of the parameters for each layer when different types of coating layers are formed on the same substrate layer. [Figure 5] Figure 5 shows the relationship between the thickness and relative permittivity of the substrate layer and the transmission attenuation of radio waves due to the substrate layer. [Modes for carrying out the invention]

[0011] The embodiments will be described in detail below with reference to the drawings. In the following description, similar components will be given the same reference numeral.

[0012] <Vehicle Configuration> First, with reference to Figures 1 and 2, a vehicle 1 having a cover member 10 for radar equipment 20 according to one embodiment will be described. Figure 1 is a schematic diagram of vehicle 1. Figure 1(A) is a perspective view of vehicle 1, and Figure 1(B) is an enlarged view of a part of the front of vehicle 1. Vehicle 1 may be an autonomous driving vehicle that is driven automatically without driver operation based on measurement results from radar equipment 20. Alternatively, vehicle 1 may be a vehicle in which driver assistance is provided based on measurement results from radar equipment 20.

[0013] Vehicle 1 has a front grille 2 at its front. As shown in Figure 1(B), the front grille 2 has a grid-like section 3 for taking in air to cool the heat-generating equipment of vehicle 1 (internal combustion engine, motor, etc.) and a plate-shaped cover member 10 that covers the radar equipment 20 installed inside.

[0014] Figure 2 is a cross-sectional view of the vicinity of the front grille 2 as seen along line II-II in Figure 1. As shown in Figure 2, the cover member 10 is disposed in front of the radar device 20 and outside the vehicle 1 more than the radar device 20. Further, the cover member 10 is disposed on the side where radio waves are radiated by the radar device 20, that is, on the passing path of the radio waves radiated by the radar device 20. By the cover member 10, the traveling wind does not hit the radar device 20, and thus the radar device 20 is protected.

[0015] The radar device 20 is a device that measures the distance and direction to the surroundings by radiating radio waves to surrounding objects and measuring the reflected waves. The radar device 20 is, for example, a millimeter-wave radar device. However, the radar device 20 may be a device using other types of radar such as a microwave radar device or LiDAR.

[0016] In addition, in the present embodiment, the radar device 20 is disposed inside the front grille 2 of the vehicle 1. However, the radar device 20 may be provided at other locations. Specifically, for example, the radar device 20 may be provided inside the front bumper. In this case, the front bumper functions as a cover member. Also, for example, the radar device 20 may be provided inside the rear bumper. In this case, the rear bumper functions as a cover member. In any case, as long as the cover member 10 is provided outside the radar device 20, the radar device 20 may be disposed at any location.

[0017] <Configuration of the cover member> Next, referring to FIG. 2, the configuration of the cover member 10 will be described. As can be seen from FIG. 2, the cover member 10 is formed to have at least three layers. In this embodiment, the cover member 10 has a base material layer 11, a coating layer 12, and an additional layer 13. In this embodiment, the base material layer 11, the coating layer 12, and the additional layer 13 are arranged in this order from the inside to the outside of the vehicle 1. Therefore, the coating layer 12 is arranged on the outside of the vehicle 1 with respect to the base material layer 11, and the additional layer 13 is arranged on the outside of the vehicle with respect to the coating layer 12. Thus, the additional layer 13 is arranged on the side opposite to the base material layer 11 side of the coating layer 12.

[0018] The base material layer 11 is formed of a material having relatively high strength and transmitting the radio waves radiated from the radar device 20. Specifically, the base material layer 11 is formed of a resin such as polypropylene or ABS, for example. The base material layer 11 is formed such that its thickness is, for example, 1 to 5 mm, or 1.5 to 3 mm. In particular, in this embodiment, the thickness of the base material layer 11 is set such that the transmission attenuation amount of the radio waves radiated from the radar device 20 is small. The base material layer 11 is formed by any molding technique such as injection molding, for example.

[0019] The coating layer 12 is a layer of paint used for painting the vehicle 1. Therefore, the coating layer 12 contains pigments, resins, solvents, and additives. The coating layer 12 is formed such that its thickness is, for example, 0.01 to 0.5 mm, or 0.02 to 0.2 mm. The coating layer 12 is formed by spraying a paint as a raw material of the coating layer on the base material layer 11, for example.

[0020] The additional layer 13 is a layer formed as a transparent sheet. The additional layer 13 is formed of a material having relatively high strength and transmitting the radio waves radiated from the radar device 20. Specifically, it is formed of a resin such as polycarbonate or PET. In this embodiment, the additional layer 13 formed as a transparent sheet is attached onto the surface of the coating layer 12.

[0021] <Configuration of the additional layer> Next, with reference to Figures 3 and 4, the configuration of the additional layer 13, particularly its thickness and relative permittivity, will be described.

[0022] Incidentally, the shape and material of the base layer 11 of the cover member 10 are determined for each type of vehicle 1. Therefore, if the type of vehicle 1 is the same, the shape and material of the base layer 11 are basically the same. Thus, the thickness and relative permittivity εr of the base layer 11 are basically the same if the type of vehicle 1 is the same. On the other hand, the type of paint layer 12 differs depending on the paint color of the vehicle 1. If the paint color is different, the components such as pigments, resins, solvents, and additives contained in the paint layer 12 will be different, and therefore the relative permittivity εr of the paint layer 12 will also be different. Therefore, if the type of paint layer 12 is different, the amount of transmission attenuation in the part of the cover member 10 including the base layer 11 and the paint layer 12 will be different.

[0023] In this embodiment, the dielectric constant or thickness of the additional layer 13 is adjusted according to the type of coating layer 12 so that the transmission attenuation amount of radio waves emitted from the radar equipment 20 by the cover member 10 falls within a predetermined reference range. In this embodiment, the reference range is determined for each type of vehicle 1, and if the type of vehicle 1 is the same, the reference range is the same regardless of the type of coating layer. In particular, in this embodiment, the dielectric constant or thickness of the additional layer 13 is adjusted according to the type of coating layer 12 so that the transmission attenuation amount by the cover member 10 becomes a certain reference value determined for each type of vehicle 1, regardless of the type of coating layer 12.

[0024] Figure 3 shows the changes in amplitude and wavelength of radio waves emitted from radar equipment 20. In the example shown in Figure 3, radar equipment 20 emits radio waves with wavelength λ and amplitude A. The relative permittivity εr in the atmosphere is 1, and the dielectric loss tangent tanδ is 0. Therefore, the loss coefficient obtained by multiplying these is 0. Thus, in the atmosphere, the power loss of radio waves emitted from radar equipment 20 is small.

[0025] Subsequently, when the radio waves emitted from the radar equipment 20 pass through the cover member 10, the wavelength λ' becomes shorter than the wavelength λ in the atmosphere because the relative permittivity is higher than that in the atmosphere. In addition, the dielectric loss tangent tanδ in the cover member 10 is also greater than 0, so the loss coefficient becomes greater than 0. As a result, power loss occurs within the cover member 10 due to the conversion of the radio waves emitted from the radar equipment 20 into thermal energy, and thus the amplitude of the radio waves gradually decreases.

[0026] Subsequently, when the radio waves that had passed through the cover member 10 begin to pass through the atmosphere again, the wavelength returns to λ, but because power loss has occurred within the cover member 10, the amplitude A' at this time is smaller than the amplitude A before passing through the cover member 10. In other words, if we consider only the power loss due to conversion to thermal energy within the cover member 10, the higher the relative permittivity of each layer constituting the cover member 10, and the thicker each layer constituting the cover member 10, the greater the power loss and therefore the greater the transmission attenuation.

[0027] Figure 4 shows an example of the parameters of each layer when different types of coating layers 12 are formed on the same substrate layer 11. Figures 4(A) to 4(C) show the case when the same substrate layer 11 with a thickness of 2.25 mm and a relative permittivity εr of 2.7 is used.

[0028] In the example shown in Figure 4(A), a coating layer 12 made of a first coating material is formed on the surface of the base material layer 11. The relative permittivity εr of the first coating material is 4, and the thickness of the coating layer 12 is 0.03 mm. In addition, an additional layer 13, formed as a transparent sheet of polycarbonate, is formed on the surface of the coating layer 12. The relative permittivity of the additional layer 13 is 2.7, and the thickness of the additional layer 13 is 0.15 mm. As a result, the transmission attenuation of radio waves (millimeter waves) emitted from the radar equipment 20 by the cover member 10 formed in this way matches a preset reference value (or falls within the reference range).

[0029] In the example shown in Figure 4(B), a coating layer 12 made of a second coating material is formed on the surface of the substrate layer 11. The second coating material has different physical properties from the first coating material. In particular, the relative permittivity of the second coating material is different from that of the first coating material. Specifically, in this embodiment, the relative permittivity of the second coating material is 20. The thickness of the coating layer 12 is 0.03 mm.

[0030] In this embodiment, as described above, the additional layer 13 is configured such that the transmission attenuation of radio waves by the cover member 10 matches the reference value (or falls within the reference range). In particular, in the example shown in Figure 4(B), the thickness of the additional layer 13 is changed from the thickness of the additional layer 13 in the example shown in Figure 4(A). Specifically, the thickness of the additional layer 13 is reduced because the relative permittivity of the coating layer 12 has increased and the loss coefficient has increased. In the example shown in Figure 4(B), the thickness of the additional layer 13 is 0.05 mm, which makes the transmission attenuation of radio waves by the cover member 10 match the reference value.

[0031] In the example shown in Figure 4(C), as in the example shown in Figure 4(B), a coating layer 12 made of a second coating material is formed on the surface of the base layer 11. In the example shown in Figure 4(C), the relative permittivity of the additional layer 13 is changed from that of the additional layer 13 in the example shown in Figure 4(A). Specifically, the relative permittivity of the additional layer 13 is decreased to compensate for the increased loss coefficient due to the increased relative permittivity of the coating layer 12. In the example shown in Figure 4(C), the relative permittivity of the additional layer 13 is set to 2.2, which brings the transmission attenuation of radio waves by the cover member 10 to match the reference value. The adjustment of the relative permittivity of the additional layer 13 is performed, for example, by changing the components of the additives mixed into the resin material.

[0032] According to this embodiment, as described above, by adjusting the thickness or dielectric constant of the additional layer 13 of the cover member 10, the amount of radio wave transmission attenuation by the cover member 10 can be adjusted to match the reference value or to fall within the reference range, even if the type of paint layer 12 changes. In particular, in this embodiment, the additional layer 13 is configured as a resin tape that is attached after the painting of the vehicle 1 is completed, so the amount of radio wave transmission attenuation by the cover member 10 can be adjusted simply by changing the resin tape attached according to the type of paint layer 12 (paint color, etc.).

[0033] In the above embodiment, the relative permittivity and thickness of the additional layer 13 are adjusted so that the transmission attenuation of radio waves by the cover member 10 matches a reference value or falls within a reference range. However, other parameters such as the dielectric loss tangent tanδ may also be adjusted.

[0034] Furthermore, in the above embodiment, only the attenuation due to the conversion of radio waves into thermal energy when they pass through the cover member 10 is considered. However, when radio waves pass through the cover member 10, the amount of attenuation changes due to mutual interference caused by the reflection of radio waves at interfaces (the interface between air and the base material layer 11, the interface between the base material layer 11 and the coating layer 12, the interface between the coating layer 12 and the additional layer 13, and the interface between the additional layer 13 and air). Specifically, if the phases of the radio waves reflected an even number of times at the interface are close to in phase, the attenuation will be small, and if the phases of the radio waves reflected an even number of times at the interface are close to out of phase, the attenuation will be large. The phase and strength of the reflected waves at this time change depending on the thickness of each layer and the ratio of the relative permittivity at the interface. Therefore, the relative permittivity and thickness of the additional layer 13 may be set taking into consideration not only the attenuation due to the conversion into thermal energy, but also the attenuation due to mutual interference caused by reflection.

[0035] According to this embodiment, the additional layer 13, which is formed as a transparent sheet, is placed on the opposite side of the coating layer 12 from the base material layer 11, that is, on the outside of the coating layer 12. By providing a transparent sheet on the coating layer 12 in this way, damage to the coating layer 12 is suppressed. In particular, if the additional layer 13 is not provided, it is assumed that the user will attempt to repair the coating layer 12 themselves if it is partially peeled off due to chipping or scratches. However, if the user attempts to repair it themselves, the transmission attenuation will change because a material with an appropriate dielectric constant is not used, and the measurement accuracy of the radar equipment 20 will decrease. By providing the additional layer 13, which is a transparent sheet, damage to the coating layer 12 is suppressed, and changes in the transmission attenuation caused by the user's own repairs can be suppressed.

[0036] Furthermore, according to this embodiment, the additional layer 13 is formed as a resin sheet. Therefore, the additional layer 13 can be easily produced by attaching a resin sheet to the surface of the painted layer 12 according to the type (color) of the painted layer.

[0037] <Manufacturing procedure for cover components> Next, the manufacturing procedure for the cover component 10 will be briefly explained.

[0038] In manufacturing the cover member 10, a base layer 11 is first produced. The base layer 11 is produced by a general molding method such as injection molding. Figure 5 shows the relationship between the plate thickness and relative permittivity εr of the base layer 11 and the transmission attenuation of radio waves by the base layer 11. As shown in Figure 5, the transmission attenuation of radio waves by the base layer 11 changes depending on the plate thickness and relative permittivity εr of the base layer 11. For example, in the example shown in Figure 5, when the base layer 11 is formed from a material with a relative permittivity of 2.7 (dashed line in the figure), the plate thickness of the base layer 11 is set to approximately 2.4 mm so as to have the necessary strength while reducing the transmission attenuation.

[0039] Once the base layer 11 is formed, the front surface of the base layer 11 is painted to form the painted layer 12. The painted layer 12 is formed, for example, by spraying paint onto the surface of the base layer 11. Different paints are used for each body color of the vehicle 1, thus forming different types of painted layers 12.

[0040] Once the coating layer 12 is formed, an additional layer 13 is formed by attaching a transparent sheet to the coating layer 12. The thickness and dielectric constant of the transparent sheet are selected, as described above, so that the transmission attenuation of radio waves by the finally formed cover member 10 falls within a standard value (or standard range). The transparent sheet is attached to the coating layer 12 with any transparent adhesive.

[0041] As described above, according to this manufacturing method, the cover member 10 is formed to include three layers: a base layer 11, a coating layer 12, and an additional layer 13. In this manufacturing method, the dielectric constant and thickness of the additional layer are adjusted according to the type of coating layer 12 so that the transmission attenuation of radio waves of the radar equipment 20 by the cover member 10 falls within a predetermined range.

[0042] While preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and various modifications and changes can be made within the scope of the claims. [Explanation of symbols]

[0043] 1 vehicle 10 Cover component 11 Base material layer 12 Paint layers 13 Additional layers 20 Radar equipment

Claims

1. A method for manufacturing a cover member that is disposed on the radio wave transmitting side of radar equipment installed in a vehicle, The cover member is formed to include three layers: a base layer, a coating layer located on the side of the base layer opposite to the radar equipment side, and an additional layer. The dielectric constant or thickness of the additional layer is adjusted according to the type of coating layer so that the transmission attenuation of radio waves from the radar equipment falls within a predetermined range due to the cover member. A manufacturing method wherein the aforementioned certain range is the same for each type of vehicle, regardless of the type of paint layer.

2. The manufacturing method according to claim 1, wherein the additional layer is arranged on the side of the coating layer opposite to the base material layer.

3. The manufacturing method according to claim 1 or 2, wherein the additional layer is formed as a resin sheet.

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