Vehicle radar unit

Abstract

This invention provides a vehicle radar unit that can improve the accuracy of radar devices while increasing the design flexibility of the radar device. [Solution] The vehicle radar unit 10 comprises a radar device 11 and an exterior member 12. The exterior member 12 has a light source 20, a housing 30, and a cover portion 40. The housing 30 has a bottom wall portion 31 and an outer peripheral wall portion 36. The bottom wall portion 31 has a projection portion 32 that protrudes away from the radar device 11 in the front-rear direction X. The radar device 11 is positioned so as not to overlap with the housing portion 37 in a direction perpendicular to the central axis C. The inclination angle θ1 of the inner peripheral wall portion 34, the length L of the inner peripheral wall portion 34, and the shortest distance D2 from the central axis C to the inner peripheral wall portion 34 are set such that the absolute value of the tilt angle θ2 of the main lobe ML transmitted from the radar device 11 is greater than 0° and less than or equal to 0.38°.

Description

【Technical Field】 , , , , , 【0006】 , , , , , , , , 【0005】 , 【0001】 The present invention relates to a vehicle radar unit. 【Background Art】 【0002】 Patent Document 1 describes a vehicle emblem unit. This emblem unit includes an emblem, an emblem lamp (hereinafter referred to as a lamp), and an emblem mounting sensor (hereinafter referred to as a sensor). The emblem is provided at the front of the vehicle. The lamp includes a light guide, an emblem light source (hereinafter referred to as a light source), and a reflection part. The light guide is provided on the back of the emblem. The light source is provided at a position facing an incident part provided on the outer peripheral surface of the light guide. The reflection part is formed on the back surface of the light guide. The sensor is disposed on the back of the light guide. The sensor transmits millimeter waves forward of the vehicle and acquires information in front of the vehicle by receiving the reflected waves. 【0003】 [[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​Incidentally, in these emblem units, the sensor is surrounded by a bracket, which limits the size and placement of the sensor to the size of the bracket. 【0007】 Therefore, one might consider positioning the sensor away from the back of the light guide so that it is not surrounded by a bracket. However, this presents the following problem: In addition to the main lobe, the radio waves transmitted from the sensor include side lobes and other radio waves transmitted in directions different from the main lobe. As a result, if the sensor is simply positioned away from the back of the light guide, for example, side lobes are more likely to be incident on the inner surface of the bracket. When side lobes are incident on the inner surface of the bracket, they are reflected by this inner surface, and the reflected side lobes interfere with the main lobe. As a result, so-called beam tilt occurs, where the direction of travel of the main lobe is tilted relative to the transmission direction, which may reduce the accuracy of the sensor. Therefore, it is difficult to improve the design flexibility of the sensor while ensuring the accuracy of the sensor. 【0008】 Furthermore, these problems are not limited to emblem units that are attached to a vehicle via a bracket. For example, they can similarly occur in any radar unit that comprises a radar device and an exterior member positioned in front of the radar device, wherein the exterior member is provided with a configuration that surrounds the radar device. [Means for solving the problem] 【0009】 This paper describes various embodiments of a vehicle radar unit designed to solve the above-mentioned problems. [Aspect 1] A radar device for transmitting and receiving electromagnetic waves, and an exterior member positioned in front of the radar device in the direction of transmission of the electromagnetic waves and having electromagnetic wave transparency, wherein the exterior member has a light source that emits visible light, a housing having an opening that opens toward the front in the transmission direction, and a cover portion that closes the opening and is transparent to visible light, wherein the housing has a bottom wall portion and an outer peripheral wall portion that rises from the periphery of the bottom wall portion toward the front in the transmission direction, wherein the bottom wall portion protrudes away from the radar device in the transmission direction and forms a housing portion between itself and the outer peripheral wall portion in which the light source is housed. Vehicle radar unit having a protruding portion, wherein the portion of the protruding portion extending rearward in the transmission direction from the periphery of the tip is defined as an inner circumferential wall portion, the radar device is positioned along the transmission direction and perpendicular to the central axis passing through the center of the radar device, and does not overlap with the inner circumferential wall portion, and the inclination angle of the inner circumferential wall portion with respect to the central axis, the length of the inner circumferential wall portion in the transmission direction, and the shortest distance from the central axis to the inner circumferential wall portion are set such that the absolute value of the tilt angle of the main lobe of the electromagnetic wave transmitted from the radar device with respect to the central axis is greater than 0° and less than or equal to 0.38°. 【0010】 According to the above configuration, the radar device is positioned away from the bottom wall of the housing in the transmission direction, and does not overlap with the housing's interior in the orthogonal direction. Therefore, the size and placement of the radar device are not restricted by the housing. This improves the design flexibility in setting the size and placement of the radar device. 【0011】 Here, side lobes transmitted from the radar system and reflected from the inner wall can interfere with the main lobe transmitted from the radar system, causing beam tilt and potentially reducing the accuracy of the radar system. In particular, when the absolute value of the main lobe's tilt angle exceeds 0.38°, the decrease in the radar system's accuracy becomes significant. In this regard, with the above configuration, by appropriately adjusting the inclination angle of the inner wall, the length of the inner wall, and the shortest distance from the central axis to the inner wall, the absolute value of the main lobe's tilt angle is kept below 0.38°. This suppresses the decrease in the radar system's accuracy due to the main lobe's beam tilt. 【0012】 Therefore, it is possible to improve the accuracy of radar systems while increasing the design flexibility of the radar system. [Aspect 2] The vehicle radar unit according to [Aspect 1], wherein the inclination angle of the inner circumferential wall portion with respect to the central axis is set to 1° or more and 12° or less. 【0013】 If the inclination angle of the inner circumferential wall is less than 1°, the absolute value of the tilt angle of the main lobe tends to exceed 0.38°. As a result, the accuracy of the radar device may decrease. In this respect, with the above configuration, the inclination angle of the inner circumferential wall is 1° or more. Therefore, the absolute value of the tilt angle of the main lobe can be preferably kept below 0.38°. 【0014】 Furthermore, increasing the inclination angle of the inner circumferential wall reduces the incidence angle of the side lobes incident on the inner circumferential wall, thus reducing the reflection angle of the side lobes reflected from the same inner circumferential wall. In this case, the transmitted component of the incident side lobes that passes through the inner circumferential wall increases, while the reflected component of the same side lobes that reflects off the inner circumferential wall decreases. This makes it possible to reduce the absolute value of the tilt angle of the main lobe. On the other hand, increasing the inclination angle of the inner circumferential wall tends to increase the size of the housing away from the central axis in order to secure the housing space for the light source. This problem becomes particularly noticeable when the inclination angle of the inner circumferential wall is set to greater than 12°. In this respect, with the above configuration, the inclination angle of the inner circumferential wall is 12° or less. Therefore, it is possible to suitably suppress the beam tilt of the main lobe while suppressing an increase in the size of the housing. 【0015】 Therefore, it is possible to improve the accuracy of the radar device while keeping the size of the housing to a minimum. [Aspect 3] The vehicle radar unit according to [Aspect 1] or [Aspect 2], wherein the length of the inner circumferential wall portion in the transmission direction is set to 15 mm or more and 20 mm or less. 【0016】 Increasing the length of the inner circumferential wall increases the area of ​​the inner circumferential wall that acts as a reflective surface for the side lobes, thus increasing the amount of side lobes reflected by the inner circumferential wall. As a result, the absolute value of the tilt angle of the main lobe tends to increase. In addition, increasing the length of the inner circumferential wall increases the size of the housing in the transmission direction, making the radar unit more susceptible to interference with components located behind the radar unit in the transmission direction. These problems become particularly noticeable when the length of the inner circumferential wall is set to more than 20 mm. In this respect, with the above configuration, the length of the inner circumferential wall is 20 mm or less. Therefore, it is possible to keep the absolute value of the tilt angle of the main lobe below 0.38° while suppressing an increase in the size of the housing. 【0017】 Furthermore, reducing the length of the inner circumferential wall reduces the area of ​​the inner circumferential wall that serves as the reflective surface for the side lobes, thus reducing the amount of side lobes reflected by the inner circumferential wall. This allows for a reduction in the absolute value of the tilt angle of the main lobe. On the other hand, reducing the length of the inner circumferential wall makes it difficult to secure the necessary space for the housing where the light source is housed. This problem becomes particularly pronounced when the length of the inner circumferential wall is set to less than 15 mm. In this respect, the above configuration ensures that the length of the inner circumferential wall is 15 mm or more. Therefore, it is possible to effectively suppress the beam tilt of the main lobe while securing the necessary space within the housing. 【0018】 Therefore, it is possible to achieve both securing sufficient space for the housing and suppressing an increase in the size of the housing, while further improving the accuracy of the radar device. [Aspect 4] A vehicle radar unit according to any one of [Aspect 1] to [Aspect 3], wherein the shortest distance from the central axis to the inner peripheral wall portion is set to 54 mm or more and 65 mm or less. 【0019】 The smaller the shortest distance from the central axis to the inner circumferential wall, the larger the area of ​​the inner circumferential wall that serves as the reflective surface for the side lobes, and therefore the greater the amount of side lobes reflected by the inner circumferential wall. As a result, the absolute value of the tilt angle of the main lobe tends to increase. Furthermore, the smaller the shortest distance, the smaller the size of the protruding part becomes on the side closer to the central axis, which can lead to problems such as a reduced field of view for the radar device. These problems become particularly noticeable when the shortest distance is set to less than 54 mm. In this respect, with the above configuration, the shortest distance is 54 mm or more. Therefore, it is possible to keep the absolute value of the tilt angle of the main lobe smaller than 0.38° while still ensuring a sufficient field of view for the radar device. 【0020】 Also, as the shortest distance increases, the area of the portion of the inner peripheral wall that serves as the reflecting surface of the side lobe decreases, so the amount of side lobes reflected by the inner peripheral wall also decreases. As a result, the absolute value of the tilt angle of the main lobe can be reduced. On the other hand, as the shortest distance increases, there is a problem that the physical size of the housing tends to increase on the side away from the central axis in order to secure the accommodation space for the light source. Such a problem becomes particularly prominent when the shortest distance is set to be greater than 65 mm. In this regard, according to the above configuration, the shortest distance is 65 mm or less. Therefore, while preferably suppressing the beam tilt of the main lobe, it is possible to suppress an increase in the physical size of the housing. 【0021】 Therefore, while suppressing an increase in the physical size of the housing, it is possible to further improve the accuracy of the radar device. 【Advantages of the Invention】 【0022】 According to the present invention, it is possible to improve the accuracy of the radar device while increasing the design freedom of the radar device. 【Brief Description of the Drawings】 【0023】 [Figure 1] FIG. 1 is a front view showing an embodiment of a vehicle radar unit. [Figure 2] FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1. [Figure 3] FIG. 3 is a schematic diagram for explaining dimensions and the like at various locations of the vehicle radar unit of the present embodiment. [Figure 4] FIG. 4 is a graph showing the relationship between the tilt angle of the inner peripheral wall of the housing and the tilt angle of the main lobe. [Figure 5] FIG. 5 is a graph showing the relationship between the length of the inner peripheral wall of the housing and the tilt angle of the main lobe. [Figure 6] FIG. 6 is a graph showing the relationship between the shortest distance from the central axis of the radar device to the inner peripheral wall of the housing and the tilt angle of the main lobe. [Modes for carrying out the invention] 【0024】 An embodiment of a vehicle radar unit will be described below with reference to Figures 1 to 6. Hereafter, the longitudinal direction of the vehicle will be referred to as the longitudinal direction X, and the front and rear of the longitudinal direction X will be simply referred to as the front and rear. The width direction of the vehicle will be referred to as the vehicle width direction W, and the vertical direction of the vehicle when the vehicle is positioned on a horizontal plane will be referred to as the vertical direction Z. 【0025】 <Basic configuration of a vehicle radar unit> As shown in Figures 1 and 2, the vehicle radar unit 10 includes a radar device 11 mounted on the front of the vehicle and an exterior member 12 positioned in front of the radar device 11. 【0026】 The radar device 11 is an on-board sensor that detects objects outside the vehicle by transmitting electromagnetic waves and receiving electromagnetic waves reflected from those objects. The radar device 11 transmits, for example, electromagnetic waves with a wavelength of 1 mm to 10 mm and a frequency of 30 GHz to 300 GHz, so-called millimeter waves. In this embodiment, the radar device 11 is mounted on the front of the vehicle so as to transmit millimeter waves forward. That is, the transmission direction of the electromagnetic waves (millimeter waves) from the radar device 11 coincides with the longitudinal direction X of the vehicle. Figure 2 schematically shows the main lobe ML of the millimeter waves transmitted from the radar device 11. 【0027】 The exterior member 12 constitutes a part of the vehicle's outer shell at the front of the vehicle. The exterior member 12 is a rectangular plate that is long in the vehicle width direction W (see Figure 1). The exterior member 12 has an emblem portion 13 and a panel portion 16 other than the emblem portion 13. The emblem portion 13 is transparent to electromagnetic waves (millimeter waves) and is located in front of the radar device 11. The emblem portion 13 is also located in the central part of the exterior member 12. More specifically, in this embodiment, the emblem portion 13 is positioned such that its center lies on the central axis C. Here, the central axis C is an axis that runs along the longitudinal direction X and passes through the center of the radar device 11 (see Figure 2). In the following explanation, in the radial direction centered on the central axis C, the side approaching the central axis C may be referred to as the inner circumference side, and the side moving away from the central axis C may be referred to as the outer circumference side. 【0028】 As shown in Figure 1, the outer edge shape of the design surface 13a of the emblem portion 13 is circular when viewed from the front. The design surface 13a is provided with a display area 14 for displaying a mark facing forward, and a background area 15 that serves as the background other than the display area 14. The term "mark" here includes, for example, designed letters (logotype) that indicate the vehicle manufacturer's name, vehicle name, grade name, etc., a figure (symbol mark) that symbolizes the vehicle manufacturer, etc., or a logo mark formed by combining letters and figures. In this embodiment, the display area 14 is composed of a letter portion 14a that shows the English letters "TG" and an annular portion 14b that extends along the outer edge of the emblem portion 13 and surrounds the letter portion 14a. 【0029】 As shown in Figures 1 and 2, the exterior component 12 comprises a light source 20, a housing 30, and a cover portion 40. Each component will be described in detail below. <Light source> As shown in Figure 2, a light source 20 is mounted on the substrate 21. The substrate 21 extends along the outer edge of the emblem portion 13. In this embodiment, a plurality of light sources 20 are arranged on the substrate 21 at intervals from each other in the direction of extension of the substrate 21. The plurality of light sources 20 are fixed to the front surface 21a of the substrate 21 and are configured to emit visible light (hereinafter simply referred to as light) toward the front. The light sources 20 are composed of light-emitting elements such as light-emitting diodes (LEDs). 【0030】 <Housing> As shown in Figure 2, the housing 30 has a bottom wall portion 31 and an outer peripheral wall portion 36 that rises forward from the periphery of the bottom wall portion 31. The bottom wall portion 31 constitutes the rear surface of the emblem portion 13 and faces the radar device 11 in the front-rear direction X. The bottom wall portion 31 has a projection portion 32 that protrudes forward away from the radar device 11 in the front-rear direction X, and a general portion 35 located on the outer periphery of the projection portion 32. The projection portion 32 is composed of a flat tip portion 33 and an inner peripheral wall portion 34 that extends rearward from the periphery of the tip portion 33. In this embodiment, the tip portion 33 is curved with respect to the vertical direction Z. The inner peripheral wall portion 34 is inclined toward the outer periphery as it moves towards the rear. The inner peripheral wall portion 34, together with the general portion 35 and the outer peripheral wall portion 36, constitutes a housing portion 37 that forms a housing space S in which the light source 20 and the substrate 21 are housed. Furthermore, the housing section 37 houses a light guide (not shown) which is positioned in front of the light source 20 and guides the light emitted from the light source 20 to the inner circumference of the emblem section 13. 【0031】 The tip of the outer peripheral wall portion 36 forms an opening 38 that opens forward. The outer peripheral wall portion 36 is provided with a flange portion 39 that protrudes outward. The housing 30 is formed from a resin material in which particles of white light-diffusing material are dispersed. Therefore, the inner surface of the housing 30 forms a reflective surface that reflects light. As the resin material forming the housing 30, for example, acrylonitrile-butadiene-styrene copolymer (ABS) resin can be used. As the light-diffusing material, for example, metal oxides such as titanium dioxide and zinc oxide can be used. 【0032】 <Cover section> As shown in Figures 1 and 2, the cover portion 40 has a first cover portion 41 that constitutes the design surface 13a side and a second cover portion 42 that is laminated on the rear surface of the first cover portion 41. 【0033】 As shown in Figure 2, the first cover portion 41 blocks the opening 38 from the front. The portion of the first cover portion 41 corresponding to the emblem portion 13 is provided with a light-transmitting portion configured to transmit light from the light source 20 and a light-shielding portion configured to block light from the light source 20 (neither of which are shown). In this embodiment, the display area 14 is formed by the light-transmitting portion. The background area 15 is formed by the light-shielding portion. 【0034】 The second cover portion 42 constitutes the rear surface 16b of the panel portion 16 of the cover portion 40. A hole 42a is formed in the second cover portion 42 at the location corresponding to the emblem portion 13, penetrating in the front-to-back direction X. The housing 30 is fitted into the hole 42a. A watertight portion 43 and a boss 44 are provided on the opening edge 42b of the hole 42a, arranged in order from the inner circumference. The watertight portion 43 seals the gap between the flange portion 39 and the opening edge 42b, for example, by hot melt adhesive. The housing 30 is fixed to the cover portion 40 by inserting the screw 50 through the fastening hole 39a formed in the flange portion 39 and screwing it into the threaded hole of the boss 44. 【0035】 The emblem portion 13 is configured such that light emitted from the light source 20 is repeatedly reflected between the housing 30 (particularly the tip portion 33) and the first cover portion 41, and then transmitted through the light-transmitting portion of the first cover portion 41 and emitted forward, thereby emitting light to display the display area 14 in a forward direction. 【0036】 <Dimensions and placement of various parts of the vehicle radar unit> As shown in Figure 3, the radar device 11 is positioned so as not to overlap with the inner peripheral wall portion 34 of the housing 37 in a direction perpendicular to the central axis C. In other words, the inner peripheral wall portion 34 of the housing 37 is not located on the virtual plane V on which the radar device 11 is located, which is a virtual plane perpendicular to the central axis C. In this embodiment, the distance D1 between the portion where the bottom wall portion 31 intersects the central axis C and the radar device 11 is set to 18 mm. 【0037】 The inclination angle θ1 of the inner peripheral wall portion 34 with respect to the central axis C, the length L of the inner peripheral wall portion 34 in the front-rear direction X, and the shortest distance D2 from the central axis C to the inner peripheral wall portion 34 are set such that the absolute value of the tilt angle θ2 of the main lobe ML transmitted from the radar device 11 with respect to the central axis C is greater than 0° and less than or equal to 0.38°. In Figure 3, the main lobe ML when no beam tilt occurs is shown as a dashed line, and the main lobe ML after beam tilt occurs is shown as a solid line. 【0038】 The relationship between the inclination angle θ1, length L, and shortest distance D2 and the tilt angle θ2 will be explained below with reference to Figures 4 to 6. Strictly speaking, the tilt angle measured in each graph is the inclination angle relative to the tilt angle of the main lobe ML when there is no exterior member 12 in front of the radar device 11, with the tilt angle set to 0°. However, for the sake of explanation, it will be described as the tilt angle θ2. 【0039】 The graph in Figure 4 shows the change in the tilt angle θ2 of the main lobe ML transmitted by the radar device 11 when the tilt angle θ1 is changed. The tilt angle θ2 approaches 0° as the tilt angle θ1 increases. This is because as the tilt angle θ1 increases, the incident angle of the side lobe SL incident on the inner peripheral wall portion 34 decreases, and as a result, the transmitted component of the side lobe SL that passes through the inner peripheral wall portion 34 increases, while the reflected component of the side lobe SL reflected by the inner peripheral wall portion 34 decreases. Also, when the tilt angle θ1 is less than 1°, the tilt angle θ2 becomes less than -0.38°. For this reason, it is preferable to set the tilt angle θ1 to 1° or more in order to keep the absolute value of the tilt angle θ2 to 0.38 or less. On the other hand, as the tilt angle θ1 increases, the size of the housing 30 tends to increase on the outer side in order to secure the housing space S of the housing portion 37 in which the light source 20 is housed. These problems become particularly pronounced when the inclination angle θ1 is set to a value greater than 12°. Therefore, from the viewpoint of suppressing an increase in the radial size of the housing 30, it is preferable to set the inclination angle θ1 to 12° or less. In this embodiment, the inclination angle θ1 is set to 3°. 【0040】 The graph in Figure 5 shows the change in the tilt angle θ2 of the main lobe ML transmitted by the radar device 11 when the length L is changed. In all cases, the measured tilt angle θ2 satisfies the condition that the absolute value is 0.38° or less. Furthermore, when the length L is made smaller than 20 mm, the tilt angle θ2 approaches 0°. This is thought to be because the area of ​​the part of the inner circumferential wall 34 that becomes the reflective surface of the side lobe SL decreases as the length L decreases. On the other hand, the smaller the length L, the more difficult it becomes to secure the housing space S of the housing section 37 in which the light source 20 is housed. This problem is particularly noticeable when the length L is set to be smaller than 15 mm. For this reason, from the viewpoint of securing the housing space S in the housing section 37, it is preferable that the length L be 15 mm or more. Also, the larger the length L, the larger the size of the housing 30 in the front-rear direction X tends to be. In this case, problems arise such as interference with a member (not shown) located behind the radar unit 10 in the front-rear direction X. In particular, these problems become more pronounced when the length L is set to be greater than 20 mm, and even more pronounced when it is set to be greater than 27 mm. Therefore, from the viewpoint of suppressing the increase in the size of the housing 30 in the front-rear direction X, the length L is preferably 27 mm or less, and more preferably 20 mm or less. In this embodiment, the length L is set to 22 mm. 【0041】 The graph in Figure 6 shows the change in the tilt angle θ2 of the main lobe ML transmitted by the radar device 11 when the shortest distance D2 is changed. In all cases, the measured tilt angle θ2 satisfies the condition that the absolute value is 0.38° or less. Furthermore, when the shortest distance D2 is increased above 54 mm, the tilt angle θ2 approaches 0°. This is thought to be because as the shortest distance D2 increases, the area of ​​the part of the inner peripheral wall 34 that becomes the incident surface (reflection surface) of the side lobe SL decreases. On the other hand, as the shortest distance D2 increases, a problem arises in that the size of the housing 30 tends to increase on the outer side in order to secure the housing space S of the housing section 37 in which the light source 20 is housed. In particular, this problem becomes noticeable when the shortest distance D2 is set to a value greater than 65 mm. For this reason, from the viewpoint of suppressing the increase in the radial size of the housing 30, it is preferable to set the shortest distance D2 to 65 mm or less. Furthermore, reducing the minimum distance D2 reduces the size of the housing 30 on the inner side, which leads to problems such as a reduced field of view of the radar device 11. This problem is particularly noticeable when the minimum distance D2 is set to less than 54 mm, and even more noticeable when it is set to less than 40 mm. For this reason, from the viewpoint of ensuring a sufficient field of view of the radar device 11, the minimum distance D2 is preferably 40 mm or more, and more preferably 54 mm or more. In this embodiment, the minimum distance D2 is set to 40 mm. 【0042】 <Operation of this embodiment> As shown in Figure 3, the radar device 11 is positioned at a distance from the bottom wall 31 of the housing 30 in the front-rear direction X, and at a position that does not overlap with the inner peripheral wall 34 of the housing section 37 of the housing 30 in the direction perpendicular to the virtual plane V. Therefore, the size and placement of the radar device 11 are not restricted by the housing 30. This improves the design freedom in setting the size and placement of the radar device 11. 【0043】 Here, the side lobe SL transmitted from the radar device 11 and reflected off the inner peripheral wall 34 may interfere with the main lobe ML transmitted from the radar device 11, causing beam tilt and potentially reducing the accuracy of the radar device 11. In this regard, according to the configuration of the vehicle radar unit 10 of this embodiment, the inclination angle θ1, length L, and shortest distance D2 are set to θ1=3(°), L=22(mm), and D2=40(mm), respectively. Therefore, even if the side lobe SL transmitted from the radar device 11 is reflected off the inner peripheral wall 34 and interferes with the main lobe ML, the absolute value of the tilt angle θ2 of the main lobe ML with respect to the central axis C is kept to 0.38° or less. This suppresses the reduction in the accuracy of the radar device 11 due to the beam tilt of the main lobe ML. 【0044】 <Effects of this embodiment> (1) The vehicle radar unit 10 comprises a radar device 11 and an exterior member 12 having millimeter-wave transparency. The exterior member 12 includes a light source 20, a housing 30 having an opening 38, and a cover portion 40 that closes the opening 38 and is transparent to visible light. The housing 30 has a bottom wall portion 31 and an outer peripheral wall portion 36 that rises forward from the periphery of the bottom wall portion 31. The bottom wall portion 31 has a projection 32 that protrudes away from the radar device 11 and forms a housing portion 37 between itself and the outer peripheral wall portion 36 in which the light source 20 is housed. The radar device 11 is located in a position that does not overlap with the inner peripheral wall portion 34 in a direction perpendicular to the central axis C passing through the center of the radar device 11. The inclination angle θ1 of the inner circumferential wall portion 34 with respect to the central axis C, the length L of the inner circumferential wall portion 34 in the front-rear direction X, and the shortest distance D2 from the central axis C to the inner circumferential wall portion 34 are set such that the absolute value of the tilt angle θ2 of the main lobe ML transmitted from the radar device 11 with respect to the central axis C is 0.38° or less. 【0045】 This configuration produces the effects described above. Therefore, it is possible to increase the design flexibility of the radar device 11 while improving the accuracy of the radar device 11. (2) The inclination angle θ1 of the inner circumferential wall portion 34 with respect to the central axis C is set to 3°. 【0046】 If the inclination angle θ1 of the inner circumferential wall portion 34 is made smaller than 1°, the absolute value of the tilt angle θ2 of the main lobe ML tends to become larger than 0.38°. As a result, the accuracy of the radar device 11 may decrease. In this respect, with the above configuration, the inclination angle θ1 of the inner circumferential wall portion 34 is 1° or more. Therefore, the absolute value of the tilt angle θ2 of the main lobe ML can be suitably kept below 0.38°. 【0047】 Furthermore, the larger the inclination angle θ1 of the inner circumferential wall portion 34, the smaller the incident angle of the side lobes SL incident on the inner circumferential wall portion 34, and therefore the smaller the reflection angle of the side lobes SL reflected from the inner circumferential wall portion 34. In this case, the transmitted component of the incident side lobes SL that passes through the inner circumferential wall portion 34 becomes larger, and the reflected component of the side lobes SL that is reflected from the inner circumferential wall portion 34 becomes smaller. This makes it possible to reduce the absolute value of the tilt angle θ2 of the main lobe ML. On the other hand, the larger the inclination angle θ1 of the inner circumferential wall portion 34 becomes, in order to secure the housing space S of the housing portion 37 in which the light source 20 is housed, the more likely the size of the housing 30 is to become larger on the side away from the central axis C. This problem is particularly noticeable when the inclination angle θ1 of the inner circumferential wall portion 34 is set to a value greater than 12°. In this respect, according to the above configuration, the inclination angle θ1 of the inner circumferential wall portion 34 is 12° or less. Therefore, it is possible to effectively suppress the beam tilt of the main lobe ML while preventing the housing 30 from becoming too large. 【0048】 Therefore, it is possible to improve the accuracy of the radar device 11 while keeping the size of the housing 30 from increasing. (3) The length L of the inner circumferential wall portion 34 in the front-rear direction X is set to be between 15 mm and 20 mm. 【0049】 The larger the length L of the inner circumferential wall portion 34, the larger the area of ​​the portion of the inner circumferential wall portion 34 that serves as the reflective surface for the side lobes SL, and therefore the larger the amount of side lobes SL reflected by the inner circumferential wall portion 34. As a result, the absolute value of the tilt angle θ2 of the main lobe ML tends to increase. In addition, the larger the length L of the inner circumferential wall portion 34, the larger the size of the housing 30 in the front-to-back direction X, making it easier for the radar unit 10 to interfere with components located behind the radar unit 10 in the front-to-back direction X. These problems become particularly noticeable when the length L of the inner circumferential wall portion 34 is set to be greater than 20 mm. In this respect, with the above configuration, the length L of the inner circumferential wall portion 34 is 20 mm or less. Therefore, it is possible to suppress the increase in the size of the housing 30 while keeping the absolute value of the tilt angle θ2 of the main lobe ML smaller than 0.38°. 【0050】 Furthermore, the smaller the length L of the inner circumferential wall portion 34, the smaller the area of ​​the portion of the inner circumferential wall portion 34 that serves as the reflective surface for the side lobes SL, thus reducing the amount of side lobes SL reflected by the inner circumferential wall portion 34. This makes it possible to reduce the absolute value of the tilt angle θ2 of the main lobe ML. On the other hand, the smaller the length L of the inner circumferential wall portion 34, the more difficult it becomes to secure the housing space S of the housing portion 37 in which the light source 20 is housed. This problem becomes particularly noticeable when the length L of the inner circumferential wall portion 34 is set to less than 15 mm. In this respect, with the above configuration, the length L of the inner circumferential wall portion 34 is 15 mm or more. Therefore, it is possible to suitably suppress the beam tilt of the main lobe ML while securing the housing space S inside the housing portion 37. 【0051】 Therefore, it is possible to achieve both securing the housing space S of the housing section 37 and suppressing an increase in the size of the housing 30, while further improving the accuracy of the radar device 11. (4) The shortest distance D2 from the central axis C to the inner circumferential wall portion 34 is set to be between 54 mm and 65 mm. 【0052】 The smaller the shortest distance D2 from the central axis C to the inner peripheral wall portion 34, the larger the area of ​​the portion of the inner peripheral wall portion 34 that becomes the reflective surface of the side lobe SL becomes, and therefore the amount of side lobe SL reflected by the inner peripheral wall portion 34 also increases. As a result, the absolute value of the tilt angle θ2 of the main lobe ML tends to increase. Also, the smaller the shortest distance D2 becomes, the smaller the protruding portion 32 becomes on the side closer to the central axis C, which can lead to problems such as a smaller field of view of the radar device 11. These problems become particularly noticeable when the shortest distance is set to less than 54 mm. In this respect, with the above configuration, the shortest distance is 54 mm or more. Therefore, it is possible to keep the absolute value of the tilt angle θ2 of the main lobe ML smaller than 0.38° while still ensuring a sufficient field of view of the radar device 11. 【0053】 Furthermore, increasing the minimum distance D2 reduces the area of ​​the inner circumferential wall portion 34 that serves as the reflective surface for the side lobe SL, thus reducing the amount of side lobe SL reflected by the inner circumferential wall portion 34. This allows for a reduction in the absolute value of the tilt angle θ2 of the main lobe ML. On the other hand, increasing the minimum distance D2 increases the size of the housing 30, which tends to increase on the side away from the central axis C, in order to secure the housing space S of the housing portion 37 in which the light source 20 is housed. This problem becomes particularly noticeable when the minimum distance D2 is set to a value greater than 65 mm. In this respect, with the above configuration, the minimum distance D2 is 65 mm or less. Therefore, it is possible to suppress the beam tilt of the main lobe ML while preventing the size of the housing 30 from increasing. 【0054】 Therefore, it is possible to further improve the accuracy of the radar device 11 while keeping the size of the housing 30 from increasing. <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically. 【0055】 The tip portion 33 is not limited to being curved with respect to the vertical direction Z, as illustrated in this embodiment, but may also be a flat plate extending along both the vehicle width direction W and the vertical direction Z. The exterior member 12 is not limited to having a panel portion 16 without ventilation holes as exemplified in this embodiment. For example, the exterior member 12 may have a front grille with ventilation holes instead of a panel portion 16. 【0056】 The exterior member according to the present invention is not limited to having the emblem portion 13 and panel portion 16 as exemplified in this embodiment. For example, the exterior member may consist only of the emblem portion 13. 【0057】 The vehicle radar unit according to the present invention is not limited to being mounted on the front of a vehicle as illustrated in this embodiment. For example, the vehicle radar unit may be mounted on the rear of the vehicle or on the side of the vehicle, as long as the exterior member is positioned in front of the radar device 11 in the direction of millimeter wave transmission. In these cases, the exterior member may be a component of the outer shell of the rear or side of the vehicle. [Explanation of symbols] 【0058】 θ1…Inclination angle θ2…Tilt angle C…Central axis line D1... Distance D2…Shortest distance L...Length ML... Main Robe SL... Side Robe S... Containment space V...Virtual plane W...vehicle width direction X…Anteroposterior direction Z…Vertical direction 10… Vehicle radar unit 11... Radar equipment 12… Exterior components 13…Emblem section 13a…Design surface 14...Display area 14a... Text section 14b... Ring section 15...Background area 16... Panel section 16b…Rear side 20…Light source 21… Circuit board 21a...Front 30… Housing 31...Bottom wall 32...Protruding part 33…The tip 34...Inner peripheral wall 35…General section 36...Outer peripheral wall 37... Detention Unit 38…Opening 39…Flange section 39a...fastening hole 40...Cover part 41...First cover section 42...Second cover section 42a...hole 42b…Opening edge 43...Water-stopping section 44... Boss 50... screw

Claims

[Claim 1] A radar device that transmits and receives electromagnetic waves, The radar device is positioned in front of the radar device in the direction of electromagnetic wave transmission and comprises an outer casing member that is transparent to electromagnetic waves, The exterior member comprises a light source that emits visible light, a housing having an opening that opens forward in the transmission direction, and a cover portion that closes the opening and is transparent to visible light. The housing has a bottom wall and an outer peripheral wall that rises forward in the transmission direction from the periphery of the bottom wall. The bottom wall portion protrudes away from the radar device in the transmission direction and has a protruding portion that forms a housing portion between itself and the outer peripheral wall portion in which the light source is housed. When the portion of the protruding part that extends backward in the transmission direction from the periphery of the tip is defined as the inner circumferential wall, The radar device is positioned in a direction perpendicular to the transmission direction and perpendicular to the central axis passing through the center of the radar device, and does not overlap with the inner circumferential wall portion. The inclination angle of the inner circumferential wall portion with respect to the central axis, the length of the inner circumferential wall portion in the transmission direction, and the shortest distance from the central axis to the inner circumferential wall portion are set such that the absolute value of the tilt angle of the main lobe of the electromagnetic wave transmitted from the radar device with respect to the central axis is greater than 0° and less than or equal to 0.38°. Vehicle radar unit. [Claim 2] The inclination angle of the inner circumferential wall portion with respect to the central axis is set to 1° or more and 12° or less. The vehicle radar unit according to claim 1. [Claim 3] The length of the inner circumferential wall portion in the transmission direction is set to 15 mm or more and 20 mm or less. The vehicle radar unit according to claim 1. [Claim 4] The shortest distance from the central axis to the inner circumferential wall is set to be between 54 mm and 65 mm. The vehicle radar unit according to claim 1.

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