Structure and performance degradation suppression device

Abstract

To effectively prevent deterioration in the performance of a radar due to icicles.SOLUTION: A structure is provided below a plate member 13 arranged on an outer face of a vehicle 10 and prevents deterioration in the performance of a radar 40 emitting radio waves toward the outside of the vehicle 10, and the structure comprises icicle prevention means 22, 25, 27, 28 that prevent formation of icicles hanging down from a lower end of the plate member 13 toward a radio wave emission range X.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a structure and a performance degradation suppression device, and to a technique suitable for suppressing performance degradation of a radar mounted on a vehicle. [Background technology]

[0002] For example, Patent Document 1 discloses a device that has a planar heating element that protrudes from the eaves of a roof, and that uses the planar heating element to heat snow that has accumulated on the roof, thereby suppressing the formation of icicles on the eaves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-311265 Summary of the Invention

[0004] A vehicle may be equipped with a radar for recognizing objects present around the vehicle. Among such radars, a radar for recognizing the area ahead of the vehicle may be disposed, for example, in a lower grill below a license plate attached to the front of the front bumper.

[0005] Generally, the lower grille is offset toward the rear of the vehicle body relative to the license plate. Therefore, in a structure in which a radar is disposed in the lower grille, when a vehicle is traveling on a road surface covered with snowfall or semi-melted snow (sherbet snow or slushy snow, hereinafter referred to as "wet snow"), the wet snow adhering to the front of the license plate may flow down and form an icicle that hangs down from the bottom edge of the license plate toward the radar. If such an icicle enters the irradiation range of the radar's radio waves, it can cause a problem of degrading the radar's recognition performance.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to effectively prevent degradation of radar performance due to icicles.

[0007] The technology disclosed herein is a structure that is provided below a plate member (13) arranged on the outer surface of a vehicle (10) and prevents performance degradation of a radar (40) that irradiates radio waves toward the outside of the vehicle (10), and is characterized by having icicle suppression means (22, 25, 27, 28) that suppresses the formation of icicles that hang down from the lower end of the plate member (13) toward the irradiation range (X) of the radio waves.

[0008] According to the above configuration, it is possible to effectively prevent the formation of icicles hanging down in the irradiation range of the radar radio waves, and it is possible to effectively suppress the degradation of radar performance. [Brief explanation of the drawings]

[0009] [Figure 1] 1A is a schematic diagram of a vehicle according to the present embodiment as viewed from the front, and FIG. 1B is a schematic cross-sectional view illustrating a structure according to the present embodiment. [Figure 2] 1 is a diagram illustrating the overall configuration of a performance degradation suppression device according to an embodiment of the present invention. [Figure 3] 10A is a flowchart illustrating a routine for calculating a judgment value, and FIG. 10B is a flowchart illustrating a routine for processing heating control. [Figure 4] FIG. 10 is a schematic cross-sectional view illustrating a structure according to a modified example. [Figure 5] FIG. 10 is a schematic front view illustrating a structure according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the structure and the performance degradation suppression device according to this embodiment will be described with reference to the drawings.

[0011] [Schematic configuration] FIG. 1(A) is a schematic diagram of a vehicle 10 according to this embodiment as seen from the front. FIG. 1(B) is a schematic cross-sectional view illustrating a structure according to this embodiment. As shown in FIG. 1(A), a front bumper 11 extending in the vehicle width direction is attached to the front of the vehicle 10. An upper grille 12 for taking in wind generated by the vehicle is provided above the front bumper 11. Note that in the present disclosure, the vehicle 10 does not necessarily have to include the upper grille 12.

[0012] A license plate bracket (hereinafter referred to as "bracket") 20 for fixing a license plate 13 is provided at approximately the center of the front bumper 11 in the vehicle width direction, at the portion that protrudes most toward the front of the vehicle 10. The bracket 20 is attached to the front bumper 11 with bolts and nuts (not shown) with its back surface in contact with the front surface of the front bumper 11. A pair of left and right back nuts (not shown) are fixed to the bracket 20. The license plate 13 is attached by screwing a pair of left and right bolts B1, B2 into the back nuts of the bracket 20 with its back surface in contact with the front surface of the bracket 20.

[0013] The length of bracket 20 in the vehicle width direction is approximately the same as the length of license plate 13 in the vehicle width direction. In addition, the height of bracket 20 in the vertical direction is approximately the same as the height of license plate 13 in the vertical direction. Note that the shapes of bracket 20 and license plate 13 may be any shape that complies with the laws and regulations of the country or region in which vehicle 10 is used, and may be a rectangle that is longer in the vehicle width direction than the rectangle shown in FIG. 1(A).

[0014] A lower grille 14 for taking in wind generated by traveling is provided below the bracket 20 of the front bumper 11. A millimeter wave radar 40 for detecting objects present in the area ahead of the vehicle 10 is attached to approximately the center of the lower grille 14 in the vehicle width direction.

[0015] The millimeter-wave radar 40 emits millimeter-wave radio waves and receives the reflected waves reflected by an object present within the irradiation range. The millimeter-wave radar 40 acquires the relative position (direction, distance) and relative speed between the vehicle 10 and the object based on the phase difference between the emitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from transmitting the millimeter waves to receiving the reflected waves. The relative position and relative speed of the object acquired by the millimeter-wave radar 40 are used, for example, for driving assistance of the vehicle 10. Examples of driving assistance include adaptive cruise control (ACC), lane tracing assist (LTA), and lane departure alert control (LDA). Driving assistance is a concept that includes autonomous driving.

[0016] As shown in FIG. 1(B), the millimeter-wave radar 40 is provided in the lower grille 14, which is offset rearward from the front surface of the front bumper 11. That is, the lower end of the bracket 20 is located diagonally above the millimeter-wave radar 40. The symbol X in FIG. 1(B) indicates the irradiation range of the radio waves (millimeter waves) of the millimeter-wave radar 40. The millimeter-wave radar 40 is attached to a desired position on the lower grille 14 so that the lower end of the bracket 20 is not included in the irradiation range X.

[0017] When the vehicle 10 travels on a road surface covered with snow or wet snow, wet snow adheres to the front of the license plate 13. The wet snow that adheres to the front of the license plate 13 flows downward along the front of the license plate 13, forming an icicle that hangs down from the bottom of the license plate 13. Because the license plate 13 is located diagonally above the millimeter-wave radar 40, the icicle that hangs down from the bottom of the license plate 13 may enter the irradiation range X of the radio waves of the millimeter-wave radar 40. The millimeter-wave radar 40 emits radio waves forward and receives the reflected waves reflected by objects. Therefore, if an icicle that hangs down from the license plate 13 enters the irradiation range X of the radio waves of the millimeter-wave radar 40 and is formed, it affects the irradiation and reception of the radio waves, which reduces the recognition performance of the millimeter-wave radar 40.

[0018] One way to prevent the formation of such icicles is to heat the entire license plate 13 using a heater or the like. However, regulations prohibit providing a heater on the front side of the license plate 13. Furthermore, if a heater were provided on the back side of the license plate 13, the license plate 13 would be cooled by the wind while driving, reducing the efficiency of heat transfer and resulting in increased power consumption.

[0019] In this embodiment, to solve these problems, a heater 25 serving as a heating element is disposed at the lower end of bracket 20. Specifically, bracket 20 has plate portion 21 on which the back of license plate 13 rests, and edge portion 22 having a rectangular cross section that is formed at the lower end of plate portion 21 and extends in the vehicle width direction. Plate portion 21 and edge portion 22 may be formed integrally or as separate members. Edge portion 22 is an example of a retaining portion of the present disclosure.

[0020] In a front view of vehicle 10, edge portion 23 is located below the bottom edge of license plate 13 and above the irradiation range X of the radio waves from millimeter-wave radar 40. A heater 25 extending in the vehicle width direction is embedded in edge portion 22. Heater 25 is, for example, an electric heating wire, and when power is supplied, the electric heating wire generates heat, thereby heating edge portion 22, i.e., the area near the bottom edge of license plate 13.

[0021] When viewed from the side of vehicle 10, edge portion 22 protrudes forward beyond the front surface of license plate 13. In other words, the upper surface of edge portion 22 forms step portion 23 near the lower end of license plate 13. Step portion 23 functions to catch wet snow that flows down along the front surface of license plate 13.

[0022] By heating edge portion 22 with heater 25 while wet snow is received on step portion 23, the wet snow adhering to license plate 13 can be efficiently melted. In other words, it is possible to reliably prevent the formation of icicles that hang down from the bottom end of license plate 13. Preventing the formation of icicles can suppress a decline in the recognition performance of millimeter-wave radar 40. Furthermore, compared to heating the entire license plate 13 from the back side, heat can be efficiently transferred to the wet snow received on step portion 23, and power consumption can also be reliably reduced.

[0023] [Performance deterioration suppression device] FIG. 2 is an overall configuration diagram of a performance degradation suppression device according to this embodiment. As shown in FIG. 2, a vehicle 10 has an ECU (Electronic Control Unit) 100. The ECU 100 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and an interface IF. The CPU is a processor that executes various programs stored in the ROM. The ROM is a non-volatile memory that stores data and the like required for the CPU to execute the various programs. The RAM is a volatile memory that provides a working area into which the various programs are expanded when the CPU executes them. The interface IF is a communication device for communicating with external devices.

[0024] The ECU 100 is a central device that performs various controls of the vehicle 10. In this embodiment, a millimeter-wave radar 40 is communicably connected to the ECU 100. The millimeter-wave radar 40 includes a transmitting antenna 41 that transmits millimeter waves, a receiving antenna 42 that receives reflected waves, a signal processing unit 43, a heater driving circuit 44 that controls driving of the heater 25, and the like.

[0025] The heater drive circuit 44 is connected to a power supply device 50 mounted on the vehicle 10. The heater drive circuit 44 has a relay (not shown). The relay of the heater drive circuit 44 selectively switches between an energized state and an interrupted state in response to an instruction signal from the ECU 100. Hereinafter, the state in which the relay is energized will be referred to as the "ON state" of the heater drive circuit 44, and the state in which the relay is interrupted will be referred to as the "OFF state" of the heater drive circuit 44. When the heater drive circuit 44 is in the ON state, power is supplied from the power supply device 50 to the heater 25, causing the heater 25 to generate heat. On the other hand, when the heater drive circuit 44 is in the OFF state, the connection between the power supply device 50 and the heater 25 is interrupted, and no power is supplied to the heater 25.

[0026] [Heating control] Next, heating control by the heater 25 will be described. Focusing on its functions, the ECU 100 has a judgment value calculation unit 110 and a heater drive control unit 120 as some of its functional elements. These functional elements will be described as being included in the ECU 100, which is an integrated piece of hardware, but some of these functional elements may also be provided in an ECU separate from the ECU 100. Furthermore, some of the functional elements of the ECU 100 may also be provided in an external information processing device or the like that is capable of communicating with the vehicle 10.

[0027] The judgment value calculation unit 110 calculates a judgment value CD, which serves as an index for determining a deterioration in the recognition performance of the millimeter-wave radar 40. If dirt adheres to a cover member (not shown) that transmits radio waves from the millimeter-wave radar 40, or if icicles form in the irradiation range A (see FIG. 1(B)) of the radio waves from the millimeter-wave radar 40, part of the radio waves transmitted from the transmitting antenna 41 are reflected by the dirt or icicles and received by the receiving antenna 42. On the other hand, if there is no dirt on the cover member or if there are no icicles in the irradiation range A, there is no reflection from the dirt or icicles. In other words, there is a difference in the reception level of the radio waves received by the receiving antenna 42 depending on whether there is dirt or icicles or not. The judgment value calculation unit 110 calculates the judgment value CD based on the reception level of the radio waves received by the receiving antenna 42.

[0028] An example of the calculation process performed by the judgment value calculation unit 110 will be described below with reference to the flowchart shown in Fig. 3(A). The routine shown in Fig. 3(A) starts when the ignition switch or power switch of the vehicle 10 is turned on and the millimeter-wave radar 40 is started.

[0029] In step S100, the judgment value calculation unit 110 acquires the reception level (power value) of the radio wave received by the receiving antenna 42 from the signal processing unit 43. Next, in step S110, the judgment value calculation unit 110 determines whether the acquired power value exceeds a preset judgment threshold. If the power value exceeds the judgment threshold (Yes), the judgment value calculation unit 110 proceeds to step S120 and increments the count value (judgment value) CD of the judgment counter. On the other hand, if the power value does not exceed the judgment threshold (No), the judgment value calculation unit 110 proceeds to step S130 and decrements the count value (judgment value) CD of the judgment counter. In step S140, the judgment value calculation unit 110 transmits the incremented or decremented judgment value CD to the heater drive control unit 120, and then temporarily terminates (returns) this routine.

[0030] The heater drive control unit 120 switches the heater drive circuit 44 between the ON state and the OFF state based on the judgment value CD transmitted from the judgment value calculation unit 110. Specifically, when the judgment value CD transmitted from the judgment value calculation unit 110 reaches a predetermined activation threshold CDv, the heater drive control unit 120 turns the heater drive circuit 44 to the ON state to energize the heater 25, thereby executing heating control to cause the heater 25 to generate heat. Furthermore, after the heater drive control unit 120 has turned the heater drive circuit 44 to the ON state, when the judgment value CD transmitted from the judgment value calculation unit 110 falls below the activation threshold CDv, the heater drive control unit 120 turns the heater drive circuit 44 to the OFF state, thereby ending the heating control.

[0031] An example of the heating control process performed by the heater drive control unit 120 will be described below with reference to the flowchart shown in Fig. 3(B). The routine shown in Fig. 3(B) is executed in parallel with the routine for calculating the judgment value shown in Fig. 3(A).

[0032] In step S200, the heater drive control unit 120 determines whether the determination value CD has reached the activation threshold CDv. If the determination value CD has reached the activation threshold CDv (Yes), the heater drive control unit 120 proceeds to the processing of step S210. On the other hand, if the determination value CD has not reached the activation threshold CDv (No), the heater drive control unit 120 returns from this routine.

[0033] In step S210, the heater drive control unit 120 turns the heater drive circuit 44 on. That is, it executes heating control by energizing the heater 25. Next, in step S220, the heater drive control unit 120 determines whether the determination value CD has decreased below the activation threshold CDv. If the determination value CD has decreased below the activation threshold CDv (Yes), the heater drive control unit 120 proceeds to the processing of step S230. On the other hand, if the determination value CD has not decreased to the activation threshold CDv (No), the heater drive control unit 120 returns to the processing of step S210 and continues the heating control.

[0034] In step S230, the heater drive control unit 120 turns off the heater drive circuit 44. That is, it ends the heating control by the heater 25. Thereafter, the heater drive control unit 120 temporarily ends (returns) this routine.

[0035] Although the heater drive control unit 120 has been described as determining whether to execute heating control based on the determination value CD, it may also be configured to determine whether to execute heating control based on other information. For example, when a situation in which snowfall is predicted is acquired, such as when an outside air temperature sensor mounted on the vehicle 10 detects a predetermined low outside air temperature and the windshield wiper device is operating, the heater drive control unit 120 may execute heating control by turning the heater drive circuit 44 ON. Alternatively, when the vehicle 10 acquires weather information about snowfall, the heater drive circuit 44 may be executed by turning the heater drive circuit 44 ON. Furthermore, when snowfall is acquired, the heater drive circuit 44 may be alternately turned ON and OFF, thereby executing heating control intermittently.

[0036] [Variations] The structure and performance degradation suppression device according to this embodiment have been described above, but the present disclosure is not limited to the above embodiment, and various modifications are possible as long as they do not deviate from the purpose of the present invention.

[0037] In the above embodiment, the edge portion 22 of the bracket 20 is described as protruding forward from the front surface of the license plate 13, but it is also possible to configure the front surface of the edge portion 22 and the front surface of the license plate 13 to be on the same plane (flush), as shown in Figure 4(A).

[0038] 4(B), the front surface of the edge portion 22 may be inclined. In this case, the front surface of the edge portion 22 may be inclined so that the lower end of the front surface of the edge portion 22 is positioned closer to the front of the vehicle than the upper end.

[0039] Furthermore, the application of the present disclosure is not limited to bracket 20, but can also be applied to a license plate frame 20A as shown in FIG. 4(C). Specifically, license plate frame 20A includes rectangular frame portion 21A and edge portion 22 extending along the lower edge of frame portion 21A. Frame portion 21A and edge portion 22 may be formed integrally or as separate members. As with the above embodiment, heater 25 may be provided in edge portion 22 in the example shown in FIG. 4(C).

[0040] Furthermore, in the present disclosure, the icicle suppression means does not necessarily have to include a heater 25 or other heating element, and may have a structure that prevents icicles from growing in the radio wave irradiation range X of the millimeter-wave radar 40, even if icicles are formed. Specifically, as shown in FIG. 5 , a notch 26 cut out in a generally inverted V shape can be provided at the lower end of the bracket 20 (or license plate frame 20A) when viewed from the front of the license plate 13. The notch 26 has a pair of inclined portions 27, 28 that slope downward from the approximate center C of the bracket 20 in the vehicle width direction—in other words, the approximate center in the left-right direction of the irradiation range X of the radar 40—toward the outside in the vehicle width direction (the left and right ends of the irradiation range X). The pair of inclined portions 27, 28 are formed so that their outer ends 27E, 28E in the vehicle width direction are outside the irradiation range X of the radio waves.

[0041] By providing the notch 26 in a generally inverted V shape at the bottom end of the bracket 20 in this way, wet snow that flows down along the front surface of the license plate 13 flows along the inclined portions 27, 28 of the notch 26 and reaches the ends 27E, 28E that are outside the irradiation range X of the radio waves of the millimeter-wave radar 40. In other words, even if icicles that hang down from the ends 27E, 28E grow, these icicles will be formed outside the irradiation range X. This makes it possible to effectively prevent a decrease in the performance of the radar 40.

[0042] Although FIG. 5 shows the cutout portion 26 as an example, it is also possible to adopt a configuration in which, for example, a guide protrusion or a guide groove having a substantially inverted V shape is provided, as long as the structure can guide wet snow outside the irradiation range X of the radio waves of the radar 40.

[0043] Furthermore, the application of the present disclosure is not limited to millimeter-wave radar 40 that detects ahead of the vehicle 10, but can also be applied to millimeter-wave radar that detects diagonally ahead, to the left and right sides, behind, etc., as long as the millimeter-wave radar is offset inward from a member disposed on the outer surface of the vehicle 10. In this case, the plate member disposed above the millimeter-wave radar may not be a license plate, but may be a decorative part attached to the fender, rear bumper, etc. of the vehicle 10. Furthermore, the radar is not limited to millimeter-wave radar, and can be widely applied to other sensors such as lidar. [Explanation of symbols]

[0044] 10...vehicle, 11...front bumper, 13...license plate, 14...lower grill, 20...bracket, 22...edge portion, 25...heater, 40...millimeter wave radar, ECU...100, 110...determination value calculation unit, 120...heater drive control unit

Claims

1. A structure provided below a plate member disposed on the outer surface of a vehicle, for preventing a decrease in performance of a radar that irradiates radio waves toward the outside of the vehicle, an icicle suppressing means for suppressing the formation of icicles hanging down from the lower end of the plate member toward the irradiation range of the radio waves; The ice pillar suppression means is a holding portion for holding a heating element is provided below the lower end of the plate member and above the irradiation range, The end of the holding portion facing the outside of the vehicle is on an extension of the surface of the plate member, or is formed to protrude further outside the vehicle than the surface. A structure characterized by:

2. 10. The structure of claim 1, The ice pillar suppression means is A pair of inclined portions are provided below the lower end of the plate member and above the irradiation range, and are inclined downward from the center side toward both ends in the horizontal direction of the irradiation range parallel to the planar direction of the plate member. A structure characterized by:

3. 3. The structure according to claim 1 or 2, the plate member is a license plate disposed on a front surface of a front bumper of the vehicle, The ice pillar suppression means is provided at the lower end of a bracket or frame for attaching the license plate to the front bumper. A structure characterized by:

Images