Approaching vehicle notification device

Abstract

To provide a vehicle approach notification device capable of increasing a sound pressure of a plurality of frequency bands without changing a sound source and suppressing an increase in manufacturing costs.SOLUTION: A vehicle approach notification device 10 mounted on a vehicle 50 and including a speaker 22 that emits notification sound to the vehicle outside from an opening 26 further includes: a plurality of ducts 32, 42 each having one end communicatively connected to the opening 26 and having different lengths from each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle approach warning device, and more particularly to a vehicle approach warning device that is mounted on a vehicle that can run using an electric motor as a power source and outputs a warning sound to the outside of the vehicle to warn of an approaching vehicle. [Background technology]

[0002] Electric vehicles (EVs) and hybrid electric vehicles (HEVs) are powered by electric motors, and do not produce loud noises like engine noise when running. As a result, pedestrians are less likely to notice an approaching vehicle.

[0003] Therefore, electric vehicles are equipped with a vehicle approach notification device that outputs a warning sound to the outside of the vehicle when running on the motor, to audibly notify pedestrians of the vehicle's presence.

[0004] As described in Patent Document 1, this vehicle approach notification device generates a signal that serves as the sound source of the notification sound in a control unit mounted on the vehicle. The generated sound signal is amplified by an amplifier and then output to the outside of the vehicle by a speaker mounted on the front of the vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-213112 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, each country has been moving toward regulating the warning sounds emitted by vehicle approach warning devices. For example, Japanese regulations require that when an electric vehicle is traveling at low speeds, it must output a sound pressure level above a specified value in two of a specified frequency band to warn of approaching vehicles.

[0007] To comply with these regulations, one method is to use a synthesized sound with two peak frequency bands as the sound source for the warning sound. However, when a single sound source with two peak frequency bands is used for multiple vehicle models, the acoustic characteristics around the speaker differ depending on the vehicle model, and the sound pressure may not meet the specified level for some vehicle models.

[0008] One way to solve this problem is to generate a sound source with a different peak frequency band for each vehicle model, but this requires changing the specifications of the control unit.To increase the sound pressure without changing the sound source, one method is to increase the sound pressure of the warning sound by using larger speakers and amplifiers, but these acoustic devices are expensive, which increases manufacturing costs.

[0009] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a vehicle approach notification device that can amplify the sound pressure of multiple frequency bands without changing the sound source, and that can suppress increases in manufacturing costs. [Means for solving the problem]

[0010] In order to achieve the above object, one embodiment of the present invention provides a vehicle approach warning device that is mounted on a vehicle and includes sound generating means for emitting a warning sound from an opening toward the outside of the vehicle, the sound generating means including at least two ducts of different lengths, one end of which is connected to the opening. The length of each duct is set so that when the notification sound is output, the frequency band in which the sound pressure increases due to the acoustic characteristics of the vehicle body shape and the frequency band of the standing wave formed by the length of each duct are approximately the same. It is characterized by:

[0011] Furthermore, one embodiment of the present invention is characterized in that, in the vehicle approach notification device, the duct has a cylindrical base portion having one end fixed to the opening, and a cylindrical length adjustment portion connected to the tip of the base portion and capable of adjusting the duct length.

[0012] In addition, one embodiment of the present invention is characterized in that in the vehicle approach warning device, the sound source of the warning sound is white noise having a uniform sound pressure over a predetermined wide frequency band.

[0013] In addition, one embodiment of the present invention is characterized in that, in the vehicle approach notification device, the duct is cylindrical. [Effects of the Invention]

[0014] According to the vehicle approach notification device of the present invention, it is possible to amplify the sound pressure of a plurality of frequency bands without changing the sound source, and it is possible to suppress an increase in manufacturing costs. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic explanatory diagram of a vehicle approach notification device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a perspective view of a sound generating unit of the vehicle approach notification device. [Figure 3] 2 is a schematic cross-sectional view of a sound generating unit of the vehicle approach warning device. FIG. [Figure 4] 4A and 4B are diagrams illustrating amplification of sound pressure by a sound generation unit. [Figure 5] 10 is a graph showing the frequency and sound pressure level of a notification sound output from a speaker. [Figure 6] 10 is a graph showing the frequency and sound pressure level of a warning sound output through a duct. [Figure 7] 10 is a graph showing another example of the frequency and sound pressure level of the notification sound output from the speaker. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1 is a schematic diagram of an embodiment of a vehicle approach notification device 10. The vehicle approach notification device 10 is mounted on an electric vehicle 1, such as an electric vehicle or hybrid vehicle, that uses an electric motor as a power source, and generates a notification sound to notify nearby pedestrians of the approach of the vehicle 1 when the vehicle is running on the electric motor.

[0017] The vehicle approach warning device 10 includes a control unit 12 that generates a sound signal that serves as a sound source for the warning sound, an amplifier 14 that serves as an amplifying means for amplifying the sound signal, and a sound generating unit 20 that emits the warning sound outside the vehicle. As shown in Figures 2 and 3, the sound generating unit 20 includes a speaker 22 that serves as a sound generating means, and a plurality of ducts 32, 42 that are connected in communication with the speaker 22. As shown in Figure 1, the control unit 12, the amplifier 14, and the speaker 22 are electrically connected.

[0018] The control unit 12 is a computer including a microcomputer, and is configured with information processing means such as a central processing unit (CPU) and an application-specific integrated circuit (ASIC), and storage means such as RAM and ROM. The central processing unit reads and executes programs recorded in the storage means, thereby functioning as various function realization units (e.g., a control unit, an arithmetic unit, a processing unit, etc.). The control unit 12 generates a sound signal that serves as the sound source of the warning sound emitted from the sound generation unit 20 based on the state of the vehicle 1 input from various sensors (not shown). In this embodiment, as an example, the sound signal of the warning sound is generated when the driving mode of the vehicle 1 is motor driving in which the vehicle 1 is driven by an electric motor and the vehicle speed is a low-speed mode below a predetermined value. In this embodiment, as an example of the sound source of the warning sound generated by the control unit 12, white noise having a similar sound pressure over a predetermined wide frequency band is used.

[0019] The amplifier 14 is disposed between the control unit 12 and the speaker 22 and serves to amplify the sound signal generated by the control unit 12 .

[0020] The sound production unit 20 includes a speaker 22 and two ducts 32 and 42 of different lengths. In the following description, the longer duct will be referred to as the first duct 32, and the shorter duct will be referred to as the second duct 42. The sound production unit 20 is attached to the front of the vehicle 1.

[0021] The speaker 22 is attached to an engine undercover that constitutes the floor of the vehicle 1. The speaker 22 has a frame 24 that expands in diameter from the sound-emitting surface into a generally truncated cone shape. The tip of the frame 24 forms a generally circular opening 26. The sound signal generated by the control unit 12 passes through the amplifier 14 and is then emitted as a warning sound from the opening 26 of the speaker 22.

[0022] As shown in FIGS. 2 and 3 , the first duct 32 and the second duct 42 are each formed in a cylindrical shape, with one end 32 a, 42 a connected to the opening 26 of the speaker 22. The inner diameter and the outer diameter of the first duct 32 and the second duct 42 are set to be approximately equal. The shape of each duct 32, 42 is not limited to a cylindrical shape and may be, for example, a cylindrical shape with a polygonal cross section or a cylindrical shape with a semicircular cross section that divides the opening 26 into approximately two equal parts. The shape of the opening 26 of the speaker 22 is also not limited to a circular shape and can be changed to match the shape of each duct 32, 42. As shown in FIG. 2 , in this embodiment, each duct 32, 42 is connected to the opening 26 via a duct connection portion 30.

[0023] The duct connection part 30 has a cylindrical part 30a that communicates with the opening 26 and a cover part 30b attached to the tip of the cylindrical part 30a. The cylindrical part 30a has an inner diameter that is approximately the same as the opening 26 of the speaker 22. The axial length of the cylindrical part 30a is preferably set to be approximately the same as or shorter than the axial length of the frame 24 of the speaker 22. The cover part 30b is formed in a disk shape so as to cover the tip of the cylindrical part 30a, and has two circular openings. One end 32a, 42a of each duct 32, 42 is connected to each opening of the cover part 30b.

[0024] The first duct 32 and the second duct 42 extend linearly and parallel to each other from the opening 26 of the speaker 22. Each duct 32, 42 has a cylindrical base 34, 44 whose one end 32a, 42a is fixed to the opening 26 via the duct connection part 30, and length adjustment parts 36, 46 that are connected to the tip ends of the bases 34, 44 and form tip openings 32b, 42b of the ducts 32, 42. The base 34 of the first duct 32 is formed longer than the base 44 of the second duct 42.

[0025] The length adjustment parts 36, 46 are parts for adjusting the duct length, and are formed in a cylindrical shape with approximately the same diameter as the base parts 34, 44, and are configured to be slidable along the axial direction of the base parts 34, 44. After the length of the length adjustment parts 36, 46 protruding from the base parts 34, 44 has been adjusted, the length adjustment parts 36, 46 are fixed to the base parts 34, 44 using fasteners 38, 48 such as bolts. The length of each duct 32, 42 can be set as appropriate, and as an example, the lengths of the base parts 34, 44 and the length adjustment parts 36, 46 can be set so that the length of the first duct 32 is 1.5 to 5 times the length of the second duct 42.

[0026] 1, the sound generation unit 20 of this embodiment is installed so that the opening 26 of the speaker 22 faces downward of the vehicle 1, and the ducts 32, 42 extend linearly downward from the opening 26. The sound generation unit 20 is preferably placed in the center of the vehicle width direction.

[0027] 1 shows an example in which the first duct 32 is disposed further forward of the second duct 42 in the vehicle to make it easier to understand that there are two ducts 32, 42, but the arrangement of the ducts 32, 42 is not limited to this, and the second duct 42 may be disposed closer to the front of the vehicle, or the first duct 32 and the second duct 42 may be disposed side by side in the vehicle width direction so as to be at approximately the same position in the vehicle fore-and-aft direction. Furthermore, the arrangement position and orientation of the sound generation unit 20 are not limited to the example shown in FIG. 1 and can be set appropriately depending on the vehicle shape. Furthermore, a configuration in which a plurality of sound generation units 20 are installed on the vehicle 1 may also be adopted.

[0028] In the vehicle approach notification device 10 described above, the notification sound emitted from the opening 26 of the speaker 22 passes through each of the ducts 32, 42 and is output from the end openings 32b, 42b of each of the ducts 32, 42. As shown in Fig. 4, in each of the ducts 32, 42, the incident sound from the speaker 22 and the reflected sound from the duct 32, 42 interfere with each other, forming a standing wave with a wavelength four times the duct length. As a result, the sound pressure of the notification sound is amplified in the frequency band where the two standing waves are formed.

[0029] Fig. 5 is a graph showing the frequency and sound pressure level of the warning sound output from the speaker 22, and Fig. 6 is a graph showing the frequency and sound pressure level of the warning sound output through each of the ducts 32, 42. As described above, in this embodiment, white noise is used as the sound source of the warning sound, and the speaker 22 outputs a warning sound with approximately the same sound pressure level over a wide frequency band, as shown in Fig. 5. When this warning sound is output from the end openings 32b, 42b of each of the ducts 32, 42 through each of the ducts 32, 42, standing waves are formed in each of the ducts 32, 42, as shown in Fig. 6, and a warning sound having two peak frequency bands corresponding to the length of each of the ducts 32, 42 is output.

[0030] The lengths of the ducts 32, 42 for determining the two peak frequency bands are set appropriately according to the body shape of the vehicle 1 on which the vehicle approach warning device 10 is mounted. Specifically, they are set according to the acoustic characteristics of the body shape around the sound generation unit 20, and are set so that when the warning sound is output outside the vehicle, the frequency band in which the sound pressure increases due to the acoustic characteristics of the body shape and the frequency band of the standing wave formed by the lengths of the ducts 32, 42 approximately match.

[0031] As described above, in the vehicle approach warning device 10 of this embodiment, the sound pressure of the warning sound can be amplified in any two frequency bands without changing the sound source of the warning sound by connecting the two ducts 32, 42 of different lengths in communication with the speaker 22. As a result, even if the model of the vehicle 1 on which the vehicle approach warning device 10 is installed is different or if the acoustic characteristics around the speaker 22 change due to a minor change to the vehicle 1, it is possible to amplify the sound pressure in any two frequency bands suitable for the vehicle body shape by appropriately changing the lengths of the ducts 32, 42 without changing the sound source of the warning sound generated by the control unit 12.

[0032] In this embodiment, the length of each duct 32, 42 is adjustable by the length adjustment units 36, 46, but the ducts 32, 42 used in the vehicle approaching notification device 10 may also be fixed in length. In the case of the present embodiment, the length adjustment units 36, 46 are provided, and the length of each duct 32, 42 can be easily adjusted by sliding the length adjustment units 36, 46 relative to the bases 34, 36. This allows the vehicle approaching notification device 10 to be adapted to various vehicle models without changing the specifications of the components thereof, making it highly versatile.

[0033] Furthermore, by using white noise that does not have a specific peak frequency band as the sound source for the warning sound, any peak frequency band that suits the acoustic characteristics of the vehicle model can be easily formed by adjusting the length of each duct 32, 42.

[0034] The sound source of the warning sound is not limited to white noise, and may be one with a frequency spectrum that has a gentle peak in a predetermined frequency band, as shown in Fig. 7. In Fig. 7, the sound source has a frequency spectrum in which the sound pressure level gradually increases in the frequency band in which the sound pressure is amplified by the two ducts 32, 42. By using such a sound source, it is possible to increase the difference between the sound pressure in the frequency band amplified by each duct 32, 42 and the sound pressure in other frequency bands. This increases the sound pressure in the required peak frequency band while reducing the sound pressure in other frequency bands, thereby suppressing the generation of unnecessary noise.

[0035] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the invention.

[0036] For example, the number of ducts connected to the opening 26 of the speaker 22 is not limited to two, and three or more ducts of different lengths may be connected. In such a case, standing waves can be formed in three or more frequency bands. [Explanation of symbols]

[0037] 1 vehicle 10. Vehicle approach notification device 12 Control Unit 14 Amplifier 20 pronunciation units 22 Speaker (sound producing means) 26 Opening 32 First Duct 34 Base 36 Length adjustment part 42 Second Duct 44 Base 46 Length adjustment part

Claims

1. A vehicle approach warning device is mounted on a vehicle and includes sound generating means for emitting a warning sound from an opening toward the outside of the vehicle, at least two ducts of different lengths, one end of which is connected to the opening; A vehicle approach notification device characterized in that the length of each duct is set so that when the notification sound is output, the frequency band in which the sound pressure increases due to the acoustic characteristics of the vehicle's body shape and the frequency band of the standing wave formed by the length of each duct approximately match.

2. 2. The vehicle approach notification device according to claim 1, wherein the duct has a cylindrical base portion having one end fixed to the opening, and a cylindrical length adjustment portion connected to a tip end of the base portion, which allows the duct length to be adjusted.

3. 3. The vehicle approach notification device according to claim 1, wherein the sound source of the notification sound is white noise having a uniform sound pressure over a predetermined wide frequency band.

4. 4. The vehicle approach notification device according to claim 1, wherein the duct is cylindrical.

5. A vehicle approach warning device is mounted on a vehicle and includes sound generating means for emitting a warning sound from an opening toward the outside of the vehicle, at least two ducts of different lengths, one end of which is connected to the opening; the duct has a cylindrical base portion having one end fixed to the opening, and a cylindrical length adjustment portion slidably connected to a tip end of the base portion and capable of adjusting the duct length, The length adjustment portion is formed in a cylindrical shape with approximately the same diameter as the cylindrical base portion, forms a tip opening of the duct, and can be operated to slide along the tip portion of the base portion to adjust the duct length.

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