JP5573766B2 - Vehicle approach warning device - Google Patents

Description

  The present invention relates to a vehicle approach warning device that warns the surroundings that a vehicle is approaching by generating sound from the vehicle.

  In recent years, electric vehicles (EV cars), hybrid cars (HV cars), etc. have structurally low noise, and it is difficult for pedestrians to notice the approach of these vehicles. Vehicle approach warning devices that generate simulated running sounds are being installed in order to raise awareness of being in a car. In the vehicle approach warning device, a pseudo running sound is automatically generated in order to recognize the approach of the vehicle to a pedestrian or the like when traveling at low speed with low road noise (see, for example, Patent Document 1).

  Specifically, the audio data stored in the memory (ROM) is set in a D / A converter or PWM output device at every sampling period, and the sound corresponding to the audio data is generated by changing to an analog waveform. . And by adding processing such as changing the sound pressure according to the driver's accelerator opening, vehicle speed, or engine speed, and increasing the accelerator pressure, vehicle speed, or engine speed, the sound pressure increases. To improve awareness of vehicle approach.

JP 2009-35195 A

  However, when the sound pressure is increased as the accelerator opening degree, the vehicle speed, or the engine speed is increased, the sound pressure is suddenly changed when the change is large. For this reason, there is a problem that the envelope of the reproduced sound is not smoothly connected, and a noise “buzz” (hereinafter, referred to as “bottom sound”) is generated, resulting in a deterioration in sound quality.

  In view of the above points, the present invention changes sound pressure in response to vehicle conditions such as accelerator opening, thereby improving the degree of recognition of vehicle approach to pedestrians and the like, and improving sound quality due to the generation of a clapping sound. The purpose is to be able to suppress the decrease of.

In order to achieve the above object, according to the first aspect of the present invention, sound is generated around the vehicle through the sounding body (3) mounted on the vehicle, and the sound pressure of the sound output from the sounding body (3) is changed to the vehicle state. In the vehicle approach alarm device that warns the approach of the vehicle by controlling according to the vehicle state, the vehicle state acquisition means (21a) for acquiring the vehicle state and the vehicle state acquired by the vehicle state acquisition means (21a) A sound pressure setting section (21b-21d) for setting the sound pressure for each predetermined control cycle, and an output section (21e) for generating a sound output corresponding to the sound pressure set by the sound pressure setting section (21b-21d) ), And an amplifier (23) for passing a current corresponding to the sound output generated from the output unit (21e) to the sound generator (3), and a sound pressure setting unit (21b to 21b). 21d) is the sound pressure corresponding to the vehicle condition. When the amount of change per unit time is greater than or equal to a predetermined determination value, the sound pressure suddenly changes, and from the first sound pressure corresponding to the vehicle state at the time of the control cycle before the sudden change to the control cycle at the time of the sudden change The sound pressure is set such that the second sound pressure corresponding to the vehicle state is changed over a plurality of control cycles.

  Thus, when the sound pressure is set based on the vehicle state, the vehicle state after the sudden change from the first sound pressure corresponding to the vehicle state before the sudden change so that the sound pressure gradually changes even when the sound pressure changes suddenly. The sound pressure is gradually changed to the second sound pressure corresponding to. That is, when the sound pressure change amount per unit time corresponding to the vehicle state is equal to or greater than a predetermined determination value, when the sound pressure suddenly changes, the vehicle state after the sudden change from the first sound pressure corresponding to the vehicle state before the sudden change As compared with the case where the sound pressure is set according to the sound pressure corresponding to the vehicle state up to the second sound pressure corresponding to, the sound pressure gradual change control that makes the increase gradient of the sound pressure gentle is performed. As a result, when the vehicle state becomes equal to or higher than a predetermined determination value, the envelope is connected before and after the vehicle state, so that a sudden change in sound pressure can be prevented, the generation of a clapping sound can be prevented, and the deterioration of sound quality can be suppressed. Is possible. Therefore, by changing the sound pressure according to the vehicle state, it is possible to improve the recognition degree of the approach of the vehicle to a pedestrian or the like, and to suppress the deterioration of the sound quality due to the generation of the murmur.

  For example, as described in claim 2, the sound pressure setting unit (21 b to 21 d) includes a data storage unit (21 b) that stores reference sound pressure data serving as a reference value of sound pressure to be generated, a vehicle state, Acquired by the vehicle state acquisition means (21a) from the correspondence relationship storage unit (21c) for storing the correspondence relationship with the increase amount of the sound pressure or the coefficient of the sound pressure, and the correspondence relationship stored in the correspondence relationship storage unit (21c). An increase in sound pressure corresponding to the vehicle state or a coefficient of sound pressure is calculated, and the calculated increase in sound pressure with respect to the reference sound pressure indicated in the data stored in the data storage unit (21b) A calculation unit (21d) for calculating the sound pressure corresponding to the vehicle state acquired by the vehicle state acquisition means (21a) by adding the amount or multiplying by the coefficient of the sound pressure; The calculation unit (21d) When the amount of change in the sound pressure is equal to or greater than a predetermined determination value, the sound pressure suddenly changes. From the first increase in sound pressure or the first coefficient of sound pressure corresponding to the vehicle state in the control cycle before the sudden change, Setting the sound pressure increase amount or the sound pressure coefficient so as to change the sound pressure corresponding to the vehicle state at the control cycle to the second increase amount or the second coefficient of the sound pressure over a plurality of control cycles. Can do.

  In addition, as described in claim 3, the vehicle state acquisition means (21a) acquires at least one of the accelerator opening and the vehicle speed or the engine speed as the vehicle state, and the calculation unit (21d) acquires the accelerator opening. Is satisfied when the vehicle speed is equal to or higher than the predetermined speed determination value and the engine speed is equal to or higher than the predetermined speed determination value.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

1 is a block diagram of a vehicle approach warning system including a vehicle approach warning device according to a first embodiment of the present invention. Sound generator current waveform when sound pressure control is not performed, sound generator current waveform (conventional waveform) when only sound pressure control is executed without performing sound pressure gradual change control, sound pressure gradual change while performing sound pressure control It is the figure which showed the sounding body electric current waveform at the time of controlling. (A), (b) is the figure which showed the relationship of the increase amount of the sound pressure with respect to the accelerator opening degree memorize | stored in the map memory | storage part 21c, and the coefficient (change rate) of the sound pressure. It is the figure shown about the change of the coefficient of the accelerator opening degree, the amount of accelerator opening change, the increase in sound pressure, or the sound pressure when the accelerator opening suddenly increases. It is a sound generator current waveform diagram corresponding to the change of the accelerator pedal opening.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 is a block diagram of a vehicle approach warning system including a vehicle approach warning device according to the present embodiment. With reference to this figure, the vehicle approach warning system including the vehicle approach warning device concerning this embodiment is demonstrated.

  As shown in FIG. 1, the vehicle approach warning system includes an accelerator opening sensor 1, a vehicle approach warning device 2, and a speaker 3. In the vehicle approach warning system, the vehicle approach warning device 2 generates a sound from the speaker 3 as a sounding body based on the accelerator opening degree detection signal transmitted from the accelerator opening degree sensor 1, thereby preventing the vehicle from approaching the surroundings. Alert pedestrians. Here, the vehicle approach warning device 2 is separated from the speaker 3, but the speaker 3 may be integrated with the vehicle approach warning device 2.

  The accelerator opening sensor 1 outputs a detection signal indicating the accelerator opening as a detection signal of the accelerator opening. The accelerator opening represents the vehicle state. If the accelerator opening is large, it is assumed that the vehicle accelerates more greatly and approaches a pedestrian or the like faster. For this reason, the sound pressure of the pronunciation is increased as the accelerator opening is larger, so that the approach of the vehicle is recognized around a pedestrian or the like. Since the accelerator opening is a value corresponding to the operation amount of the accelerator pedal, the accelerator opening can also be detected based on the operation amount of the accelerator pedal (for example, a stroke sensor or a pedal force sensor).

  The vehicle approach warning device 2 includes a microcomputer 21, a low-pass filter (hereinafter referred to as LPF) 22, and a power amplifier (hereinafter referred to as AMP) 23.

  The microcomputer 21 is configured by a known microcomputer including a CPU, ROM, RAM, I / O, and the like, and generates sound at a low speed (for example, 0 to 20 km / h) based on a program stored in the ROM or the like. Thus, the pedestrian and the like are notified of the approach of the vehicle, and sound pressure control is performed to change the sound pressure according to the vehicle state such as the accelerator opening. The microcomputer 21 repeatedly performs sound pressure control execution processing at predetermined control cycles, and changes the sound pressure according to the vehicle state such as the accelerator opening. In the present embodiment, the microcomputer 21 includes an accelerator opening degree acquisition unit 21a, a data storage unit 21b, a map storage unit 21c, a calculation unit 21d, and a digital analog converter (hereinafter referred to as DAC) 21e.

  The accelerator opening acquisition unit 21a corresponds to vehicle state acquisition means, and acquires the accelerator opening based on a detection signal indicating the accelerator opening input from the accelerator opening sensor 1.

  The data storage unit 21b, the map storage unit 21c, and the calculation unit 21d correspond to the sound pressure setting unit of the present invention. The data storage unit 21b is a memory that stores sound generation PCM (pulse code modulation) data. The data storage unit 21b stores a reference sound pressure (hereinafter referred to as a reference sound pressure), its frequency, and the like. For example, sound generation is started when the accelerator is off and the brake is off, and the sound pressure at the start of sound generation is set as the reference sound pressure (sound amplitude).

  The map storage unit 21c corresponds to a correspondence storage unit, and is a map (or function) of an increase in sound pressure or a coefficient (change rate) of sound pressure associated with a vehicle state (accelerator opening in the case of this embodiment). Is stored. The map storage unit 21c uses the stored map (or function formula) to determine the amount of increase in sound pressure or the coefficient of sound pressure corresponding to the accelerator opening detected by the accelerator opening sensor 1. More specifically, the map storage unit 21c stores a map in which the sound pressure increases as the accelerator opening increases. From the map indicating the relationship between the accelerator opening and the increase in sound pressure or the coefficient of sound pressure, the increase in sound pressure or the coefficient of sound pressure corresponding to the accelerator opening at that time is obtained.

  In the calculation unit 21d, based on the accelerator opening and the amount of increase in sound pressure corresponding to the accelerator opening obtained in the map storage unit 21c and the accelerator opening change per unit time (hereinafter simply referred to as accelerator opening change), The amount of increase in sound pressure used for the above, that is, the amount of increase in sound pressure relative to the reference sound pressure stored in the data storage unit 21b is calculated. Alternatively, the computing unit 21d computes a sound pressure coefficient that is actually used based on the sound pressure coefficient and the accelerator opening change amount corresponding to the accelerator opening obtained in the map storage unit 21c. Then, the actually outputted sound pressure is calculated by adding the calculated increase amount of the actually used sound pressure to the reference sound pressure or by multiplying the calculated sound pressure coefficient actually used by the reference sound pressure.

  The sound pressure increase amount or sound pressure coefficient obtained by the map storage unit 21c is a value corresponding to the accelerator opening, but when the accelerator opening change amount is large, the sound obtained by the map storage unit 21c. When sound generation is performed by setting the sound pressure to be actually generated using the increase amount of the pressure or the sound pressure coefficient as it is, the sound pressure is suddenly changed to generate a noise. For this reason, the calculation unit 21d compares the accelerator opening change amount with a determination value (threshold value), and the map storage unit 21c determines whether the accelerator opening change amount is greater than or less than the determination value. It is determined whether or not to use the obtained sound pressure increase amount or sound pressure coefficient as it is, and based on the result, the actually used sound pressure increase amount and sound pressure coefficient are set. Specifically, if the accelerator opening change amount is equal to or greater than the determination value, the calculation unit 21d processes the sound pressure increase amount or the sound pressure coefficient obtained by the map storage unit 21c to actually generate the sound. Sound pressure gradual change control is performed to moderate the change in sound pressure by setting the amount of increase in pressure or the coefficient of sound pressure. If the accelerator opening change amount is less than the determination value, the calculation unit 21d does not perform the sound pressure gradual change control, and directly uses the sound pressure increase amount or the sound pressure coefficient obtained by the map storage unit 21c. Use to set the sound pressure that is actually generated.

  The calculation unit 21d calculates a digital value when sounding is performed with the finally calculated sound pressure that is actually calculated, and the calculation result is analog-converted by the DAC 21e and output from the DAC 21e as the sound output of the microcomputer 21. Is done.

  The DAC 21e functions as an output unit, reads out sound pressure data corresponding to the accelerator opening obtained by calculation in the calculation unit 21d at a predetermined sampling period, and generates an output by converting the data into an analog value. A sound output having an amplitude with a sound pressure corresponding to the opening is generated.

  The LPF 22 corresponds to filter means, removes high frequency noise components, and generates an output corresponding to the output of the DAC 21e. For example, the LPF 22 stores a voltage corresponding to the output of the DAC 21 e in a built-in capacitor and outputs it to the AMP 23.

  The AMP 23 causes a current corresponding to the output of the LPF 22 to flow through the speaker 3 based on voltage application from a constant voltage source (not shown). The sound pressure generated by the speaker 3 is determined according to the magnitude (amplitude) of the current supplied from the AMP 23, and the magnitude of the current supplied from the AMP 23 is determined by the output waveform of the LPF 22 corresponding to the output of the DAC 21e. For this reason, if the output according to a vehicle state detection signal is generated from the microcomputer 21, the electric current which AMP23 flows will be changed according to this.

  The vehicle approach warning system provided with the vehicle approach warning device 2 concerning this embodiment is comprised by the above structures. Next, sound pressure control including sound pressure gradual change control by a vehicle approach warning system including the vehicle approach warning device 2 according to the present embodiment will be described.

  FIG. 2 shows a sounding body current waveform when sound pressure control is not performed, a sounding body current waveform (conventional waveform) when only sound pressure control is performed without performing sound pressure gradual change control, and sound pressure control is performed. The sound generator current waveform when the sound pressure gradual change control is performed is shown. The sounding body current waveform is a waveform of the current passed through the speaker 3 by the AMP 23, and the sound pressure is changed by changing the amplitude of the current at a desired frequency. The peak of the current amplitude changes with time, and the waveform (amplitude envelope waveform) of the peak is called an envelope, and the peak of this envelope corresponds to the sound pressure actually generated set by the microcomputer 21.

  As shown in FIG. 2A, the sounding body current waveform when the sound pressure control is not performed has an amplitude change periodically determined at a constant frequency, and has a constant envelope. This sounding body current waveform corresponds to a waveform when the sounding PCM data stored in the data storage unit 21d has a sound pressure that is actually generated as it is.

  On the other hand, as shown in FIG. 2B, the sounding body current waveform (conventional waveform) in the case where only the sound pressure control is executed without performing the sound pressure gradual change control is the time when the accelerator opening suddenly increases. The sound pressure suddenly increases. For this reason, the amplitude of the sound generator current waveform suddenly increases, the envelope is not connected before and after that, and a sound is generated, resulting in deterioration of sound quality.

  For this reason, as shown in FIG. 2 (c), in this embodiment, the sound generator is controlled even when the accelerator opening is suddenly increased by performing the sound pressure gradual change control while executing the sound pressure control. The amplitude of the current waveform is not suddenly increased, but is gradually increased so that the envelopes are connected before and after that, and the deterioration of the sound quality is suppressed so as not to generate a noise.

  FIGS. 3A and 3B show the relationship between the amount of increase in sound pressure and the coefficient (change rate) of sound pressure with respect to the accelerator opening stored in the map storage unit 21c. As shown in FIG. 3A, the amount of increase in sound pressure from the reference sound pressure increases as the accelerator opening increases. Similarly, as shown in FIG. 3B, the rate of change of the sound pressure applied to the reference sound pressure increases as the accelerator opening increases. If the amount of increase in the sound pressure or the rate of change in the sound pressure suddenly increases, it becomes a factor for generating a bot sound as described above. Accordingly, the calculation unit 21d obtains the accelerator pedal opening change amount and compares the accelerator opening change amount with a determination value (threshold value) that is assumed to generate a noise, and the accelerator opening change amount is greater than or equal to the determination value. Then, the sound pressure gradual change control is executed.

  Specifically, the microcomputer 21 performs a sound pressure control process for each predetermined control cycle, and stores the accelerator opening acquired by the accelerator opening acquisition unit 21a for each control cycle in the calculation unit 21d. The accelerator opening change amount is calculated by calculating the difference between the accelerator opening at the previous control cycle and the accelerator opening at the current control cycle. In addition, the calculation unit 21d stores a sound pressure increase amount or a sound pressure coefficient corresponding to the accelerator opening obtained by the map storage unit 21c for each control period.

  Based on these, in the calculation unit 21d, when the accelerator opening change amount is equal to or larger than the determination value, the control start value is set to the sound pressure increase amount or the sound pressure coefficient corresponding to the accelerator opening at the previous control cycle. And an increase in sound pressure or a coefficient of sound pressure corresponding to the accelerator opening at the current control cycle is stored as a control end value. For example, as shown in FIGS. 3A and 3B, when the sound pressure increase P1 or the sound pressure coefficient K1 in the control cycle immediately before exceeding the judgment value is stored and the judgment value is exceeded. The sound pressure increase P2 or the sound pressure coefficient K2 is stored. Then, the amount of increase in sound pressure or the coefficient of sound pressure is not changed for one control cycle from the control start value to the control end value, but is changed for a plurality of control cycles. The control cycle may be a fixed cycle such as 10 cycles, or it may take a difference between the control end value and the control start value when it is changed by a constant sound pressure increase or coefficient. It is good also as a cycle number. In this way, when the accelerator opening suddenly increases, the amount of increase in sound pressure or the coefficient of sound pressure can be gradually changed from the control start value to the control end value. Thereby, the sound pressure to be actually generated can be gradually changed, the envelope can be connected before and after the accelerator opening suddenly increases, and the deterioration of the sound quality due to the generation of the sound can be suppressed.

  FIG. 4 is a diagram showing changes in accelerator opening, accelerator opening change, sound pressure increase, or sound pressure coefficient when the accelerator opening suddenly increases. As shown in this figure, when the accelerator opening suddenly increases, the amount of change in the accelerator opening increases and becomes greater than or equal to the determination value. The sound pressure increase (first increase) corresponding to the accelerator opening in the control cycle immediately before this sudden change in the accelerator opening is detected is P1, or the sound pressure coefficient (first coefficient) is K1. It is assumed that the sound pressure increase amount (second increase amount) corresponding to the accelerator opening in the control cycle is P2 or the sound pressure coefficient (second coefficient) is K2.

  In this case, if there is no sound pressure gradual change control as in the present embodiment, a broken line in the figure in a period of one cycle from the control cycle immediately before the sudden change in accelerator opening is detected to the detected control cycle. As shown in FIG. 4, the sound pressure increase amount is increased from P1 to P2, or the sound pressure coefficient is increased from K1 to K2. For this reason, a sudden change in sound pressure occurs, which generates a squealing sound and causes a reduction in sound quality.

  On the other hand, if there is a sound pressure gradual change control as in this embodiment, it is indicated by a solid line in the figure from the control cycle immediately before the sudden change in the accelerator opening is detected to a plurality of cycles after the detected control cycle. As described above, the amount of increase in sound pressure is gradually increased from P1 to P2, or the coefficient of sound pressure is gradually increased from K1 to K2. As a result, the sound pressure changes gradually, so that no nuisance can be generated, and deterioration in sound quality can be suppressed. Here, it is explained that the amount of increase in sound pressure is gradually increased from P1 to P2 or the coefficient of sound pressure is gradually increased from 1.0 to 2.0, and these increase linearly in FIG. In the actual control, an increase amount and a coefficient of sound pressure are set for each control cycle, and these are increased step by step for each control cycle.

  FIG. 5 shows a sound generator current waveform diagram corresponding to a change in the accelerator pedal opening. Since the sound pressure control is performed with the change in the accelerator opening, the amplitude of the sound generator current waveform is increased with the increase in the accelerator opening, as compared with the case where the sound pressure control is not performed. When only the sound pressure control is executed, the envelope is not connected due to a sudden change in the accelerator opening, but the amount of change in the accelerator opening is equal to or greater than the determination value while performing the sound pressure control as in this embodiment. Since the sound pressure change control is sometimes performed, the envelope is connected before and after that, so that a sudden change in the sound pressure can be prevented, the generation of a clapping sound can be prevented, and the deterioration of the sound quality can be suppressed. It becomes.

  As described above, according to the vehicle approach warning system of the present embodiment, when the sound pressure is set based on the vehicle state, the vehicle before the sudden change so that the sound pressure gradually changes even when the sound pressure changes suddenly. The sound pressure is gradually changed from the sound pressure corresponding to the state to the sound pressure corresponding to the vehicle state after the sudden change.

  Specifically, the sound pressure corresponding to the vehicle state before the sudden change is defined as the sudden change of the sound pressure when the amount of change per unit time of the sound pressure corresponding to the vehicle state such as the accelerator opening is equal to or greater than a predetermined judgment value. Compared to the case where the sound pressure is set according to the sound pressure corresponding to the vehicle state from the sound pressure corresponding to the vehicle state after the sudden change to the sound pressure, the sound pressure gradual change control that makes the sound pressure increase gradient gentle is performed. ing. For example, if the accelerator opening change amount is equal to or greater than the determination value, the vehicle state exceeds the predetermined determination value, and the vehicle state is determined with respect to the increase in sound pressure relative to the reference sound pressure or the coefficient of sound pressure applied to the reference sound pressure. The amount of increase in the sound pressure corresponding to or the increase gradient of the coefficient of the sound pressure is gradually increased.

  As a result, when the vehicle state becomes equal to or higher than a predetermined determination value, the envelope is connected before and after the vehicle state, so that a sudden change in sound pressure can be prevented, the generation of a clapping sound can be prevented, and the deterioration of sound quality can be suppressed. Is possible. Therefore, by changing the sound pressure in accordance with the vehicle state such as the accelerator opening degree, it is possible to improve the recognition degree of the vehicle approaching to a pedestrian or the like, and to suppress the deterioration of the sound quality due to the generation of the noise.

(Other embodiments)
In the above-described embodiment, the accelerator opening is cited as the vehicle state and the accelerator opening sensor is used as the vehicle state acquisition means. However, the vehicle speed can be cited as a representation of the vehicle state. Since the vehicle approaches faster as the vehicle speed increases, it is preferable to increase the sound pressure of the sound as the vehicle speed increases so that the approach of the vehicle is recognized around pedestrians and the like. . For example, using a vehicle speed sensor (or a wheel speed sensor), the vehicle state acquisition means provided in the microcomputer 2 inputs a vehicle speed detection signal output from the vehicle speed sensor, and acquires the vehicle speed based on the vehicle speed detection signal. Can do.

  Further, the engine speed can also be mentioned as the vehicle state. As the engine speed increases, a larger driving force is generated, and the vehicle accelerates faster and approaches faster. In this case as well, the higher the engine speed, the higher the sound pressure of the pronunciation, the pedestrian It is preferable to recognize the approach of the vehicle around the vehicle. The engine speed basically corresponds to the accelerator opening, but even if the accelerator opening is the same, the engine speed varies depending on the selected gear position, and the approach of the vehicle depends on the engine speed. Since the way is different, it is more preferable to detect the engine speed and set the sound pressure according to the engine speed. For example, an engine speed detection signal output from the engine speed sensor is input by the vehicle state acquisition means provided in the microcomputer 2 using an engine speed sensor, and the engine speed is determined based on the engine speed detection signal. Can be obtained.

  Of course, the sound pressure setting may be performed using all of the accelerator opening degree, the vehicle speed, and the engine speed described here, or the sound generation is controlled according to only one or two of them. Also good. When the accelerator opening is equal to or greater than a predetermined determination value (opening determination value), when the vehicle speed is equal to a predetermined determination value (speed determination value), the engine speed is equal to or greater than a predetermined determination value (rotation speed determination value). What is necessary is just to detect that the sound pressure is suddenly changed when any one of the times is satisfied.

  Although the case where the sound pressure is changed according to the accelerator opening degree, the vehicle speed, and the engine speed has been described here, for example, the pitch of the sound generation can be changed according to the vehicle speed. For example, the pitch of pronunciation is set to be faster (shorter) as the vehicle speed increases. The pronunciation pitch is adjusted by changing the sampling period, and the shorter the sampling period, the faster the pronunciation pitch. Therefore, the faster the vehicle approaches the pedestrian, the faster the pronunciation pitch, the easier it is for the pedestrian to recognize the running state of the vehicle.

  Further, in the above embodiment, when the accelerator opening change amount becomes equal to or larger than the determination value, the calculation unit 21d gradually increases the sound pressure increase amount and the sound pressure coefficient. However, when the sound pressure set based on the vehicle state is assumed to change suddenly, the increasing gradient of the sound pressure from the sound pressure before the sudden change to the sound pressure after the sudden change is set corresponding to the vehicle state It is only necessary to perform the sound pressure gradual change control so as to be more gradual. For example, the sound pressure corresponding to the accelerator opening before the sudden change and the sound pressure corresponding to the accelerator opening after the sudden change (that is, the increase in the sound pressure corresponding to the accelerator opening with respect to the sound pressure stored in the data storage unit 21b). The sound pressure itself may be gradually increased so that the sound pressure after the sudden change is changed from the sound pressure before the sudden change to the sound pressure after the sudden change. .

  Moreover, in the said embodiment, the case where a sound pressure changes suddenly according to a vehicle state was detected based on the amount of accelerator opening change. However, this is an example of a method for detecting a case where the sound pressure change amount per unit time corresponding to the vehicle state is assumed to be larger than a predetermined determination value (threshold value) and the sound pressure is expected to change suddenly. Of course, the sound pressure change amount per unit time corresponding to the vehicle state itself may be used to detect that the sound pressure changes suddenly when the sound pressure change amount exceeds a predetermined determination value. .

  In addition, although the explanation was given by taking an example of a clapping sound that occurs when the sound pressure is changed from a small state to a large state, a sudden change in sound pressure also occurs when the sound pressure is changed from a large state to a small state. there's a possibility that. In this case as well, it is only necessary to detect that the amount of change in the accelerator opening is equal to or greater than the determination value, and execute the sound pressure gradual change control so that the sound pressure is gradually changed from a large state to a small state. In other words, whether the sound pressure is changed from a small state to a large state or the sound pressure is changed from a large state to a small state, the amount of change per unit time of the sound pressure corresponding to the vehicle state is predetermined. From the first sound pressure corresponding to the vehicle state at the control cycle before the sudden change to the second sound pressure corresponding to the vehicle state at the control cycle at the time of sudden change The sound pressure may be set so as to change over a plurality of control cycles.

  In the above embodiment, the relationship shown in FIGS. 3A and 3B is given as an example of the relationship between the amount of increase in sound pressure and the coefficient of sound pressure with respect to the accelerator opening. However, these are merely examples of the relationship between the increase in sound pressure and the coefficient of sound pressure with respect to the vehicle state. For example, FIGS. 3A and 3B show a case where the amount of increase in sound pressure and the coefficient of sound pressure increase linearly as the accelerator opening increases, but these are quadratic curves. In other words, the amount of increase in sound pressure or the rate of increase in coefficient of sound pressure may increase as the accelerator opening increases.

DESCRIPTION OF SYMBOLS 1 Accelerator opening sensor 2 Vehicle approach warning device 3 Speaker 21 Microcomputer 21a Accelerator opening acquisition part 21b Data memory | storage part 21c Map memory | storage part 21d Operation part 21e DAC
22 LPF
23 AMP

Claims (3)

A sound is generated around the vehicle through a sounding body (3) mounted on the vehicle, and the sound pressure from the sounding body (3) is controlled in accordance with the vehicle state to warn of the approach of the vehicle. In the vehicle approach warning device,
Vehicle state acquisition means (21a) for acquiring the vehicle state;
A sound pressure setting unit (21b to 21d) for setting a sound pressure corresponding to the vehicle state acquired by the vehicle state acquisition means (21a) for each predetermined control period;
A microcomputer (21) having an output unit (21e) for generating a sound output corresponding to the sound pressure set by the sound pressure setting unit (21b to 21d);
An amplifier (23) for supplying a current corresponding to the sound output generated from the output unit (21e) to the sound generator (3);
The sound pressure setting unit (21b to 21d) sets the control period before the sudden change as a sudden change of the sound pressure when the change amount per unit time of the sound pressure corresponding to the vehicle state is equal to or greater than a predetermined determination value. From the first sound pressure corresponding to the vehicle state at the time to the second sound pressure corresponding to the vehicle state at the time of the control cycle at the time of the sudden change, the sound pressure is set to be changed over the plurality of control cycles. A vehicle approach warning device. The sound pressure setting unit (21b to 21d)
A data storage unit (21b) that stores reference sound pressure data that is a reference value of sound pressure to be generated;
A correspondence storage unit (21c) that stores the correspondence between the vehicle state and the amount of increase in sound pressure or the coefficient of sound pressure;
While calculating the increase amount of the sound pressure or the coefficient of the sound pressure corresponding to the vehicle state acquired by the vehicle state acquisition means (21a) from the correspondence relationship stored in the correspondence relationship storage unit (21c), The vehicle state acquisition is performed by adding the calculated increase in the sound pressure or multiplying the coefficient of the sound pressure to the reference sound pressure indicated in the data stored in the data storage unit (21b). A calculation unit (21d) for calculating a sound pressure corresponding to the vehicle state acquired by the means (21a),
The computing unit (21d) first increases sound pressure corresponding to the vehicle state in the control cycle before the sudden change, when the change amount of the vehicle state is equal to or greater than a predetermined determination value, when the sound pressure suddenly changes. From the first coefficient of the volume or the sound pressure to the second increase amount of the sound pressure or the second coefficient of the sound pressure corresponding to the vehicle state at the control cycle at the time of the sudden change, the control cycle is changed by a plurality of cycles. 2. The vehicle approach warning device according to claim 1, wherein an increase amount of the sound pressure or a coefficient of the sound pressure is set. The vehicle state acquisition means (21a) acquires at least one of an accelerator opening and a vehicle speed or an engine speed as the vehicle state,
The calculation unit (21d) satisfies any one of the accelerator opening equal to or greater than a predetermined opening determination value, the vehicle speed equal to or greater than a predetermined speed determination value, and the engine rotation speed equal to or greater than a predetermined rotation speed determination value. The vehicle approach warning device according to claim 2, wherein the sound pressure is suddenly changed.

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