JP2015016787A - Vehicle approach notification device - Google Patents

Abstract

An object of the present invention is to make it possible to grasp the traveling speed of a vehicle as an actual sense while suppressing fluctuations in the sound pressure of a notification sound. A phaser circuit for outputting a sound signal for outputting a sound in which a fluctuation sound that periodically fluctuates to a notification sound corresponding to the notification sound signal is output. A microcomputer 10 represents the speed of the vehicle. Based on the vehicle speed signal, a phase shifter control signal is specified such that a fluctuation sound that is synchronized with the rotation of the vehicle wheel is added to the notification sound, and the phase shifter control signal is output to the phaser circuit 40. [Selection] Figure 1

Description

  The present invention relates to a vehicle approach notification device that outputs a notification sound from a speaker to report the approach of a vehicle.

  An electric vehicle including only an electric motor as a driving source for traveling has extremely quiet traveling noise during low-speed traveling. In addition, a hybrid vehicle including an electric motor and an internal combustion engine as a driving source for traveling has extremely quiet traveling noise when traveling with only the driving force of the electric motor during low-speed traveling. For this reason, a pedestrian or the like may not notice the approach of the vehicle.

  Therefore, in such a low-noise vehicle, a notification sound signal whose frequency changes according to the vehicle speed is generated, and a notification sound based on the generated notification sound signal is generated outside the vehicle so that the presence of the vehicle is detected around the vehicle. A vehicle approach notification device has been proposed that informs pedestrians and the like (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 5-213112

  However, as in the device described in Patent Document 1, in a configuration that generates a notification sound signal whose frequency changes according to the vehicle speed and generates a notification sound based on the generated notification sound signal toward the outside of the vehicle. The sound pressure of the notification sound may fluctuate and deviate greatly from the specified sound pressure range. Specifically, when the frequency of the notification sound signal is changed according to the vehicle speed, the output sound pressure does not change in the frequency band where the speaker output sound pressure vs. frequency characteristic is flat, but the speaker output sound pressure vs. frequency characteristic does not change. Since the output sound pressure increases or decreases in a frequency band that is not flat, the sound pressure of the notification sound may deviate significantly from the specified sound pressure range as the vehicle speed changes. As a result, the sound pressure of the notification sound is reduced, making it difficult for pedestrians to notice the approach of the vehicle, or the sound pressure of the notification sound is increased and the notification sound is made noise to pedestrians and drivers in the passenger compartment. There is a problem that makes you feel.

  Further, in such a vehicle approach notification device, it is important whether or not the pedestrian can be reminded of the traveling state of the automobile. As in the device described in Patent Document 1, in a configuration that generates a notification sound signal whose frequency changes according to the vehicle speed and generates a notification sound based on the generated notification sound signal toward the outside of the vehicle, the notification Although it is possible to recognize to some extent whether the running speed of the vehicle is fast or slow based on the pitch of the sound, there is a problem that it is difficult to grasp the running speed of the vehicle as a real sense.

  The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to capture the traveling speed of the vehicle as a real sense while suppressing fluctuations in the sound pressure of the notification sound.

  In order to achieve the above object, the invention according to claim 1 generates a notification sound signal composed of a plurality of frequency components, and outputs a notification sound corresponding to the notification sound signal from a speaker to approach the vehicle. A vehicle approach notification device for reporting, having a plurality of phase shifters (41 to 44) for shifting the phase of the notification sound signal, and according to the phase shifter control signal input from the control unit (10), The frequency band in which the phase of the notification sound signal is shifted by multiple phase shifters and the notification sound signal are shifted, and a fluctuation sound that periodically fluctuates is added to the notification sound according to the notification sound signal. Equipped with a phaser circuit (40) that outputs an audio signal for outputting audio, and the control unit adds a fluctuation sound that synchronizes with the rotation of the vehicle wheel based on the vehicle speed signal representing the vehicle speed to the notification sound Phase shifter control Identify No. is characterized by outputting the phase shifter control signal to the phaser circuit.

  According to such a configuration, in accordance with the phase shifter control signal input from the control unit (10), a signal obtained by shifting the phase of the notification sound signal composed of a plurality of frequency components by a plurality of phase shifters. A phaser circuit (40) that outputs a sound signal for outputting a sound in which a fluctuation sound that periodically fluctuates is added to the notification sound corresponding to the notification sound signal by shifting a frequency band in which the notification sound signal weakens The control unit specifies a phase shifter control signal that adds a fluctuation sound that is synchronized with the rotation of the wheel of the vehicle to the notification sound based on a vehicle speed signal that represents the speed of the vehicle, and Since the controller control signal is output to the phaser circuit, an audio signal is output from the phaser circuit to output a sound in which a fluctuation sound that synchronizes with the rotation of the vehicle wheel is added to the notification sound. Notification sound Since the output from the speaker can be made to capture the traveling speed of the vehicle as the actual sense. In addition, the fluctuation sound generated by the phaser circuit has little fluctuation in sound pressure, and the fluctuation in sound pressure of the notification sound can be suppressed.

  In the invention according to claim 2, in the phaser circuit, the higher the frequency of the phase shifter control signal, the shorter the fluctuation cycle of the fluctuation sound. It is characterized in that the frequency of the phase shifter control signal whose period is synchronized with the rotation of the wheel of the vehicle is specified, and the phase shifter control signal of the frequency is output to the phaser circuit.

  As described above, the phaser circuit can be configured such that the fluctuation cycle of the fluctuation sound becomes shorter as the frequency of the phase shifter control signal becomes higher. It is possible to specify the frequency of the phase shifter control signal that synchronizes with the rotation of the wheel and output the phase shifter control signal of the frequency to the phaser circuit.

  According to a third aspect of the present invention, the phaser circuit is characterized in that the degree of fluctuation of the fluctuation sound increases as the amplitude of the phase shifter control signal increases.

  Thus, the phaser circuit can be configured such that the degree of fluctuation of the fluctuation sound increases as the amplitude of the phase shifter control signal increases.

  According to a fourth aspect of the present invention, the control unit sets the amplitude of the phase shifter control signal so that the degree of fluctuation of the fluctuation sound increases as the amount of increase in the accelerator opening of the vehicle per unit time increases. A phase shifter control signal having the specified amplitude is output to the phaser circuit.

  As described above, the control unit specifies the amplitude of the phase shifter control signal such that the degree of fluctuation of the fluctuation sound increases as the amount of increase in the accelerator opening of the vehicle per unit time increases, and the amplitude shift. The phaser control signal can be output to the phaser circuit.

  According to the fifth aspect of the present invention, when the control unit determines that the change amount per unit time of the accelerator opening degree of the vehicle is positive, the control unit responds to the change amount of the accelerator opening degree of the vehicle. It is characterized in that the amplitude of the phase shifter control signal is made larger than a predetermined constant amplitude.

  According to such a configuration, when it is determined that the amount of change in the accelerator opening of the vehicle per unit time is positive, the control unit shifts according to the amount of change in the accelerator opening of the vehicle. Since the amplitude of the control signal is larger than a predetermined constant amplitude, the degree of fluctuation of the fluctuation sound can be increased in a situation where the amount of change in the accelerator opening of the vehicle per unit time is positive. .

  In a sixth aspect of the present invention, when the control unit determines that a certain period of time has not elapsed since the amount of change in the accelerator opening of the vehicle becomes zero or negative, the phase shifter control signal Is gradually returned to a predetermined constant amplitude.

  According to such a configuration, when the control unit determines that a certain period has not elapsed since the change amount of the accelerator opening of the vehicle becomes zero or negative, the control unit sets the amplitude of the phase shifter control signal. Since the amplitude is gradually returned to a predetermined amplitude, the degree of fluctuation of the fluctuation sound is gradually reduced in a situation where a certain period has not elapsed since the change in the accelerator opening of the vehicle becomes 0 or negative. be able to.

  According to the seventh aspect of the present invention, when the control unit determines that the fixed period has elapsed from the time when the change amount of the accelerator opening becomes zero or negative, the control unit sets the amplitude of the phase shifter control signal in advance. It is characterized by specifying a predetermined constant amplitude.

  According to such a configuration, when the control unit determines that a certain period has elapsed from the time when the change amount of the accelerator opening becomes 0 or negative, the amplitude of the phase shifter control signal is determined in advance. Since the constant amplitude is specified, the degree of fluctuation of the fluctuation sound can be made constant in a situation where a predetermined period has elapsed from the time when the change amount of the accelerator opening becomes zero or negative.

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

It is the figure which showed the structure of the vehicle approach notification apparatus which concerns on one Embodiment of this invention. It is the figure which showed the basic circuit of the phase shifter. It is the figure which showed the phase-frequency characteristic of the basic circuit of the phase shifter shown in FIG. It is the figure which showed the output level-frequency characteristic of the circuit which connected the basic circuit of the phase shifter shown in FIG. 2 in four stages. It is the figure which showed the output level-frequency characteristic of the phaser circuit at the time of changing the amplitude of a phase shifter control signal. It is a flowchart of a microcomputer. It is the figure which showed the example of the table which showed the relationship between a vehicle speed and a tire rotation speed. It is the figure which showed the relationship between the vehicle speed, accelerator opening, the accelerator opening variation | change_quantity, and a phase shifter control signal until the fixed fixed time passes from immediately after driving | running | working of a vehicle.

  The configuration of a vehicle approach notification device according to an embodiment of the present invention is shown in FIG. The vehicle approach notification device includes a microcomputer 10, a capacitor 20, resistors 21 and 22, a buffer 30, a phaser circuit 40, a power amplifier 50, a capacitor 60, and a speaker 70. The vehicle approach notification device generates a notification sound signal composed of a plurality of frequency components, and outputs a notification sound corresponding to the notification sound signal from the speaker 70 to notify the approach of the vehicle.

  The microcomputer 10 is configured as a computer including a RAM, a ROM, an EEPROM, an I / O, a DA converter, and the like, and performs various processes according to a program stored in the ROM.

  The microcomputer 10 is input with a vehicle speed signal corresponding to the vehicle speed from a vehicle speed sensor provided in the vehicle. In addition, an accelerator opening signal corresponding to the accelerator opening is input to the microcomputer 10 from an accelerator opening sensor provided in the vehicle.

  The microcomputer 10 performs processing for generating a notification sound signal composed of a plurality of frequency components, processing for generating a phase shifter control signal based on the vehicle speed signal and the accelerator opening signal, and the like. The notification sound signal and the phase shifter control signal are output as analog signals via the DA converter.

  The buffer 30 includes an operational amplifier 300, resistors 301 and 302, and a capacitor 303. The buffer 30 is used as a voltage follower circuit, and outputs the notification sound signal input from the microcomputer 10 to the phaser circuit 40 with the same amplitude.

  The phaser circuit 40 includes phase shifters 41 to 44 and an adder 45. The phase shifters 41 to 44 are cascade-connected in the order of the phase shifters 41, 42, 43, 44. The phase shifters 41 to 44 have the same configuration.

  The phaser circuit 40 also outputs a notification sound signal input terminal SIN1 for inputting a notification sound signal, a phase shifter control signal input terminal SIN2 for inputting a phase shifter control signal, and an output signal. An output terminal SOUT is provided.

  A notification sound signal composed of a plurality of frequency components is input from the microcomputer 10 via the buffer 30 to the notification sound signal input terminal SIN1 of the phaser circuit 40. Further, an AC phase shifter control signal is input from the microcomputer 10 via the capacitor 20 to the phase shifter control signal input terminal SIN2 of the phaser circuit 40.

  The phase shifters 41 to 44 each output a signal in which the phase of the input signal is shifted according to the frequency. The adder 45 outputs a signal obtained by adding the signal input from the phase shifter 44 and the notification sound signal.

  The phase shifters 41 to 44 each have an N-channel FET 400, an operational amplifier 401, resistors 402 to 404, and a capacitor 405. The resistance values of the resistors 402 to 404 are equal to each other.

  When the voltage of the phase shifter control signal input from the microcomputer 10 through the capacitor 20 is applied to the gate terminal of the FET 400, a current corresponding to the frequency and amplitude of the phase shifter control signal flows to the FET 400, and the resistor 402 It seems that the resistance value changes. Then, according to the frequency of the phase shifter control signal, the frequency band in which the phase shift of the notification sound signal by the phase shifters 41 to 44 and the notification sound signal weaken is periodically shifted, and the notification sound signal A voice signal for outputting a sound in which a fluctuation sound that periodically fluctuates is added to the notification sound according to the signal is output from the output terminal SOUT.

  The power amplifier 50 causes a current corresponding to a signal output from the output terminal SOUT of the phaser circuit 40 to flow through the speaker 70. The sound pressure of the notification sound output from the speaker 70 is determined according to the magnitude (amplitude) of the current supplied from the power amplifier 50, and the magnitude of the current supplied from the AMP 25 is the output terminal SOUT of the phaser circuit 40. It depends on the output signal waveform.

Here, the basic operation of the phase shifter will be described. FIG. 2 shows a basic circuit of the phase shifter. As shown in the figure, the basic circuit of the phase shifter is configured to include an operational amplifier OP, resistors R _{1 to} R ₃ , and a capacitor C ₁ . Here, it is assumed that the resistance values of the resistors R _{1 to} R ₃ are equal. This phase shifter shifts the phase according to the frequency.

FIG. 3 shows the phase-frequency characteristics of the basic circuit of the phase shifter shown in FIG. Here, the resistance value of the resistor _{R 1} R1, when the electrostatic capacitance of the capacitor _{C 1} and C1, the frequency f can be expressed as f = 1 / (2π · C1 · R1). Further, as shown in FIG. 3, the phase at the frequency f is 90 °. Here, for example, when the resistance value R1 of the resistor _{R 1} to 100 times, frequency is 100f. The phase at this frequency 100f is 0 °. Further, when the resistance value R1 of the resistor _{R 1} to 1/100, frequency is f / 100. The phase at f / 100 is 180 °. The frequency f shown in FIG. 3 is changed in accordance with the resistance value R1 and the capacitor C ₁ of the capacitance C1 of the resistor R _1.

  In FIG. 4, four stages of the phase shifter shown in FIG. 2 are prepared and cascade-connected, and the signal whose phase is shifted by these phase shifters and the original signal before the phase is shifted are added at the output stage. The output level vs. frequency characteristics when this is done are shown.

  For example, as in the case where the signal whose phase is shifted by four phase shifters and the original signal before the phase is shifted have the same phase (0 °, 360 °, 720 °) frequency, 2 When the frequencies are such that the two signals are intensifying, the level of the signal added at the output stage is high.

  Conversely, for example, when the signal whose phase is shifted by four phase shifters and the original signal before the phase is shifted have frequencies of opposite phases (180 °, 540 °), 2 When the frequencies are such that the two signals weaken each other, the level of the signal added at the output stage is low.

  FIG. 5 shows the output level-frequency characteristics of the phaser circuit 40 when the amplitude of the phase shifter control signal is changed. Note that the phase shifter control signal in this embodiment is a low-frequency sine wave signal. In FIG. 5, when the voltage of the phase shifter control signal is a default value, the characteristic indicated by the solid line B is obtained. Here, when the voltage of the phase shifter control signal becomes larger than the default value, the characteristic indicated by the dotted line A is obtained, and when the voltage of the phase shifter control signal becomes smaller than the default value, the characteristic indicated by the one-dot chain line C is obtained. Thus, the output level-frequency characteristic of the phaser circuit 40 changes according to the change in the voltage value of the phase shifter control signal.

  In the phaser circuit 40, the degree of fluctuation of the fluctuation sound increases as the amplitude of the phase shifter control signal increases. Specifically, in FIG. 5, as the amplitude of the phase shifter control signal is increased, the variable width is increased, and the frequency band in which the level is rapidly decreased greatly fluctuates left and right.

  Further, in the present phaser circuit 40, the fluctuation cycle of the fluctuation sound is shortened as the frequency of the phase shifter control signal is increased. Specifically, in FIG. 5, the higher the frequency of the phase shifter control signal, the shorter the variable period, and the shorter the changing period of the frequency band in which the level is rapidly lowered.

  In the above-described phaser circuit 40, the frequency band in which the phase of the notification sound signal is shifted by the phase shifters 41 to 44 and the notification sound signal before the phase is weakened is shifted, and this shifted destructive frequency. If a part of the frequency components constituting the notification sound signal is included in the band, the level of the frequency components is greatly reduced. When the weakening frequency band returns to the frequency band before the shift again, a phenomenon occurs in which the level of the frequency component whose level has greatly decreased returns to the original level.

  That is, in the above-described phaser circuit 40, when a notification sound signal composed of a plurality of frequency components is input, the level of a certain frequency component is reduced to another frequency component according to the amplitude of the phase shifter control signal. There is a phenomenon that the level remains constant or the level of one frequency component remains constant and the level of another frequency component decreases.

  Note that the sound signal output from the output terminal SOUT of the phaser circuit 40 is amplified by the power amplifier 50, and the notification sound in which the fluctuation sound that periodically fluctuates the notification sound corresponding to the notification sound signal is added to the speaker 70. Is output. Therefore, the notification sound output from the speaker 70 has little sound pressure fluctuation.

  The fluctuation sound is a sound such as “Shwar, Schwer”. Therefore, the sound output from the speaker 70 is, for example, a sound in which a sound such as “Shwer, Schwer” is periodically added to a notification sound such as “Fuwa” composed of a plurality of frequency components.

  In the present embodiment, the microcomputer 10 controls the phaser circuit 40 so that the fluctuation period of the fluctuation sound is synchronized with the rotation of the wheels of the vehicle, and as the increase amount per unit time of the accelerator opening degree of the vehicle increases, The phaser circuit 40 is controlled so that the degree of fluctuation of the fluctuation sound is increased.

  FIG. 6 shows a flowchart of the microcomputer 10. When the ignition switch of the vehicle is turned on and the vehicle approach notification device is activated, the microcomputer 10 periodically performs the process shown in FIG.

  First, it is determined whether the sound generation condition is satisfied (S100). The vehicle approach notification device does not always generate a vehicle approach notification sound when the vehicle travels, but generates a vehicle approach notification sound when a predetermined sound generation condition is satisfied. Specifically, the sounding condition is that the vehicle speed is less than 20 kilometers per hour (km / h) and the engine is stopped and the vehicle is running only with a motor. When this sounding condition is satisfied, the vehicle approach notification sound Is generated. In other words, when the vehicle is stopped, when the vehicle speed is 20 km / h (km / h) or more, or when the engine is running even if the vehicle speed is less than 20 km / h (km / h), the vehicle approach notification sound Does not occur.

  If the sound generation condition is satisfied, the determination in S100 is YES, and then the vehicle speed-tire (wheel) rotation speed conversion is performed (S102). The vehicle speed of the vehicle can be specified based on the vehicle speed signal. The ROM of the microcomputer 120 stores a table showing the relationship between the vehicle speed and the tire rotation speed, and the tire rotation speed of the vehicle is specified from the vehicle speed with reference to this table. FIG. 7 shows an example of a table when the tire diameter is 50 centimeters. Here, the tire rotation speed of the vehicle is specified with reference to the table shown in FIG.

  Next, the frequency of the phase shifter control signal is determined from the tire rotational speed specified in S102 (S104). Here, in order for pedestrians and the like around the vehicle to grasp the traveling speed of the vehicle as a real sense, the fluctuation sound added to the notification sound is synchronized with the rotation of the tire. Specifically, the frequency of the phase shifter control signal is determined such that the fluctuation sound added to the notification sound is synchronized with the rotation of the tire. In order to cause the fluctuation sound to fluctuate once in one rotation of the tire, the tire rotation speed (Hz) shown in FIG. 7 is used as the frequency of the phase shifter control signal as it is. In order to cause the fluctuation sound to fluctuate once in 1/2 rotation of the tire, the frequency obtained by doubling the tire rotation speed (Hz) shown in FIG. In order to cause the fluctuation sound to fluctuate once in four rotations, the frequency obtained by quadrupling the tire rotation speed (Hz) shown in FIG. 7 may be used as the frequency of the phase shifter control signal.

  Next, it is determined whether it is an acceleration moment (S106). Specifically, the amount of change in the accelerator opening per unit time is specified based on the accelerator opening signal, and when the amount of change in the accelerator opening is positive, it is determined that it is an acceleration moment, and the accelerator is opened. If the degree of change is 0 or negative, it is determined that it is not an acceleration moment.

  Here, it is assumed that the change amount per unit time of the accelerator opening is positive. In this case, the determination in S106 is YES, and then the amplitude of the phase shifter control signal is increased in accordance with the amount of change in the accelerator opening (S108). Here, in order to make it easy to recognize the acceleration state of the vehicle, the degree of fluctuation of the fluctuation sound added to the notification sound is increased according to the amount of increase in the accelerator opening per unit time. Specifically, the amplitude of the phase shifter control signal is increased from a predetermined constant amplitude in accordance with the change amount of the accelerator opening.

  Next, a phase shifter control signal is output (S110). Specifically, the phase shifter control signal having the frequency determined in S104 and the amplitude determined in S108 is output to the phaser circuit 40.

  As described above, the phase shifter control signal having the frequency determined in S104 and the amplitude determined in S108 is continuously obtained until the positive change amount per unit time of the accelerator opening becomes 0 or negative. Is output.

  As a result, a fluctuation sound that is synchronized with the rotation of the tires of the vehicle and whose degree of fluctuation increases according to the positive change amount per unit time of the accelerator opening is added to the notification sound according to the notification sound signal. Sound is output from the speaker 70.

  When the positive change amount per unit time of the accelerator opening becomes 0 or negative, the determination in S106 is NO, and it is determined whether or not the acceleration instantaneous control is finished (S112). Specifically, after the change amount of the accelerator opening becomes positive, the acceleration instant control period is from the time when the change amount of the accelerator opening becomes 0 or negative until a certain period elapses. It is determined whether or not the control period has ended.

  If the acceleration instantaneous control period has not ended, the determination in S112 is NO, and then the amplitude of the phase shifter control signal is gradually returned to a predetermined constant amplitude (S114). Specifically, the amplitude of the phase shifter control signal is decreased so that the amplitude of the phase shifter control signal gradually approaches a predetermined constant amplitude.

  Next, a phase shifter control signal is output (S110). Specifically, the phase shifter control signal having the frequency determined in S104 and the amplitude determined in S114 is output to the phaser circuit 40.

  As a result, the speaker 70 outputs a sound in which a fluctuation sound that is synchronized with the rotation of the tires of the vehicle and the degree of fluctuation gradually decreases is added to the notification sound corresponding to the notification sound signal.

  When the acceleration instantaneous control period ends, the determination in S112 becomes YES, and the amplitude of the phase shifter control signal is determined to be a predetermined constant amplitude (S116).

  Next, a phase shifter control signal is output (S110). Specifically, the phase shifter control signal having the frequency determined in S104 and the amplitude determined in S116 is output to the phaser circuit 40.

  Thus, the phase shifter control signal having the frequency determined in S104 and the amplitude determined in S116 is continuously output.

  As a result, a sound in which a fluctuation sound having a certain degree of fluctuation is added to the notification sound corresponding to the notification sound signal is output from the speaker 70 in synchronization with the rotation of the vehicle tire.

  FIG. 8 shows the relationship between the vehicle speed, the accelerator opening, the accelerator opening change amount, and the phase shifter control signal from when the vehicle travels until a certain time elapses.

  When the driver depresses the accelerator immediately after the vehicle starts to travel, the accelerator opening becomes large, and the accelerator opening change amount becomes a large positive value. Moreover, the vehicle speed of the vehicle is a small value. In this case, the amplitude of the phase shifter control signal is relatively large, and the frequency of the phase shifter control signal is relatively low.

  When the driver continues to step on the accelerator so that the accelerator opening becomes constant, the amount of change in the accelerator opening gradually decreases and the vehicle speed gradually increases. Therefore, the amplitude of the phase shifter control signal gradually decreases, and the frequency of the phase shifter control signal gradually increases.

  Further, when the driver continuously depresses the accelerator so that the accelerator opening becomes constant, the amount of change in the accelerator opening becomes zero and the vehicle speed gradually increases. Therefore, the amplitude of the phase shifter control signal becomes a predetermined constant amplitude, and the frequency of the phase shifter control signal gradually increases.

  According to the configuration described above, in accordance with the phase shifter control signal input from the microcomputer 10, a signal obtained by shifting the phase of the notification sound signal composed of a plurality of frequency components by the plurality of phase shifters and the notification sound signal And a phaser circuit 40 that outputs a sound signal for outputting a sound in which a fluctuation sound that periodically fluctuates is added to the notification sound according to the notification sound signal. Based on the vehicle speed signal representing the vehicle speed, the phase shifter control signal is specified such that a fluctuation sound that is synchronized with the rotation of the vehicle wheel is added to the notification sound, and the phase shifter control signal is specified as a phaser circuit. Therefore, an audio signal is output from the phaser circuit to output a sound with a fluctuation sound that synchronizes with the rotation of the vehicle wheel added to the notification sound. Since the more output can be made to capture the traveling speed of the vehicle as the actual sense. In addition, the fluctuation sound generated by the phaser circuit has little fluctuation in sound pressure, and the fluctuation in sound pressure of the notification sound can be suppressed.

  Further, the phaser circuit 40 can be configured so that the fluctuation period of the fluctuation sound becomes shorter as the frequency of the phase shifter control signal becomes higher. Further, the microcomputer 10 has a fluctuation period of the fluctuation sound of the vehicle. The frequency of the phase shifter control signal that is synchronized with the rotation of the wheel can be specified, and the phase shifter control signal having the frequency can be output to the phaser circuit.

  Further, the phaser circuit 40 can be configured such that the degree of fluctuation of the fluctuation sound increases as the amplitude of the phase shifter control signal increases.

  Further, the microcomputer 10 specifies the amplitude of the phase shifter control signal such that the degree of fluctuation of the fluctuation sound increases as the increase amount of the accelerator opening of the vehicle per unit time increases, and the phase shifter of the amplitude A control signal can be output to the phaser circuit.

  If the microcomputer 10 determines that the amount of change in the accelerator opening of the vehicle per unit time is positive, the microcomputer 10 previously sets the amplitude of the phase shifter control signal in accordance with the amount of change in the accelerator opening of the vehicle. Since the amplitude is larger than the predetermined constant amplitude, the degree of fluctuation of the fluctuation sound can be increased in a situation where the change amount per unit time of the accelerator opening of the vehicle is positive.

  Further, when the microcomputer 10 determines that the predetermined period has not elapsed since the change amount of the accelerator opening of the vehicle becomes 0 or negative, the microcomputer 10 sets the amplitude of the phase shifter control signal to a predetermined constant amplitude. Therefore, the degree of fluctuation of the fluctuation sound can be gradually reduced in a situation where a certain period has not elapsed since the time when the change amount of the accelerator opening of the vehicle becomes zero or negative.

  Furthermore, when the microcomputer 10 determines that a certain period has elapsed from the time when the amount of change in the accelerator opening becomes 0 or negative, the microcomputer 10 specifies the amplitude of the phase shifter control signal as a predetermined constant amplitude. The degree of fluctuation of the fluctuation sound can be made constant in a situation where a certain period has elapsed from the time when the change amount of the accelerator opening becomes zero or negative.

  In addition, this invention is not limited to the said embodiment, Based on the meaning of this invention, it can implement with a various form.

  For example, in the above embodiment, a fluctuation sound that synchronizes with the rotation of the wheels of the vehicle is added to the phaser circuit 40 without changing the frequencies of the plurality of frequency components that make up the notification sound signal. Control that shifts the frequency of multiple frequency components that make up the notification sound signal to the high frequency side, that is, pitch-up as the vehicle travel speed increases. In the vehicle approach notification device that performs the process, it is also possible to perform a process of generating an audio signal such that a fluctuation sound that is synchronized with the rotation of the vehicle wheel is added to the notification sound. In this case, the amplitude of the phase shifter control signal of the phaser circuit 40 is changed according to the pitch-up amount of the plurality of frequency components so that the degree of fluctuation of the fluctuation sound changes according to the pitch-up amount of the plurality of frequency components. You may make it make it.

  Moreover, although the structure provided with the phaser circuit 40 which has the 4-stage phase shifters 41-44 was shown in the said embodiment, the number of stages of a phase shifter is not limited to 4 stages.

10 microcomputer 30 buffer 40 phaser circuit 41 to 44 phase shifter 45 adder 50 power amplifier 60 speaker

Claims (7)

A vehicle approach notification device that generates a notification sound signal composed of a plurality of frequency components, outputs a notification sound according to the notification sound signal from a speaker, and reports the approach of the vehicle,
A plurality of phase shifters (41 to 44) for shifting the phase of the notification sound signal, and the notification by the plurality of phase shifters according to a phase shifter control signal input from the control unit (10) To shift the frequency band in which the phase of the sound signal is shifted and the notification sound signal are weakened, and to output a sound with a fluctuation sound that periodically fluctuates in the notification sound according to the notification sound signal Phaser circuit (40) that outputs the audio signal of
The control unit specifies the phase shifter control signal such that the fluctuation sound that is synchronized with the rotation of the wheel of the vehicle is added to the notification sound based on a vehicle speed signal that represents the speed of the vehicle, The vehicle approach notification device characterized by outputting the phase shifter control signal to the phaser circuit. The phaser circuit is configured such that as the frequency of the phase shifter control signal increases, the fluctuation cycle of the fluctuation sound is shortened.
The control unit specifies a frequency of the phase shifter control signal such that a fluctuation cycle of the fluctuation sound is synchronized with rotation of a wheel of the vehicle, and outputs the phase shifter control signal of the frequency to the phaser circuit. The vehicle approach notification device according to claim 1.   The vehicle approach notification device according to claim 1, wherein the phaser circuit is configured such that the degree of fluctuation of the fluctuation sound increases as the amplitude of the phase shifter control signal increases.   The control unit specifies the amplitude of the phase shifter control signal such that the degree of fluctuation of the fluctuation sound increases as the amount of increase in the accelerator opening of the vehicle per unit time increases, and shifts the amplitude. The vehicle approach notification device according to claim 3, wherein a phaser control signal is output to the phaser circuit.   When the controller determines that the amount of change in the accelerator opening of the vehicle per unit time is positive, the amplitude of the phase shifter control signal according to the amount of change in the accelerator opening of the vehicle The vehicle approach notification device according to claim 3, wherein the vehicle is made larger than a predetermined constant amplitude.   When it is determined that a certain period has not elapsed since the change amount of the accelerator opening of the vehicle becomes zero or negative, the control unit sets a predetermined constant amplitude of the phase shifter control signal. The vehicle approach notification device according to claim 5, wherein the vehicle approach notification device is gradually returned to the amplitude.   The control unit specifies the amplitude of the phase shifter control signal as a predetermined constant amplitude when it is determined that a certain period of time has elapsed since the change amount of the accelerator opening is 0 or negative. The vehicle approach notification device according to claim 6.

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