Vehicle sound generation device

Abstract

To allow an occupant to feel the pleasure of vehicle acceleration.SOLUTION: A sound generation device for a vehicle includes: a sound control part 12 configured to generate a sound signal indicating sound; a speaker 20 for outputting sound corresponding to the sound signal generated by the sound control part; and an acceleration state detection part 13 for detecting that a vehicle 2 is in an acceleration state. The sound control part sets time transition of a parameter of the sound signal when the vehicle is detected to be in the acceleration state, and generates the sound signal on the basis of the time transition of the parameter. The time transition of the parameter includes repetition of a first trend and a second trend following the first trend. A time interval of each change timing when the first trend changes to the second trend is n / 2 times of a time T1 from when the vehicle is detected to be in the acceleration state to the change of the first trend to the second trend, and n is set to be a natural number of 3 or more and to increase at each change timing.SELECTED DRAWING: Figure 7A

Description

Technical Field

[0005]

[0001] The present invention relates to a vehicle sound generation device, and particularly to a vehicle sound generation device that outputs a predetermined sound during vehicle travel.

Background Art

[0002] Conventionally, there is known a technique for outputting a pseudo engine sound or motor sound toward a driver in accordance with a driving state of a vehicle such as a vehicle speed or a driving operation of a driver such as an accelerator opening. For example, the vehicle sound generation device described in Patent Document 1 outputs a synthesized sound including a plurality of frequencies set to be proportional to the rotational speed of an electric motor, and sets the increase amount of the output of the sound in the low frequency band to be larger than the increase amount of the output of the sound in the high frequency band in accordance with an increase in the motor torque value. Thereby, the driver can easily recognize the strength of the acceleration of the vehicle according to the accelerator operation, and an accurate accelerator operation is promoted.

Prior Art Documents

Patent Documents

[0006] To achieve the above objective, the present invention provides a vehicle sound generation device mounted on a vehicle powered by an electric motor, comprising: a sound control unit configured to generate a sound signal representing sound; a sound output unit that outputs sound corresponding to the sound signal generated by the sound control unit; and an acceleration state detection unit that detects when the vehicle is in an accelerating state. When the sound control unit detects that the vehicle is in an accelerating state, it sets the time progression of the parameters of the sound signal, generates a sound signal based on the time progression of the parameters, and the time progression of the parameters includes a repetition of a first trend and a second trend following the first trend, and the first trend changes to the second trend. ruhen Time interval of transformation timing In this case, the time interval from the first change timing to the second change timing. This is the first time the vehicle is detected to be in an accelerating state. Timing of change up to First time 2 It is double, The time interval between the second change timing and the third change timing is 2.5 times the time of the first change. It is set to The first trend is one in which the parameter increases over time, and the second trend is one in which the parameter decreases over time. ru.

[0007] According to the present invention configured in this way, the output sound has a "sense of rhythm," that is, (1) the sense of rhythm perceived from the temporal progression of the sound, (2) the degree of correspondence between the occupant's expectations regarding the temporal progression of the sound and the actual temporal progression of the sound, and (3) the degree of correspondence between the changing scenery in accordance with the acceleration of the vehicle and the temporal progression of the sound are all achieved at a high level without bias, and changes in the sound can be made at an appropriate timing to make the occupant recognize this, thereby making them feel the pleasantness of the vehicle's acceleration. Furthermore, the system allows occupants to clearly perceive changes in sound over time, enhancing the exhilarating feeling of the vehicle's acceleration.

[0008] Furthermore, preferably in the present invention, the parameter includes either or both of frequency and sound pressure. nothing .

[0009] Furthermore, preferably in the present invention, the vehicle sound generation device has a motor rotation speed sensor for detecting the rotation speed of the electric motor, and the sound control unit generates a sound signal based at least on the rotation speed of the electric motor if it is not detected that the vehicle is in an accelerating state. According to the present invention configured in this way, the time progression of the sound output when it is detected that the vehicle is accelerating can be highlighted in contrast to the sound based on the motor rotation speed, thereby allowing the occupants to feel the exhilaration of the vehicle's acceleration even more strongly.

[0010] Furthermore, preferably in the present invention, the vehicle sound generation device has an accelerator opening sensor for detecting the accelerator opening of the vehicle, and the acceleration state detection unit detects that the vehicle is in an accelerating state when the accelerator opening increases, and the amount of increase from the start to the end of the increase in the accelerator opening is greater than or equal to a predetermined amount, and the accelerator opening at the end of the increase is greater than or equal to a predetermined opening. According to the present invention configured in this way, the acceleration state of the vehicle can be detected with high responsiveness based on the accelerator opening, which first reflects the driver's intention to accelerate, and the sound can be changed accordingly, thereby allowing the occupants to feel the exhilaration of the vehicle's acceleration even more.

[0011] Furthermore, preferably in the present invention, the sound control unit sets the time from when it is detected that the vehicle is in an accelerating state until the first trend changes to the second trend to a shorter duration, the larger the accelerator opening at the end of the increase in accelerator opening. With the present invention configured in this way, the larger the accelerator opening at the end of the increase in accelerator opening, the shorter the period of change in sound over time, so that the occupants can feel the strength of the vehicle's acceleration in proportion to the size of the accelerator opening.

[0012] Furthermore, preferably in the present invention, the sound control unit sets the time from when it is detected that the vehicle is in an accelerating state until the first trend changes to the second trend to be shorter, as the time from the start to the end of the increase in the accelerator opening is shorter. According to the present invention configured in this way, the shorter the time from the start to the end of the increase in accelerator opening, the shorter the period of change in sound over time, so that the occupants can feel the strength of the vehicle's acceleration in proportion to the speed of the increase in accelerator opening. [Effects of the Invention]

[0013] According to the vehicle sound generation device of the present invention, it is possible to make the driver feel the pleasant feeling of accelerating the vehicle.

Brief Description of the Drawings

[0014] [Figure 1] It is an explanatory diagram of a vehicle sound generation device according to an embodiment of the present invention. [Figure 2] It is a configuration diagram of a vehicle sound generation device according to an embodiment of the present invention. [Figure 3] It is a radar chart showing an example of experimental results related to the present invention. [Figure 4] It is a flowchart of sound generation processing according to an embodiment of the present invention. [Figure 5A] It is a frequency map defining the relationship between the motor rotation speed and the frequency according to an embodiment of the present invention. [Figure 5B] It is a sound pressure map defining the relationship between the motor rotation speed and the sound pressure according to an embodiment of the present invention. [Figure 6] It is a map defining the time until the first trend change timing according to an embodiment of the present invention. [Figure 7A] It is a frequency map defining the time transition of the frequency when the vehicle is in an accelerating state according to an embodiment of the present invention. [Figure 7B] It is a sound pressure map defining the time transition of the sound pressure when the vehicle is in an accelerating state according to an embodiment of the present invention.

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0016] <Configuration of Vehicle Sound Generation Device> First, referring to FIGS. 1 and 2, the configuration of the vehicle sound generation device of the present invention will be described. FIG. 1 is an explanatory diagram of the vehicle sound generation device, and FIG. 2 is a configuration diagram of the vehicle sound generation device.

[0017] As shown in Figures 1 and 2, the vehicle sound generation device 1 of this embodiment comprises a sound control device 10 mounted on the vehicle 2, a speaker 20 that outputs a predetermined sound to the driver inside the vehicle, and a group of various sensors 30 that detect the state of the vehicle 2. The vehicle 2 is an electric vehicle (EV) equipped with an electric motor 3 as a rotational power source.

[0018] The sound control device 10 is a well-known computer-based controller that includes a circuit. The sound control device 10 includes one or more processors as a central processing unit (CPU) for executing programs, a memory (storage unit 14) which stores various programs and databases and is composed of, for example, RAM (Random Access Memory) and ROM (Read Only Memory), and data input / output devices for inputting and outputting electrical signals.

[0019] The database in the memory unit 14 stores various maps used for generating sound signals. The sound control device 10 is connected to other in-vehicle devices via an in-vehicle communication line. The sound control device 10 is configured to output a sound signal Ss to the speaker 20 by having the processor execute a program based on various information from the sensor group 30. At that time, the processor of the sound control device 10 functions as a sound control unit 12 and an acceleration state detection unit 13, as will be described later.

[0020] Speaker 20 is a sound output unit equipped with an amplifier. Speaker 20 receives a sound signal Ss from the sound control device 10, amplifies the sound signal Ss at a predetermined amplification factor, and outputs a sound (typically a synthesized sound) SC based on the sound signal Ss. Speaker 20 does not necessarily have to be installed inside the vehicle cabin; it is sufficient that the driver can recognize the sound SC generated by speaker 20.

[0021] The sensor group 30 includes a rotation speed sensor 31 for detecting the rotation speed of the electric motor 3, an accelerator opening sensor 32 for detecting the accelerator opening corresponding to the amount of operation of the accelerator pedal of the vehicle 2, and a motor torque sensor 33 for detecting the motor torque of the electric motor 3. These sensors 30 transmit signals S31, S32, and S33 indicating the detected vehicle status via the in-vehicle communication line. The sound control device 10 can receive various signals from the sensor group 30 via the in-vehicle communication line.

[0022] In this embodiment, the motor torque is detected by the motor torque sensor 33, but this is not limited to this; the motor torque value requested for the electric motor 3 may also be used as the motor torque. Alternatively, the sound control device 10 may calculate the motor torque from the accelerator opening using an acceleration characteristic map or the like.

[0023] <Control by vehicle sound generation device> Next, the basic concept of control by the vehicle sound generation device 1 of this embodiment will be explained. As with the conventional technology described above, simply outputting a synthesized sound that includes a frequency set to be proportional to the motor's rotation speed is insufficient to produce a sound that allows the occupant to fully feel the pleasure of the vehicle's acceleration when the accelerator pedal is pressed hard to accelerate the vehicle. Therefore, the inventors of this invention investigated what kind of sound should be output to make the occupant feel the pleasure of the vehicle's acceleration. As a result, they found that when the occupant perceives the outputted sound as having a "sense of rhythm," that occupant will feel the pleasure of the vehicle's acceleration from the outputted sound. Furthermore, when outputting a sound that changes over time while the vehicle is accelerating, it was found that the occupant perceives the outputted sound as having a "sense of rhythm" when each of the three subjective evaluation items—(1) the sense of rhythm perceived from the time progression of the sound, (2) the degree of correspondence between the occupant's expectations regarding the time progression of the sound and the actual time progression of the sound, and (3) the degree of correspondence between the scenery changing in accordance with the vehicle's acceleration and the time progression of the sound—is evaluated highly without bias.

[0024] Therefore, the inventors conducted an experiment in which subjects boarded a vehicle simulator and, while reproducing the changes in scenery when the vehicle is accelerating, outputted sounds with various time progression patterns and had the subjects evaluate scores on the three subjective evaluation items mentioned above. Specifically, the time progression of two parameters, frequency and sound pressure, of the sound signal representing the sound was set, and sounds corresponding to the sound signals generated based on the time progression of these set parameters were output. The time progression of each parameter included a repetition of a first trend in which each parameter increases over time, and a second trend in which each parameter decreases over time following the first trend. Then, sounds were output under multiple conditions in which the time interval of each change timing in which the first trend changes to the second trend was varied, and subjects were asked to evaluate scores on the three subjective evaluation items mentioned above under each condition.

[0025] As a result, it was found that the time interval between each change timing, where the first trend changes to the second trend, has the greatest impact on the score of each evaluation item. More specifically, if T1 is the time from when the vehicle enters an acceleration state until the first change from the first trend to the second trend occurs (i.e., until the first change timing), and the time progression of each parameter is set to T1 × n / 2 (where n is a natural number greater than or equal to 3 and increases with each change timing), it was found that each evaluation item would receive high scores without bias.

[0026] Figure 3 is a radar chart showing an example of the experimental results described above. The radar chart in Figure 3 plots the scores for three evaluation items, namely (1) the sense of rhythm perceived from the temporal progression of sound (referred to as "sense of rhythm" in Figure 3), (2) the degree of correspondence between the occupants' expectations regarding the temporal progression of sound and the actual temporal progression of sound (referred to as "correspondence with expectations" in Figure 3), and (3) the degree of correspondence between the temporal progression of sound and the scenery that changes in response to the vehicle's acceleration (referred to as "correspondence with scenery changes" in Figure 3), after standardizing them using Z-scores (i.e., the scores for each evaluation are transformed so that the mean is 0 and the standard deviation is 1).

[0027] In Figure 3, the charts are shown for each change timing where the first trend changes to the second trend, with T2 being the time from the first change timing to the second change timing, and T3 being the time from the second change timing to the third change timing, and T1:T2:T3 being 1:2:2.5 (solid line in Figure 3), 1:1:1 (dashed line in Figure 3), and 1:1.85:2.3 (dotted line in Figure 3). As is clear from Figure 3, when T1:T2:T3=1:2:2.5=1:4 / 2:5 / 2, that is, when the time intervals T2 and T3 for each change timing are set to T1×n / 2 (where n is a natural number greater than or equal to 3 and increases with each change timing), each evaluation item receives the highest score without bias, indicating that the output sound is perceived as having a "sense of rhythm". On the other hand, when T1:T2:T3=1:1.85:2.3, that is, when the time intervals T2 and T3 for each change timing are not T1×n / 2, each evaluation item receives a low score (less than 0), indicating that the output sound is not perceived as having a "sense of rhythm."

[0028] Therefore, in this embodiment, the time from when the vehicle 2 enters an acceleration state to the first change timing is defined as T1, and the time progression of each parameter is set so that the time interval between each change timing is T1 × n / 2 (where n is a natural number of 3 or more and increases with each change timing), and a sound corresponding to the sound signal is output by the vehicle sound generator 1. This makes the occupants perceive the output sound as having a "rhythmic feel" and allows them to feel the pleasantness of the vehicle 2's acceleration.

[0029] <Sound generation processing> Next, with reference to Figures 4 to 7B, the flow of sound generation processing by the vehicle sound generation device 1 of this embodiment will be described. Figure 4 is a flowchart of the sound generation processing according to this embodiment, Figures 5A and 5B are maps that define the relationship between motor rotation speed and sound signal parameters according to this embodiment, Figure 6 is a map that sets the time until the first trend change timing according to this embodiment, and Figures 7A and 7B are maps that set the time progression of sound signal parameters when the vehicle is in an accelerating state according to this embodiment.

[0030] The sound generation process shown in Figure 4 is repeatedly executed at a predetermined cycle by the vehicle sound generation device 1 (mainly the sound control device 10 and speaker 20).

[0031] First, in step S1, the sound control device 10 acquires various information from the sensor group 30. Specifically, the sound control device 10 acquires the motor rotation speed detected by the motor rotation speed sensor 31, the accelerator opening detected by the accelerator opening sensor 32, and the motor torque detected by the motor torque sensor 33.

[0032] Next, in step S2, the sound control device 10 (specifically the acceleration state detection unit 13) determines whether or not the vehicle 2 is in an accelerating state based on the information acquired in step S1. Specifically, the sound control device 10 determines that the vehicle 2 is in an accelerating state if the accelerator opening has increased (for example, if the rate of increase of the accelerator opening is 20% / sec or more), the amount of increase from the start to the end of the increase in the accelerator opening is a predetermined amount (for example, 30%) or more, and the accelerator opening at the end of the increase is a predetermined opening (for example, 40%) or more.

[0033] Alternatively, instead of the accelerator opening, the system may determine whether or not the vehicle 2 is accelerating based on the motor torque. For example, the sound control device 10 may determine that the vehicle 2 is accelerating if, when the motor torque increases, the amount of increase from the start to the end of the increase is greater than or equal to a predetermined amount, and the motor torque at the end of the increase is greater than or equal to a predetermined value.

[0034] If, as a result of step S2, it is not determined that vehicle 2 is in an accelerating state (step S2: No), that is, if the acceleration state detection unit 13 does not detect that vehicle 2 is in an accelerating state, the process proceeds to step S3, where the sound control device 10 (specifically the sound control unit 12) sets the frequency F1 of the sound signal based on the motor rotation speed of the electric motor 3.

[0035] Specifically, the frequency F1 is set according to the motor speed R by referring to a frequency map that defines the relationship between motor speed R and frequency F1. Figure 5A is a frequency map that defines the relationship between motor speed R and frequency F1. In the frequency map shown in Figure 5A, the frequency F1 of the sound signal is defined to increase as the motor speed R increases.

[0036] Next, in step S4, the sound control device 10 (more specifically, the sound control unit 12) sets the sound pressure P1 of the sound signal based on the motor rotation speed of the electric motor 3.

[0037] Specifically, the sound pressure P1 is set according to the motor speed R by referring to a sound pressure map that defines the relationship between motor speed R and sound pressure P1. Figure 5B is a sound pressure map that defines the relationship between motor speed R and sound pressure P1. In the sound pressure map shown in Figure 5B, the sound pressure P1 of the sound signal is defined to increase as the motor speed R increases.

[0038] On the other hand, if step S2 determines that vehicle 2 is in an accelerating state (step S2: Yes), that is, if the acceleration state detection unit 13 detects that vehicle 2 is in an accelerating state, the sound control device 10 (more specifically, the sound control unit 12) sets the time progression of the sound signal parameters, frequency F2 and sound pressure P2. As described above, the time progression of frequency F2 and sound pressure P2 includes a repetition of a first trend in which each parameter increases over time, and a second trend in which each parameter decreases over time following the first trend.

[0039] In detail, first, in step S5, the sound control device 10 sets a time interval T1 from the time it detects that the vehicle 2 is in an accelerating state until the first change from the first trend to the second trend (i.e., until the first change timing).

[0040] Specifically, the time interval T1 is set by referring to a map that defines the relationship between the time required from the start to the end of the increase in accelerator opening (the time taken to press the pedal), the accelerator opening at the end of the increase, and the time interval T1 from the time it is detected that vehicle 2 is in an accelerating state until the first change from the first trend to the second trend, as shown in Figure 6. As shown in Figure 6, the shorter the time from the start to the end of the increase in accelerator opening, and the larger the accelerator opening at the end of the increase, the shorter the time interval T1 becomes. Also, if the accelerator opening at the end of the increase is less than a predetermined opening (40% in Figure 6), it is not detected that vehicle 2 is in an accelerating state, so the time interval T1 is not defined.

[0041] According to the map shown in Figure 6, for example, if the time from the start to the end of the increase in accelerator opening is 0.8 seconds, and the accelerator opening at the end of the increase is 80%, then the time interval T1 is set to 1000 ms.

[0042] Next, in step S6, the sound control device 10 sets the time progression of the sound signal frequency F2 based on the time interval T1 set in step S5.

[0043] Specifically, the frequency F2 is set according to the elapsed time t, by referring to a frequency map that defines the relationship between the time elapsed t since the detection of vehicle 2 being in an accelerating state and the frequency F2 (i.e., the time progression of frequency F2 when vehicle 2 is in an accelerating state). Figure 7A is a frequency map that defines the time progression of frequency F2 when vehicle 2 is in an accelerating state.

[0044] In the frequency map shown in Figure 7A, the time evolution of frequency F2 includes a repetition of a first trend in which frequency F2 increases over time, followed by a second trend in which frequency F2 decreases over time. The time interval T2 from the first change timing to the second change timing is T2 = T1 × 4 / 2, and the time interval T3 from the second change timing to the third change timing is T3 = T1 × 5 / 2, thus defining the time evolution.

[0045] Furthermore, the time interval ΔT1 from the first change timing until the second trend changes back to the first trend, the time interval ΔT2 from the second change timing until the second trend changes back to the first trend, and the time interval ΔT3 from the third change timing until the second trend changes back to the first trend are all equal and shorter than T1.

[0046] Furthermore, the maximum value of frequency F2 at each transition timing where the first trend changes to the second trend is specified to increase with each transition timing (i.e., with the passage of time).

[0047] Next, in step S7, the sound control device 10 sets the time progression of the sound pressure P2 of the sound signal based on the time interval T1 set in step S5.

[0048] Specifically, the sound pressure P2 is set according to the elapsed time t, by referring to a sound pressure map that defines the relationship between the time elapsed t since the detection of vehicle 2 being in an accelerating state and the sound pressure P2 (i.e., the time progression of sound pressure P2 when vehicle 2 is in an accelerating state). Figure 7B is a sound pressure map that defines the time progression of sound pressure P2 when vehicle 2 is in an accelerating state.

[0049] In the sound pressure map shown in Figure 7B, the time course of sound pressure P2, like the time course of frequency F2, includes a repetition of a first trend in which sound pressure P2 increases over time, followed by a second trend in which sound pressure P2 decreases over time. Furthermore, the time interval T1 from the detection of vehicle 2 being in an accelerating state until the first change from the first trend to the second trend, and the time intervals T2 and T3 at each change timing where the first trend changes to the second trend, are the same as the time intervals T1, T2, and T3 in the time course of frequency F2. Similarly, the time intervals ΔT1, ΔT2, and ΔT3 from each change timing until the second trend changes back to the first trend are the same as the time intervals ΔT1, ΔT2, and ΔT3 in the time course of frequency F2.

[0050] Furthermore, the maximum value of sound pressure P2 at each transition timing where the first trend changes to the second trend is specified to be approximately the same at each transition timing.

[0051] After step S4 or S7, the process proceeds to step S8, in which the sound control device 10 (specifically the sound control unit 12) generates a sound signal and outputs the sound signal to the speaker 20.

[0052] In step S8, if the sound control device 10 does not detect that the vehicle 2 is in an accelerating state in step S2, and if the frequency F1 and sound pressure P1 are set based on the motor rotation speed in steps S3 and S4, the sound control device 10 generates a sound signal based on those frequencies F1 and sound pressure P1. That is, if the vehicle 2 is not detected to be in an accelerating state, the sound control device 10 sequentially generates a sound signal based on the motor rotation speed and outputs it to the speaker 20.

[0053] On the other hand, if the time progression of frequency F2 is set in step S6 and the time progression of sound pressure P2 is set in step S7, the sound control device 10 generates a sound signal based on the time progressions of frequency F2 and sound pressure P2. That is, when it is detected that the vehicle 2 is in an accelerating state, the sound control device 10 generates a sound signal according to the time progressions of frequency F2 and sound pressure P2 that were set in advance in steps S6 and S7 and outputs it to the speaker 20.

[0054] Next, in step S9, the speaker 20 receives an audio signal and outputs a sound corresponding to this audio signal. After step S9, the vehicle sound generation device 1 finishes the sound generation process and returns to step S1.

[0055] <Variation> In the embodiment described above, if it is not detected that the vehicle 2 is in an accelerating state in step S2 of the sound generation process, an example was described in which one frequency F1 is set in step S3 based on the motor rotation speed. However, multiple frequencies F1 may be set here. In this case, in step S8, the sound control device 10 generates a sound signal by synthesizing multiple frequencies.

[0056] Furthermore, in the embodiment described above, when it is detected in step S2 of the sound generation process that the vehicle 2 is in an accelerating state, an example was described in step S5 in which the time interval T1 from the time it is detected that the vehicle 2 is in an accelerating state until the first trend changes to the second trend is set based on the accelerator opening. However, instead of the accelerator opening, the time interval T1 may be set based on the motor torque. Specifically, the shorter the time from the start to the end of the increase in motor torque, and the larger the motor torque at the end of the increase in motor torque, the shorter the time interval T1 may be set.

[0057] Furthermore, in the above-described embodiment, an example was explained in which, when it is detected in step S2 of the sound generation process that the vehicle 2 is in an accelerating state, the time progression of the frequency F2 is set in step S6 and the time progression of the sound pressure P2 is set in step S7. However, in step S6, the frequency F2 may be set based on the motor rotation speed (i.e., set in the same way as the frequency F1 in step S3), and in step S7, the time progression of the sound pressure P2 may be set. Alternatively, the time progression of the frequency F2 may be set in step S6, and the sound pressure P2 may be set based on the motor rotation speed in step S7 (i.e., set in the same way as the sound pressure P1 in step S4).

[0058] Furthermore, in the embodiment described above, the frequency map in Figure 7A and the sound pressure map in Figure 7B show an example in which the first trend and the second trend are repeated three times, but this repetition may be more than three times (for example, four or five times).

[0059] <Mechanism and Effects> Next, the operation and effects of the vehicle sound generation device 1 of this embodiment will be described.

[0060] In this embodiment, the vehicle sound generator 1 detects that the vehicle 2 is in an accelerating state, sets the time progression of the sound signal parameters, and generates a sound signal based on the time progression of the parameters. The time progression of the parameters includes a repetition of a first trend and a second trend that follows the first trend, and the time interval of each change timing in which the first trend changes to the second trend is n / 2 times the time T1 from when the vehicle 2 is detected to be in an accelerating state until the first change from the first trend to the second trend, where n is a natural number of 3 or more and is set to increase with each change timing.

[0061] This allows the sound to be changed at the appropriate timing to make the occupants recognize that the outputted sound has a "sense of rhythm," that is, that (1) the sense of rhythm perceived from the temporal progression of the sound, (2) the degree of correspondence between the occupants' expectations regarding the temporal progression of the sound and the actual temporal progression of the sound, and (3) the degree of correspondence between the changing scenery in response to the acceleration of vehicle 2 and the temporal progression of the sound are all achieved at a high level without bias, thereby making the occupants feel the exhilaration of vehicle 2's acceleration.

[0062] Furthermore, the parameters of the sound signal include either frequency or sound pressure, and the first trend is a trend in which the parameters increase over time, while the second trend is a trend in which the parameters decrease over time. This allows the occupants to clearly perceive the changes in sound over time, thereby enhancing the feeling of exhilaration as vehicle 2 accelerates.

[0063] Furthermore, if the vehicle sound generator 1 does not detect that the vehicle 2 is accelerating, it generates a sound signal based at least on the rotation speed of the electric motor. This makes it possible to highlight the temporal progression of the sound output when the vehicle 2 is detected to be accelerating, in contrast to the sound based on the motor rotation speed, thereby allowing the occupants to feel the exhilaration of the vehicle 2's acceleration even more strongly.

[0064] Furthermore, the vehicle sound generator 1 detects that the vehicle 2 is accelerating when the accelerator opening increases, and the amount of increase from the start to the end of the increase in the accelerator opening is greater than or equal to a predetermined amount, and the accelerator opening at the end of the increase is greater than or equal to a predetermined opening. Therefore, based on the accelerator opening that first reflects the driver's intention to accelerate, the vehicle 2's acceleration state can be detected with high responsiveness and the sound can be changed accordingly, allowing the occupants to feel the exhilaration of the vehicle 2's acceleration even more.

[0065] Furthermore, the vehicle sound generator 1 sets the time T1 from the detection that the vehicle 2 is accelerating until the first trend changes to the second trend to a shorter time, the larger the accelerator opening at the end of the increase in accelerator opening. As a result, the larger the accelerator opening at the end of the increase in accelerator opening, the shorter the period of change in sound over time, allowing the occupants to perceive the strength of the vehicle 2's acceleration in proportion to the size of the accelerator opening.

[0066] Furthermore, the vehicle sound generator 1 sets the time T1 from when it is detected that the vehicle 2 is accelerating until the first trend changes to the second trend to the second trend to be shorter the shorter the time from when it starts to when it stops increasing the accelerator pedal position. As a result, the shorter the time from when it starts to when it stops increasing the accelerator pedal position, the shorter the period of change in sound over time, allowing the occupants to feel the strength of the vehicle 2's acceleration in proportion to the speed of the increase in the accelerator pedal position. [Explanation of Symbols]

[0067] 1. Vehicle sound generation device 2 vehicles 3 Electric motor 10. Sound control device 12 Sound Control Unit 13. Acceleration state detection unit 14 Storage section 20 speakers 30 sensor group 31 Motor rotation speed sensor 32. Accelerator position sensor 33 Motor Torque Sensor

Claims

1. A vehicle sound generation device mounted on a vehicle that runs using an electric motor as a power source, A sound control unit configured to generate sound signals representing sound, A sound output unit that outputs sound corresponding to the sound signal generated by the sound control unit, The vehicle has an acceleration state detection unit that detects when the vehicle is in an accelerating state, When the sound control unit detects that the vehicle is in an accelerating state, it sets the time progression of the parameters of the sound signal and generates the sound signal based on the time progression of those parameters. The time progression of the parameters includes a repetition of a first trend and a second trend following the first trend, and in the time interval of change timings in which the first trend changes to the second trend, the time interval from the first change timing to the second change timing is set to twice the first time from when the vehicle is detected to be in an accelerating state to the first change timing, and the time interval from the second change timing to the third change timing is set to 2.5 times the first time. The first trend is a trend in which the parameter increases over time, and the second trend is a trend in which the parameter decreases over time. A sound generator for vehicles.

2. The aforementioned parameters include either or both frequency and sound pressure. The vehicle sound generating device according to claim 1.

3. The electric motor has a motor speed sensor that detects the rotation speed of the electric motor, If the sound control unit does not detect that the vehicle is in an accelerating state, it generates the sound signal based at least on the rotational speed of the electric motor. The vehicle sound generating device according to claim 1 or 2.

4. The vehicle has an accelerator opening sensor that detects the accelerator opening degree, The acceleration state detection unit detects that the vehicle is in an accelerating state when the accelerator opening increases, and the amount of increase from the start to the end of the increase in the accelerator opening is greater than or equal to a predetermined amount, and the accelerator opening at the end of the increase is greater than or equal to a predetermined opening. The vehicle sound generating device according to claim 1.

5. The sound control unit sets the time from when it is detected that the vehicle is in an accelerating state until the first trend changes to the second trend to the greater the accelerator opening at the end of the increase in the accelerator opening, to be shorter.

6. The sound control unit sets the time from when the vehicle is detected to when the first trend changes to the second trend for the shorter the time from when the increase in the accelerator opening starts to when it ends, to shorten the time from when the vehicle is detected to when it first changes to the second trend, according to claim 4 or 5.

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