Vehicle sound generating device

Abstract

To enable an occupant to feel the comfortableness of vehicle acceleration.SOLUTION: A sound generation apparatus for a vehicle includes: a sound control unit 12 for generating a sound signal representing a sound; a speaker 20 for outputting a sound according to the sound signal generated by the sound control unit; and an acceleration state detection unit 13 for detecting that a vehicle 2 is in an acceleration state. When it is detected that the vehicle is in the acceleration state, the sound control unit sets a time transition of a parameter of the sound signal and generates the sound signal on the basis of the time transition of the parameter. The time transition of the parameter includes a repeat of a first trend and a second trend following the first trend. A time until the first trend changes to the second trend for the first time after it is detected that the vehicle is in the acceleration state, and a time interval between each change timing at which the first trend changes to the second trend and the next change timing are set to be the same in a range of 1000 milliseconds or more and 2000 milliseconds or less.SELECTED DRAWING: Figure 7A

Description

[Technical Field]

[0001] The present invention relates to a sound generating device for a vehicle, and more particularly to a sound generating device for a vehicle that outputs a predetermined sound while the vehicle is running. [Background technology]

[0002] Conventionally, there are known technologies that output simulated engine sounds or motor sounds to the driver in response to vehicle operating conditions such as vehicle speed and driver operation such as accelerator pedal depression. For example, a vehicle sound generating device described in Patent Document 1 outputs a synthesized sound containing multiple frequencies set to be proportional to the rotation speed of an electric motor, and sets the increase in the output of low-frequency sounds to be greater than the increase in the output of high-frequency sounds in response to an increase in motor torque value. This allows the driver to easily recognize the strength of the vehicle's acceleration in response to accelerator operation, promoting accurate accelerator operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-32972 Summary of the Invention [Problem to be solved by the invention]

[0004] However, while the technology in the above-mentioned patent documents can encourage drivers to operate the accelerator accurately, it is not possible to output a sound that allows occupants to fully feel the pleasantness of the vehicle's acceleration when the accelerator pedal is pressed hard to accelerate the vehicle (for example, when merging onto a highway).

[0005] The present invention has been made to solve such problems, and has an object to provide a sound generating device for a vehicle that allows the occupants to feel the pleasantness of the acceleration of the vehicle. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a vehicle sound generation device mounted on a vehicle that runs using an electric motor as a power source, the device comprising: a sound control unit configured to generate a sound signal representing a sound; a sound output unit that outputs a sound corresponding to the sound signal generated by the sound control unit; and an acceleration state detection unit that detects whether the vehicle is in an accelerating state, wherein when it is detected that the vehicle is in an accelerating state, the sound control unit sets a time transition of a parameter of the sound signal and generates the sound signal based on the time transition of the parameter, the time transition of the parameter includes a repetition of a first trend and a second trend following the first trend, and the time from when it is detected that the vehicle is in an accelerating state to when the first trend first changes to the second trend and the time interval between each change timing at which the first trend changes to the second trend are set to be equal within a range of 1000 milliseconds to 2000 milliseconds. 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. do.

[0007] According to the present invention configured in this manner, the sound output has a "sense of rhythm," meaning that (1) the sense of rhythm recognized from the time progression of the sound, (2) the degree of correspondence between the occupants' 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 that changes in response to the acceleration of the vehicle and the time progression of the sound are all realized at a high level without bias, and the sound can be changed at an appropriate timing to make the occupants recognize this, allowing them to feel the pleasure of the vehicle's acceleration.

[0008] In the present invention, the parameters preferably include one or both of frequency and sound pressure. nothing . According to the present invention configured in this manner, the change in sound over time can be clearly recognized by the occupants, and the acceleration of the vehicle can be felt more pleasantly.

[0009] Also, in the present invention, preferably, the vehicle sound generating device has a motor rotation speed sensor that detects the rotation speed of the electric motor, and the sound control unit generates a sound signal based on at least the rotation speed of the electric motor when it is not detected that the vehicle is in an accelerating state. According to the present invention configured in this manner, the time progression of the sound output when it is detected that the vehicle is in an accelerating state can be made to stand out in contrast to the sound based on the motor rotation speed, allowing the occupants to feel an even more pleasant sensation of the vehicle's acceleration.

[0010] Also, in the present invention, preferably, the vehicle sound generating device has an accelerator opening sensor that detects 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 increase in the accelerator opening from the start to the end of the increase is equal to or greater than a predetermined amount, and when the accelerator opening at the end of the increase is equal to or greater than the predetermined opening. According to the present invention configured in this manner, the vehicle's acceleration state can be detected with high responsiveness based on the accelerator opening, which is the first to reflect the driver's intention to accelerate, and the sound can be changed, allowing the occupants to feel an even more pleasant acceleration of the vehicle.

[0011] Also, in the present invention, preferably, the sound control unit sets the time from when it is detected that the vehicle is in an accelerating state to when the first trend first changes to the second trend and the time interval between each change timing at which the first trend changes to the second trend to be shorter the greater the accelerator opening at the end of the increase in accelerator opening. According to the present invention configured in this manner, the greater the accelerator opening at the end of the increase in accelerator opening, the shorter the period of sound change over time, so that the occupants can feel the strength of the vehicle's acceleration according to the magnitude of the accelerator opening.

[0012] Also, in the present invention, preferably, the sound control unit sets the time from when the vehicle is detected to be in an accelerating state until the first trend changes to the second trend and the time interval between each change timing at which the first trend changes to the second trend shorter the shorter the time from when the increase in accelerator opening starts to when it ends. According to the present invention configured in this manner, the shorter the time from the start to the end of the increase in accelerator opening, the shorter the period of sound change over time, so that the occupants can feel the strength of the vehicle's acceleration according to the speed of the increase in accelerator opening. [Effects of the Invention]

[0013] The vehicle sound generating device of the present invention can make the occupants feel the pleasant sensation of vehicle acceleration. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram of a vehicle sound generating device according to an embodiment of the present invention; [Figure 2] 1 is a configuration diagram of a vehicle sound generating device according to an embodiment of the present invention. [Figure 3] 1 is a radar chart showing an example of experimental results relating to the present invention. [Figure 4] 1 is a flowchart of a sound generation process according to an embodiment of the present invention. [Figure 5A] 1 is a frequency map that defines the relationship between the motor rotation speed and frequency according to an embodiment of the present invention. [Figure 5B] 1 is a sound pressure map that defines the relationship between the motor rotation speed and sound pressure according to an embodiment of the present invention. [Figure 6] 1 is a map that defines the time until the first trend change timing and the time interval between each change timing according to an embodiment of the present invention. [Figure 7A] 10 is a frequency map defining the time transition of frequency when a vehicle is in an accelerating state according to an embodiment of the present invention. [Figure 7B]10 is a sound pressure map that defines the time transition of sound pressure when a vehicle is accelerating according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

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

[0016] <Configuration of vehicle sound generation device> First, the configuration of a sound generation device for a vehicle of the present invention will be described with reference to Figures 1 and 2. Figure 1 is an explanatory diagram of a sound generation device for a vehicle, and Figure 2 is a diagram of the configuration of the sound generation device for a vehicle.

[0017] 1 and 2, a vehicle sound generating device 1 of this embodiment includes a sound control device 10 mounted on a vehicle 2, a speaker 20 that outputs a predetermined sound to the driver in the vehicle cabin, and a group of various sensors 30 that detects the state of the vehicle 2. The vehicle 2 is an electric vehicle (EV) that includes an electric motor 3 as a rotational power source.

[0018] The sound control device 10 is a well-known computer-based controller that includes circuits. The sound control device 10 includes one or more processors as a central processing unit (CPU) that executes programs, a memory (storage unit 14) that is configured, for example, with RAM (Random Access Memory) or ROM (Read Only Memory) and stores various programs and databases, and a data input / output device that inputs and outputs electrical signals.

[0019] Various maps used to generate sound signals are stored in a database in the memory unit 14. The sound control device 10 is communicably connected to other in-vehicle devices via an in-vehicle communication line. The sound control device 10 is configured so that the processor executes a program based on various information from the sensor group 30, thereby outputting a sound signal Ss to the speaker 20. In this case, 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] The speaker 20 is a sound output unit equipped with an amplifier. The speaker 20 receives a sound signal Ss from the sound control device 10, amplifies the sound signal Ss by a predetermined amplification factor, and outputs a sound (typically a synthesized sound) SC based on the sound signal Ss. The speaker 20 does not have to be provided inside the vehicle cabin as long as the driver can recognize the sound SC generated by the speaker 20.

[0021] The sensor group 30 includes a rotation speed sensor 31 that detects the rotation speed of the electric motor 3, an accelerator opening sensor 32 that detects the accelerator opening corresponding to the amount of operation of the accelerator pedal of the vehicle 2, and a motor torque sensor 33 that detects the motor torque of the electric motor 3. These sensors 30 transmit signals S31, S32, and S33 that indicate the detected vehicle state through an 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 limiting, and the motor torque may be a requested motor torque value for the electric motor 3. Alternatively, the sound control device 10 may calculate the motor torque from the accelerator opening degree, etc., using an acceleration characteristics map, etc.

[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 described. Simply outputting a synthetic sound containing a frequency set to be proportional to the motor's rotation speed, as in the conventional technology described above, does not allow the occupant to fully appreciate the pleasantness of vehicle acceleration when accelerating the vehicle by pressing the accelerator pedal hard. The inventors of the present invention therefore investigated what kind of sound would make the occupant feel the pleasantness of vehicle acceleration. As a result, they found that if the occupant perceives the output sound as having a "rhythmic" quality, the occupant will perceive the pleasantness of vehicle acceleration from the output sound. Furthermore, when a sound that changes over time is output while the vehicle is accelerating, the occupant will perceive the output sound as having a "rhythmic" quality if the occupant receives high ratings without bias in 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 expectation of the time progression of the sound and the actual time progression of the sound; and (3) the degree of correspondence between the time progression of the sound and the scenery that changes as the vehicle accelerates.

[0024] Therefore, the inventors conducted an experiment in which subjects boarded a vehicle simulator, reproduced the changing scenery when the vehicle was accelerating, and output sounds with various time transition patterns, and had the subjects evaluate the scores of the three subjective evaluation items. Specifically, time transitions of two parameters representing the sound, namely the frequency and sound pressure of a sound signal, were set, and sounds corresponding to the sound signals generated based on the time transitions of the set parameters were output. The time transitions of each parameter included a first trend in which each parameter increased over time, and a second trend in which each parameter decreased over time following the first trend. The sounds were output under multiple conditions in which the time intervals at which the first trend changed to the second trend were varied, and the subjects evaluated the scores of the three subjective evaluation items under each condition.

[0025] As a result, it was found that the time interval between each change in the timing when the first trend changes to the second trend has the greatest effect on the score for each evaluation item. More specifically, it was found that when the time from when the vehicle enters an accelerating state to when the first trend first changes to the second trend (i.e., until the first change), and the time interval between each change, are equal within the range of 1000 milliseconds to 2000 milliseconds, each evaluation item will receive a high score without bias.

[0026] Figure 3 is a radar chart showing an example of the results of the above experiment. The radar chart in Figure 3 plots the scores for each of three evaluation items: (1) the sense of rhythm recognized from the time progression of sound ("sense of rhythm" in Figure 3), (2) the degree to which the passenger's expectations regarding the time progression of sound correspond to the actual time progression of sound ("correspondence with expectations" in Figure 3), and (3) the degree to which the time progression of sound corresponds to the scenery that changes in response to the acceleration of the vehicle and the time progression of sound ("correspondence with scenery change" in Figure 3), standardized using Z scores (i.e., the scores for each evaluation were converted so that the average is 0 and the standard deviation is 1).

[0027] FIG. 3(a) shows the time from when the vehicle enters an accelerating state until the first change from the first trend to the second trend, and the time intervals between each change are all equal, T, for the cases where T = 1000 milliseconds (solid line in FIG. 3(a)), T = 900 milliseconds (dashed line in FIG. 3(a)), and T = 800 milliseconds (dotted line in FIG. 3(a)). FIG. 3(b) shows the charts for the cases where T = 1900 milliseconds (solid line in FIG. 3(b)), T = 2000 milliseconds (dashed line in FIG. 3(b)), and T = 2100 milliseconds (dotted line in FIG. 3(b)). As is clear from FIGS. 3(a) and (b), when T is in the range of 1000 milliseconds to 2000 milliseconds, each evaluation item receives a high score (at least 0 or above) without bias, indicating that the output sound is perceived as having a "sense of rhythm." On the other hand, when T is less than 1000 milliseconds or greater than 2000 milliseconds, at least one evaluation item receives a low score (less than 0), indicating that the output sound is not recognized as having a "sense of rhythm."

[0028] Therefore, in this embodiment, the vehicle sound generating device 1 outputs a sound corresponding to a sound signal in which the time transition of each parameter is set so that the time T from when the vehicle 2 enters an accelerating state to the first change timing and the time interval T between each change timing are 1000 milliseconds or more and 2000 milliseconds or less. This allows the occupant to recognize that the output sound has a "sense of rhythm" and can feel the pleasantness of the acceleration of the vehicle 2.

[0029] <Sound generation processing> Next, the flow of the sound generation process by the vehicle sound generation device 1 of this embodiment will be described with reference to Figures 4 to 7B. Figure 4 is a flowchart of the sound generation process according to this embodiment, Figures 5A and 5B are maps that define the relationship between the 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 transition of the sound signal parameters when the vehicle is accelerating according to this embodiment.

[0030] The sound generation process shown in FIG. 4 is repeatedly executed at a predetermined cycle by the vehicle sound generation device 1 (mainly the sound control device 10 and the 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 (more specifically, the acceleration state detection unit 13) determines whether the vehicle 2 is in an accelerating state based on the information acquired in step S1. Specifically, when the accelerator opening increases (for example, when the rate of increase in accelerator opening is 20% / sec or more), the sound control device 10 determines that the vehicle 2 is in an accelerating state if the increase in accelerator opening from the start to the end of the increase is a predetermined amount (for example, 30%) or more, and the accelerator opening at the end of the increase is a predetermined amount (for example, 40%) or more.

[0033] Alternatively, instead of the accelerator opening, the sound control device 10 may determine whether the vehicle 2 is accelerating based on the motor torque. For example, when the motor torque increases, the sound control device 10 may determine that the vehicle 2 is accelerating if the increase in motor torque from the start to the end of the increase is equal to or greater than a predetermined amount, and if the motor torque at the end of the increase is equal to or greater than a predetermined value.

[0034] If the result of step S2 is that it is not determined that the vehicle 2 is in an accelerating state (step S2: No), that is, if the acceleration state detection unit 13 does not detect that the vehicle 2 is in an accelerating state, the process proceeds to step S3, and the sound control device 10 (more 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, a frequency map that defines the relationship between the motor rotation speed R and the frequency F1 is referenced to set the frequency F1 according to the motor rotation speed R. Fig. 5A shows the frequency map that defines the relationship between the motor rotation speed R and the frequency F1. The frequency map shown in Fig. 5A defines that the frequency F1 of the sound signal increases as the motor rotation 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, a sound pressure map that defines the relationship between the motor rotation speed R and the sound pressure P1 is referenced to set the sound pressure P1 according to the motor rotation speed R. Figure 5B shows the sound pressure map that defines the relationship between the motor rotation speed R and the sound pressure P1. The sound pressure map shown in Figure 5B defines that the sound pressure P1 of the sound signal increases as the motor rotation speed R increases.

[0038] On the other hand, if it is determined in step S2 that the vehicle 2 is in an accelerating state (step S2: Yes), that is, if the acceleration state detection unit 13 detects that the vehicle 2 is in an accelerating state, the sound control device 10 (more specifically, the sound control unit 12) sets the time trends of the sound signal parameters, frequency F2 and sound pressure P2. As described above, the time trends of frequency F2 and sound pressure P2 include 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 the time T from when it is detected 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), and T, which is the time interval between each change timing.

[0040] Specifically, as shown in FIG. 6, the time interval T 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 it takes to depress the accelerator pedal), the accelerator opening at the end of the increase in accelerator opening, the time T from when it is detected that the vehicle 2 is accelerating until the first trend changes to the second trend, and the time interval T between each change timing. As shown in FIG. 6, the time interval T is defined to be between 1000 milliseconds and 2000 milliseconds. 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 in accelerator opening, the shorter the time interval T. Furthermore, if the accelerator opening at the end of the increase in accelerator opening is less than a predetermined opening (40% in FIG. 6), it is not detected that the vehicle 2 is accelerating, so the time interval T is not defined.

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

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

[0043] Specifically, the frequency F2 corresponding to the elapsed time t is set by referring to a frequency map that defines the relationship between the time t elapsed since it was detected that the vehicle 2 is in an accelerating state and the frequency F2 (i.e., the time transition of the frequency F2 when the vehicle 2 is in an accelerating state). Fig. 7A is a frequency map that defines the time transition of the frequency F2 when the vehicle 2 is in an accelerating state.

[0044] 7A, the time transition of the frequency F2 includes a repetition of a first trend in which the frequency F2 increases over time and a second trend in which the frequency F2 decreases over time following the first trend. The time transition is specified so that the time T from when it is detected that the vehicle 2 is accelerating to when the first trend first changes to the second trend, and the time interval T between each change, are between 1000 milliseconds and 2000 milliseconds.

[0045] Furthermore, the time intervals ΔT from each change timing until the second trend changes to the first trend are set equal to each other and shorter than T.

[0046] Furthermore, the maximum values ​​of the frequency F2 at each change timing when the first trend changes to the second trend are defined to be approximately equal.

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

[0048] Specifically, the sound pressure P2 corresponding to the elapsed time t is set by referring to a sound pressure map that defines the relationship between the time t elapsed since it was detected that the vehicle 2 is accelerating and the sound pressure P2 (i.e., the time transition of the sound pressure P2 when the vehicle 2 is accelerating). Fig. 7B is a sound pressure map that defines the time transition of the sound pressure P2 when the vehicle 2 is accelerating.

[0049] 7B, the time transition of the sound pressure P2, like the time transition of the frequency F2, includes a repetition of a first trend in which the sound pressure P2 increases over time and a second trend in which the sound pressure P2 decreases over time following the first trend. Furthermore, the time T from when it is detected that the vehicle 2 is accelerating to when the first trend first changes to the second trend, and the time interval T between each change timing at which the first trend changes to the second trend, are the same as the time interval T in the time transition of the frequency F2. Similarly, the time interval ΔT from each change timing to when the second trend changes to the first trend is also the same as the time interval ΔT in the time transition of the frequency F2.

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

[0051] After step S4 or S7, the process proceeds to step S8, where the sound control device 10 (more 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 accelerating in step S2 and has set the frequency F1 and sound pressure P1 based on the motor rotation speed in steps S3 and S4, the sound control device 10 generates a sound signal based on those frequency F1 and sound pressure P1. In other words, if it does not detect that the vehicle 2 is accelerating, the sound control device 10 sequentially generates sound signals based on the motor rotation speed and outputs them to the speaker 20.

[0053] On the other hand, if 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, the sound control device 10 generates a sound signal based on the time progression of the frequency F2 and the sound pressure P2. In other words, if it is detected that the vehicle 2 is accelerating, the sound control device 10 generates a sound signal in accordance with the time progression of the frequency F2 and the sound pressure P2 that were previously set in steps S6 and S7, and outputs it to the speaker 20.

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

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

[0056] Furthermore, in the above-described embodiment, when it is detected in step S2 of the sound generation processing that the vehicle 2 is in an accelerating state, the time T from when it is detected that the vehicle 2 is in an accelerating state until the first trend changes to the second trend in step S5, and the time interval T between each change timing, are set based on the accelerator opening degree. However, the time interval T may be set based on the motor torque instead of the accelerator opening degree. Specifically, the time interval T may be set to be shorter as the time from the start to the end of the increase in motor torque is shorter and as the motor torque at the end of the increase in motor torque is greater.

[0057] Furthermore, in the above-described embodiment, when it is detected in step S2 of the sound generation processing that the vehicle 2 is in an accelerating state, an example has been described in which the time course of the frequency F2 is set in step S6 and the time course of the sound pressure P2 is set in step S7, but the frequency F2 may be set based on the motor rotation speed in step S6 (i.e., set in the same way as the frequency F1 in step S3), and the time course of the sound pressure P2 may be set in step S7. Alternatively, the time course 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] In addition, in the above-described embodiment, an example was shown in which the first trend and the second trend are repeated three times using the frequency map of Figure 7A and the sound pressure map of Figure 7B, but this repetition may be more than three times (for example, four or five times).

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

[0060] When it is detected that the vehicle 2 is accelerating, the vehicle sound generation device 1 of this embodiment sets a time transition of a parameter of a sound signal and generates a sound signal based on the time transition of the parameter. The time transition of the parameter includes a repetition of a first trend and a second trend following the first trend, and the time from when it is detected that the vehicle is accelerating to when the first trend first changes to the second trend, and the time intervals between each change timing at which the first trend changes to the second trend, are set to be equal within a range of 1000 milliseconds to 2000 milliseconds.

[0061] This allows the sound to be changed at an appropriate time to make the occupants realize that the output sound has a "sense of rhythm," that is, that (1) the sense of rhythm recognized from the time progression of the sound, (2) the degree of correspondence between the occupants' 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 that changes in response to the acceleration of vehicle 2 and the time progression of the sound are all realized at a high level without bias, allowing the occupants to feel the pleasure of accelerating vehicle 2.

[0062] Furthermore, the parameters of the sound signal include one or both of frequency and sound pressure, and 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, so that the occupants can clearly recognize the change in sound over time, and can feel the acceleration of vehicle 2 even more pleasant.

[0063] Furthermore, when it is not detected that the vehicle 2 is in an accelerating state, the vehicle sound generating device 1 generates a sound signal based on at least the rotation speed of the electric motor. Therefore, the time progression of the sound output when it is detected that the vehicle 2 is in an accelerating state can be made to stand out in comparison with the sound based on the motor rotation speed, allowing the occupants to feel an even more pleasant acceleration of the vehicle 2.

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

[0065] Furthermore, the vehicle sound generation device 1 sets shorter the time T from when it is detected that the vehicle 2 is in an accelerating state until the first trend changes to the second trend, and the time interval T between each change timing at which the first trend changes to the second trend, as the accelerator opening degree increases when the accelerator opening degree increase is complete. As a result, the period of the sound change over time becomes shorter as the accelerator opening degree increases when the accelerator opening degree increase is complete, allowing the occupants to feel the strength of the acceleration of the vehicle 2 corresponding to the magnitude of the accelerator opening degree.

[0066] Furthermore, the shorter the time from the start to the end of the increase in accelerator opening, the shorter the time T is set by the vehicle sound generation device 1 to the time from when it is detected that the vehicle 2 is in an accelerating state until the first trend changes to the second trend, and the shorter the time interval T between each change timing at which the first trend changes to the second trend. As a result, the shorter the time from the start to the end of the increase in accelerator opening, the shorter the period of the change in sound over time, making it possible for the occupants to sense the strength of the acceleration of the vehicle 2 according to the speed of the increase in accelerator opening. [Explanation of symbols]

[0067] 1 Vehicle sound generation device 2 vehicles 3 Electric motor 10 Sound control device 12 Sound control section 13 Acceleration state detection unit 14 Storage section 20 speakers 30 sensors 31 Motor rotation speed sensor 32 Accelerator opening sensor 33 Motor torque sensor

Claims

1. A vehicle sound generating device mounted on a vehicle that runs using an electric motor as a power source, a sound control unit configured to generate a sound signal representative of a sound; a sound output unit that outputs a sound corresponding to the sound signal generated by the sound control unit; an acceleration state detection unit that detects that the vehicle is in an accelerating state, when it is detected that the vehicle is in an accelerating state, the sound control unit sets a time transition of a parameter of the sound signal, and generates the sound signal based on the time transition of the parameter; the time transition of the parameter includes a repetition of a first trend and a second trend following the first trend, and the time from when it is detected that the vehicle is in an accelerating state to when the first trend first changes to the second trend and the time intervals at which the first trend changes to the second trend are set to be equal within a range of 1000 milliseconds to 2000 milliseconds, 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. Vehicle sound generating device.

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

3. a motor rotation speed sensor for detecting the rotation speed of the electric motor; When it is not detected that the vehicle is in an accelerating state, the sound control unit generates the sound signal based on at least the rotation speed of the electric motor.

3. The vehicle sound generating device according to claim 1 or 2.

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

5. 5. The sound generation device for a vehicle according to claim 4, wherein the sound control unit sets a time from when it is detected that the vehicle is in an accelerating state to when the first trend first changes to the second trend and a time interval between each change timing at which the first trend changes to the second trend to be shorter the greater the accelerator opening degree at the end of the increase in the accelerator opening degree.

6. 6. The sound generation device for a vehicle according to claim 4 or 5, wherein the sound control unit sets a time from when it is detected that the vehicle is in an accelerating state to when the first trend first changes to the second trend and a time interval between each change timing at which the first trend changes to the second trend to be shorter the shorter the time from when the increase in the accelerator opening degree starts to end.

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