Sound control method, sound control device, and electric vehicle

Abstract

To make it possible that when pseudo engine sounds are outputted in a compartment of a vehicle which can be travelled by an electric motor, a sense of realism by this output is given to a driver.SOLUTION: Pseudo engine sounds are generated on the basis of operation information concerning a manual operation element of an electric car. The pseudo engine sounds are outputted from a plurality of speakers provided in a compartment of the electric car. The plurality of speakers include a first speaker provided on a front part of the electric car, and a second speaker provided at a place excluding the front part. When outputting pseudo engine sound from the plurality of speakers, each sound pressure of pseudo engine sounds outputted from the first and second speakers is adjusted on the basis of sound image setting information in the electric car.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to a technology applied to an electric vehicle that uses an electric motor as a driving power device.

Background Art

[0002] Japanese Patent No. 6787507 discloses an electric vehicle that uses an electric motor as a driving power device. This conventional electric vehicle controls the output of the electric motor so as to simulate the torque characteristics peculiar to an engine vehicle with a manual transmission (hereinafter, also referred to as an "MT engine vehicle"). The control of the output of the electric motor is performed based on a signal from a pseudo-manual transmission operated by a driver. The pseudo-manual transmission has a configuration similar to the manual transmission mounted on an MT engine vehicle.

[0003] Japanese Unexamined Patent Application Publication No. 2020-120290 discloses a three-dimensional audio system for generating a three-dimensional sound field in a vehicle interior. This conventional audio system is a system retrofitted to an existing speaker system in the vehicle interior and includes speakers for three-dimensional audio. This conventional audio system outputs sound from the speakers for three-dimensional audio in conjunction with the existing speaker system.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Japanese Patent Publication No. 6787507 does not mention the sound produced during the output control of an electric motor based on the driver's manual gear shifting operation. In this regard, if a sound that simulates the engine sound of a typical engine vehicle (hereinafter also referred to as "simulated engine sound") is output from a speaker installed in the cabin of an electric vehicle, the driver can get the feeling of driving an engine vehicle. However, simply outputting a simulated engine sound from a speaker may not provide a sufficient sense of realism to a driver accustomed to driving engine vehicles.

[0006] This disclosure has been made in view of the above-mentioned issues. One objective of this disclosure is to provide a technology that can give the driver a sense of realism by outputting a simulated engine sound into the cabin of a vehicle that is powered by an electric motor. [Means for solving the problem]

[0007] The first aspect of this disclosure is a sound control method applicable to an electric vehicle that uses an electric motor as a power source for driving, and has the following features: The sound control method includes the steps of generating a simulated engine sound based on operation information of the manual driving elements of the electric vehicle, and outputting the simulated engine sound from a plurality of speakers installed in the cabin of the electric vehicle. The plurality of speakers include a first speaker provided at the front of the electric vehicle and a second speaker provided at a location other than the front. The step of outputting the simulated engine sound further includes the step of adjusting the sound pressure of the simulated engine sound output from the first and second speakers based on the sound image setting information in the electric vehicle.

[0008] A second aspect of this disclosure is a sound control device applicable to an electric vehicle that uses an electric motor as a power source for driving, and has the following features: The sound control device includes a processor configured to perform various processes. The processor is configured to generate a simulated engine sound based on the operation information of the manual driving elements of the electric vehicle, and to output the simulated engine sound to a plurality of speakers installed in the cabin of the electric vehicle. The plurality of speakers include a first speaker provided at the front of the electric vehicle and a second speaker provided at a location other than the front. The processor is further configured to adjust the sound pressure of the simulated engine sound output from the first and second speakers based on the sound image setting information in the electric vehicle.

[0009] A third aspect of this disclosure is an electric vehicle that uses an electric motor as a power source for driving, and has the following features: The electric vehicle comprises a plurality of speakers installed inside the vehicle's cabin and a processor configured to perform various processing tasks. The processor is configured to generate a simulated engine sound based on the operation information of the manual driving elements of the electric vehicle, and to output the simulated engine sound to the plurality of speakers. The plurality of speakers include a first speaker provided at the front of the electric vehicle and a second speaker provided at a location other than the front. The processor is further configured to adjust the sound pressure of the simulated engine sound output from the first and second speakers based on the sound image setting information in the electric vehicle. [Effects of the Invention]

[0010] According to this disclosure, when simulated engine sounds are generated for output from first and second speakers installed in the cabin of an electric vehicle, the sound pressure of each simulated engine sound output from these speakers is adjusted based on sound image setting information. Therefore, it is possible to enhance the sense of realism from this output compared to when only simulated engine sounds are output from the first and second speakers. [Brief explanation of the drawing]

[0011] [Figure 1] It is a conceptual diagram showing an electric vehicle and a sound control device according to an embodiment of the present disclosure. [Figure 2] It is a diagram showing an example of the layout of the first speaker and the second speaker. [Figure 3] It is a block diagram showing an example of the basic functional configuration of the sound control device. [Figure 4] It is a block diagram showing another example of the basic functional configuration of the sound control device. [Figure 5] It is a block diagram showing an example of the functional configuration of the sound control device particularly related to the embodiment. [Figure 6] It is a diagram for explaining information regarding the settings of the speaker. [Figure 7] It is a diagram for explaining information regarding the settings of the speaker. [Figure 8] It is a diagram for explaining an example of acquiring information regarding the settings of the speaker from an input / output terminal other than the HMI unit. [Figure 9] It is a flowchart showing the flow of the sound control process particularly related to the embodiment. [Figure 10] It is a block diagram showing a first configuration example of the power control system of the electric vehicle. [Figure 11] It is a diagram showing examples of an engine model, a clutch model, and a transmission model constituting an MT engine vehicle model. [Figure 12] It is a diagram showing a comparison of the torque characteristics of an electric motor realized by motor control using an MT engine vehicle model with the torque characteristics of an electric motor realized by normal motor control as an electric vehicle. [Figure 13] It is a block diagram showing a second configuration example of the power control system of the electric vehicle.

Embodiments for Carrying Out the Invention

[0012] Embodiments of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding components are denoted by the same reference numerals, and the description thereof is simplified or omitted.

[0013] 1. Overall configuration and simulated engine sound Figure 1 is a conceptual diagram showing an electric vehicle 10 according to an embodiment of the present disclosure and a sound control device 100 applied to the electric vehicle 10. The electric vehicle 10 is equipped with an electric motor 44. Examples of the electric motor 44 include a brushless DC motor and a three-phase AC synchronous motor. The electric vehicle 10 uses the electric motor 44 as a power device for driving.

[0014] The electric vehicle 10 is also equipped with various sensors 12. These sensors 12 include operating state sensors such as an accelerator position sensor, a brake position sensor, and a shift position sensor, as well as driving state sensors such as a wheel speed sensor, an acceleration sensor, and a rotational speed sensor. The accelerator position sensor detects the amount of accelerator pedal operation (accelerator opening). The brake position sensor detects the amount of brake pedal operation. The shift position sensor detects the shift position. The wheel speed sensor detects the rotational speed of the wheels of the electric vehicle 10. The acceleration sensor detects the lateral and longitudinal acceleration of the electric vehicle 10. The rotational speed sensor detects the rotational speed of the electric motor 44.

[0015] The various sensors 12 also include position sensors such as GNSS (Global Navigation Satellite System) sensors, and recognition sensors such as cameras, radar, and LIDAR (Laser Imaging Detection and Ranging). The GNSS detects the position and attitude of the electric vehicle 10. The camera captures images of at least the area in front of the electric vehicle 10. The radar and LIDAR recognize the surrounding environment of the electric vehicle 10.

[0016] The electric vehicle 10 also includes a first speaker 14 and a second speaker 16. The first speaker 14 and the second speaker 16 output sound into the cabin of the electric vehicle 10. Figure 2 shows an example layout of the first speaker 14 and the second speaker 16. In the example shown in Figure 2, the first speaker 14 includes three front speakers 14a, 14b, and 14c. These front speakers are located in the front of the electric vehicle 10. Front speaker 14a is located, for example, on the dashboard. Front speaker 14b is located, for example, on the left front door. Front speaker 14c is located, for example, on the right front door. The front speakers 14a, 14b, and 14c may include speakers for different frequency ranges, such as a subwoofer, midrange, and tweeter. Furthermore, the total number of speakers constituting the first speaker 14 and the layout of these speakers can be changed as desired.

[0017] The second speaker 16 is a speaker installed in a location other than the front. In the example shown in Figure 2, the second speaker 16 includes rear speakers 16a and 16b. These rear speakers are installed in the rear of the electric vehicle 10. Rear speaker 16a is installed, for example, in the left rear door. Rear speaker 16b is installed, for example, in the right rear door. The second speaker 16 also includes seat speakers 16c, 16d, 16e and 16f. Seat speakers 16c and 16d are installed, for example, in the headrest of the driver's seat. Seat speakers 16e and 16f are installed, for example, in the headrest of the passenger seat. The rear speakers 16a and 16b and the seat speakers 16c to 16f may include speakers for different frequency ranges, such as a subwoofer, midrange, and tweeter. Furthermore, the total number of speakers constituting the second speaker 16, as well as the layout of these speakers, can be changed as desired.

[0018] The electric vehicle 10 is further equipped with an HMI (Human Machine Interface) unit 18. The HMI unit 18 is an input / output terminal for providing information to and receiving information from the driver of the electric vehicle 10. The HMI unit 18 includes, for example, an input device, a display device, and a microphone. Examples of input devices include a touch panel, a keyboard, switches, and buttons. The information provided to the driver includes information about the driving status of the electric vehicle 10 and information specific to this disclosure. Information specific to this disclosure includes information about the driving mode of the electric vehicle 10 and information about sound image settings. Information is provided to the driver using the display device. Information is received from the driver using the input device and microphone.

[0019] The sound control device 100 generates sound (hereinafter also referred to as "room sound") to be output from the first speaker 14 and the second speaker 16. The sound control device 100 also outputs the generated room sound from the first speaker 14 and the second speaker 16. For example, the sound control device 100 generates a simulated engine sound as the room sound and outputs it from the first speaker 14 and the second speaker 16. In another example, the sound control device 100 generates room sound including a simulated engine sound and outputs it from the first speaker 14 and the second speaker 16.

[0020] The entire sound control device 100 may be mounted on the electric vehicle 10. Alternatively, at least a part of the sound control device 100 may be included in an external management server outside the electric vehicle 10. In that case, the sound control device 100 may remotely generate interior sound, receive the generated interior sound, and output it from the first speaker 14 and the second speaker 16.

[0021] Generally speaking, the sound control device 100 includes at least one processor 102 and at least one storage device 104. The processor 102 performs various processes. Examples of processors 102 include CPU (Central Processing Unit), GPU (Graphics Processing Unit), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), etc. The storage device 104 stores (stores) various information. Examples of storage devices 104 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc.

[0022] Figure 3 is a block diagram showing an example of the basic functional configuration of the sound control device 100. The sound control device 100 includes, as functional blocks, an information acquisition unit 110, a vehicle sound source management unit 120, an engine sound generation unit 130, and a sound output control unit 140. These functional blocks are realized, for example, through the cooperation of a processor 102 and a storage device 104.

[0023] The information acquisition unit 110 acquires BEV information about the electric vehicle 10. The BEV information includes information about the driving status of the electric vehicle 10, information about the driving environment of the electric vehicle 10, and input information from the driver of the electric vehicle 10. The BEV information is typically detected by various sensors 12 and the HMI unit 18. Some of the information about the driving environment of the electric vehicle 10 may be acquired by combining information detected by the various sensors 12 (for example, location information of the electric vehicle 10) with map data.

[0024] Furthermore, the BEV information includes the virtual engine rotation speed Ne. Here, it is assumed that the electric vehicle 10 uses a virtual engine as the power source for driving. The virtual engine rotation speed Ne is the rotation speed of the virtual engine when it is assumed that the electric vehicle 10 is driven by the virtual engine. For example, the information acquisition unit 110 may calculate the virtual engine rotation speed Ne so that it increases as the wheel speed increases. Also, if the electric vehicle 10 has a manual mode as described later, the information acquisition unit 110 may calculate the virtual engine rotation speed Ne in the manual mode based on the wheel speed, the overall reduction ratio, and the slip ratio of the virtual clutch. Details of the method for calculating the virtual engine rotation speed Ne in this manual mode will be described later.

[0025] The vehicle sound source management unit 120 stores sound source data EVS of an engine vehicle used to generate simulated engine sounds. The vehicle sound source management unit 120 is mainly implemented by the storage device 104. Typically, the sound source data EVS includes multiple types of sound source data. These multiple types of sound source data include, for example, sound source data for sounds caused by engine combustion (for low, medium, and high rotational speeds), sound source data for sounds caused by the operation of input devices such as gears (for low, medium, and high rotational speeds), sound source data for engine intake sounds, sound source data for engine exhaust sounds, sound source data for noise sounds, sound source data for event sounds (e.g., engine stall sounds), etc. Each sound source data is pre-generated through simulations based on the engine model and vehicle model of the engine vehicle. Each sound source data is flexibly adjustable. That is, at least one of the sound pressure and frequency of the sound indicated by the sound source data can be flexibly adjusted.

[0026] The engine sound generation unit 130 (engine sound simulator) is a simulator that generates a simulated engine sound. The engine sound generation unit 130 acquires at least a portion of the BEV information from the information acquisition unit 110. In particular, the engine sound generation unit 130 acquires information on the virtual engine rotation speed Ne and vehicle speed from the information acquisition unit 110. The engine sound generation unit 130 also reads the sound source data EVS of the engine vehicle from the vehicle sound source management unit 120. Then, the engine sound generation unit 130 generates a simulated engine sound corresponding to the driving state of the electric vehicle 10 (virtual engine rotation speed Ne and vehicle speed) by combining one or more sound source data included in the sound source data EVS of the engine vehicle. The engine sound data EGS is data that indicates the generated simulated engine sound.

[0027] Furthermore, the generation of simulated engine sounds is a well-known technique, and the methods for generating simulated engine sounds applicable to this disclosure are not particularly limited. For example, simulated engine sounds may be generated using well-known engine sound simulators used in games, etc. Another method involves maintaining a map of virtual engine rotational speed Ne-frequency and a map of virtual engine torque-sound pressure, and increasing or decreasing the frequency of the simulated engine sound in proportion to the virtual engine rotational speed Ne, and increasing or decreasing the sound pressure of the simulated engine sound in proportion to the virtual engine torque.

[0028] The sound output control unit 140 receives engine sound data EGS generated by the engine sound generation unit 130. The sound output control unit 140 then outputs the engine sound data EGS to the speaker 16. When outputting the engine sound data EGS, the sound output control unit 140 controls the sound pressure of the simulated engine sound by controlling the amplifier. The sound output control unit 140 also changes the frequency of the simulated engine sound by controlling the FMC (frequency modulator).

[0029] Figure 4 is a block diagram showing another example of the basic functional configuration of the sound control device 100. In the example shown in Figure 4, the vehicle sound source management unit 120 stores sound source data EVS (EVS1,...EVSn) for multiple types of engine vehicles corresponding to each of multiple vehicle types (1,...,n). In other words, the vehicle sound source management unit 120 stores sound source data EVS for engine vehicles for each vehicle type. The sound source data EVSk (1≦k≦n) is pre-generated based on the engine model and vehicle model of the corresponding vehicle type. The driver may specify their preferred vehicle type from among the multiple vehicle types. In that case, the engine sound generation unit 130 acquires the sound source data EVSk corresponding to the vehicle type specified by the driver. Then, the engine sound generation unit 130 generates a simulated engine sound using the acquired engine vehicle sound source data EVSk. This allows the driver to get the feeling that they are driving their preferred vehicle type.

[0030] 2. Adjusting the sound pressure of the simulated engine sound. The simulated engine sound is output from the first speaker 14 and the second speaker 16, providing the driver of the electric vehicle 10 with a sense of realism as if driving a real engine-powered vehicle. However, simply outputting the simulated engine sound from these speakers may not provide sufficient realism to drivers accustomed to driving engine-powered vehicles. Therefore, in this embodiment, the sound pressure of the simulated engine sound output from the first speaker 14 and the second speaker 16 is adjusted. By adjusting the sound pressure of each sound, it becomes easier for the driver to recognize the direction of the sound source. As a result, it is possible to enhance the sense of realism compared to simply outputting the simulated engine sound from the first speaker 14 and the second speaker 16.

[0031] Figure 5 is a block diagram showing an example of the functional configuration of a sound control device 100 that is particularly relevant to the embodiment. In the example shown in Figure 5, the sound control device 100 includes a sound image setting unit 150 in addition to the functional blocks described in Figure 3. These functional blocks are realized, for example, through the cooperation of a processor 102 and a storage device 104.

[0032] The sound image setting unit 150 sets the sound image inside the electric vehicle 10 based on the information SPK. The information SPK is information relating to the settings of the first speaker 14 and the second speaker 16, and is an example of the "sound image setting information" in this disclosure. The information SPK is included, for example, in the input information from the driver acquired from the HMI unit 18.

[0033] Figure 6 is a diagram illustrating information regarding speaker settings. In the example shown in Figure 6, the HMI unit 18 is configured as a touch panel. This touch panel displays a screen for setting the sound pressure levels of the first speaker 14 and the second speaker 16. The vehicle mounting position of each speaker is shown on the left side of this setting screen, and the sound pressure bars for each speaker are shown on the right side of the same setting screen. The button BT shown above the sound pressure bars can be slid left or right. Sliding button BT to the right increases the sound pressure, and sliding button BT to the left decreases the sound pressure. In this way, in the example shown in Figure 6, the sound pressure levels of the first speaker 14 and the second speaker 16 are set by the driver.

[0034] In another example, information regarding speaker settings is automatically generated based on the engine mounting location information for the vehicle model specified by the driver. Figure 7 illustrates the SPK information when a simulated engine sound is generated using the sound source data EVSk described in Figure 4. If the vehicle model Ek is specified by the driver, the default sound pressure settings for the first speaker 14 and the second speaker 16 are output to the HMI unit 18 (touch panel) based on the engine mounting location information (e.g., front, rear, midship) for this vehicle model Ek.

[0035] Figure 7 shows the default settings for the Ek model when it is a mid-engine vehicle. In a mid-engine vehicle, the engine is mounted in front of the rear axle, so in the default settings, the sound pressure levels of the rear speakers 16a and 16b and the seat speakers 16c to 16f are higher around the engine mounting position. On the other hand, the sound pressure levels of the front speakers 14a to 14c, which are relatively farther from the engine mounting position, are lower (lowest value in Figure 7). Drivers who select the Ek model can use these default settings as is. Drivers can also adjust the default settings. For example, if there is no passenger in the front passenger seat, the sound pressure levels of the seat speakers 16e and 16f can be lowered.

[0036] The information SPK may be obtained from an input / output terminal other than the HMI unit 18. Figure 8 illustrates an example of obtaining the information SPK from a user terminal 200. The user terminal 200 shown in Figure 8 is a terminal (e.g., a smartphone or tablet) carried by the driver or an occupant of the electric vehicle 10. The user terminal 200 is configured to communicate with the sound control device 100. By launching a predetermined application on the user terminal 200, a settings screen similar to the settings screen output to the HMI unit 18 is output to the display unit of the user terminal 200. By outputting this settings screen to the display unit, the driver can configure the speaker settings without going through the HMI unit 18. In addition, an occupant of the electric vehicle 10 can change the settings of the sound image around their seat to their preferred settings.

[0037] Figures 6 and 8 also show information regarding the settings for engine intake sound and engine exhaust sound at the bottom of the settings screen. This information sets whether or not to superimpose the simulated engine intake sound and simulated engine exhaust sound onto the simulated engine sound. When the engine intake sound superposition setting is enabled, a simulated engine intake sound, which simulates the engine intake sound, is superimposed on the simulated engine sound output from the first speaker 14 (i.e., the front speakers 14a, 14b, and 14c). When the engine exhaust sound superposition setting is enabled, a simulated engine exhaust sound, which simulates the engine exhaust sound, is superimposed on the simulated engine sound output from the rear speakers 16a and 16b. The superposition of the simulated engine exhaust sound may also be performed on the simulated engine sound output from the seat speakers 16c to 16f. The superposition processing of the simulated engine intake sound and simulated engine exhaust sound is performed in the engine sound generation unit 130.

[0038] When the sound image setting unit 150 sets the sound image inside the electric vehicle 10, it transmits sound pressure adjustment information MDF for each speaker to the sound output control unit 140.

[0039] The sound output control unit 140 outputs the engine sound data EGS received from the engine sound generation unit 130 through the speaker 14. Up to this point, the function is the same as described in Figure 3. When the sound output control unit 140 receives sound pressure adjustment information MDF from the sound image setting unit 150, it adjusts the sound pressure of the simulated engine sound output from each speaker based on the sound pressure adjustment information MDF and outputs the engine sound data EGS to the first speaker 14 and the second speaker 16. The sound pressure adjustment is performed, for example, by controlling the amplifiers of the first speaker 14 and the second speaker 16.

[0040] 3. Sound control processing Figure 9 is a flowchart showing the flow of sound control processing particularly relevant to the embodiment. The flowchart shown in Figure 9 is repeatedly executed by the processor 102 shown in Figure 1 at a predetermined control cycle.

[0041] In the routine shown in Figure 9, information BEV is first acquired (step S11). As previously described, this includes information about the driving state of the electric vehicle 10, information about the driving environment of the electric vehicle 10, input information from the driver of the electric vehicle 10, and the virtual engine rotation speed Ne.

[0042] Following the processing in step S11, engine sound data EGS is generated (step S12). The engine sound data EGS is generated based on the virtual engine rotation speed Ne and vehicle speed information obtained in the processing of step S11. If the vehicle type information of the engine specified by the driver is obtained in the processing of step S11, the engine sound data EGS is generated by combining this vehicle type information with the virtual engine rotation speed Ne and vehicle speed information.

[0043] Following the processing in step S12, sound pressure adjustment information MDF is generated (step S13). The sound pressure adjustment information MDF is generated based on the input information from the driver obtained in the processing of step S11. The input information from the driver may be input via the HMI unit 18 or via the user terminal 200. If the occupant of the electric vehicle 10 is carrying the user terminal 200, the sound pressure adjustment information MDF is generated based on the input information from the driver and the input information from the occupant.

[0044] Following the processing in step S13, the sound pressure of the simulated engine sound output from each speaker is adjusted (step S14). The sound pressure adjustment is performed based on the sound pressure adjustment information MDF generated in the processing of step S13. Following the processing in step S14, the engine sound data EGS is output to the first speaker 14 and the second speaker 16, respectively (step S15).

[0045] 4. Effects According to this embodiment, engine sound data EGS is output from the first speaker 14 and the second speaker 16. Therefore, the driver of the electric vehicle 10 can be provided with a sense of realism as if they were driving a real engine vehicle. In addition, the sound pressure of each simulated engine sound output from these speakers is adjusted based on sound pressure adjustment information MDF. Therefore, compared to the case where only simulated engine sounds are output from the first speaker 14 and the second speaker 16, it is possible to enhance the sense of realism provided by this output.

[0046] 5. Application to electric vehicles with manual mode The electric motors used as the power source in typical electric vehicles have significantly different torque characteristics compared to the internal combustion engines used as the power source in conventional engine-powered vehicles. Due to these differences in torque characteristics, conventional engine-powered vehicles require a transmission, whereas electric vehicles generally do not. Furthermore, typical electric vehicles do not have a manual transmission operated by the driver. Therefore, there is a significant difference in driving feel between driving an engine-powered vehicle with a manual transmission and driving an electric vehicle.

[0047] On the other hand, the torque of an electric motor can be controlled relatively easily by controlling the applied voltage and field. Therefore, with an electric motor, it is possible to obtain the desired torque characteristics within the motor's operating range by implementing appropriate control. Taking advantage of this characteristic, the torque of an electric vehicle can be controlled to simulate the torque characteristics unique to a manual transmission (MT) engine vehicle. Furthermore, a pseudo-manual transmission can be installed in an electric vehicle so that the driver can experience a driving feel similar to that of an MT engine vehicle. In this way, it becomes possible to simulate an MT engine vehicle in an electric vehicle.

[0048] In this embodiment, the output of the electric motor 44 may be controlled to simulate the torque characteristics specific to a manual transmission (MT) engine vehicle. By controlling the output of the electric motor 44, the driver of the electric vehicle 10 can get the feeling that they are driving an MT engine vehicle. This control mode of the electric motor 44 for simulating the torque characteristics specific to an MT engine vehicle will also be referred to as the "manual mode" below. The control mode of the electric motor 44 for driving the electric vehicle 10 as a general electric vehicle will also be referred to as the "automatic mode" below.

[0049] The following describes an example configuration of an electric vehicle 10 equipped with a manual mode.

[0050] 5-1. First Configuration Example Figure 10 is a block diagram showing a first configuration example of the power control system of an electric vehicle 10. The electric vehicle 10 is equipped with an electric motor 44, a battery 46, and an inverter 42. The electric motor 44 is the power unit for driving. The battery 46 stores the electrical energy that drives the electric motor 44. In other words, the electric vehicle 10 is a battery electric vehicle (BEV) that runs on the electrical energy stored in the battery 46. The inverter 42 converts the DC power input from the battery 46 during acceleration into driving power for the electric motor 44. The inverter 42 also converts the regenerative power input from the electric motor 44 during deceleration into DC power and charges the battery 46.

[0051] The electric vehicle 10 is equipped with an accelerator pedal 22 for the driver to input an acceleration request to the electric vehicle 10. The accelerator pedal 22 is equipped with an accelerator position sensor 32 for detecting the accelerator opening degree.

[0052] The electric vehicle 10 is equipped with a simulated shift paddle 24. This simulated shift paddle 24 is a dummy and is different from a real paddle shifter. The simulated shift paddle 24 has a structure that resembles the shift paddles found in manual transmission vehicles without a clutch pedal. The simulated shift paddle 24 is mounted on the steering wheel. The simulated shift paddle 24 has an upshift switch and a downshift switch that determine the operating position. When the upshift switch is pulled towards the driver, it emits an upshift signal 34u, and when the downshift switch is pulled towards the driver, it emits a downshift signal 34d.

[0053] Wheel speed sensors 36 are provided on the wheels 26 of the electric vehicle 10. The wheel speed sensors 36 are used as vehicle speed sensors to detect the vehicle speed of the electric vehicle 10. In addition, a rotational speed sensor 38 is provided on the electric motor 44 to detect its rotational speed.

[0054] The electric vehicle 10 is equipped with a control device 50. The control device 50 is typically an electronic control unit (ECU) installed in the electric vehicle 10. The control device 50 may be a combination of multiple ECUs. The control device 50 comprises an interface, memory, and a processor. An in-vehicle network is connected to the interface. The memory includes RAM for temporarily recording data and ROM for storing programs and various data related to programs that can be executed by the processor. The program consists of multiple instructions. The processor reads and executes the program and data from memory and generates control signals based on signals obtained from each sensor.

[0055] For example, the control device 50 controls the electric motor 44 by PWM control of the inverter 42. The control device 50 receives signals from the accelerator position sensor 32, the pseudo-shift paddle 24, the wheel speed sensor 36, and the rotational speed sensor 38 (the signals from the pseudo-shift paddle 24 are an upshift signal 34u and a downshift signal 34d). The control device 50 processes these signals and calculates a motor torque command value for PWM control of the inverter 42.

[0056] The control device 50 includes an automatic mode and a manual mode as control modes. The automatic mode is the normal control mode for driving the electric vehicle 10 as a typical electric vehicle. The automatic mode is programmed to continuously change the output of the electric motor 44 in response to the operation of the accelerator pedal 22. On the other hand, the manual mode is a control mode for driving the electric vehicle 10 like a manual transmission engine vehicle. The manual mode is programmed to change the output characteristics of the electric motor 44 in response to the operation of the accelerator pedal 22 in response to upshift and downshift operations on the simulated shift paddle 24. In other words, the manual mode is a control mode that can change the output of the electric motor 44 in response to driving operations of manual driving elements other than the accelerator pedal 22 and brake pedal. The automatic mode and manual mode are switchable.

[0057] The control device 50 includes an automatic mode torque calculation unit 54 and a manual mode torque calculation unit 56. Each unit 54 and 56 may be an independent ECU, or it may be an ECU function obtained by executing a program stored in memory on a processor.

[0058] The automatic mode torque calculation unit 54 has a function to calculate the motor torque when the electric motor 44 is controlled in automatic mode. The automatic mode torque calculation unit 54 stores a motor torque command map. The motor torque command map is a map that determines the motor torque from the accelerator opening and the rotational speed of the electric motor 44. Signals from the accelerator position sensor 32 and the rotational speed sensor 38 are input to each parameter of the motor torque command map. The motor torque corresponding to these signals is output from the motor torque command map. Therefore, in automatic mode, even if the driver operates the pseudo-shift paddle 24, that operation is not reflected in the motor torque.

[0059] The manual mode torque calculation unit 56 includes an MT engine vehicle model. The MT engine vehicle model is a model for calculating the drive wheel torque that should be obtained by operating the accelerator pedal 22 and the pseudo-shift paddle 24, assuming that the electric vehicle 10 is an MT engine vehicle.

[0060] The MT engine vehicle model provided by the manual mode torque calculation unit 56 will be described with reference to Figure 11. As shown in Figure 11, the MT engine vehicle model includes an engine model 561, a clutch model 562, and a transmission model 563. The engine, clutch, and transmission virtually realized by the MT engine vehicle model are referred to as the virtual engine, virtual clutch, and virtual transmission, respectively. The engine model 561 models the virtual engine. The clutch model 562 models the virtual clutch. The transmission model 563 models the virtual transmission.

[0061] Engine model 561 calculates the virtual engine speed Ne and virtual engine output torque Teout. The virtual engine speed Ne is calculated based on the wheel rotation speed Nw, the overall reduction ratio R, and the virtual clutch slip ratio Rslip. For example, the virtual engine speed Ne is expressed by equation (1) below. Equation (1): Ne = Nw × R / (1 - Rslip)

[0062] The virtual engine output torque Teout is calculated from the virtual engine rotational speed Ne and the accelerator opening Pap. As shown in Figure 11, a map defining the relationship between the accelerator opening Pap, the virtual engine rotational speed Ne, and the virtual engine output torque Teout is used to calculate the virtual engine output torque Teout. This map provides the virtual engine output torque Teout for each accelerator opening Pap relative to the virtual engine rotational speed Ne. The torque characteristics shown in Figure 11 can be set to represent a gasoline engine, a diesel engine, a naturally aspirated engine, or a turbocharged engine.

[0063] The clutch model 562 calculates the torque transmission gain k. The torque transmission gain k is a gain used to calculate the degree of torque transmission of the virtual clutch according to the virtual clutch opening Pc. The virtual clutch opening Pc is normally 0%, and is temporarily opened to 100% in conjunction with the switching of the virtual gear stage of the virtual transmission. The clutch model 562 has a map as shown in Figure 11. In this map, the torque transmission gain k is given for the virtual clutch opening Pc. In Figure 11, Pc0 corresponds to the position where the virtual clutch opening Pc is 0%, and Pc3 corresponds to the position where the virtual clutch opening Pc is 100%. The range from Pc0 to Pc1 and the range from Pc2 to Pc3 are dead zones where the torque transmission gain k does not change with respect to the virtual clutch opening Pc. The clutch model 562 uses the torque transmission gain k to calculate the clutch output torque Tcout. The clutch output torque Tcout is the torque output from the virtual clutch. For example, the clutch output torque Tcout is given by the product of the virtual engine output torque Teout and the torque transfer gain k (Tcout = Teout × k).

[0064] Furthermore, clutch model 562 calculates the slip ratio Rslip. The slip ratio Rslip is used to calculate the virtual engine speed Ne in engine model 561. Similar to the torque transmission gain k, a map can be used to calculate the slip ratio Rslip, where the slip ratio Rslip is given to the virtual clutch opening Pc.

[0065] The transmission model 563 calculates the gear ratio (shift ratio) r. The gear ratio r is the gear ratio determined by the virtual gear stage GP in the virtual transmission. The virtual gear stage GP is increased by one step when the pseudo-shift paddle 24 is operated up. Conversely, the virtual gear stage GP is decreased by one step when the pseudo-shift paddle 24 is operated down. The transmission model 563 has a map as shown in Figure 11. In this map, the gear ratio r is assigned to the virtual gear stage GP such that the larger the virtual gear stage GP, the smaller the gear ratio r becomes. The transmission model 563 calculates the transmission output torque Tgout using the gear ratio r obtained from the map and the clutch output torque Tcout. For example, the transmission output torque Tgout is given by the product of the clutch output torque Tcout and the gear ratio r (Tgout = Tcout × r). The transmission output torque Tgout changes discontinuously according to the gear ratio r switching. This discontinuous change in transmission output torque Tgout creates a shift shock, giving the vehicle the feel of having a stepped transmission.

[0066] The MT engine vehicle model calculates the drive wheel torque Tw using a predetermined reduction ratio rr. The reduction ratio rr is a fixed value determined by the mechanical structure from the virtual transmission to the drive wheels. The value obtained by multiplying the reduction ratio rr by the gear ratio r is the aforementioned overall reduction ratio R. The MT engine vehicle model calculates the drive wheel torque Tw from the transmission output torque Tgout and the reduction ratio rr. For example, the drive wheel torque Tw is given by the product of the transmission output torque Tgout and the reduction ratio rr (Tw = Tgout × rr).

[0067] The control device 50 converts the drive wheel torque Tw calculated for the MT engine vehicle model into a required motor torque Tm. The required motor torque Tm is the motor torque required to achieve the drive wheel torque Tw calculated for the MT engine vehicle model. The reduction ratio from the output shaft of the electric motor 44 to the drive wheels is used to convert the drive wheel torque Tw into the required motor torque Tm. The control device 50 then controls the inverter 42 to control the electric motor 44 according to the required motor torque Tm.

[0068] Figure 12 shows a comparison of the torque characteristics of an electric motor 44 realized by motor control using an MT engine vehicle model with the torque characteristics of an electric motor 44 realized by normal motor control as an electric vehicle (EV). As shown in Figure 12, motor control using an MT engine vehicle model makes it possible to realize torque characteristics (solid line in the figure) that simulate the torque characteristics of an MT engine vehicle, according to the virtual gear stage set by the pseudo-shift paddle 24. Note that in Figure 12, the number of gear stages is set to 6.

[0069] 5-2. Second Configuration Example Figure 13 is a block diagram showing a second configuration example of the power control system of the electric vehicle 10. Here, only the configurations that differ from the first configuration example described above will be explained. Specifically, in the second configuration example, the electric vehicle 10 is equipped with a pseudo-shift lever 27 and a pseudo-clutch pedal 28 instead of the pseudo-shift paddles 24 provided in the first configuration example. The pseudo-shift lever 27 and pseudo-clutch pedal 28 are merely dummies and are not the actual shift lever and clutch pedal.

[0070] The simulated shift lever 27 has a structure that simulates the shift lever found in a manual transmission (MT) engine vehicle. The placement and feel of the simulated shift lever 27 are equivalent to those of an actual MT engine vehicle. The simulated shift lever 27 has positions corresponding to each gear, such as 1st, 2nd, 3rd, 4th, 5th, 6th, reverse, and neutral. The simulated shift lever 27 is equipped with a shift position sensor 27a that detects the gear by determining which position the simulated shift lever 27 is in.

[0071] The simulated clutch pedal 28 has a structure that simulates the clutch pedal found in a manual transmission (MT) engine vehicle. The placement and feel of the simulated clutch pedal 28 are equivalent to those of an actual MT engine vehicle. The simulated clutch pedal 28 is operated when the simulated shift lever 27 is operated. In other words, the driver depresses the simulated clutch pedal 28 when they want to change the gear setting using the simulated shift lever 27, and releases the pedal when the gear setting change is complete, returning the simulated clutch pedal 28 to its original position. The simulated clutch pedal 28 is equipped with a clutch position sensor 28a for detecting the amount the simulated clutch pedal 28 is depressed.

[0072] The control device 50 receives signals from the accelerator position sensor 32, the shift position sensor 27a, the clutch position sensor 28a, the wheel speed sensor 36, and the rotational speed sensor 38. The control device 50 processes these signals and calculates a motor torque command value for PWM control of the inverter 42.

[0073] The control device 50, similar to the first configuration example described above, includes an automatic mode and a manual mode as control modes. The automatic mode is programmed to continuously change the output of the electric motor 44 in response to the operation of the accelerator pedal 22. On the other hand, the manual mode is a control mode for driving the electric vehicle 10 like a manual transmission engine vehicle. The manual mode is programmed to change the output of the electric motor 44 in response to the operation of the accelerator pedal 22 in response to the operation of the simulated clutch pedal 28 and the simulated shift lever 27. In other words, the manual mode is a control mode that can change the output of the electric motor 44 in response to driving operations of manual driving elements other than the accelerator pedal 22 or the brake pedal.

[0074] The vehicle model provided by the manual mode torque calculation unit 56 is the same as that shown in Figure 11. However, the virtual clutch opening Pc is replaced by the amount of depression of the pseudo clutch pedal 28 detected by the clutch position sensor 28a. In addition, the virtual gear stage GP is determined by the position of the pseudo shift lever 27 detected by the shift position sensor 27a. [Explanation of Symbols]

[0075] 10…Electric vehicle, 12…Various sensors, 14…First speaker, 14a~14c…Front speakers, 16…Second speaker, 16a~16b…Rear speakers, 16c~16f…Seat speakers, 18…HMI unit, 22…Accelerator pedal, 24…Simulated shift paddle, 27…Simulated shift lever, 28…Simulated clutch pedal, 44…Electric motor, 100…Sound control device, 102…Processor, 104…Storage device, 110…Information acquisition unit, 120…Vehicle sound source management unit, 130…Engine sound generation unit, 140…Sound output control unit, 150…Sound image setting unit, 200…User terminal, BEV…Information related to electric vehicles, SPK…Information related to speaker settings, EGS…Engine sound data, MDF…Sound pressure adjustment information

Claims

1. A sound control method applicable to an electric vehicle that uses an electric motor as a power source for driving, The steps include generating a simulated engine sound based on the operation information of the manual driving elements of the electric vehicle, The steps include outputting the simulated engine sound from multiple speakers installed inside the electric vehicle, Includes, The plurality of speakers include a first speaker provided in the front of the electric vehicle and a second speaker provided in a location other than the front. The step of outputting the simulated engine sound further includes the step of adjusting the sound pressure of the simulated engine sound output from the first and second speakers based on the sound image setting information in the electric vehicle, In the step of generating the simulated engine sound, the simulated engine sound is generated from sound source data of an engine vehicle specified from among multiple vehicle types. The sound image setting information includes information on the mounting position of the engine in the specified engine vehicle. A sound control method characterized in that, in the step of adjusting each of the sound pressures, adjustment is made to increase the sound pressure of the simulated engine sound output from speakers provided around the mounting position in the electric vehicle.

2. The method according to claim 1, In the step of adjusting each of the sound pressures, adjustments are made to reduce the sound pressure of the simulated engine sound output from speakers other than those provided around the mounting position. A sound control method characterized by the following.

3. The method according to claim 1, The second speaker includes a rear speaker provided at the rear of the electric vehicle. The step of outputting the aforementioned simulated engine sound is, The steps include superimposing a simulated engine intake sound onto the simulated engine sound output from the first speaker, The steps include superimposing a simulated engine exhaust sound onto the simulated engine sound output from the rear speaker, Includes A sound control method characterized by the following.

4. The method according to claim 1, If a request to change the sound image setting information is received, the method further includes the step of changing the sound image setting information. The aforementioned change request is input from a terminal installed inside the electric vehicle, or from a terminal capable of communicating with the electric vehicle. A sound control method characterized by the following.

5. The method according to any one of claims 1 to 4, The manual driving element includes an accelerator pedal and a simulated shift paddle that resembles the shift paddles of an engine-powered vehicle. A sound control method characterized by the following.

6. The method according to any one of claims 1 to 4, The manual driving element includes an accelerator pedal, a simulated clutch pedal that resembles the clutch pedal of an engine-powered vehicle, and a simulated shift lever that resembles the shift lever of an engine-powered vehicle. A sound control method characterized by the following.

7. A sound control device applicable to an electric vehicle that uses an electric motor as a power source for driving, It is equipped with a processor configured to perform various processes, The aforementioned processor, Based on the operation information of the manual driving elements of the electric vehicle, a simulated engine sound is generated. The simulated engine sound is output to multiple speakers installed inside the electric vehicle. It is configured in such a way, The plurality of speakers include a first speaker provided in the front of the electric vehicle and a second speaker provided in a location other than the front. The aforementioned processor further, Based on the sound image setting information in the electric vehicle, the sound pressure of the simulated engine sound output from the first and second speakers is adjusted. It is configured in such a way, In the generation of the simulated engine sound, the simulated engine sound is generated from sound source data of an engine vehicle specified from among multiple vehicle types. The sound image setting information includes information on the mounting position of the engine in the specified engine vehicle. The sound control device is characterized in that, in adjusting each of the aforementioned sound pressures, adjustment is made to increase the sound pressure of the simulated engine sound output from speakers provided around the mounting position in the electric vehicle.

8. An electric vehicle that uses an electric motor as a power source for driving, Multiple speakers installed inside the interior of the electric vehicle, A processor configured to perform various processes, Equipped with, The aforementioned processor, Based on the operation information of the manual driving elements of the electric vehicle, a simulated engine sound is generated. Output the simulated engine sound to the aforementioned multiple speakers. It is configured in such a way, The plurality of speakers include a first speaker provided in the front of the electric vehicle and a second speaker provided in a location other than the front. The aforementioned processor further, Based on the sound image setting information in the electric vehicle, the sound pressure of the simulated engine sound output from the first and second speakers is adjusted. It is configured in such a way, In the generation of the simulated engine sound, the simulated engine sound is generated from sound source data of an engine vehicle specified from among multiple vehicle types. The sound image setting information includes information on the mounting position of the engine in the specified engine vehicle. An electric vehicle characterized in that, in adjusting each of the aforementioned sound pressures, the sound pressure of the simulated engine sound output from speakers provided around the mounting position in the electric vehicle is increased.

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