Electric vehicle

Abstract

To provide an electric vehicle with a MT mode and an EV mode which appropriately configures a virtual gear position when switching from the EV mode to the MT mode.SOLUTION: An electric vehicle includes an electric motor as a driving source. The electric vehicle comprises: a controller which controls the electric motor; an accelerator pedal; and a shifter. The electric vehicle includes: an EV mode where shift operation of the shifter is invalid; and a MT mode where the shift operation of the shifter is valid. The controller executes: switching, when the electric motor is controlled in the MT mode, the relation between accelerator operation amount and torque of the electric motor among a plurality of predetermined relations according to operation of the shift operation; and switching, when switching from the EV mode to the MT mode, the relation between the accelerator operation amount and the torque of the electric motor among the plurality of predetermined relations according to vehicle speed of the electric vehicle.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle having an electric motor as a drive source. [Background technology]

[0002] Japanese Patent Publication No. 6787507 discloses an electric vehicle that can virtually reproduce the behavior of a vehicle equipped with a manual transmission (transmission vehicle) powered by an engine by controlling an electric motor. In addition to an EV driving mode (EV mode) for general EV driving, the electric vehicle also has a MT driving mode (MT mode) that reproduces the behavior of a transmission vehicle. The driver can switch between MT mode and EV mode using a switch or the like. In MT mode, the gear position of a transmission vehicle is also virtually reproduced, allowing the driver to manually shift gears as if driving a transmission vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6787507 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric vehicle that has both a manual and an electric mode, let's consider the selection of gear position when switching from EV mode to manual mode. In EV mode, operation of the shift device is disabled and the electric vehicle runs in normal EV mode. In MT mode, gear shifting using the shift device is enabled. The gear shifting operation is used to switch virtual gear positions, and when the gear position is switched, the relationship between the accelerator pedal operation amount and the virtual engine torque reproduced by the torque of the electric motor is switched.

[0005] If the shift device is designed to uniquely specify the gear position depending on the position of the stick, the gear position reproduced when switching to MT mode will also be uniquely determined according to the position of the stick. However, if the shift device is designed to specify the gear position relatively, that is, to instruct an upshift or downshift based on the current gear position, it is not possible to uniquely determine the gear position when switching from EV mode, in which no virtual gear position is set, to MT mode. Therefore, selecting the gear position becomes an issue. [Means for solving the problem]

[0006] The present disclosure relates to an electric vehicle having an electric motor as a drive source. The electric vehicle includes a control device that controls the electric motor, a first indicator that issues continuous instructions to the control device in accordance with an operation amount, and a second indicator that issues discrete instructions to the control device for each operation. The control device executes the following processes. The first process is to determine the torque of the electric motor in accordance with the operation amount of the first indicator when controlling the electric motor in a first mode in which operation of the second indicator is invalid. The second process is to switch the relationship between the operation amount of the first indicator and the torque of the electric motor from among multiple predetermined relationships in accordance with operation of the second indicator when controlling the electric motor in a second mode in which operation of the second indicator is valid. The third process is to select the relationship between the operation amount of the first indicator and the torque of the electric motor from among the multiple predetermined relationships in accordance with the vehicle speed of the electric vehicle when switching from the first mode to the second mode. [Effects of the Invention]

[0007] According to the electric vehicle of the present disclosure, when the vehicle is switched from a first mode (EV mode) in which operation of the second indicator is disabled to a second mode (MT mode) in which operation of the second indicator is enabled, the relationship between the operation amount of the first indicator and the torque of the electric motor is selected from a plurality of predetermined relationships in accordance with the vehicle speed. The plurality of predetermined relationships corresponds to a plurality of virtually set gear positions. In other words, according to the electric vehicle of the present disclosure, when the vehicle is switched from the EV mode to the MT mode, a virtual gear position is automatically selected in accordance with the vehicle speed. As a result, even if the shift device is a device that relatively specifies the gear position and the driver cannot uniquely specify the gear position using the shift device, the gear position when switching to the MT mode can be set to an appropriate gear position that matches the driving conditions. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a configuration of an electric vehicle according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a diagram illustrating an example of a relative indication type shift device. [Figure 3] FIG. 10 is a diagram showing another example of a relative indication type shift device. [Figure 4] FIG. 10 is a diagram showing yet another example of a relative indication type shift device. [Figure 5] FIG. 10 is a diagram showing yet another example of a relative indication type shift device. [Figure 6] FIG. 2 is a diagram showing the configuration of a control device related to driving control of an electric vehicle. [Figure 7] 10 is a graph showing the relationship between vehicle speed and virtual engine speed. [Figure 8] 4 is a time chart showing how a gear position is selected in the first embodiment. [Figure 9] FIG. 10 is a graph for explaining selection of a gear position in a normal mode. [Figure 10] FIG. 10 is a graph for explaining selection of a gear position in a snow mode. [Figure 11] 10 is a time chart showing how a gear position is selected in the third embodiment. [Figure 12] 10 is a flowchart illustrating an example of a process related to selection of a gear position according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0010] 1. Electric vehicle power system configuration 1 is a diagram schematically illustrating the configuration of an electric vehicle 100 according to an embodiment of the present disclosure. First, the configuration of the power system of the electric vehicle 100 will be described with reference to FIG.

[0011] The electric vehicle 100 is equipped with two electric motors (M) 4F, 4R at the front and rear as a power source for driving. The electric motors 4F, 4R are, for example, three-phase AC motors. The front electric motor 4F is connected to a front drive shaft 5F that drives the front wheels 6F. The rear electric motor 4R is connected to a rear drive shaft 5R that drives the rear wheels 6R. The front wheels 6F are suspended by independent left and right electronically controlled front suspensions 7F. The rear wheels 6R are suspended by independent left and right electronically controlled rear suspensions 7R.

[0012] The front electric motor 4F and the rear electric motor 4R are respectively equipped with inverters (INV) 3F and 3R. The front inverter 3F and the rear inverter 3R are each connected to a battery (BATT) 2. The battery 2 stores electric energy to drive the electric motors 4F and 4R. In other words, the electric vehicle 100 is a battery electric vehicle (BEV) that runs on the electric energy stored in the battery 2. The inverters 3F and 3R are, for example, voltage-type inverters that control the torque of the electric motors 4F and 4R by PWM control. Note that the configuration shown in FIG. 1 is just one example, and the electric vehicle 100 may be a front-wheel drive vehicle equipped with one electric motor at the front, or a rear-wheel drive vehicle equipped with one electric motor at the rear.

[0013] 2. Electric vehicle control system configuration Next, the configuration of the control system of the electric vehicle 100 will be described with reference to FIGS.

[0014] The electric vehicle 100 is equipped with a vehicle speed sensor 11. At least one of wheel speed sensors (not shown) provided on each of the left and right front wheels 6F and the left and right rear wheels 6R is used as the vehicle speed sensor 11. The electric vehicle 100 is also equipped with an accelerator pedal stroke sensor 12. The accelerator pedal stroke sensor 12 is provided on the accelerator pedal 22 and outputs a signal indicating the depression amount of the accelerator pedal 22, i.e., the accelerator opening. The driver operates the accelerator pedal 22 continuously, and while the electric vehicle 100 is traveling, a signal indicating the accelerator opening is continuously sent to the control device 101. Note that the accelerator pedal 22 is a pedal-type device operated by foot, but the device for operating the accelerator may also be a device operated by hand. For example, the electric vehicle 100 may be equipped with a lever-type accelerator operating device or a dial-type accelerator operating device operated by hand instead of the accelerator pedal 22.

[0015] Furthermore, the electric vehicle 100 is equipped with a brake pedal stroke sensor 13. The brake pedal stroke sensor 13 is provided on the brake pedal 23 and outputs a signal indicating the depression amount of the brake pedal 23, i.e., the brake opening. The driver operates the brake pedal 23 continuously, and while the electric vehicle 100 is traveling, the signal indicating the brake opening is continuously sent to the control device 101.

[0016] The accelerator pedal 22 and the brake pedal 23 are driving operation members used to drive the electric vehicle 100. In addition to these driving operation members, the electric vehicle 100 is equipped with gearshift operation members for performing virtual gearshift operations that simulate the gearshift operations of a transmission vehicle. The gearshift operation members include a relative instruction type shift device 24 and a pseudo clutch pedal 25, which will be described below.

[0017] The relative command type shift device 24 is a device that allows the driver to perform gear shifting operations. The relative command type shift device 24 allows the gear position (gear stage) to be increased or decreased one stage at a time. For example, the relative command type shift device 24 allows the gear position to be changed in sequence from first to second to third, and so on. The driver selects the gear position they wish to specify by changing the gear positions in sequence. In other words, the relative command type shift device 24 is a device that relatively specifies the gear position. However, because the electric vehicle 100 does not have an actual transmission, the gear position specified by the relative command type shift device 24 is a virtual gear position.

[0018] There are no particular limitations on the structure of the relative indicator-type shift device 24, as long as it is a device that allows the driver to relatively indicate the gear position. Specific examples of the relative indicator-type shift device 24 are shown in Figures 2 to 5.

[0019] FIG. 2 shows a pseudo paddle shifter 24 simulating a paddle shifter, a type of sequential shifter, as an example of a relative instruction type shift device 24. The pseudo paddle shifter 24 is a dummy that is different from a real paddle shifter. The pseudo paddle shifter 24 has a structure similar to shift paddles attached to the steering wheel 26, and is capable of moving the left and right paddles independently. The pseudo paddle shifter 24 may be attached to the steering wheel or the steering column. (a) shows a pseudo paddle shifter simulating a paddle shifter attached to the steering wheel, and (b) shows a pseudo paddle shifter simulating a paddle shifter attached to the steering column. The pseudo paddle shifter 24 is equipped with a shift switch 14. The shift switch 14 outputs an upshift signal when the right paddle is pulled, and outputs a downshift signal when the left paddle is pulled.

[0020] FIG. 3 shows another example of the relative indicator shift device 24, which is a button-type device mounted on the steering wheel 26. The button-type relative indicator shift device 24 is provided with the shift switch 14. The shift switch 14 outputs an upshift signal when the right button is pressed, and outputs a downshift signal when the left button is pressed. Note that the button-type relative indicator shift device 24 may be mounted in a location other than the steering wheel. For example, a button mounted on the center console may be used as the relative indicator shift device 24.

[0021] FIG. 4 shows a pseudo shift lever 24 that simulates a shift lever, which is a type of sequential shifter, as yet another example of a relative instruction type shift device 24. The pseudo shift lever 24 is a dummy that is different from an actual shift lever. (a) is an example of the pseudo shift lever 24 mounted on the center console, and (b) is an example of the pseudo shift lever 24 mounted on the steering column. The pseudo shift lever 24 is provided with a shift switch 14. The shift switch 14 outputs an upshift signal when the shift lever is moved toward the rear or upward, and outputs a downshift signal when the shift lever is moved toward the front or downward. The pseudo shift lever 24 may be provided in a location other than the center console or the steering column.

[0022] FIG. 5 shows yet another example of the relative command shift device 24. For example, the relative command shift device 24 may be a toggle switch as shown in (a). When the driver pushes the knob back, the switch outputs an upshift signal, and when the driver pushes the knob forward, the switch outputs a downshift signal. Alternatively, the relative command shift device 24 may be a rotary switch as shown in (b). When the driver turns the knob to the right, the switch outputs an upshift signal, and when the driver turns the knob to the left, the switch outputs a downshift signal. These switches may be located anywhere inside the electric vehicle 100, as long as the driver can operate them from the driver's seat.

[0023] As yet another example, the relative instruction type shift device 24 may be a touch panel type, that is, a screen for selecting an upshift or downshift may be displayed on the touch panel.

[0024] The driver's operation of the relative instruction type shift device 24 as exemplified above is a discrete operation, and the relative instruction type shift device 24 (shift switch 14) outputs a signal indicating an upshift or downshift discretely each time the driver operates the relative instruction type shift device 24.

[0025] Referring again to FIG. 1, the pseudo clutch pedal 25 is a dummy that is different from an actual clutch pedal. The pseudo clutch pedal 25 has a structure similar to that of a clutch pedal provided in a conventional transmission vehicle. For example, the pseudo clutch pedal 25 is equipped with a reaction force mechanism that generates a reaction force in response to the driver's depression. The position when no depression force is applied to the pseudo clutch pedal 25 is the starting position of the pseudo clutch pedal 25, and the position when the pseudo clutch pedal is fully depressed is the ending position of the pseudo clutch pedal 25. The driver can operate the pseudo clutch pedal 25 from the starting position to the ending position against the reaction force from the reaction force mechanism. The pseudo clutch pedal 25 is equipped with a clutch pedal stroke sensor 15. The clutch pedal stroke sensor 15 outputs a signal indicating the amount of depression of the pseudo clutch pedal 25. Because the electric vehicle 100 does not have an actual clutch, the amount of operation of the pseudo clutch pedal 25, i.e., the clutch opening, is a virtual clutch opening.

[0026] Although the pseudo clutch pedal 25 is a pedal-type operating device operated by foot, a lever-type operating device or a dial-type operating device operated by hand may also be provided as the pseudo clutch operating device. The pseudo clutch operating device can be configured in a variety of ways as long as the driver can operate it from the start position to the end position against a reaction force and can provide the same feel as a clutch pedal provided in a conventional transmission vehicle with a foot or hand.

[0027] The electric vehicle 100 also has a human-machine interface (HMI) 20 as an interface with the driver, and an in-vehicle speaker 21. The HMI 20 has a touch panel display. The HMI 20 displays information on the touch panel display and accepts input from the driver via touch operations on the touch panel display. The information displayed on the touch panel display of the HMI 20 includes a virtual rotation speed of a virtual engine (hereinafter referred to as virtual engine speed), which will be described later. The in-vehicle speaker 21 provides information to the driver by voice and is also capable of outputting a pseudo engine sound, which will be described later.

[0028] The electric vehicle 100 is equipped with a control device 101. Sensors and devices to be controlled mounted on the electric vehicle 100 are connected to the control device 101 via an in-vehicle network. The electric vehicle 100 is equipped with various sensors in addition to a vehicle speed sensor 11, an accelerator pedal stroke sensor 12, a brake pedal stroke sensor 13, a shift switch 14, and a clutch pedal stroke sensor 15. For example, the electric vehicle 100 may be equipped with a recognition sensor such as a camera that recognizes the surroundings of the vehicle.

[0029] The control device 101 is typically an electronic control unit (ECU). The control device 101 may be a combination of multiple ECUs. The control device 101 includes at least a processor 102 and a memory 103. The memory 103 includes a RAM for temporarily storing data and a ROM for storing a program 104 executable by the processor 102 and various data 105 related to the program. The program 104 is made up of multiple instructions. The processor 102 reads and executes the program 104 and data 105 from the memory 103, and generates control signals based on signals acquired from each sensor. The control device 101 may include one or more processors 102.

[0030] The control device 101 can control the electric vehicle 100 in various control modes. The driver can select a control mode by touching the touch panel display of the HMI 20. More specifically, by touching the touch panel display of the HMI 20, one or more programs 104 associated with each touch operation are read from the memory 103 and executed by the processor 102. Below, we will explain the control modes of the electric vehicle 100 by the control device 101 that the driver can select by operating the HMI 20.

[0031] 3. Electric vehicle control mode The control modes of the electric vehicle 100 that can be selected by the control device 101 include at least the EV mode and the MT mode. The driver can select the control mode from a selection screen that is displayed on the touch panel display of the HMI 20.

[0032] When the EV mode is selected, the control mode of the electric vehicle 100 switches to the EV mode. The EV mode is a mode in which the electric motor is controlled with normal torque characteristics to drive the vehicle. In the EV mode, the gear shift operation of the relative command type shift device 24 and the clutch operation of the pseudo clutch pedal 25 are disabled. In the EV mode, the driver can basically drive the electric vehicle 100 by operating only the accelerator pedal 22, the brake pedal 23, and the steering wheel. Alternatively, in the EV mode, the driver may be able to select a mode that enables operation of the pseudo clutch pedal 25. In this case, at least the operation of the relative command type shift device 24 is also disabled.

[0033] When the MT mode is selected, the control mode of the electric vehicle 100 switches to the MT mode. The MT mode is a control mode for operating the electric vehicle 100 like a transmission vehicle. In the MT mode, the operation of the relative command type shift device 24 is enabled, and the operation when the gear ratio of a manual transmission is switched is reproduced by the gear shift operation of the relative command type shift device 24.

[0034] In the MT mode, the driver may be able to select a more detailed control mode. For example, the driver may be able to select a shift mode with or without clutch operation. In the clutch-operated shift mode, in addition to shifting gears using the relative instruction type shift device 24, the driver must also operate the clutch using the pseudo clutch pedal 25. On the other hand, in the clutch-less shift mode, the clutch operation is automatically performed by the robot. When the shift mode is switched to the clutch-less shift mode, the clutch operation using the pseudo clutch pedal 25 is disabled.

[0035] The driver may also be able to select options related to engine characteristics, engine sound, drive mode, suspension characteristics, number of gear positions, etc. By appropriately combining these options, the driver can determine the characteristics of a transmission vehicle that he or she wants electric vehicle 100 to simulate. In this way, by operating the touch panel display of HMI 20, the control mode of electric vehicle 100 can be switched to suit the driver's preferences.

[0036] In addition, the electric vehicle 100 may be provided with a mode changeover switch for switching between the EV mode and the MT mode, and the driver may be able to switch between the EV mode and the MT mode by pressing the mode changeover switch instead of operating the display screen of the touch panel display.

[0037] Such control modes that can be switched by the driver relate to the driving control of the electric vehicle 100. In the next chapter, the driving control of the electric vehicle 100 by the control device 101 will be described.

[0038] 4. Electric vehicle driving control Fig. 6 is a diagram showing the configuration of a control device 101 related to driving control of an electric vehicle 100. In detail, Fig. 6 shows the configuration particularly related to torque control among driving control. One or more driving control programs 104 stored in a memory 103 are executed by a processor 102, causing the processor 102 to function as a driving control device.

[0039] A control mode signal is input from the HMI 20 to the control device 101, which functions as a driving control device. The control mode signal includes information about the control mode selected by the driver. The control device 101 executes process P110 based on the control mode signal. In process P110, the control mode is switched in accordance with the control mode signal. The control mode switching that particularly affects driving control is the switch between EV mode and MT mode.

[0040] When the control mode is switched to EV mode, the control device 101 executes process P120 for torque calculation in EV mode. In process P120, the control device 101 obtains the vehicle speed from the signal of the vehicle speed sensor 11 and obtains the accelerator opening from the signal of the accelerator pedal stroke sensor 12. The control device 101 has a motor torque map that uses the accelerator opening and vehicle speed as parameters. The control device 101 inputs the vehicle speed and accelerator opening into the motor torque map and controls the inverters 3F, 3R so that the electric motors 4F, 4R generate the torque obtained from the motor torque map.

[0041] When the control mode is switched to MT mode, the control device 101 executes process P130 for calculating torque in MT mode. Process P130 includes process P131 for calculating torque to be generated at the drive wheels. Process P130 also includes process P132 and process P133. Process P132 is for calculating torque to be generated at the front electric motor 4F, and process P133 is for calculating torque to be generated at the rear electric motor 4R. Processes P132 and P133 are executed in accordance with the drive wheel torque calculated in process P130 and the torque distribution between the front wheels 6F and the rear wheels 6R.

[0042] A vehicle model MOD01 is used to calculate the drive wheel torque in process P131. The vehicle model MOD01 includes an engine model MOD11, a clutch model MOD12, and a transmission model MOD13. The engine virtually realized by the vehicle model MOD01 is called a virtual engine, the clutch virtually realized is called a virtual clutch, and the transmission virtually realized is called a virtual transmission. The engine model MOD11 models the virtual engine. The clutch model MOD12 models the virtual clutch. The transmission model MOD13 models the virtual transmission.

[0043] The engine model MOD11 calculates a virtual engine speed and a virtual engine torque. The virtual engine speed is calculated from the vehicle speed, the overall reduction ratio, and the slip ratio of the virtual clutch. The virtual engine torque is calculated from the virtual engine speed and the accelerator opening. The vehicle speed is obtained from a signal from the vehicle speed sensor 11. The accelerator opening is obtained from a signal from the accelerator pedal stroke sensor 12. The overall reduction ratio is a value obtained by multiplying the gear ratio of the virtual transmission by the reduction ratio determined by the mechanical structure from the virtual transmission to the drive wheels. In the engine model MOD11, the relationship between the virtual engine speed and the virtual engine torque is specified for each accelerator opening. Note that the engine characteristics of the engine model MOD11 may be selectable by the driver by operating the HMI 20.

[0044] The clutch model MOD12 calculates a torque transmission gain. The torque transmission gain is a gain used to calculate the degree of torque transmission of the virtual clutch according to the clutch opening. When the clutch operation shift mode is selected as the shift mode, the clutch opening is obtained from the signal of the clutch pedal stroke sensor 15. The clutch opening is 0% at the start position of the pseudo clutch pedal 25 and 100% at the end position of the pseudo clutch pedal 25. The clutch model MOD12 assigns a torque transmission gain to the clutch opening. The torque transmission gain is converted into the clutch torque capacity of the virtual clutch, i.e., the virtual clutch torque capacity. Then, based on a comparison between the virtual clutch torque capacity and the virtual engine torque calculated by the engine model MOD11, the virtual clutch torque input from the virtual clutch to the virtual transmission is calculated. The clutch model MOD12 also calculates a slip ratio by subtracting the torque transmission gain from 1. The slip ratio is used to calculate the virtual engine speed in the engine model MOD11.

[0045] When the clutch operation-less shift mode is selected as the shift mode, the clutch opening input to the clutch model MOD12 is calculated using a clutch operation model. The clutch operation model is a model that simulates the clutch operation of a model driver. The clutch operation model receives as input the vehicle speed, virtual engine speed, and a signal from the shift switch 14 (relative instruction type shift device 24).

[0046] The signal from the shift switch 14 is used to determine the timing of clutch operation. When a gear change operation by the driver is detected by the signal from the shift switch 14, the clutch operation model maximizes the clutch opening so as to disengage the virtual clutch. The vehicle speed and virtual engine speed are used to calculate the clutch opening. The clutch operation model calculates the clutch opening based on the rotational speed difference between the rotational speed of the input shaft of the virtual transmission, which is calculated from the vehicle speed, and the virtual engine speed, so that the rotational speed of the input shaft of the virtual transmission smoothly matches the virtual engine speed.

[0047] The transmission model MOD13 calculates a virtual gear ratio. The virtual gear ratio is a gear ratio determined by the virtual gear position in the virtual transmission. A virtual gear ratio is set for each gear position. The largest virtual gear ratio is set for first gear, and the virtual gear ratios decrease in the order of second gear, third gear, fourth gear, and so on. The gear position is increased by one step when an upshift signal from the shift switch 14 is received, and the gear position is decreased by one step when a downshift signal from the shift switch 14 is received. There are no physical restrictions on the number of gear positions instructed by the relative instruction shift device 24. Therefore, the number of gear positions may be variable, and different transmission models MOD13 may be used depending on the number of gear positions.

[0048] The transmission model MOD13 calculates a virtual transmission torque using the virtual gear ratio and the virtual clutch torque. The virtual transmission torque is a virtual torque output from the virtual transmission. The control device 101 controls the inverters 3F, 3R so that the output torque of the electric motors 4F, 4R changes according to the virtual transmission torque. The virtual transmission torque changes discontinuously according to the switching of the virtual gear ratio. This discontinuous change in the virtual transmission torque generates a torque shock in the electric vehicle 100, creating the appearance of a vehicle equipped with a stepped transmission.

[0049] The vehicle model MOD01 calculates the drive wheel torque from the virtual transmission torque and the reduction ratio. The drive wheel torque is the sum of the torques acting on the left and right front wheels 6F and the left and right rear wheels 6R. The torque distribution between the front wheels 6F and the rear wheels 6R can be fixed or can be changed actively or passively. For example, the driver may be able to select a four-wheel drive mode in which all four wheels are driven or a rear-wheel drive mode in which only the rear wheels are driven.

[0050] The vehicle model MOD01 is determined in advance. The relationship between the drive wheel torque calculated based on the vehicle model MOD01 and the accelerator pedal position changes when the virtual gear position is switched. In other words, when an arbitrary gear position is selected, the relationship between the accelerator pedal position and the torque output from the electric motors 4F, 4R is set to a relationship corresponding to the selected gear position from among multiple relationships determined in advance by the vehicle model MOD01.

[0051] In process P132, the torque of the front electric motor 4F in the MT mode (front motor torque) is calculated by multiplying the drive wheel torque calculated in process P131 by the torque distribution rate to the front wheels 6F and the reduction ratio from the output shaft of the front electric motor 4F to the front wheels 6F. The control device 101 controls the front inverter 3F so that the front electric motor 4F generates the front motor torque calculated in process P132.

[0052] In process P133, the torque of the rear electric motor 4R in MT mode (rear motor torque) is calculated by multiplying the drive wheel torque calculated in process P131 by the torque distribution rate to the rear wheels 6R and the reduction ratio from the output shaft of the rear electric motor 4R to the rear wheels 6R. The control device 101 controls the rear inverter 3R so that the rear electric motor 4R generates the rear motor torque calculated in process P133.

[0053] If the electric vehicle 100 is a front-wheel drive vehicle, the drive wheel torque calculated in process P131 is the sum of the torques acting on the left and right front wheels 6F. Alternatively, if the electric vehicle 100 is a rear-wheel drive vehicle, the drive wheel torque calculated in process P131 is the sum of the torques acting on the left and right rear wheels 6R.

[0054] 5. Sound control for electric vehicles The control device 101 may also perform sound control to control the sound emitted from the in-vehicle speaker 21. The processor 102 functions as a sound control device by executing one or more sound control programs 104 stored in the memory 103. The processor 102 functioning as the torque control device and the processor 102 functioning as the sound control device may be separate processors or may be the same processor.

[0055] The control device 101 as a sound control device can emit artificially generated sounds from the in-vehicle speaker 21. One of the artificial sounds is a pseudo engine sound that resembles the engine sound of a conventional internal combustion engine vehicle. When a control mode signal indicating that the MT mode has been selected is input from the HMI 20, the control device 101 as a sound control device generates the pseudo engine sound based on the virtual engine torque and virtual engine speed calculated in process P131.

[0056] When the driver can select an engine sound, the engine sound selected by the HMI 20 is used as the sound source of the pseudo engine sound to be generated from the in-vehicle speaker 21. However, the sound of the sound source is not used as is; the sound pressure of the engine sound is calculated so that the greater the virtual engine torque, the greater the sound pressure, and the frequency of the engine sound is calculated so that the greater the virtual engine speed, the higher the frequency. Then, for example, the sound pressure of the sound source is changed by an amplifier, and the frequency of the sound source is changed by a frequency modulator, and the pseudo engine sound is reproduced from the in-vehicle speaker 21. The virtual engine torque and virtual engine speed change depending on the driver's accelerator operation, gear shift operation, and clutch operation. In this way, by changing the sound pressure and frequency of the pseudo engine sound in accordance with the virtual engine torque and virtual engine speed that change in accordance with the driver's operation, the driver can be given a sense of realism as if they were driving a vehicle with a real transmission.

[0057] 6. Gear position selection when switching control modes As described above, the driver of electric vehicle 100 can select either EV mode or MT mode as the control mode. In MT mode, the driver can drive electric vehicle 100 while performing gear changes, just as when driving a vehicle with a transmission. Here, we consider the setting of the gear position when the control mode is switched from EV mode to MT mode.

[0058] As mentioned above, the electric vehicle 100 does not have an actual transmission, and the gear position set in MT mode is merely a virtual gear position. Therefore, in EV mode, operation of the relative instruction type shift device 24 is disabled, and no gear position is set. Therefore, when the control mode is switched to MT mode, a new virtual gear position must be set.

[0059] If the shift device used by the driver to specify the virtual gear position uniquely specifies the gear position, the virtual gear position can be set to the gear position indicated by the shift device, and the setting of the gear position when switching is not an issue. For example, if the shift device is a device that simulates an H-type shifter and the physical positions of the stick correspond to each gear position, even when switching to MT mode, the virtual gear position is uniquely determined to the gear position corresponding to the position of the stick.

[0060] However, the relative instruction type shift device 24 is a device for specifying a gear position relatively based on the current gear position. Therefore, if a virtual gear position has not been set, it is not possible to specify a gear position using the relative instruction type shift device 24. Therefore, when switching to the MT mode, it is necessary to set a virtual gear position independently of the driver's instructions.

[0061] One possible method for setting the virtual gear position when switching is to always set it to the same gear position. For example, a method can be considered in which the gear position is always set to first gear when switching to MT mode. However, in this case, if the vehicle speed of the electric vehicle 100 is high, the virtual engine speed may become too high, which may result in driving performance that is not comfortable for the driver. Similarly, when a gear position other than first gear is set, the virtual engine output may fall outside the appropriate range.

[0062] Therefore, when switching from the EV mode to the MT mode, the control device 101 selects the virtual gear position according to the vehicle speed of the electric vehicle 100. Below, three embodiments of the selection of the virtual gear position by the control device 101 will be described.

[0063] 7. First embodiment In the first embodiment, the gear position that maximizes the virtual engine torque is selected according to the vehicle speed. FIG. 7 shows the relationship between the vehicle speed and the virtual engine speed for each of the virtual gear positions from first to sixth. In this way, the relationship between the vehicle speed and the virtual engine speed is determined in advance by the vehicle model MOD01 so as to be constant for each of the multiple virtual gear positions. Note that FIG. 7 is just an example, and the number of virtual gear positions may be more or less than six.

[0064] The relationship between the virtual engine speed and the virtual engine torque is also determined in advance by the vehicle model MOD01, and the electric motors 4F, 4R are controlled based on the results calculated using the vehicle model MOD01. Therefore, the gear position at which the virtual engine torque is maximized at a certain vehicle speed can be calculated based on the vehicle model MOD01. In the first embodiment, the virtual gear position calculated in this manner is selected.

[0065] The selected virtual gear position is the gear position where the relationship between the vehicle speed and the virtual engine speed is within the range indicated by the thick line. In other words, when the control mode is switched from EV mode to MT mode, if the vehicle speed is b or less, first gear is selected, if it is between bc, second gear is selected, if it is between cd, third gear is selected, if it is between de, fourth gear is selected, if it is between ef, fifth gear is selected, and if it is f or more, sixth gear is selected.

[0066] The selection of such a virtual gear position is shown in a time chart in Figure 8. At time T0, the EV mode is selected. At this point, the virtual gear position and virtual engine speed have not been determined.

[0067] At time T1, the driver operates the HMI 20 or presses the control mode selector switch to instruct a control mode changeover, and the control mode changes from EV mode to MT mode. At this time, the control device 101 selects a virtual gear position according to the vehicle speed. At time T1, the vehicle speed is between cd. Therefore, the control device 101 selects third gear, which is the virtual gear position that maximizes the virtual engine torque when the vehicle speed is between cd. The virtual engine speed is calculated based on the vehicle speed, the selected virtual gear position, and the clutch opening.

[0068] Thereafter, at time T2, the control mode is switched to EV mode. Then, at time T3, the control mode is switched back to MT mode. At this time, the vehicle speed is between bc. Therefore, the control device 101 selects second speed, which is the virtual gear position at which the virtual engine torque is maximized when the vehicle speed is between bc. The virtual engine speed at this time is calculated based on the vehicle speed, the selected virtual gear position, and the clutch opening.

[0069] In this way, when switching to MT mode, the gear position that maximizes the virtual engine torque is selected. This ensures sufficient acceleration performance when switching to MT mode. Also, by selecting the gear position in this way, it is possible to prevent the virtual engine speed from being too high or too low when switching. These factors lead to improved drivability.

[0070] 8. Second embodiment Next, a second embodiment will be described. In the second embodiment, there are a plurality of drive modes within the MT mode, and the virtual gear position selected when switching the control mode differs depending on the drive mode.

[0071] Here, an example will be described in which there are three drive modes: sport mode, normal mode, and snow mode. However, these three drive modes are just an example, and there are no limitations on the number of drive modes or the method of selecting the virtual gear position in each mode.

[0072] Of the three drive modes, the sport mode is a mode for drivers who want quick acceleration and brisk driving. When the sport mode is selected, a virtual gear position that maximizes the virtual engine torque is selected according to the vehicle speed. The selected gear position is the same as in the first embodiment, and a gear position in which the relationship between the vehicle speed and the virtual engine speed is within the range indicated by the bold line in the graph of FIG. 7 is selected. Because a gear position that maximizes the virtual engine torque is selected, a driver who wants to accelerate quickly can obtain driving performance that is satisfactory.

[0073] In contrast, normal mode is a mode for drivers who want to avoid sudden acceleration and obtain a stable driving feel. In normal mode, a gear position that is one step faster than the virtual gear position selected in sport mode is selected. Figure 9 is a graph showing the virtual gear position selected when switching to MT mode in normal mode. In the graph, a gear position is selected where the relationship between vehicle speed and virtual engine speed is within the range indicated by the thick line. Note that if there is no gear position on the speed-up side, the same gear position as in sport mode is selected. In the graph of Figure 9, when the vehicle speed is equal to or higher than f, sixth gear is selected even in normal mode.

[0074] As a result of selecting the gear position in this way, the virtual engine torque when switching to MT mode is slightly smaller than the maximum torque range. This makes it possible to prevent the vehicle from accelerating too quickly. Furthermore, by selecting a gear position determined according to the vehicle speed, it is possible to prevent the virtual engine torque from becoming too small or the virtual engine speed from becoming too high when switching.

[0075] Furthermore, the snow mode is a mode suitable for slippery road surfaces such as snowy roads. In the snow mode, a gear position one step higher than the virtual gear position selected in the normal mode is selected. Figure 10 is a graph showing the virtual gear positions selected when switching to the MT mode in the snow mode. In the graph, a gear position is selected where the relationship between the vehicle speed and the virtual engine speed is within the range indicated by the bold line. Note that if no gear position is available for higher speeds, the same gear position as in the normal mode is selected. In the graph of Figure 10, when the vehicle speed is equal to or higher than e, sixth gear is selected in the snow mode. As a result of selecting such a gear position, the virtual engine torque when switching to the MT mode is even smaller than the torque in the normal mode. This reduces the vehicle's acceleration force, improves controllability, and reduces the risk of slipping on snowy roads. Furthermore, selecting a gear position determined according to the vehicle speed prevents the virtual engine torque from becoming too small and the virtual engine speed from becoming too large.

[0076] As described above, in the second embodiment, multiple drive modes are selectable, and the gear position selected according to the vehicle speed is set to vary depending on the drive mode. In this way, the gear position can be selected for each drive mode so that the virtual engine torque is suited to the situation. Furthermore, in any drive mode, the selected gear position is determined according to the vehicle speed, so the virtual engine speed and virtual engine torque after switching can be quantified relative to the vehicle speed. This prevents the virtual engine torque from becoming too small or the virtual engine speed from becoming too high.

[0077] The three drive modes may be selectable by the driver. For example, the driver may be able to set the drive mode through the HMI 20 before starting to drive the electric vehicle 100. Alternatively, the three drive modes may be automatically selected by the control device 101. For example, the control device 101 may acquire the state of the road surface on which the electric vehicle 100 is driving using a camera, and automatically select the snow mode when it is determined that the electric vehicle 100 is driving on a road surface with low friction.

[0078] 9. Third embodiment A third embodiment will be described. The third embodiment can be combined with the first or second embodiment. In the third embodiment, when the vehicle speed of the electric vehicle 100 is 0 in MT mode, that is, when the electric vehicle 100 is stopped, neutral is selected as the gear position. By selecting neutral, it is possible to prevent the virtual engine from stalling while the vehicle is stopped. Furthermore, when the electric vehicle 100 is switched from EV mode to MT mode while stopped, neutral is also selected as the gear position.

[0079] 11 is a time chart showing how the gear position is selected in the third embodiment. At time T0, the EV mode is selected. At time T1, the driver operates the HMI 20 or presses the control mode selector switch to select the MT mode. At this time, the electric vehicle 100 is stopped, that is, the vehicle speed is 0. Therefore, the control device 101 selects neutral as the gear position when switching the control mode to the MT mode at time T1.

[0080] In EV mode, the virtual engine speed is not calculated. Therefore, while the control mode is in EV mode, that is, until time T1, the virtual engine speed is not displayed on the HMI 20. In other words, the display on the HMI 20 is disabled. Then, when the control mode is switched to MT mode at time T1, the virtual engine speed is displayed on the HMI 20. The virtual engine speed at this time is set to the idle speed. The idle speed is determined in advance, for example, according to the engine characteristics to be simulated.

[0081] After that, at time T2, the driver selects EV mode, and the control mode is switched to EV mode. Then, at time T3, the driver selects MT mode again, and the control mode is switched to MT mode. At this time, as at time T1, the vehicle speed is 0, so the neutral gear position is selected. The virtual engine speed displayed on the HMI 20 is set to idle speed.

[0082] 10. Processing example 12 is a flowchart showing an example of processing by the control device 101. The series of processing shown in the flowchart is realized by the processor 102 executing the program 104. The series of processing is repeatedly executed at a predetermined control period, for example, while the electric vehicle 100 is running. Note that here, an example of processing in an embodiment that combines the first or second embodiment with the third embodiment is shown.

[0083] In step S101, processor 102 determines whether the driver has instructed to switch to MT mode. Processor 102 determines that a switch has been instructed when, for example, the driver operates a screen displayed on the touch panel display of HMI 20 to select a control mode switch. Alternatively, processor 102 may determine that a switch has been instructed when the driver presses a mode change switch. If a switch to MT mode has been instructed (step S101; Yes), the process proceeds to step S102. If a switch to MT mode has not been instructed (step S101; No), the current process ends.

[0084] In step S102, the processor 102 acquires the vehicle speed of the electric vehicle 100. The vehicle speed is acquired from the vehicle speed sensor 11. Once the vehicle speed is acquired, the process proceeds to step S103.

[0085] In step S103, the processor 102 determines whether the electric vehicle 100 is moving. Whether the electric vehicle 100 is moving can be determined from the vehicle speed. That is, if the vehicle speed is 0, the electric vehicle 100 is determined to be stopped, and if the vehicle speed is greater than 0, the electric vehicle 100 is determined to be moving. Alternatively, the processor 102 may determine that the electric vehicle 100 is stopped if the vehicle speed is lower than a predetermined threshold, and may determine that the electric vehicle 100 is moving if the vehicle speed is equal to or greater than the threshold. If the electric vehicle 100 is moving (step S103; Yes), the process proceeds to step S104. If the electric vehicle 100 is stopped (step S103; No), the process proceeds to step S105.

[0086] In step S104, the processor 102 automatically selects a virtual gear position according to the vehicle speed. The method of selecting a virtual gear position according to the vehicle speed is as described in the first and second embodiments, and the virtual gear position is selected according to either of the embodiments. Once the virtual gear position is selected, the series of processes ends.

[0087] In step S105, the processor 102 sets the gear position to neutral. When the gear position is set to neutral, the series of processes ends. [Explanation of symbols]

[0088] 2 Battery, 3F Front inverter, 3R Rear inverter, 4F Front electric motor, 4R Rear electric motor, 5F Front drive shaft, 5R Rear drive shaft, 6F Front wheel, 6R Rear wheel, 7F Front suspension, 7R Rear suspension, 11 Vehicle speed sensor, 12 Accelerator pedal stroke sensor, 13 Brake pedal stroke sensor, 14 Shift switch, 15 Clutch pedal stroke sensor, 21 In-car speaker, 22 Accelerator pedal, 23 Brake pedal, 24 Relative indication type shift device, 25 Pseudo clutch pedal, 26 Steering, 100 Electric vehicle, 101 Control device, 102 Processor, 103 Memory, 104 Program, 105 Data

Claims

1. An electric vehicle having an electric motor as a drive source, a control device for controlling the electric motor; a first indicator that outputs continuous instructions to the control device in accordance with an operation amount; a second indicator that issues a discrete instruction to the control device for each operation, The control device determining a torque of the electric motor in accordance with an amount of operation of the first indicator when controlling the electric motor in a first mode in which operation of the second indicator is disabled; when controlling the electric motor in a second mode in which operation of the second indicator is valid, switching the relationship between the operation amount of the first indicator and the torque of the electric motor from among a plurality of predetermined relationships in accordance with the operation of the second indicator; when the first mode is switched to the second mode, selecting a relationship between an operation amount of the first indicator and a torque of the electric motor from among the plurality of predetermined relationships in accordance with a vehicle speed of the electric vehicle; configured to run An electric vehicle characterized by:

2. 2. The electric vehicle according to claim 1, The control device is further configured to select, when switching from the first mode to the second mode, a relationship in which the torque of the electric motor relative to the operation amount of the first indicator under the current vehicle speed is maximized from among the plurality of predetermined relationships. An electric vehicle characterized by:

3. 3. The electric vehicle according to claim 2, Further comprising a display for displaying a virtual rotation speed; each of the plurality of predetermined relationships includes a relationship between an operation amount of the first indicator and the virtual rotation speed; The control device Disabling the display on the indicator when controlling the electric motor in the first mode; When controlling the electric motor in the second mode, changing the virtual rotation speed displayed on the display device in accordance with an operation amount of the first indicator in accordance with a relationship selected from the plurality of predetermined relationships. When the first mode is switched to the second mode while the vehicle is stopped, a predetermined rotation speed is displayed on the display. An electric vehicle characterized by:

4. 2. The electric vehicle according to claim 1, the second mode further includes a plurality of modes, When the first mode is switched to the second mode, the relationship selected by the control device from among the plurality of predetermined relationships is different for each of the plurality of modes. An electric vehicle characterized by:

5. 5. The electric vehicle according to claim 4, Further comprising a display for displaying a virtual rotation speed; each of the plurality of predetermined relationships includes a relationship between an operation amount of the first indicator and the virtual rotation speed; The control device Disabling the display on the indicator when controlling the electric motor in the first mode; When controlling the electric motor in the second mode, changing the virtual rotation speed displayed on the display device in accordance with an operation amount of the first indicator in accordance with a relationship selected from the plurality of predetermined relationships. When the first mode is switched to the second mode while the vehicle is stopped, a predetermined rotation speed is displayed on the display. An electric vehicle characterized by:

6. The electric vehicle according to any one of claims 1 to 5, a plurality of predetermined relationships between the operation amount of the first indicator and the torque of the electric motor correspond to a plurality of virtual gear positions, each of which is a virtual gear position; The second indicator is an indicator for relatively designating the virtual gear position. An electric vehicle characterized by:

7. 7. The electric vehicle according to claim 6, The second indicator is a pseudo paddle shifter that simulates a paddle shifter of a transmission vehicle. An electric vehicle characterized by:

8. 7. The electric vehicle according to claim 6, The second indicator is a pseudo shift lever that simulates a shift lever of a transmission vehicle. An electric vehicle characterized by:

9. The electric vehicle according to any one of claims 1 to 5, The relationship between the operation amount of the first indicator and the torque of the electric motor in the second mode is predetermined so that the torque of the electric motor is smaller than the torque of the electric motor corresponding to the operation amount of the first indicator in the first mode. An electric vehicle characterized by:

10. The electric vehicle according to any one of claims 1 to 5, the first indicator is an accelerator pedal; The predetermined relationships are determined so as to replicate the relationship between accelerator pedal operation amount and engine torque for each of a plurality of gear ratios of a transmission vehicle. An electric vehicle characterized by:

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