Electric automobile and program for controlling the same

Abstract

To improve driving easiness of an electric automobile capable of reproducing shift operation of a manual shift type internal combustion engine.SOLUTION: This electric automobile comprises: an accelerator pedal; and a pseudo sequential shifter. The pseudo sequential shifter simulates a sequential shifter used for shift operation of a manual shift type internal combustion engine. The electric automobile executes a manual mode through selection of a driver. In the manual mode, the operation of the pseudo sequential shifter is associated with a virtual shift position which is a virtual shift position. In the manual mode, the opening of the accelerator pedal, the virtual shift position, and the speed of the electric automobile are associated with torque of an electric motor. The electric automobile automatically shifts down the virtual shift position in accordance with the speed of the electric automobile when the steering angle of a steering wheel becomes equal to or larger than a prescribed angle, during the execution of the manual mode.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a technique for controlling an electric vehicle having an electric motor as a drive source.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2021-151168 discloses a related art of an electric vehicle capable of pseudo-reproducing a manual shifting operation of a vehicle equipped with a manual transmission having an internal combustion engine as a power source (hereinafter referred to as a manual transmission type internal combustion engine vehicle) by controlling an electric motor. The driver of the electric vehicle can select a plurality of virtual gear stages (virtual shift positions) by a paddle switch or the like. The paddle switch is a shift device (hereinafter referred to as a pseudo-sequential shifter) that simulates a sequential shifter provided on the steering wheel.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the above prior art, a driver can experience a shifting operation of a manual transmission type internal combustion engine vehicle in an electric vehicle. At this time, the driver can select a virtual shift position that reproduces the shift position of the manual transmission type internal combustion engine vehicle by a pseudo-sequential shifter. However, when the pseudo-sequential shifter is provided on the steering wheel, if the steering wheel is largely steered to steer the electric vehicle, the positional relationship between the hand placed on the steering wheel and the pseudo-sequential shifter changes. Therefore, in a state where the steering angle of the steering wheel is large, it becomes difficult for the driver to smoothly operate the pseudo-sequential shifter.

[0005] The present disclosure has been made in view of the above problems. One object of the present disclosure is to enable a driver to select a mode in an electric vehicle capable of reproducing a shifting operation of a manual transmission internal combustion engine vehicle, in which the driver can experience the operation of a manual transmission internal combustion engine vehicle, and to provide an electric vehicle capable of improving the ease of driving in the mode.

Means for Solving the Problems

[0006] The present disclosure provides an electric vehicle having an electric motor as a drive source. The electric vehicle includes an accelerator pedal used for driving, a pseudo-sequential shifter, and a control device that controls the electric vehicle according to an operation of the accelerator pedal. The pseudo-sequential shifter is an operation member installed on a steering wheel that simulates a sequential shifter used for a shifting operation of a manual transmission internal combustion engine vehicle. The control device is configured to execute the following. The first is to execute a manual mode, which is one of the control modes, by the driver's selection. In the manual mode, an operation of the pseudo-sequential shifter is associated with a virtual shift position, which is a virtual shift position. Also, in the manual mode, the opening degree of the accelerator pedal, the virtual shift position, and the vehicle speed of the electric vehicle are associated with the torque of the electric motor. The second is to automatically downshift the virtual shift position according to the vehicle speed of the electric vehicle when the steering angle of the steering wheel becomes equal to or greater than a predetermined angle during the execution of the manual mode.

[0007] According to one aspect of the present disclosure, the pseudo-sequential shifter may be installed on the steering wheel. Alternatively, the pseudo-sequential shifter may be installed on the steering column.

[0008] Furthermore, the present disclosure provides a program for controlling an electric vehicle. The electric vehicle has an electric motor as a drive source, and includes an accelerator pedal used for driving, a pseudo-sequential shifter, and a control device for controlling the electric vehicle according to an operation of the accelerator pedal. The pseudo-sequential shifter is an operation member installed on the steering wheel that simulates a sequential shifter used for a shifting operation of a manual transmission internal combustion locomotive. The program causes a computer to execute the following. The first is to execute a manual mode, which is one of the control modes, by the driver's selection. In the manual mode, the operation of the pseudo-sequential shifter is associated with a virtual shift position, which is a virtual shift position. Also, in the manual mode, the opening degree of the accelerator pedal, the virtual shift position, and the vehicle speed of the electric vehicle are associated with the torque of the electric motor. The second is to automatically downshift the virtual shift position according to the vehicle speed of the electric vehicle when the steering angle of the steering wheel becomes equal to or greater than a predetermined angle during the execution of the manual mode.

Effect of the Invention

[0009] According to the electric vehicle of the present disclosure, when the steering angle of the steering wheel becomes equal to or greater than a predetermined angle in the manual mode, the virtual shift position is automatically downshifted according to the vehicle speed of the electric vehicle. That is, even when the steering angle of the steering wheel becomes large and it becomes difficult for the driver to operate the pseudo-sequential shifter, a downshift according to the vehicle speed is automatically performed. As a result, it becomes possible to perform a downshift without waiting until the steering angle of the steering wheel becomes small and it becomes easy for the driver to operate the pseudo-sequential shifter, and smooth acceleration becomes possible when the driver attempts to accelerate the electric vehicle again. In this way, drivability can be improved.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Mode for Carrying Out the Invention

[0011] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0012] 1. Configuration of the Power System of an Electric Vehicle FIG. 1 is a diagram schematically showing 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. 1.

[0013] The electric vehicle 100 is equipped with two electric motors (M) 4F and 4R at the front and rear as driving power sources. The electric motors 4F and 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 an electronically controlled front suspension 7F with independent left and right sides. The rear wheels 6R are suspended by an electronically controlled rear suspension 7R with independent left and right sides.

[0014] Inverters (INV) 3F and 3R are respectively attached to the front electric motor 4F and the rear electric motor 4R. The front inverter 3F and the rear inverter 3R are respectively connected to a battery (BATT) 2. The battery 2 stores electrical energy for driving the electric motors 4F and 4R. That is, the electric vehicle 100 is a battery electric vehicle (BEV) that runs on the electrical energy stored in the battery 2. The inverters 3F and 3R are, for example, voltage source inverters, and control the torque of the electric motors 4F and 4R by PWM control.

[0015] 2. Configuration of the control system of the electric vehicle Subsequently, the configuration of the control system of the electric vehicle 100 will be described with reference to FIGS. 1 to 3.

[0016] The electric vehicle 100 is equipped with a battery management system (BMS) 10. The battery management system 10 is a device that monitors the cell voltage, current, temperature, etc. of the battery 2. The battery management system 10 has a function of estimating the state of charge (SOC) of the battery 2.

[0017] The electric vehicle 100 is equipped with a vehicle speed sensor 11. At least one of the 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. Further, the electric vehicle 100 is 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, that is, the accelerator opening. Also, 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, that is, the brake opening. Furthermore, the electric vehicle 100 is equipped with a steering angle sensor 14. The steering angle sensor 14 is provided on the steering 24 and outputs a signal indicating the steering angle of the steering 24, that is, the rotation angle of the steering wheel.

[0018] The accelerator pedal 22, the brake pedal 23, and the steering 24 are driving operation members used for driving the electric vehicle 100. Separately from these driving operation members, the electric vehicle 100 is provided with a pseudo-shifting operation member that mimics the operation members used for the shifting operation of a manual transmission internal combustion engine vehicle. The pseudo-shifting operation member includes at least the following pseudo-sequential shifter 25.

[0019] In the present embodiment, the pseudo-sequential shifter 25 is provided on the steering 24. FIGS. 2 and 3 show an example of the pseudo-sequential shifter 25.

[0020] FIG. 2 shows a pseudo paddle shifter 51 attached to a steering wheel 41 as an example of the pseudo sequential shifter 25. The pseudo paddle shifter 51 is a dummy different from the original steering wheel-fixed paddle shifter which is a type of sequential shifter. The pseudo paddle shifter 51 consists of a pair of paddles having a structure imitating the shift paddles attached to the steering wheel, and the left and right paddles can be moved independently. Since the pseudo paddle shifter 51 is fixed to the steering wheel 41, when the steering wheel 41 rotates, the pseudo paddle shifter 51 also rotates together with the steering wheel 41.

[0021] The pseudo paddle shifter 51 is provided with a shift switch 15 (see FIG. 1). The shift switch 15 outputs an upshift signal when the right paddle is pulled and outputs a downshift signal when the left paddle is pulled. Alternatively, the left paddle may correspond to the upshift signal and the right paddle may correspond to the downshift signal. However, since the electric vehicle 100 does not have an actual transmission, the shift positions upshifted or downshifted by the signal from the shift switch 15 are virtual shift positions.

[0022] FIG. 3 shows a pseudo paddle shifter 52 attached to a steering column (steering shaft) 42 as an example of the pseudo sequential shifter 25. The pseudo paddle shifter 52 is a dummy different from the original steering column-fixed paddle shifter. The pseudo paddle shifter 52 consists of a pair of paddles having a structure imitating the shift paddles attached to the steering column, and the left and right paddles can be moved independently. Since the pseudo paddle shifter 52 is fixed to the steering column 42, the position of the pseudo paddle shifter 52 does not change even when the steering wheel 41 rotates.

[0023] The pseudo paddle shifter 52 is provided with a shift switch 15 (see FIG. 1). When the right paddle is pulled, an upshift signal is output from the shift switch 15, and when the left paddle is pulled, a downshift signal is output from the shift switch 15. Alternatively, the left paddle may correspond to the upshift signal and the right paddle may correspond to the downshift signal.

[0024] As yet another example, the pseudo sequential shifter 25 may be a button installed on the steering wheel 41. The buttons are provided, for example, one on each of the left and right sides of the steering wheel 41. When the right button is pressed, the shift switch 15 outputs an upshift signal, and when the left button is pressed, the shift switch 15 outputs a downshift signal.

[0025] Referring to FIG. 1 again, the electric vehicle 100 includes a human machine interface (HMI) 20 as an interface with the driver and an in-vehicle speaker 21. The HMI 20 includes a touch panel display. The HMI 20 displays information on the touch panel display and receives an input from the driver by a touch operation on the touch panel display. The in-vehicle speaker 21 provides information to the driver by voice and is capable of outputting a pseudo engine sound described later.

[0026] The electric vehicle 100 includes 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. In addition to the battery management system 10, the vehicle speed sensor 11, the accelerator pedal stroke sensor 12, the brake pedal stroke sensor 13, the steering angle sensor 14, and the shift switch 15, various other sensors are mounted on the electric vehicle 100.

[0027] 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 recording 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 composed of a plurality of instructions. The processor 102 reads the program 104 and the data 105 from the memory 103 and executes them, and generates a control signal based on the signals acquired from each sensor. The number of processors 102 included in the control device 101 may be one or more.

[0028] The control modes for the control device 101 to control the electric vehicle 100 include at least a plurality of modes including an automatic mode and a manual mode. The control mode can be selected by the driver himself / herself by touching the touch panel display of the HMI 20. 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. Hereinafter, the control modes of the electric vehicle 100 by the control device 101 that can be selected by the driver through the operation of the HMI 20, and the driving control and sound control of the electric vehicle 100 related to the control modes will be described.

[0029] 3. Control Modes of Electric Vehicle FIG. 4 is a tree diagram showing an example of the control modes of the electric vehicle 100 that can be selected by the control device 101. On the HMI 20, a selection screen is displayed on the touch panel display according to the control tree shown in FIG. 4.

[0030] On the initial screen of the HMI20, an option "Control Mode" OP100 is displayed. By selecting the option "Control Mode" OP100, options "Automatic Mode" OP110 and "Manual Mode" OP120 are displayed on the touch panel display. When the option "Automatic Mode" OP110 is selected, the control mode of the electric vehicle 100 switches to the automatic mode. The automatic mode is a control mode for driving the electric vehicle 100 as a normal BEV. In the automatic mode, the driver can basically drive the electric vehicle 100 only by operating the accelerator pedal 22, the brake pedal 23, and the steering wheel 41. In the automatic mode, the shift operation of the pseudo-sequential shifter 25 is disabled.

[0031] When the option "Manual Mode" OP120 is selected, the control mode of the electric vehicle 100 switches to the manual mode. The manual mode is a control mode for operating the electric vehicle 100 like a manual transmission internal combustion engine vehicle. In the manual mode, the driver performs a shift operation using the pseudo-sequential shifter 25. Then, the operation when the gear ratio of the manual transmission is switched is reproduced by the shift operation of the pseudo-sequential shifter 25. Incidentally, the clutch operation in a genuine sequential shift type manual transmission is automatically performed by a robot. Therefore, even in the manual mode of the electric vehicle 100, the clutch opening is automatically calculated. Since the electric vehicle 100 does not have a genuine clutch, the clutch opening calculated in the manual mode is a virtual clutch opening.

[0032] The manual mode may further include a plurality of control modes. The control modes selectable by the driver may include, for example, control modes related to drive modes such as four-wheel drive and rear-wheel drive, and control modes related to the types of engine sounds reproduced by the electric vehicle 100.

[0033] 4. Driving Control of Electric Vehicle FIG. 5 is a diagram showing the configuration of a control device 101 related to the driving control of the electric vehicle 100. Specifically, it shows the configuration related to torque control among the driving controls. One or more driving control programs 104 stored in the memory 103 are executed by the processor 102, whereby the processor 102 functions as a driving control device.

[0034] A control mode signal is input to the control device 101 as a driving control device from the HMI 20. The control mode signal includes information regarding the control mode selected by the driver. The control device 101 executes a process P110 based on the control mode signal. In the process P110, the control mode is switched according to the control mode signal. What particularly affects the driving control upon switching of the control mode is the switching between the automatic mode and the manual mode.

[0035] When the control mode is switched to the automatic mode, the control device 101 executes a process P120 for torque calculation in the automatic mode. In the process P120, the control device 101 acquires the vehicle speed from the signal of the vehicle speed sensor 11 and acquires the accelerator opening from the signal of the accelerator pedal stroke sensor 12. The control device 101 has a motor torque map using the accelerator opening and the vehicle speed as parameters. The control device 101 inputs the vehicle speed and the accelerator opening into the motor torque map, and controls the inverters 3F, 3R so as to generate the torque obtained from the motor torque map in the electric motors 4F, 4R.

[0036] When the control mode is switched to the manual mode, the control device 101 executes a process P130 for torque calculation in the manual mode. The process P130 includes a process P131 for calculating the torque to be generated at the drive wheels. Further, the process P130 includes processes P132 and P133. The process P132 is a process for calculating the torque to be generated in the front electric motor 4F, and the process P133 is a process for calculating the torque to be generated in the rear electric motor 4R. The processes P132 and P133 are executed according to the torque distribution between the drive wheel torque calculated in the process P130 and the front wheels 6F and the rear wheels 6R.

[0037] In the calculation of the driving wheel torque in process P131, vehicle model MOD01 is used. Vehicle model MOD01 includes engine model MOD11, clutch model MOD12, and transmission model MOD13. The engine virtually realized by 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. In engine model MOD11, the virtual engine is modeled. In clutch model MOD12, the virtual clutch is modeled. In transmission model MOD13, the virtual transmission is modeled.

[0038] Engine model MOD11 calculates the virtual engine speed and the 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 the signal of vehicle speed sensor 11. The accelerator opening is obtained from the signal of accelerator pedal stroke sensor 12. The overall reduction ratio is a numerical 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 driving wheels. In engine model MOD11, the relationship between the virtual engine speed and the virtual engine torque is defined for each accelerator opening. The engine characteristics of engine model MOD11 may be selectable by the driver through the operation of HMI20. For example, the engine characteristics may be selectable from among low and medium rotation type, high rotation type, and full range type.

[0039] Clutch model MOD12 calculates the torque transmission gain. The torque transmission gain is a gain for calculating the degree of torque transmission of the virtual clutch. In clutch model MOD12, the torque transmission gain is given with respect to the clutch opening. The clutch opening is calculated using the clutch operation model. The clutch operation model is a model that simulates the clutch operation of an exemplary driver. Signals from the vehicle speed, the virtual engine speed, and shift switch 15 are input to the clutch operation model.

[0040] The signal from the shift switch 15 is used to measure the timing of the clutch operation. When the driver's shift operation is detected by the signal from the shift switch 15, in the clutch operation model, the clutch opening is maximized to disengage the virtual clutch. The vehicle speed and the virtual engine speed are used in the calculation of the clutch opening. In the clutch operation model, the clutch opening is calculated based on the rotational speed difference between the rotational speed of the input shaft of the virtual transmission calculated from the vehicle speed and the virtual engine speed so as to smoothly match them.

[0041] The torque transmission gain calculated by the clutch model MOD12 is converted into the clutch torque capacity of the virtual clutch, that is, the virtual clutch torque capacity. And based on the 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. Also, in the clutch model MOD12, the value obtained by subtracting the torque transmission gain from 1 is calculated as the slip ratio. The slip ratio is used in the calculation of the virtual engine speed in the engine model MOD11.

[0042] The transmission model MOD13 calculates the virtual gear ratio. The virtual gear ratio is the gear ratio determined by the virtual shift position in the virtual transmission. The virtual gear ratio is set for each virtual shift position. The maximum virtual gear ratio is set for the first gear, and the virtual gear ratio is decreased in the order of the second gear, the third gear, the fourth gear, ···. The virtual shift position is shifted up one step when receiving the upshift signal of the shift switch 15, and shifted down one step when receiving the downshift signal of the shift switch 15. Note that there is no physical constraint on the number of shift positions determined by the pseudo-sequential shifter 25. Therefore, for example, the driver may be able to arbitrarily set the number of shift positions through the HMI20.

[0043] The transmission model MOD13 calculates the virtual transmission torque using the virtual gear ratio and the virtual clutch torque. The virtual transmission torque is the virtual torque output from the virtual transmission. The control device 101 controls the inverters 3F and 3R so that the output torques of the electric motors 4F and 4R change 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 feel of a vehicle equipped with a stepped transmission.

[0044] The vehicle model MOD01 calculates the drive wheel torque from the virtual transmission torque and the reduction ratio. The torque distribution between the front wheels 6F and the rear wheels 6R can be fixed or variable by controlling the electric motors 4F and 4R with the inverters 3F and 3R. When the four-wheel drive mode is selected as the drive mode, 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 to the front wheels 6F and the rear wheels 6R can be fixed or actively or passively changed. When the rear-wheel drive mode is selected as the drive mode, the drive wheel torque is the sum of the torques acting on the left and right rear wheels 6R.

[0045] In process P132, the torque of the front electric motor 4F (front motor torque) in the manual mode is calculated by multiplying the drive wheel torque calculated in process P131 by the torque distribution ratio 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 as to generate the front motor torque calculated in process P132 in the front electric motor 4F.

[0046] In process P133, the torque of the rear electric motor 4R (rear motor torque) in the manual mode is calculated by multiplying the drive wheel torque calculated in process P131 by the torque distribution ratio 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 as to generate the rear motor torque calculated in process P133 in the rear electric motor 4R.

[0047] Note that in the configuration shown in FIG. 5, the battery management system 10 and the brake pedal stroke sensor 13 are not necessarily required for the above-described travel control. However, when the switching of the control mode affects the SOC of the battery 2, the signal of the battery management system 10 may be used as information for determining whether or not to switch the control mode. Also, in a case where the operation method of the electric vehicle 100 changes significantly, such as switching between the automatic mode and the manual mode, it may be a condition for switching that the brake pedal 23 is depressed. In that case, the signal of the brake pedal stroke sensor 13 can be used as information for determining that the brake pedal 23 is depressed.

[0048] 5. Sound Control of Electric Vehicle FIG. 6 is a diagram showing the configuration of the control device 101 related to the sound control of the electric vehicle 100. By executing one or more sound control programs 104 stored in the memory 103 by the processor 102, the processor 102 functions as a sound control device. The processor 102 functioning as a torque control device and the processor 102 functioning as a sound control device may be separate processors or the same processor.

[0049] The control device 101 as a sound control device can generate artificially produced sounds from the in-vehicle speaker 21. One of the artificial sounds is a pseudo engine sound imitating the engine sound in a conventional internal combustion engine vehicle. When a control mode signal indicating that the manual mode has been selected from the HMI 20 is input, the control device 101 as a sound control device executes process P140. In process P140, a pseudo engine sound is generated based on the virtual engine torque and the virtual engine speed calculated in process P131.

[0050] In process P140, a predetermined engine sound is used as a sound source for the pseudo engine sound generated from the in-vehicle speaker 21. The type of engine sound may be selectable by the driver using the HMI 20, for example. However, in process P140, the sound of the sound source is not used as it is. In process P140, 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, for example.

[0051] Process P140 includes a process P141 for calculating the engine sound pressure and a process P142 for calculating the engine sound frequency. In process P141, the sound pressure of the pseudo engine sound is calculated from the virtual engine torque using the sound pressure map M11. The sound pressure map M11 is created such that the sound pressure increases as the virtual engine torque increases. In process P142, the frequency of the pseudo engine sound is calculated from the virtual engine speed using the frequency map M12. The frequency map M12 is created such that the frequency increases as the virtual engine speed increases. The virtual engine torque and the virtual engine speed change according to the driver's accelerator operation, shift operation, and clutch operation. By changing the sound pressure and frequency of the pseudo engine sound according to the changing virtual engine torque and virtual engine speed, a sense of reality can be given to the driver as if driving a real manual transmission internal combustion engine vehicle.

[0052] 6. First Embodiment - Pseudo Sequential Shifter Installed on the Steering Wheel 6-1. Automatic Downshift During Steering and Driving As described above, the driver of the electric vehicle 100 can experience the operation of a manual transmission internal combustion engine vehicle by operating the HMI 20 to switch the control mode to the manual mode. Even if only the operation feeling of a manual transmission internal combustion engine vehicle is simulated, it can provide sufficient enjoyment for the driver. However, while enabling the driver to experience the operation of a manual transmission internal combustion engine vehicle, it is considered to further improve the convenience.

[0053] As one of the scenarios where the driver may feel inconvenient, as shown in FIG. 7, consider a scenario where the electric vehicle 100 is traveling on a road surface with continuous curves such as a mountain road. In the first embodiment, a case where the pseudo-sequential shifter 25 is the pseudo-paddle shifter 51 installed on the steering wheel 41 is considered.

[0054] Suppose the electric vehicle 100 enters a curved road while maintaining a high vehicle speed when traveling on a straight section before the curve. At the time of entering the curved road, the virtual shift position is set to an upper-stage shift position, for example, the 5th or 6th speed, according to the vehicle speed. And assume that the driver reduces the vehicle speed of the electric vehicle 100 after entering the curved road. As the vehicle speed decreases, the virtual engine speed also decreases.

[0055] Considering accelerating again on a straight road surface after passing through a curve, it is desirable for the driver to lower the virtual shift position in advance according to the virtual engine speed. For a driver of a manual transmission internal combustion engine vehicle, usually, while using the loudness of the engine sound as a reference, the driver judges how much the engine speed has decreased. When the engine speed has decreased to a certain extent, a downshift is performed so that the shift position matches the engine speed and vehicle speed. The operation of the driver for an electric vehicle 100 that simulates the operation of a manual transmission internal combustion engine vehicle is basically the same. That is, as the vehicle speed decreases, the virtual engine speed gradually decreases, and the pseudo engine sound becomes smaller. Then, while using the loudness of the pseudo engine sound and the vehicle speed as references, the driver should consider downshifting the virtual shift position when the virtual engine speed has decreased to a certain extent.

[0056] However, at this time, the driver is turning the steering wheel 41 according to the curve of the road surface. Then, when the steering wheel 41 is turned, the pseudo paddle shifter 51 also rotates together, and its position changes.

[0057] FIG. 7 shows the state of rotation of the steering wheel 41. When the steering wheel 41 is turned and the rotation angle of the steering wheel 41 becomes large up to around 180° like the bottommost state, the left and right of the pseudo paddle shifter 51 are reversed, and the paddle on the left side corresponds to upshift and the paddle on the right side corresponds to downshift when viewed from the driver. Therefore, for the driver, there may be confusion as to which paddle corresponds to downshift, making the operation difficult. Also, when the rotation angle becomes large, the driver may change the way of holding the steering wheel 41. In that case, confusion is more likely to occur, and the operation may become difficult due to changing the way of holding the hand.

[0058] Thus, even if the driver attempts to downshift after entering a curved road, since the position of the pseudo paddle shifter 51 has changed, the driver may not be able to perform the operation as intended. In such a situation, it is possible to continue driving without downshifting, but it is smoother to accelerate after exiting the curved road if a downshift is performed before exiting the curved road. Therefore, in the electric vehicle 100 according to the present embodiment, when the virtual engine speed becomes equal to or lower than a predetermined speed while the steering angle of the steering 24 is large during driving in the manual mode, the virtual shift position is automatically downshifted according to the virtual engine speed. Note that the steering angle of the steering 24 can also be referred to as the rotation angle of the steering wheel 41.

[0059] FIG. 8 is a flowchart showing an example of a process executed by the electric vehicle 100. The process shown in the flowchart of FIG. 8 is realized by one or a plurality of driving control programs 104 stored in the memory 103 being executed by the processor 102.

[0060] According to the flowchart shown in FIG. 8, first, in step S101, it is determined whether the manual mode is selected as the control mode. If the manual mode is not selected, the flowchart ends.

[0061] When the manual mode is selected as the control mode, step S102 is executed. In step S102, it is determined whether the rotation angle of the steering wheel 41 is equal to or greater than a predetermined angle. The predetermined angle here is set in advance. If the rotation angle of the steering wheel is less than the predetermined angle, the flowchart ends.

[0062] When the rotation angle of the steering wheel 41 is equal to or greater than a predetermined angle, step S103 is executed. In step S103, it is determined whether the virtual engine speed is equal to or lower than a predetermined speed. In step S103, the processor 102 determines that the virtual engine speed is equal to or lower than the predetermined speed when the state where the virtual engine speed is equal to or lower than the predetermined speed continues for a certain period of time or more, and may determine that the virtual engine speed is higher than the predetermined speed when the state where the virtual engine speed is equal to or lower than the predetermined speed ends before a certain period of time has elapsed. When the virtual engine speed is higher than the predetermined speed, the flow ends.

[0063] When the virtual engine speed is equal to or lower than the predetermined speed, step S104 is executed. In step S104, the virtual shift position is downshifted to a shift position one step lower than the current shift position.

[0064] 6-2. Effect According to the above processing, when the virtual engine speed decreases while the steering 24 is being greatly steered during the running of the electric vehicle 100, an automatic downshift corresponding to the virtual engine speed is performed. The state where the steering 24 is being greatly steered occurs when the electric vehicle 100 travels along a curve or a turning angle. In such a state, it becomes difficult for the driver to grasp the position of the paddle corresponding to the downshift. However, since the downshift is automatically performed according to the virtual engine speed, smooth acceleration after passing through a curve or a turning angle can be enabled. In this way, the convenience for the driver can be improved.

[0065] Note that when the driver stops the electric vehicle 100 as it is on a curved road or the like, and it is not assumed that the electric vehicle 100 will be accelerated again, the downshift is not necessarily required. However, even in such a case, since the downshift does not have an adverse effect on the running of the electric vehicle 100, the above processing does not interfere with the driver.

[0066] 6-3. Predetermined Angle In step S102, the predetermined angle serving as the determination criterion is set to an angle close to 180°. When the rotation angle of the steering wheel 41 approaches 180°, the left and right sides of the pseudo paddle shifter 51 are reversed, making it difficult for the driver to grasp the position of the paddle. However, the predetermined angle may be set to, for example, 150° or 120°. Furthermore, based on 90° where the positions of the left and right paddles are reversed left and right with respect to the vertical line passing through the center of the steering wheel 41, when the rotation angle of the steering wheel 41 becomes 90° or more, it may be considered that the determination in step S102 is established.

[0067] 7. Second Embodiment - Pseudo Paddle Shifter Installed on the Steering Column The second embodiment is an embodiment in the case where the pseudo sequential shifter 25 is a pseudo paddle shifter 52 installed on the steering column 42. Similar to the first embodiment, consider a scenario where the driver reduces the amount of depression of the accelerator pedal 22 while the electric vehicle 100 is traveling on a curved road surface and the virtual engine speed decreases. Also in the second embodiment, there may arise a problem that downshifting cannot be smoothly performed in a scenario where the driver wants to downshift.

[0068] FIG. 9 shows the state when the steering wheel 41 rotates. The gray area surrounded by the dashed line is the position where the left hand is placed when the steering wheel 41 is in the initial position. Since it is fixed to the steering column 42, the position of the pseudo paddle shifter 52 itself does not change, but as the steering wheel 41 rotates, the positional relationship with the position of the hand changes, making it difficult for the driver to operate the pseudo paddle shifter 52. For example, when the rotation angle of the steering wheel 41 is around 90°, the position of the left hand moves away from the position of the left paddle of the pseudo paddle shifter 52, making it difficult to perform a downshift operation. As the rotation angle further increases, the position of the left hand and the position of the left paddle of the pseudo paddle shifter 52 become even farther apart. Although the driver may change the way of holding the steering wheel 41 as the rotation angle increases, even if there is a change in the way of holding, the positional relationship between the hand position and the pseudo paddle shifter 52 changes compared to when the steering wheel 41 is in the initial position, so it may become difficult to operate the pseudo paddle shifter 52. Therefore, also in the second embodiment, when the manual mode is selected in the electric vehicle 100 and the steering angle of the steering 24 becomes larger than a predetermined angle during traveling, the virtual shift position is automatically downshifted according to the virtual engine speed.

[0069] The process executed by the electric vehicle 100 can be represented by the flowchart of FIG. 8 in the same manner as in the first embodiment. The processes performed in steps S101 to S104 are the same as in the first embodiment. However, the predetermined angle used for the determination in step S102 is set to a smaller angle than in the case of the first embodiment. In the second embodiment, before the rotation angle of the steering wheel 41 reaches 90°, the position of the left hand moves away from the position of the left paddle of the pseudo paddle shifter 52, resulting in difficulty in operation for the driver to perform a downshift. The predetermined angle may be, for example, 80°.

[0070] Through such processing of the electric vehicle 100, even in a situation where the driver has difficulty operating the pseudo paddle shifter 52 due to an increase in the steering angle of the steering 24, an automatic downshift according to the virtual engine speed is performed. A state where the steering angle of the steering 24 increases occurs when the electric vehicle 100 is traveling through a curve or a turning angle, etc., but smooth acceleration after passing through the curve or turning angle can be enabled. In this way, the convenience for the driver can be improved.

[0071] 8. Timing of Downshift As described above, the automatic downshift according to the virtual engine speed by the electric vehicle 100 has been explained. It can also be said that the timing at which the automatic downshift is performed is determined according to the vehicle speed. Fig. 10 shows the relationship between the vehicle speed and the virtual engine speed of the electric vehicle 100. Also, the circles represented by the dotted lines indicate the switching timing of the virtual shift position when the automatic downshift is performed. In Fig. 10, the virtual shift position has five steps from the first gear to the fifth gear, but the number of steps of the shift position is an example. As shown in Fig. 10, if there is no operation of the pseudo sequential shifter 25 and the clutch opening is constant, the vehicle speed and the virtual engine speed under a certain shift position have a one-to-one correspondence. Therefore, it can also be said that the downshift timing determined by the virtual engine speed is determined by the vehicle speed corresponding to the shift position.

[0072] 9. Notification to the Driver The fact that the automatic downshift by the electric vehicle 100 has been performed may be notified to the driver by the HMI 20. For example, the current shift position may be displayed on the display of the HMI 20, and the driver may be able to know that the shift position has changed by looking at the display.

[0073] Alternatively, the fact that an automatic downshift has occurred may not be explicitly notified to the driver. When the virtual shift position changes due to a downshift, the virtual engine torque increases, causing the engine sound to increase discontinuously. Therefore, even without notification by display or the like, the driver can notice the automatic downshift.

Explanation of Signs

[0074] 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, 10 Battery Management System, 11 Vehicle Speed Sensor, 12 Accelerator Pedal Stroke Sensor, 13 Brake Pedal Stroke Sensor, 14 Steering Angle Sensor, 15 Shift Switch, 20 HMI, 21 In-vehicle Speaker, 22 Accelerator Pedal, 23 Brake Pedal, 24 Steering, 25 Pseudo Sequential Shifter, 41 Steering Wheel, 42 Steering Column, 51 Pseudo Paddle Shifter, 52 Pseudo Paddle Shifter, 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, an accelerator pedal used for driving the electric vehicle, a pseudo-sequential shifter installed on the steering wheel that simulates a sequential shifter used for gear shifting operations of a manual transmission internal combustion engine vehicle, and a control device that controls the electric vehicle according to an operation of the accelerator pedal, wherein the control device associates an operation of the pseudo-sequential shifter with a virtual shift position, which is a virtual shift position, according to a driver's selection, and executes a control mode that associates an opening degree of the accelerator pedal, the virtual shift position, and a vehicle speed of the electric vehicle with torque of the electric motor, and is configured to automatically downshift the virtual shift position according to the vehicle speed when a steering angle of the steering wheel becomes equal to or greater than a predetermined angle during execution of the control mode. An electric vehicle characterized by the above.

2. In the electric vehicle according to Claim 1, the pseudo-sequential shifter is installed on the steering wheel An electric vehicle characterized by the above.

3. In the electric vehicle according to Claim 1, the pseudo-sequential shifter is installed on the steering column An electric vehicle characterized by the above.

4. In the electric vehicle according to Claim 2, the pseudo-sequential shifter is a button installed on the steering wheel An electric vehicle characterized by the above.

5. In the electric vehicle according to Claim 2 or 3, the pseudo-sequential shifter is a pseudo-paddle shifter that simulates a paddle shifter An electric vehicle characterized by the above.

6. In the electric vehicle according to Claim 5, the pseudo-paddle shifter is a pair of paddles attached to the left and right of the steering wheel An electric vehicle characterized by the above.

7. In the electric vehicle according to any one of Claims 1 to 4, automatically downshifting the virtual shift position according to the vehicle speed means downshifting the virtual shift position in response to the vehicle speed decreasing and falling below the vehicle speed set for each of the virtual shift positions. An electric vehicle characterized by the above.

8. In the electric vehicle according to any one of Claims 1 to 4, The electric vehicle further includes a speaker that outputs a pseudo engine sound reproducing the engine sound of the manual transmission internal combustion engine vehicle inside the vehicle. During the execution of the control mode, the control device plays the pseudo engine sound from the speaker, and further associates the opening degree of the accelerator pedal, the virtual shift position, and the vehicle speed with the volume of the pseudo engine sound. The electric vehicle is characterized by the above.

9. In the electric vehicle according to any one of Claims 1 to 4, automatically downshifting the virtual shift position according to the vehicle speed includes changing the virtual shift position from the current shift position to a shift position one step lower according to the vehicle speed. The electric vehicle is characterized by the above.

10. A program for controlling the electric vehicle, comprising: an accelerator pedal used for driving the electric vehicle with an electric motor as a driving source; a pseudo sequential shifter installed on the steering wheel that simulates a sequential shifter used for the shifting operation of a manual transmission internal combustion engine vehicle; and a control device that controls the electric vehicle according to the operation of the accelerator pedal, executing a control mode in which, by the driver's selection, the operation of the pseudo sequential shifter is associated with a virtual shift position that is a virtual shift position, and the opening degree of the accelerator pedal, the virtual shift position, and the vehicle speed of the electric vehicle are associated with the torque of the electric motor; and automatically downshifting the virtual shift position according to the vehicle speed when the steering angle of the steering wheel becomes equal to or greater than a predetermined angle during the execution of the control mode. The program is characterized by causing a computer to execute the above.

Images