Electric vehicle

Abstract

The purpose of the present disclosure is to provide an electric vehicle that enables a driver to experience the operation of an MT vehicle and, at the same time, can maintain easiness at the time of starting. The electric vehicle is provided with an MT mode for controlling an electric motor so as to simulate the operation of a virtual vehicle provided with a virtual engine and a virtual clutch. The electric vehicle includes a pseudo clutch operation device and a control device communicably connected to the pseudo clutch operation device. In the MT mode, the control device reflects an instruction from the pseudo clutch operation device on the control of the electric motor. When the start condition of the electric vehicle is established, the control device starts the electric vehicle even when there is no instruction from the pseudo clutch operation device.

Description

electric vehicles

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

[0002] Japanese Patent No. 6787507 discloses a conventional technology relating to an electric vehicle that can simulate the manual gear shifting of a vehicle (MT vehicle) powered by an engine equipped with a transmission for manual gear shifting by the driver by controlling an electric motor. In this electric vehicle, the driver can switch between an MT mode (MT driving mode) in which the vehicle is driven with simulated manual gear shifting, and an EV mode (EV driving mode) in which the vehicle is driven as a regular EV, using a switch or the like.

[0003] Japanese Patent No. 6787507

[0004] According to the above-described conventional technology, a driver can select the MT mode in an electric vehicle and experience driving similar to that of a manual transmission vehicle (hereinafter referred to as an MT vehicle), which involves pseudo-manual shifting and clutch operation. However, if the behavior of an MT vehicle is perfectly reproduced in all situations, the driver will have to perform many operations. In particular, when starting, complex operations such as a half-clutch are required, and if the behavior of an MT vehicle is perfectly reproduced, the driver may find the operations cumbersome.

[0005] One object of the present disclosure is to provide an electric vehicle that allows the driver to experience operating a manual transmission vehicle while at the same time maintaining ease of starting.

[0006] The present disclosure relates to an electric vehicle with an MT mode that controls an electric motor to simulate the operation of a virtual vehicle equipped with a virtual engine and a virtual clutch. The electric vehicle includes a pseudo-clutch operation device and a control device communicably connected to the pseudo-clutch operation device. In the MT mode, the control device accepts instructions from the pseudo-clutch operation device and, when a start condition for the electric vehicle is met, starts the electric vehicle without an instruction from the pseudo-clutch operation device.

[0007] The electric vehicle disclosed herein has an MT mode in which the electric motor is controlled to simulate the operation of a virtual vehicle equipped with a virtual engine and a virtual clutch. In the MT mode in which the operation of a virtual vehicle equipped with a virtual engine and a virtual clutch is simulated, instructions from a pseudo clutch operating device are accepted and reflected in the control of the electric motor. This allows the driver to enjoy clutch operation as if driving a manual transmission vehicle. Furthermore, in the electric vehicle disclosed herein, when a start condition is met, the electric vehicle can be started without an instruction from the pseudo clutch operating device. This allows the driver to enjoy driving while simultaneously maintaining ease of starting.

[0008] FIG. 1 is a diagram illustrating a configuration of an electric vehicle according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a configuration of a control device related to driving control of the electric vehicle. FIG. 3 is a graph illustrating an example of a torque map that defines the relationship between virtual engine rotation speed and virtual engine torque. FIG. 4 is a graph illustrating another example of a torque map that defines the relationship between virtual engine rotation speed and virtual engine torque. FIG. 5 is a time chart for explaining control at start-up in a comparative example. FIG. 6 is a time chart for explaining control at start-up in a first example of start-up conditions. FIG. 7 is a time chart for explaining control at start-up in a second example of start-up conditions. FIG. 8 is a diagram illustrating a configuration of an electric vehicle according to a modified example. FIG. 9 is a diagram illustrating an example of a correspondence relationship between gear stages and virtual shift positions in a modified example.

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

[0010] 1. Configuration of the Power System of the 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.

[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.

[0013] 2. Configuration of the Control System of the Electric Vehicle The configuration of the control system of the electric vehicle 100 will now be described with reference to FIG.

[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 also has 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 degree. Although the accelerator pedal 22 is a pedal-type device operated by the foot, the device for operating the accelerator may 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. A sensor is also provided for each of these accelerator operating devices, and outputs a signal indicating the operation amount, i.e., the accelerator opening degree. The driver operates the accelerator operating device continuously, and a signal indicating the accelerator opening degree is continuously sent to the vehicle control device 101 while the electric vehicle 100 is traveling.

[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 amount of depression of the brake pedal 23, i.e., the brake opening degree.

[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 (shift operations) of an MT vehicle. The gearshift operation members include an absolute command type shift device 24 and a pseudo clutch operation device 25 described below.

[0017] The absolute command type shift device 24 is a device in which shift positions are associated with predetermined physical positions and the physical positions are selected by an operating member. The driver can directly select the desired shift position with a single operation. However, because the electric vehicle 100 does not have an actual transmission, the shift positions of the absolute command type shift device 24 are virtual shift positions.

[0018] One example of the absolute indication type shift device 24 is a pseudo-H-type shifter that simulates an H-type shifter. The pseudo-H-type shifter is a dummy that is different from an actual H-type shifter. The pseudo-H-type shifter has a structure that resembles a shift stick provided on a console, and can be moved along an H-shaped gate between shift positions. The pseudo-H-type shifter is provided with a shift position sensor 14. The shift position sensor 14 outputs a signal that indicates the shift position selected by the pseudo-H-type shifter.

[0019] The operation performed by the driver on the absolute command type shift device 24 is a discrete operation, and the absolute command type shift device 24 (shift position sensor 14) outputs a signal indicating the shift position discretely each time the driver performs an operation.

[0020] The pseudo clutch operating device 25 is a device for reproducing clutch operation in a manual transmission vehicle. One example of the pseudo clutch operating device 25 is a pseudo clutch pedal that simulates the clutch pedal of a manual transmission vehicle. The pseudo clutch pedal is a dummy that is different from an actual clutch pedal. The pseudo clutch pedal has a structure that resembles the clutch pedal provided in a conventional manual transmission vehicle. For example, the pseudo clutch pedal is equipped with a reaction force mechanism that generates a reaction force when the driver presses the pedal. The position when no pedal force is applied is the start position of the pseudo clutch pedal, and the position when the pseudo clutch pedal is pressed all the way down is the end position of the pseudo clutch pedal. The driver can operate the pseudo clutch pedal from the start position to the end position against the reaction force from the reaction force mechanism.

[0021] Alternatively, the pseudo clutch operating device 25 may be a lever-type operating device or a dial-type operating device that is operated by hand. The driver can also operate the lever-type or dial-type operating device provided as the pseudo clutch operating device 25 from the start position to the end position against a reaction force, allowing the driver to experience the same operating feel as the clutch pedal provided in a conventional MT vehicle.

[0022] The pseudo clutch operating device 25 is provided with a clutch sensor 15. The clutch sensor 15 outputs a signal indicating the amount of operation of the pseudo clutch operating device 25. The operation of the pseudo clutch operating device 25 by the driver is a continuous operation, and the signal indicating the amount of operation is continuously sent to the vehicle control device 101 while the electric vehicle 100 is running or stopped. If the pseudo clutch operating device 25 is a pseudo clutch pedal, the amount of depression of the pedal is obtained as the amount of operation of the pseudo clutch operating device 25. However, because the electric vehicle 100 does not have an actual clutch, the amount of operation of the pseudo clutch operating device 25, i.e., the clutch opening, is a virtual clutch opening.

[0023] 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 accepts input from the driver via touch operations on the touch panel display. While an MT mode (described later) is selected, the HMI 20 may display a meter that indicates a virtual engine rotation speed (described later). The in-vehicle speaker 21 provides information to the driver by voice and is also capable of outputting a simulated engine sound (described later).

[0024] The electric vehicle 100 is equipped with a vehicle control device 101. Sensors and devices to be controlled mounted on the electric vehicle 100 are connected to the vehicle control device 101 via an in-vehicle network. In addition to a vehicle speed sensor 11, an accelerator pedal stroke sensor 12, a brake pedal stroke sensor 13, a shift position sensor 14, and a clutch sensor 15, the electric vehicle 100 is also equipped with various other sensors.

[0025] The vehicle control device 101 includes at least a processor (processing circuit) 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 composed of a plurality of 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 vehicle control device 101 may include one or more processors 102 and memories 103.

[0026] The vehicle 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 vehicle control device 101 that the driver can select by operating the HMI 20.

[0027] 3. Control Modes of the Electric Vehicle The control modes of the electric vehicle 100 that can be selected by the vehicle control device 101 include at least the EV mode and the MT mode. The driver can select the control mode from a selection screen displayed on the touch panel display of the HMI 20.

[0028] 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 absolute command type shift device 24 and the clutch operation of the pseudo clutch operation device 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 (not shown).

[0029] 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 manual transmission vehicle. In the MT mode, the operation of the absolute command shift device 24 and the pseudo clutch operating device 25 is enabled. In the MT mode, the operation when the gear ratio of a manual transmission is switched is reproduced by the gear shift operation of the absolute command shift device 24, allowing the driver to perform a virtual gear shift operation. The MT mode, which involves gear shift operation by the driver, may be called a manual mode. In addition, in contrast to the manual mode, the EV mode may be called an automatic mode.

[0030] The absolute command type shift device 24 is not an essential component of the electric vehicle 100. The electric vehicle 100 does not have to be equipped with the absolute command type shift device 24, and the mode in which the operation of the pseudo clutch operation device 25 is disabled may be called the EV mode, and the mode in which the operation of the pseudo clutch operation device 25 is enabled may be called the MT mode.

[0031] Furthermore, 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 options related to engine characteristics, engine sound, drive mode, suspension characteristics, number of shift positions, etc. The idle rotation speed and idle control lower limit rotation speed, which will be described later, may be determined according to the engine characteristics. By appropriately combining these options, the driver can determine the characteristics of an MT vehicle that he or she wants the electric vehicle 100 to emulate. In this way, by operating the touch panel display of the HMI 20, the control mode of the electric vehicle 100 can be switched to suit the driver's preferences.

[0032] 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 vehicle control device 101 will be described.

[0033] 4. Cruise Control of Electric Vehicle Figure 2 shows the configuration of the vehicle control device 101 related to cruise control of the electric vehicle 100. In particular, Figure 2 shows the configuration related to motor control, which controls the torque of the electric motors 4F, 4R, among other cruise control functions. The processor 102 executes one or more motor control programs 104 stored in the memory 103, causing the processor 102 to function as a motor control device.

[0034] A control mode signal is input from the HMI 20 to the vehicle control device 101, which functions as a motor control device. The control mode signal includes information about the control mode selected by the driver. The vehicle 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.

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

[0036] When the control mode is switched to MT mode, the vehicle control device 101 executes process P130 for torque calculation in MT mode. Process P130 includes process P131 for calculating the torque to be generated at the drive wheels. Process P130 also includes process P132 and process P133. Process P132 is a process for calculating the torque to be generated at the front electric motor 4F, and process P133 is a process for calculating the 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.

[0037] 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 a virtual engine. The clutch model MOD12 models a virtual clutch. The transmission model MOD13 models a virtual transmission.

[0038] The engine model MOD11 calculates a virtual engine rotation speed and a virtual engine torque. The virtual engine rotation 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 rotation 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 numerical value obtained by multiplying the gear ratio of the virtual transmission by a 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 rotation speed and the virtual engine torque for each accelerator opening is defined by a torque map. Note that the engine characteristics of the engine model MOD11 may be selectable by the driver by operating the HMI 20.

[0039] According to the torque map described above, when the accelerator opening is zero, the virtual engine torque becomes negative, and the virtual engine rotation speed decreases. However, in order for the engine to maintain stable rotation, it is necessary to maintain a constant rotation speed. For this reason, in a real engine, idle control is performed in which the engine torque is controlled so that the engine rotation speed is maintained at an idle rotation speed. Therefore, the vehicle control device 101 may also perform idle control on the virtual engine, as described below.

[0040] The clutch model MOD12 calculates a torque transmission gain. The torque transmission gain is a gain for calculating the degree of torque transmission of the virtual clutch according to the clutch opening. The clutch opening is acquired from a signal from the clutch sensor 15. The clutch opening is 0% at the start position of the pseudo clutch operating device 25 and 100% at the end position of the pseudo clutch operating device 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. Furthermore, the clutch model MOD12 calculates a slip ratio by subtracting the torque transmission gain from 1. The slip ratio is used to calculate the virtual engine rotation speed in the engine model MOD11.

[0041] The transmission model MOD13 calculates a virtual gear ratio. The virtual gear ratio is a gear ratio in a virtual transmission that is determined by a virtual shift position. A virtual gear ratio is set for each shift position. The maximum 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 shift positions are in one-to-one correspondence with the signal from the shift position sensor 14.

[0042] 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 vehicle 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 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.

[0043] 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.

[0044] 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 shift position is switched. That is, in EV mode, the torque relative to the accelerator pedal position changes continuously, whereas in MT mode, the relationship between the accelerator pedal position and the torque output from the electric motors 4F, 4R is switched to a relationship corresponding to a selected shift position from among multiple relationships determined in advance by the vehicle model MOD01 when the virtual shift position is switched.

[0045] 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 vehicle control device 101 controls the front inverter 3F so that the front electric motor 4F generates the front motor torque calculated in process P132.

[0046] In process P133, the torque of the rear electric motor 4R in the 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 vehicle control device 101 controls the rear inverter 3R so that the rear electric motor 4R generates the rear motor torque calculated in process P133.

[0047] In other words, in the MT mode, the vehicle control device 101 processes the instruction from the accelerator pedal 22 as an acceleration request for the virtual engine, and processes the instruction from the pseudo clutch operating device 25 as the amount of operation of the virtual clutch. The vehicle control device 101 then controls the electric motors 4F and 4R in accordance with the amount of operation of the accelerator pedal 22 and the pseudo clutch operating device 25 by the driver. That is, in the MT mode, the vehicle control device 101 reflects the instruction from the pseudo clutch operating device 25 in the control of the electric motors 4F, 4R. In this way, the operation of a MT vehicle having an engine and a clutch is simulated by the electric vehicle 100.

[0048] 5. Sound Control of Electric Vehicle The vehicle control device 101 may also perform sound control to control the sound emitted by the in-vehicle speakers 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 a driving control device and the processor 102 functioning as a sound control device may be separate processors or may be the same processor.

[0049] The vehicle control device 101 as a sound control device can generate artificially generated sounds from the in-vehicle speakers 21. One of the artificial sounds is a pseudo engine sound that resembles the engine sound of a conventional manual transmission vehicle. When a control mode signal indicating that the manual transmission mode has been selected is input from the HMI 20, the vehicle control device 101 as a sound control device generates the pseudo engine sound based on the virtual engine torque and virtual engine rotation speed calculated in process P131.

[0050] 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 rotation 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 the virtual engine rotation speed change depending on the driver's accelerator operation, gear shift operation, and clutch operation. By changing the sound pressure and frequency of the pseudo engine sound in accordance with the virtual engine torque and virtual engine rotation speed, which change in accordance with the driver's operation, the driver can be given a sense of realism as if they were driving a real manual transmission vehicle.

[0051] 6. Start Control 6-1. Overview As described above, the driver of electric vehicle 100 can experience the operation of a manual transmission vehicle in electric vehicle 100 by operating HMI 20 to switch the control mode to manual transmission mode. This increases the driver's enjoyment of driving. On the other hand, in manual transmission mode, the driver must operate a gearshift operation member in addition to operating driving operation members such as the accelerator and brake, which makes operation cumbersome for the driver. Therefore, if the behavior of a manual transmission vehicle is faithfully reproduced in all situations, the driver, especially a driver who is not accustomed to driving a manual transmission vehicle, may find the operation cumbersome.

[0052] One situation where operation is particularly complicated for the driver is when starting. That is, when starting a manual transmission vehicle, a clutch operation that is more complicated than during steady driving, such as a so-called half-clutch, is required, and the driver may find such an operation troublesome. Therefore, in the electric vehicle 100 according to this embodiment, the vehicle control device 101 starts the electric vehicle 100 when a start condition is met, even if the driver has not operated the pseudo-clutch operating device 25. Specific examples of the start condition will be described later. This allows the driver to enjoy a driving experience similar to that of a manual transmission vehicle, while maintaining ease of starting.

[0053] As explained in Chapter 4, when the MT mode is selected, the engine model MOD11 calculates a virtual engine torque based on a torque map that defines the relationship between the virtual engine rotation speed and the virtual engine torque. This torque map is used to reproduce the torque characteristics of the virtual engine using the torque of the electric motors 4F, 4R. The torque map is set in advance and stored in the memory 103.

[0054] In order to realize the above-described start control, the following torque map may be used.

[0055] Figure 3 shows an example of a torque map used in the engine model MOD11. According to the torque map of Figure 3, the relationship between the virtual engine rotation speed and the virtual engine torque is defined for each accelerator position so as to reproduce the engine characteristics of the virtual engine in a region where the virtual engine rotation speed is equal to or higher than the idle control lower limit rotation speed. The idle control lower limit rotation speed is determined according to the engine characteristics of the selected virtual engine. Furthermore, in the torque map, in a region where the virtual engine rotation speed is equal to or lower than the idle control lower limit rotation speed, the relationship between the virtual engine rotation speed and the virtual engine torque for each accelerator position is defined so that the virtual engine torque approaches zero as the virtual engine rotation speed decreases.

[0056] In the example of FIG. 3 , the virtual engine torque is 0 when the virtual engine rotation speed is 0, but this does not necessarily have to be 0. The idle control lower limit rotation speed is set in advance according to the engine characteristics of the virtual engine. For example, the idle control lower limit rotation speed may be set to 500 rpm. If the driver can select the engine characteristics, the idle control lower limit rotation speed may be changed according to the engine characteristics selected by the driver.

[0057] Figure 4 shows another example of a torque map used by the engine model MOD11. When the driver is depressing the accelerator pedal 22, the torque map of Figure 4 may be used. In the example of Figure 4, in the region where the virtual engine rotation speed is equal to or higher than the idle control lower limit rotation speed, the relationship between the virtual engine rotation speed and the virtual engine torque is defined so as to simulate the engine characteristics of the virtual engine, as in the example of Figure 3. In the region where the virtual engine rotation speed is equal to or lower than the idle control lower limit rotation speed, the virtual engine torque for each accelerator opening is defined so that the torque is constant.

[0058] Alternatively, the virtual engine torque in the region where the virtual engine rotation speed is equal to or lower than the idle control lower limit rotation speed may be variable depending on the running resistance of electric vehicle 100. For example, the torque map of Fig. 3 and the torque map of Fig. 4 may be switched depending on the running resistance.

[0059] In a conventional manual transmission vehicle, engine torque is not output in the region where the virtual engine speed is equal to or lower than the idle control lower limit speed. By using the torque maps shown in Figures 3 and 4, torque is calculated by the engine model MOD11 even in this region and output as virtual engine torque.

[0060] That is, in the engine model MOD11, the relationship between the virtual engine rotation speed and the virtual engine torque is defined so as to reproduce the torque characteristics of the virtual engine in the range where the virtual engine rotation speed is equal to or higher than the idle control lower limit rotation speed. The relationship between the virtual engine rotation speed and the virtual engine torque is also defined in the range where the virtual engine rotation speed is equal to or lower than the idle control lower limit rotation speed. As a result, unlike an actual engine, the virtual engine realized by the engine model MOD1 can be controlled over the entire engine rotation speed range equal to or higher than zero.

[0061] 6-3. Time Chart The following describes in more detail the start control by the vehicle control device 101, using a time chart showing a scene in which the driver stops the electric vehicle 100 while it is running and then starts it again. Note that although the time chart described below does not show a virtual shift position, it is assumed that the virtual shift position is first gear from the beginning to the end of the time chart.

[0062] First, a comparative example will be described. Figure 5 shows a time chart for a case in which the behavior of a manual transmission vehicle is reproduced even when starting off. In this case, the driver must operate the pseudo clutch operating device 25 so as to reproduce the clutch operation of an actual manual transmission vehicle.

[0063] At time A when the time chart starts, the driver depresses the brake pedal 23 to stop the electric vehicle 100. The vehicle speed gradually decreases, and the virtual engine rotation speed also decreases accordingly. Furthermore, because the accelerator opening is 0%, the virtual engine torque is negative.

[0064] At time B, the virtual engine speed drops to the idle speed. To prevent the engine from stalling, the driver operates the pseudo clutch operating device 25 before the virtual engine speed drops to the idle speed, setting the clutch opening to 100%. Furthermore, as the virtual engine speed drops to the idle speed, the idle control is activated. When the idle control is activated, a virtual engine torque required to maintain the idle speed is output, reproducing the idle control of a conventional MT vehicle.

[0065] The idle rotation speed is preset according to the engine characteristics of the virtual engine. For example, the idle rotation speed may be set to 1000 rpm. If the driver can select the engine characteristics, the idle rotation speed may be changed according to the engine characteristics selected by the driver.

[0066] Because the clutch opening is maintained at 100%, the electric vehicle 100 stops at time D without stalling. Then, at time E, the driver starts the electric vehicle 100 again. To prevent the engine from stalling, the driver operates the pseudo clutch operation device 25 to gradually reduce the clutch opening, first achieving a so-called half-clutch state. At the same time, the driver depresses the accelerator pedal 22. As the accelerator opening increases, the virtual engine torque also increases. When the vehicle starts moving, the driver ends the operation that was being input to the pseudo clutch operation device 25 and sets the clutch opening to 0%. In this way, the operation for starting is completed.

[0067] Thus, if an attempt is made to completely simulate the operation of a manual transmission, the operations that the driver must perform when starting the vehicle become complicated. On the other hand, in the electric vehicle 100 according to this embodiment, when the start conditions are met, the vehicle control device 101 starts the electric vehicle 100 regardless of whether the driver operates the pseudo clutch operation device 25. In other words, the vehicle control device 101 temporarily cancels the MT mode before and after the electric vehicle 100 starts. During the MT mode cancellation period when the MT mode is temporarily cancelled, the operation of the pseudo clutch operation device 25 by the driver is ignored, and the start control of the electric vehicle 100 is performed using logic that is different from that used in the MT mode.

[0068] A first example of a starting condition is when the driver presses down on the accelerator. Figure 6 shows a time chart for when the electric vehicle 100 starts moving in response to the accelerator being pressed down. From the start to the end of the time chart, the driver does not operate the pseudo clutch operating device 25, and the virtual clutch is in an engaged state.

[0069] The movement from point A to point B is the same as in Figure 5. At point A, the driver depresses the brake pedal 23, and the brakes are applied. As the brakes are applied, the vehicle speed gradually decreases, and the virtual engine rotation speed also decreases accordingly. Because the accelerator opening is 0%, the virtual engine torque is negative. The negative virtual engine torque is reproduced by the regenerative torque of the electric motors 4F and 4R.

[0070] At point B, the virtual engine rotation speed falls below the idle rotation speed. Because the virtual clutch is engaged, if the virtual engine rotation speed continues to decrease, the engine will stall. Therefore, the vehicle control device 101 temporarily cancels the MT mode.

[0071] At time B, the virtual engine speed falls below the idle speed, and the idle control is activated. The idle control increases the virtual engine torque to maintain the idle speed. However, because the accelerator opening is 0%, an upper limit is imposed on the virtual engine torque to prevent an increase in driving force that is not intended by the driver.

[0072] However, the virtual engine torque that increases due to idle control is not reflected in the torque of the motors 4F, 4R. This is to prevent a sudden change in deceleration due to a sudden change in motor torque, and during this time, the motors 4F, 4R continue to output regenerative torque according to the vehicle speed.

[0073] As the vehicle speed decreases, the virtual engine rotation speed decreases, and eventually falls below the idle control lower limit rotation speed at point C. This state corresponds to an engine stall in a conventional manual transmission vehicle. When the virtual engine rotation speed falls below the idle control lower limit rotation speed, the idle control ends. At this time, the vehicle control device 101 may output a message indicating an engine stall state on the display of the HMI 20. However, to prevent the driver from feeling uncomfortable, the vehicle control device 101 does not bring the electric vehicle 100 to a sudden stop, but brings it to a gradual stop.

[0074] At time D, the electric vehicle 100 comes to a complete stop. Then, at time E, the driver turns on the accelerator, that is, depresses the accelerator pedal 22, and inputs an operation amount to the accelerator pedal 22. In response to the operation of the accelerator pedal 22, the vehicle control device 101 starts the electric vehicle 100.

[0075] At point D, the virtual engine rotation speed falls below the idle control lower limit rotation speed, i.e., a state equivalent to an engine stall. In a conventional manual transmission vehicle, this would require an operation to restart the engine. However, in the electric vehicle 100, such an operation is not required. When the driver depresses the accelerator pedal 22 and increases the accelerator opening, a virtual engine torque corresponding to the virtual engine rotation speed and accelerator opening is output according to the torque map described in the previous chapter (e.g., the torque map shown in FIG. 3 ), even if the virtual engine rotation speed is below the idle control lower limit rotation speed. In a conventional manual transmission vehicle, the region where the virtual engine rotation speed is below the idle control lower limit rotation speed is a region where no engine torque is output. However, by using the torque maps shown in FIGS. 3 and 4 , it is possible to calculate the virtual engine torque even in such a region. Note that during the MT mode release period, the driver's operation of the pseudo clutch operating device 25 is invalid. During this period, the amount of operation of the pseudo clutch operating device 25 is not reflected in the calculation of the virtual engine torque, and the virtual engine torque is calculated from the accelerator opening.

[0076] Torque based on the virtual engine torque is output from the motors 4F, 4R, and the vehicle begins to move forward. The MT mode release period ends, for example, when the vehicle speed of the electric vehicle 100 increases and reaches a predetermined speed. Alternatively, the MT mode release period may end when the virtual engine rotation speed exceeds the idle rotation speed. When the MT mode release period ends, control of the electric vehicle 100 in accordance with the control logic in MT mode is resumed. In this way, the electric vehicle 100 can be started without the driver operating the pseudo clutch operating device 25.

[0077] In the torque maps illustrated in FIGS. 3 and 4 , the torque in the region where the virtual engine rotation speed is equal to or lower than the idle control lower limit rotation speed can be set arbitrarily. However, it is desirable to set the torque so that the change in torque is continuous around the idle control lower limit rotation speed. It is also desirable to set the torque so that it approaches zero as the virtual engine rotation speed decreases, or so that the torque is constant. When the torque is set so that it approaches zero, the torque increases as the virtual engine rotation speed displayed on the display of the HMI 20 or represented by the pseudo engine sound increases, making it less likely that the occupants of the electric vehicle 100 will feel uncomfortable. Alternatively, when the torque is set so that it is constant or slightly approaches zero, torque is output even in a region where the vehicle speed of the electric vehicle 100 is extremely low, making it easier for the driver to start the vehicle.

[0078] Next, a second example of the starting condition will be described with reference to the time chart of Fig. 7. The second example of the starting condition is when the brake is released by the driver.

[0079] The operation from point A to point B is the same as in Fig. 6. The vehicle speed decreases as the driver depresses the brake pedal 23. The virtual engine torque becomes negative, and regenerative torque is output from the electric motors 4F and 4R.

[0080] At time B, when the virtual engine speed falls below the idle speed, the MT mode is temporarily canceled. In response to the virtual engine speed falling below the idle speed, the virtual engine torque is increased to the idle speed maintenance torque for maintaining the idle speed. Until electric vehicle 100 starts moving again, the virtual engine torque is maintained at the idle speed maintenance torque, and the virtual engine speed is maintained at the idle speed.

[0081] Furthermore, when the virtual engine rotation speed drops below the idle rotation speed, the torque output from the motors 4F, 4R is switched to creep torque. The creep torque output here simulates the torque generated by the creep phenomenon in an automatic transmission vehicle (hereinafter referred to as an AT vehicle). The output of creep torque allows for smoother starting.

[0082] Because the driver is depressing the brake pedal 23, the electric vehicle 100 eventually stops. Thereafter, at point D, the driver takes his or her foot off the brake pedal 23, releasing the brake. At this time, the driver is not operating the accelerator pedal 22, but torque equivalent to creep torque is being output from the electric motors 4F, 4R, so the vehicle begins to move forward. In this way, the electric vehicle 100 is started when the start conditions are met, regardless of whether the driver operates the pseudo-clutch operating device 25.

[0083] Thereafter, at time E, when the driver depresses the accelerator pedal 22, the virtual engine torque increases. Note that operation of the pseudo clutch operating device 25 by the driver is invalidated until the MT mode release period ends. The virtual engine torque is calculated based on the accelerator opening, and the amount of operation of the pseudo clutch operating device 25 is not reflected in the calculation of the virtual engine torque. Torque based on the virtual engine torque is output from the motors 4F, 4R.

[0084] The MT mode release period ends, for example, when the vehicle speed reaches a predetermined speed. When the MT mode release period ends, the electric vehicle 100 is controlled according to the control logic in the MT mode.

[0085] The above describes the operation at the time of starting using a time chart. If the behavior of a conventional manual transmission vehicle were to be reproduced even when starting, the driver would have to perform many complicated operations. Therefore, drivers, especially those unfamiliar with driving manual transmission vehicles, may find the operations cumbersome. In contrast, as shown in the time charts of FIGS. 6 and 7 , the electric vehicle 100 can start the vehicle even if the driver does not operate the pseudo clutch operating device 25. This simplifies the operation for starting the vehicle for the driver, thereby reducing the cumbersomeness of the operation. Furthermore, during the MT mode release period, input from the driver to the pseudo clutch operating device 25 is invalidated. This prevents the electric vehicle 100 from behaving in a way that is unintended by the driver, such as by operating it erroneously.

[0086] 2, the driving wheel torque in the MT mode is described as being realized by the torque of the electric motors 4F, 4R. However, the driving wheel torque does not necessarily have to be realized by the torque of the electric motors alone, and may be realized by a combination of the torque of the electric motors and the actual transmission.

[0087] 8 shows the configuration of an electric vehicle 100 according to a modified example. The electric vehicle 100 includes a transmission (T / M) 16. The output shaft of the electric motor 4 is connected to the transmission 16. The transmission 16 is a stepped transmission having a plurality of shiftable gear stages. The shifting of the plurality of gear stages of the transmission 16 is performed by a vehicle control device 101.

[0088] The transmission 16 is connected to a differential gear 17 via a propeller shaft. The differential gear 17 is connected to left and right rear wheels 6R via left and right drive shafts 5R. The front wheels may be the drive wheels. Alternatively, the electric vehicle 100 may be configured as an all-wheel drive vehicle. In this case, a center differential gear may be provided on the propeller shaft, and the drive torque divided by the center differential gear may be transmitted to the front wheels and the rear wheels, respectively.

[0089] The driving control of the electric vehicle 100 is basically the same as that shown in FIG. 2 , and the drive wheel torque is calculated using the vehicle model MOD01. In addition, the vehicle control device 101 determines the gear position of the transmission 16. The gear position is determined according to predetermined control rules, and the vehicle control device 101 controls the transmission 16 to operate at the determined gear position. The transmission 16 switches gear positions or maintains the current gear position. The vehicle control device 101 then calculates the motor torque based on the gear position of the transmission 16 so that the drive wheel torque generated at the drive wheels 6 changes in accordance with the virtual transmission torque. The vehicle control device 101 controls the inverter 3 to output the motor torque calculated based on the gear position of the transmission 16 to the electric motor 4.

[0090] The gear stages of the transmission 16 may be two stages, i.e., a high-speed gear and a low-speed gear, or may be three or more stages. The number of gear stages of the transmission 16 may or may not match the number of virtual shift positions. FIG. 9 shows the correspondence between the virtual gear stages of the virtual transmission and the gear stages of the transmission 16. Although not shown in the figure, maps defining the relationship between motor speed and motor torque for each virtual shift position are prepared for each required value of driving wheel torque and each gear stage. The vehicle control device 101 selects a map corresponding to the required value of driving wheel torque and the gear stage of the transmission 16, and determines the motor torque based on the virtual shift position and motor speed according to the selected map.

[0091] (A) shows an example in which the transmission 16 has six gear stages, which matches the number of gear stages of the virtual transmission. Each virtual shift position is associated with a corresponding gear stage, and when the virtual shift position is changed, the vehicle control device 101 changes the gear stage of the transmission 16 accordingly. The motor torque at each gear stage is determined based on the motor speed in accordance with the map described above.

[0092] (B) shows an example in which the transmission 16 has two gear stages: a high gear and a low gear. Of the virtual shift positions from first to sixth, first to third gears are associated with low gears, and fourth to sixth gears are associated with high gears. In other words, switching between the low-speed and high-speed shift positions is reproduced by switching the actual gear stages of the transmission 16, and switching between the first to third and fourth to sixth shift positions is virtually reproduced by electric motor torque.

[0093] (C) is an example in which the transmission 16 has five gear stages. Of the virtual shift positions from first to sixth gears, first to fifth gears are associated with the respective gear stages. The virtual shift position for sixth gear is associated with the fifth gear stage of the transmission 16 and is virtually reproduced by the torque of the electric motor 4.

[0094] Even when the electric vehicle 100 is equipped with an actual transmission 16, the start control is performed in the same manner as in the time charts of Figures 6 and 7. The vehicle control device 101 starts the electric vehicle 100 when the start conditions are met, regardless of whether the driver operates the pseudo clutch operation device 25. Because the driver does not need to operate the pseudo clutch operation device 25 when starting, the driver can enjoy the driving feel of a manual transmission vehicle while ensuring ease of starting.

[0095] 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 wheels 6R...Rear wheels 7F...Front suspension 7R...Rear suspension 11...Vehicle speed sensor 12...Accelerator pedal stroke sensor 13...Brake pedal stroke sensor 14...Shift position sensor 15...Clutch sensor 16...Transmission 17...Differential gear 21...In-vehicle speaker 22...Accelerator pedal 23...Brake pedal 24...Absolute instruction type shift device 25...Pseudo clutch operation device 100...Electric vehicle 101...Vehicle control device 102...Processor 103...Memory 104...Program 105...Data

Claims

1. An electric vehicle with an MT mode that controls an electric motor to simulate the operation of a virtual vehicle equipped with a virtual engine and a virtual clutch, comprising: a pseudo-clutch operating device; and a control device connected to be able to communicate with said pseudo-clutch operating device, wherein said control device, in said MT mode, accepts instructions from said pseudo-clutch operating device, and when a start condition for said electric vehicle is met, starts said electric vehicle even without an instruction from said pseudo-clutch operating device.

2. An electric vehicle as described in claim 1, wherein the control device includes a storage device that stores a torque map for simulating the torque characteristics of the virtual engine using the torque of the electric motor, and the torque map reproduces the torque characteristics of the virtual engine in a region where the virtual engine rotation speed of the virtual engine is equal to or higher than a predetermined rotation speed, and has torque characteristics different from the torque characteristics of the virtual engine in a region where the virtual engine rotation speed is equal to or lower than the predetermined rotation speed.

3. An electric vehicle as described in claim 2, wherein the torque map is a map that represents the relationship between the virtual engine rotation speed and the torque of the electric motor, and is set so that in the region where the virtual engine rotation speed is equal to or lower than the predetermined rotation speed, the torque of the electric motor approaches zero as the virtual engine rotation speed decreases.

4. An electric vehicle as described in claim 2, wherein the torque map is a map that represents the relationship between the virtual engine rotation speed and the torque of the electric motor, and is set so that the torque of the electric motor is constant in the region where the virtual engine rotation speed is equal to or lower than the predetermined rotation speed.

5. An electric vehicle as described in claim 2, wherein the torque map is a map that shows the relationship between the virtual engine rotation speed and the torque of the electric motor, and the torque of the electric motor in the region where the virtual engine rotation speed is equal to or lower than the predetermined rotation speed is made variable according to the running resistance of the electric vehicle.

6. An electric vehicle as claimed in any one of claims 1 to 5, comprising a brake operating device, wherein the starting condition is that the driver of the electric vehicle no longer inputs an operation amount to the brake operating device.

7. An electric vehicle according to any one of claims 1 to 5, comprising an accelerator operation device, wherein the starting condition is that the driver of the electric vehicle operates the accelerator operation device.

8. An electric vehicle according to any one of claims 1 to 5, wherein the control device disables input to the pseudo clutch operating device when the electric vehicle starts moving.

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