Electric vehicle control device

Abstract

The present invention relates to a control device for an electric vehicle. The control device for an electric vehicle can simulate engine stall and suppress situations that may cause adverse conditions by simulating engine stall. The control device includes a virtual engine rotational speed calculation unit that calculates a virtual engine rotational speed based on the amount of operation of an accelerator operating unit and a clutch operating unit. When the virtual engine rotational speed calculated by the virtual engine rotational speed calculation unit is less than a predetermined predetermined rotational speed, an engine stall control is executed to stop a rotating motor to simulate engine stall. When the engine stall control is executed, a holding assist control is executed in which a braking device applies a braking torque to the wheels (step S2).

Description

Technical Field

[0001] The present invention relates to a control device for reproducing the behavior of a vehicle equipped with an engine and a manual transmission in an electric vehicle using an electric motor as a driving force source. Background Art

[0002] Patent Document 1 describes a control device configured to simulate the behavior of a vehicle equipped with a manual transmission between the engine and the drive wheels, using an electric vehicle in which a rotating electric machine serving as a driving force source is connected to the drive wheels via a gear mechanism and a transmission shaft. The manual transmission sets a gear position corresponding to a shift operation performed by the driver. The electric vehicle includes an accelerator pedal, a shift lever, and a clutch pedal as driver-operated motion request input devices. The control device is configured to determine the output torque of the rotating electric machine based on the amount of operation of these motion request input devices. Specifically, the control device is configured to calculate a virtual engine output torque based on the accelerator operation amount and to determine the output torque of the rotating electric machine by multiplying the virtual engine output torque by a gain corresponding to the amount of operation of the clutch pedal. It should be noted that the control device is configured to calculate a virtual engine speed in addition to the output torque of the rotating electric machine.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6787507 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] The control device described in Patent Document 1 is configured to simulate the behavior of a vehicle with an engine and a manual transmission using an electric vehicle without an engine and a manual transmission. Thus, for example, when the amount of clutch pedal depression is reduced while the accelerator pedal is operated a small amount, an engine stall can be simulated. In the case of simulating such an engine stall, since the torque of the rotating electric machine serving as the driving force source is 0 (zero), there are undesirable situations such as the following in which simulating an engine stall is undesirable: when simulating an engine stall on an uphill slope, the vehicle unexpectedly moves backward when the driver depresses the clutch pedal. On the other hand, if the engine stall is not simulated in order to prevent such an undesirable situation from occurring, a driver who prefers the operability of the vehicle may feel uncomfortable.

[0008] The present invention has been made in view of the above-mentioned technical problems, and an object of the present invention is to provide a control device for an electric vehicle that can simulate an engine stall and can prevent a malfunction from occurring due to the simulated engine stall.

[0009] Solutions for solving problems

[0010] To achieve the above-mentioned object, the present invention provides a control device for an electric vehicle, comprising a rotating electric machine for transmitting torque to wheels and a braking device for applying braking torque to the wheels, and not comprising an engine, a clutch mechanism, or a transmission coupled to the engine. The control device for the electric vehicle comprises: an accelerator operating unit operated by a driver to determine a required drive amount of the electric vehicle; a shift operating unit operated by the driver to simulate operation of the transmission; a clutch operating unit operated by the driver to simulate operation of the clutch mechanism; and a controller for controlling the braking device. The controller comprises a virtual engine rotational speed calculating unit that calculates a virtual engine rotational speed based on the operation amounts of the accelerator operating unit and the clutch operating unit. When the virtual engine rotational speed calculated by the virtual engine rotational speed calculating unit is less than a predetermined rotational speed, engine shutdown control is executed to stop the rotating electric machine to simulate engine shutdown. When the engine shutdown control is executed, holding assist control is executed to apply braking torque to the wheels via the braking device.

[0011] In the present invention, the controller may be configured to determine the output torque of the rotating electric machine based on the operation amount of the accelerator operation unit, and the controller may prohibit the output of torque from the rotating electric machine based on the operation amount of the accelerator operation unit when the engine shutdown control is executed.

[0012] In the present invention, the controller may issue a recovery notification for recovering from engine shutdown when the engine shutdown control is executed.

[0013] In the present invention, there may also be a brake operating unit, which is operated by the driver and is used to determine the braking torque of the braking device. The recovery notification includes the operation of the brake operating unit to increase the braking torque based on the braking device and the operation of the clutch operating unit to simulate the release of the clutch mechanism.

[0014] In the present invention, the controller may stop the engine shutdown control when the brake operating unit and the clutch operating unit are operated.

[0015] In the present invention, the controller may determine whether the driver's driving skill is low, and execute the holding assist control if the driver's driving skill is low.

[0016] In the present invention, the controller may execute the holding assist control when the driver has high driving skills and the electric vehicle is parked on a slope.

[0017] In the present invention, the holding assist control may be executed when the driver has high driving skills and another vehicle is present in the moving direction of the electric vehicle.

[0018] In the present invention, the controller may stop the holding assist control when the electric vehicle is capable of starting.

[0019] In the present invention, the controller may execute start assist control for suppressing re-execution of the engine shutdown control when the engine shutdown control is executed.

[0020] In the present invention, the start assist control may include setting a lower limit value of the virtual engine rotation speed calculated by the virtual engine rotation speed calculation unit to be equal to or higher than the predetermined rotation speed to prohibit execution of the engine shutdown control.

[0021] Effects of the Invention

[0022] According to the present invention, a virtual rotational speed of an engine that an electric vehicle does not have is calculated based on the amount of operation of the accelerator operating unit and the clutch operating unit. Then, when the calculated virtual rotational speed of the engine is less than a predetermined rotational speed, engine shutdown control is performed to simulate engine shutdown. That is, the rotating electric machine is stopped. When the engine shutdown control is performed in this way, since no torque is output from the rotating electric machine, the present invention performs a holding assist control to apply a braking torque to the wheels using a braking device. Therefore, for example, when the clutch operating unit is operated to restart the vehicle, it is possible to suppress undesirable conditions such as the electric vehicle moving unexpectedly. In addition, by performing the holding assist control in this way, it is not necessary to prohibit the engine shutdown control for reproducing the engine shutdown, and the behavior of the simulated vehicle can be faithfully reproduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a diagram schematically showing the structure of an electric vehicle according to an embodiment of the present invention.

[0024] Figure 2 This diagram shows the structure of the ECU using functional blocks.

[0025] Figure 3 This is a flowchart for explaining a control example executed by the control device in the embodiment of the present invention.

[0026] Figure 4This is a flowchart for explaining a control example for determining whether to execute assist control according to the driver's driving skill.

[0027] Figure 5 This is a flowchart for explaining a control example for reproducing the behavior of the vehicle immediately before the engine is turned off.

[0028] Description of Reference Numerals

[0029] 1. Motor; 2. 9. Wheel; 11. Electronic control unit (ECU); 12. Accelerator pedal; 14. Brake pedal; 17. Shift mechanism; 18. Clutch pedal; 110. Virtual engine rotation speed calculation unit; 111. Virtual engine output torque calculation unit; 112. Torque transfer gain calculation unit; 113. Clutch output torque calculation unit; 114. Gear ratio calculation unit; 115. Transmission output torque calculation unit; B. Brake mechanism; Ve. Electric vehicle. DETAILED DESCRIPTION

[0030] The present invention will be described based on the embodiments shown in the drawings. However, the embodiments described below are merely examples of the present invention and do not limit the present invention.

[0031] Figure 1 An example of an electric vehicle (hereinafter referred to as a vehicle) in an embodiment of the present invention is schematically shown. The vehicle Ve is a front-wheel drive vehicle having a motor (MG) 1 as a driving force source, and transmitting torque from the motor 1 to a pair of front wheels 2 to travel. The motor 1, like the motors previously known to be provided in electric vehicles and hybrid vehicles, can be composed of a so-called electric generator, which, in addition to functioning as a motor that outputs driving torque by supplying electricity from a power storage device (BATT) 3, also has the function of a generator that generates electricity by being forcibly rotated by torque transmitted from the outside. Specifically, a permanent magnet synchronous motor or an induction motor can be used. It should be noted that the motor 1 is equivalent to the "rotating electric machine" in the embodiment of the present invention.

[0032] The output shaft 4 of the motor 1 is connected to a gear mechanism 5, which is further connected to a differential gear mechanism 7 serving as a final reducer via a propeller shaft 6. The output torque of the motor 1 is distributed to the left and right drive shafts 8 via the differential gear mechanism 7, and the pair of front wheels (drive wheels) 2 connected to these drive shafts 8 are driven by the motor 1, causing the vehicle Ve to travel. In other words, the vehicle Ve does not include an engine, a transmission connected to the engine, or a clutch mechanism capable of cutting off torque transmission between the engine and the drive wheels. Furthermore, as with conventional vehicles, each wheel 2 is provided with a brake mechanism B that applies a braking torque to the respective wheel 2. The brake mechanism B corresponds to the "brake device" in the embodiment of the present invention.

[0033] It should be noted that Figure 1 The vehicle Ve shown is a front-wheel drive vehicle, but the electric vehicle in the present invention can be a rear-wheel drive electric vehicle that transmits torque from a motor 1 to a pair of rear wheels 9 and travels, and can also be a four-wheel drive vehicle that is provided with a transfer case and transmits torque from a motor 1 to a pair of front wheels 2 and a pair of rear wheels 9 and travels.

[0034] An inverter (INV) 10 is provided for controlling the magnitude of the current supplied to the motor 1 and the frequency of the current supplied to each phase. A power storage device (BATT) 3 that outputs a DC current is connected to the inverter 10. It should be noted that in addition to the inverter 10, other electrical equipment such as a converter for amplifying the voltage output from the power storage device 3 may also be provided. Furthermore, in addition to secondary batteries such as lithium-ion batteries, the power storage device 3 may also include power storage components such as capacitors.

[0035] An electronic control unit (hereinafter referred to as an ECU) 11 is provided for controlling the switching elements of the inverter 10 and the brake mechanism B. This ECU 11 corresponds to the "controller" in the embodiments of the present invention and, like conventional ECUs provided in vehicles, is primarily composed of a microcomputer. The ECU 11 is configured to receive input signals from various sensors, perform calculations based on the input signals and pre-stored calculation expressions or maps, and output the results of these calculations as control signals to various devices, such as the inverter 10, an actuator (not shown) that controls the brake mechanism B, and a speaker (not shown).

[0036] Figure 1 The illustrated vehicle Ve is equipped with an accelerator pedal 12 for determining the acceleration / deceleration operation (output increase / decrease operation) of the driver (not shown), i.e., the requested drive amount of the vehicle Ve; and an accelerator position sensor 13 for detecting the amount of depression. Furthermore, a brake pedal 14 and a brake sensor 15 are provided. When the driver depresses the brake pedal 14 to decelerate or stop the vehicle, the brake pedal 14 determines the braking torque of the brake mechanism B based on the depression amount, and the brake sensor 15 detects the depression amount and the depression force of the dynamic pedal 14. A vehicle speed sensor (rotational speed sensor) 16 is also provided for detecting the rotational speed of the propeller shaft 6 (i.e., vehicle speed). These sensors 13, 15, and 16 are connected to the ECU 11, and their detection signals (detected data) are input to the ECU 11. The accelerator pedal 12 corresponds to the "accelerator operating unit" in this embodiment of the present invention, and the brake pedal 14 corresponds to the "brake operating unit" in this embodiment of the present invention.

[0037] Figure 1The vehicle Ve shown is also equipped with a device for simulating manual gear shifting operations. First, there is a gear shift mechanism 17 mainly composed of a gear shift lever or a paddle switch, which allows manual selection of multiple forward gears, reverse gears, and neutral positions that do not actually exist. When performing a gear shift operation in a vehicle equipped with a manual transmission, the transmission of torque between a driving force source such as an engine and a drive wheel is temporarily cut off in order to be able to connect and disconnect the gears and to reduce the gear shift shock. The clutch for this purpose is usually disconnected and / or connected (intermittently) by a clutch pedal. In Figure 1 The illustrated vehicle Ve simulates a vehicle equipped with such a manual transmission and includes a clutch pedal 18 as a clutch mechanism. It should be noted that an operating unit may be provided on the steering wheel in place of the clutch pedal 18. The shift device 17 described above corresponds to the "shift operating unit" in the embodiment of the present invention, and the clutch pedal 18 corresponds to the "clutch operating unit" in the embodiment of the present invention.

[0038] Furthermore, a shift position sensor 19 is provided for detecting the position (or mode) of the gear selected by the shift mechanism 17, and a clutch position sensor 20 is provided for detecting the amount of depression of the clutch pedal 18. These sensors 19 and 20 are connected to the ECU 11, and their detection signals (detected data) are input to the ECU 11.

[0039] The vehicle Ve is configured to exhibit, in addition to conventional EV driving, a system in which the torque of the motor 1 is controlled to drive and brake according to a driver's driving request expressed as an accelerator position, driving and shifting behaviors that simulate the driving and shifting operations of a vehicle equipped with an engine, a transmission (manual transmission) coupled to the engine, and a clutch mechanism (hereinafter referred to as an MT vehicle). The control for simulating the driving of the MT vehicle may be that described in Patent Document 1, which will be briefly described below.

[0040] A model of the MT vehicle to be simulated is pre-set and stored as a numerical model in ECU 11. The actual accelerator opening (depression amount) detected by the aforementioned accelerator position sensor 13, the shift position on the shift mechanism 17 detected by the shift position sensor 19, the actual depression amount of the clutch pedal 18 detected by the clutch position sensor 20, and the actual rotational speed of the drive shaft 6 detected by the rotational speed sensor 16 are applied to the modeled MT vehicle to calculate the torque (driving torque and braking torque) that the motor 1 should output, and the ECU 11 controls the inverter 10 to achieve the torque.

[0041] The modeled MT vehicle (hereinafter referred to as the virtual vehicle) includes an internal combustion engine (engine) and a stepped transmission coupled to its output side. A virtual engine rotational speed, representing the engine's rotational speed, is calculated based on the actual driving conditions input from the aforementioned sensors 13, 19, 20, and 16. For example, the virtual engine rotational speed can be calculated by multiplying the rotational speed of the propeller shaft 6, as detected by the rotational speed sensor 16, by the gear ratio at the shift position (gear stage) selected by the shift mechanism 17, and further by the slip ratio corresponding to the amount of clutch pedal 18 depressed, as detected by the clutch position sensor 20. Furthermore, the virtual engine rotational speed can be calculated as the predetermined idle rotational speed, assuming that the rotational speed of the propeller shaft 6 is 0 (zero), the accelerator opening detected by the accelerator position sensor 13 is 0%, and the amount of clutch pedal 18 depressed, as detected by the clutch position sensor 20, is greater than a predetermined amount, and the clutch mechanism in the virtual vehicle is not transmitting torque. The functional component or functional block that performs such calculation is shown as a "virtual engine rotation speed calculation unit 110". Figure 2 It should be noted that the virtual engine rotation speed calculated by the virtual engine rotation speed calculation unit 110 is output to a speaker (not shown), and a sound simulating an engine sound is emitted from the speaker.

[0042] The virtual engine mounted on the virtual vehicle is assumed to be an engine whose displacement, the relationship between the rotational speed and the output torque, the efficiency, etc. are determined in its design. Therefore, if the virtual engine rotational speed is calculated, the output torque of the virtual engine can be calculated based on this value, the accelerator position, and the mapping that determines the relationship between the rotational speed and the output torque of the virtual engine. The functional component or function block that performs such calculations is shown as "virtual engine output torque calculation unit 111" Figure 2 middle.

[0043] It is assumed that the clutch mechanism in the virtual vehicle is a friction clutch whose transmission torque capacity continuously changes. Therefore, a predetermined relationship determined by design is established between the depression amount of the clutch pedal 18 and the transmission torque capacity, and this relationship can be prepared in advance as a map and stored in the ECU 11. For example, it can be set as the following mapping: the transmission torque capacity is set to a gain that changes from "0" to "1", and the gain is "1" during the period when the depression amount of the clutch pedal 18 is from "0" to the predetermined value. As the depression amount increases to above the predetermined value, the gain gradually (linearly or proportionally) decreases according to the depression amount. Therefore, the torque output from the virtual clutch mechanism assumed to be mounted on the virtual vehicle is determined by the above-mentioned gain, which can be calculated based on the above-mentioned mapping and the actual depression amount of the clutch pedal 18 detected by the clutch position sensor 20. The functional component or functional block that performs such calculations is shown as a "torque transfer gain calculation unit 112" Figure 2 middle.

[0044] The torque input to the manual transmission assumed to be mounted on the virtual vehicle is the torque that changes the virtual engine output torque according to the above-mentioned gain, that is, the clutch output torque. Therefore, the clutch output torque can be calculated by multiplying the virtual engine output torque calculated by the above-mentioned virtual engine output torque calculation unit 111 by the gain calculated by the torque transfer gain calculation unit 112. The functional component or function block that performs such calculation is shown as "clutch output torque calculation unit 113" in FIG. Figure 2 middle.

[0045] In order to simulate the gear ratio (speed ratio) set by the manual transmission in the virtual vehicle, the gear ratio of the manual transmission is calculated based on the actual driving state of the above-mentioned vehicle Ve. The gear ratio is the ratio of the engine rotation speed in the virtual vehicle to the output rotation speed of the manual transmission (specifically, the rotation speed of the transmission shaft 6). The aforementioned virtual engine rotation speed is equivalent to the engine rotation speed in the virtual vehicle. In addition, the rotation speed of the transmission shaft 6 detected by the aforementioned rotation speed sensor 16 is equivalent to the output rotation speed. Therefore, the gear ratio is obtained by dividing the virtual engine rotation speed by the rotation speed of the transmission shaft 6. The functional component or functional block that performs such calculations is shown as a "gear ratio calculation unit 114" Figure 2 middle.

[0046] In order to make the behavior of the vehicle Ve described above, including the behavior during gear shifting, consistent or similar to that of the virtual vehicle, the output torque of the motor 1 is controlled in such a way that the torque of the transmission shaft 6 is consistent or similar to the output torque of the manual transmission in the virtual vehicle. Therefore, the output torque of the manual transmission in the virtual vehicle needs to be calculated, which is determined by the following equation: Figure 2The calculation is performed by a functional component or functional block described as "transmission output torque calculation unit 115" in the manual transmission. Specifically, since the manual transmission increases or decreases the input torque according to the speed ratio and outputs it, the transmission output torque is calculated by multiplying the aforementioned clutch output torque input to the manual transmission by the speed ratio. The clutch output torque is a torque that reflects the gain calculated by the above-mentioned torque transfer gain calculation unit 112, and therefore becomes a torque corresponding to the intermittent transmission torque capacity of the clutch mechanism during the speed transition. Therefore, by controlling the inverter 10 by the ECU 11 in a manner that realizes the torque calculated by the transmission output torque calculation unit 115 (the torque of the drive shaft 6), it is possible to cause the above-mentioned actual vehicle Ve to exhibit a behavior that simulates the behavior of the virtual vehicle during speed change.

[0047] When the vehicle is stopped with the clutch pedal 18 depressed, the virtual engine speed of the virtual vehicle is faster than the virtual output speed of the clutch mechanism's output side. Therefore, when the clutch pedal 18 is depressed less during a start, a resistive torque acts on the virtual engine from the clutch mechanism's output side. Consequently, the virtual engine generates a torque greater than this resistive torque, transmitting drive torque from the virtual engine via the clutch mechanism. In this case, if the virtual engine torque is greater than the resistive torque, the virtual engine speed increases due to the remaining virtual engine torque. If the virtual engine torque is less than the resistive torque, the virtual engine speed decreases due to this remaining resistive torque.

[0048] Therefore, at the start, the virtual engine rotational speed calculation unit 110 calculates the torque difference between the output torque of the virtual engine calculated by the virtual engine output torque calculation unit 111 and the resistance torque calculated based on the depression amount of the clutch pedal 18 and the virtual engine rotational speed at the current time point, and calculates the rate of change of the virtual engine rotational speed based on the torque difference and the predetermined rotational inertia of the virtual engine, so as to change (update) the virtual engine rotational speed.

[0049] Furthermore, if the virtual engine speed is less than a predetermined speed, engine shutdown control is executed to simulate engine shutdown. Specifically, to simulate an engine shutdown state, the engine sound from the speaker is stopped, and the output of torque corresponding to the amount of operation on the accelerator pedal 12 is prohibited. In other words, the accelerator request is rejected.

[0050] On the other hand, for example, if the vehicle Ve is executing engine shutdown control on an uphill slope, if the accelerator request is rejected by simulating engine shutdown as described above, there is a possibility that the vehicle Ve will roll backward when the driver depresses the clutch pedal 18 to restart the vehicle. Therefore, the control device of the present invention is configured to suppress the movement of the vehicle Ve when the engine shutdown control is executed. Figure 3 An example of this control is shown in FIG.

[0051] exist Figure 3 In the example shown, first, a determination is made as to whether engine shutdown control has been executed (step S1). As described above, this determination in step S1 can be based on factors such as whether the virtual engine speed calculated by the virtual engine speed calculation unit 110 is less than a predetermined first speed, such as a speed at which the engine can rotate autonomously, or whether the virtual engine speed is 0 (zero) and the accelerator request rejection flag is on. It should be noted that the aforementioned first predetermined speed corresponds to the "predetermined speed" in this embodiment of the present invention.

[0052] In the case where a negative judgment is made in step S1 due to the fact that the engine shutdown control is not executed, the routine is directly temporarily ended. On the contrary, in the case where a positive judgment is made in step S1 due to the fact that the engine shutdown control is executed, a maintenance auxiliary control for fixing the vehicle position is executed (step S2). This maintenance auxiliary control can be performed by switching to the previous slope holding control, etc. That is, even if the driver does not operate the brakes, the brake mechanism B provided at each wheel 2, 9 is used to make the braking torque act. In addition, in step S2, for example, it is also possible to energize the motor 1 and output torque so as to generate a load that counteracts the load acting on the vehicle Ve in the front and rear directions, rather than based on the driver's accelerator operation amount.

[0053] Next, a notification (recovery notification) is output for performing a recovery operation from engine shutdown control (step S3). Specifically, a notification is output indicating the following steps have been performed in sequence: depressing the brake pedal 14 to increase the braking torque of the brake mechanism B, depressing the clutch pedal 18 to simulate the release of the clutch mechanism, selecting the first forward speed (starting gear) using the shift mechanism 17, and performing a restart operation. This step S3 can be performed by outputting a signal from the ECU 11 to a speaker to provide an audible recovery notification, or by outputting a signal to an instrument panel (not shown) to provide a display on the instrument panel. The aforementioned restart operation involves reducing the amount of depression on the clutch pedal 18 and increasing the amount of depression on the accelerator pedal 12, similar to the starting operation of a conventional MT vehicle. It should be noted that in this control example, the virtual engine is started by depressing the brake pedal 14 and the clutch pedal 18. In other words, the rotational speed of the virtual engine is set to the idle rotational speed, generating sounds and vibrations corresponding to the idle rotational speed. Furthermore, the rejection of the accelerator request is canceled by selecting the first forward speed using the shift mechanism 17. It should be noted that the rejection of the accelerator request can also be canceled when the brake pedal 14 and the clutch pedal 18 are depressed. In other words, the engine shutdown control ends when at least the brake pedal 14 and the clutch pedal 18 are depressed.

[0054] Next, a determination is made as to whether the vehicle can be restarted (step S4). Specifically, a determination is made as to whether the driver has performed the brake pedal 14, clutch pedal 18, shift mechanism 17, or restart operation notified in step S3. This determination in step S4 can be based on detection signals from the accelerator position sensor 13, brake sensor 15, clutch position sensor 20, and shift position sensor 19.

[0055] If the vehicle cannot be restarted due to the lack of an operation based on the recovery notification in step S3, and a negative determination is made in step S4, the process returns to step S3. In other words, the recovery notification continues until the vehicle can be restarted. Conversely, if the vehicle can be restarted and a positive determination is made in step S4, the hold assist control executed in step S2 is stopped (step S5), temporarily terminating the routine.

[0056] It should be noted that in the above control example, the resumption notification includes the shift operation and the restart operation. However, as long as the resumption notification can at least resume from the engine shutdown control, the shift operation and the restart operation notification do not need to be included. In this case, the determination of whether the restart is possible in step S4 can be based on whether the brake and clutch operations have been performed. In other words, the hold assist control can also be stopped before the shift operation and the restart operation are performed.

[0057] When engine stall control simulating engine stall is executed as described above, the position of the vehicle Ve is fixed by executing the hold assist control. In other words, by applying braking torque to the wheels, this can prevent the vehicle Ve from unintentionally rolling backward, for example, when the clutch pedal 18 is depressed for restarting. Furthermore, by executing the hold assist control in this manner, the behavior of the virtual vehicle can be faithfully reproduced without prohibiting the reproduction of engine stall.

[0058] In the above control example, the holding assist control is always executed when the engine shutdown control is executed. However, the driver may feel that the holding assist control is excessive. Figure 4 In the control example shown, whether to execute the holding assist control is determined based on the driver's driving skills, or based on the surrounding conditions of the vehicle Ve. Figure 3 The same steps are denoted by the same reference numerals and their descriptions are omitted.

[0059] exist Figure 4 In the example shown, if a negative determination is made in step S1 due to execution of engine shutdown control, a determination is made as to whether the driver's driving skill is low (step S10). This determination in step S10 can be made, for example, by the driver selecting a driving skill level by operating a touch panel while boarding the vehicle Ve and storing the selected level in the ECU 11. Alternatively, the driver's driving operations can be stored in the ECU 11 and the determination made based on a history of the driving operations.

[0060] If the driver's driving skill is low and a positive determination is made in step S10, the process proceeds to step S2. That is, hold assist control is executed. Conversely, if the driver's driving skill is not low and a negative determination is made in step S10, a determination is made as to whether the road is a slope (step S11). Step S11 is used to determine whether the situation is suitable for executing hold assist control. The term "slope" in step S11 includes both downhill and uphill slopes. Whether the road is a slope can be determined based on either the acceleration sensor mounted on the vehicle Ve or the information about the traveled route stored in the navigation system.

[0061] If the road is on a slope and a positive determination is made in step S11, the process proceeds to step S2 where the holding assist control is executed. Conversely, if the road is not on a slope and a negative determination is made in step S11, the process proceeds to step S3. In other words, the holding assist control is not executed.

[0062] In the above example, whether to perform hold assist control is determined based on whether the driver's driving skill is low. Furthermore, if the driver's driving skill is not low, whether to perform hold assist control is determined based on whether the vehicle is on a slope. However, the determination of whether to perform hold assist control can also be made by categorizing the driver's driving skill level into three stages. Specifically, a configuration can be employed in which, if the driver's driving skill is low, hold assist control is performed regardless of whether the vehicle is on a slope; if the driver's driving skill is intermediate among the three stages, hold assist control is performed only on slopes; and if the driver's driving skill is high, hold assist control is not performed regardless of whether the vehicle is on a slope. Alternatively, a configuration can be employed in which, if the driver's driving skill is high, an onboard camera or the like is used to detect the presence of other vehicles in the direction in which the vehicle Ve may unexpectedly move, i.e., behind the vehicle if the vehicle is on an uphill slope, or ahead of the vehicle if the vehicle is on a downhill slope, and hold assist control is performed only if other vehicles are present.

[0063] In addition, Figure 4 In the example shown, following step S3, start assist control for suppressing execution of engine stall control is performed again (step S12), and the process then moves to step S4. This start assist control sets the lower limit of the virtual engine rotational speed to a rotational speed greater than the virtual engine rotational speed at which the virtual engine can rotate autonomously, that is, to a rotational speed greater than the first predetermined rotational speed for executing engine stall control, thereby prohibiting control from simulating engine stall. Alternatively, as with the above-mentioned hold assist control, whether to perform start assist control may be determined based on the driver's driving skill. Specifically, for example, if the driver's driving skill is low, start assist control may be performed regardless of whether the vehicle is on a slope. If the driver's driving skill is at an intermediate level among the three stages, start assist control may be performed only on slopes. If the driver's driving skill is high, start assist control may not be performed regardless of whether the vehicle is on a slope, or start assist control may be performed only when there are other vehicles in the moving direction of vehicle Ve.

[0064] By determining whether to perform the hold assist control or the start assist control based on the driver's driving skill, it is possible to prevent a skilled driver from feeling that the assist control is excessive. In other words, it is possible to reproduce the vehicle behavior that the driver prefers.

[0065] It should be noted that the control device of the present invention may also be configured to reproduce the behavior immediately before the engine is turned off. Figure 5 A flowchart for explaining the control example is shown in FIG. Figure 3 and Figure 4 The same steps are marked with the same reference numerals.

[0066] exist Figure 5In the example shown, if a negative determination is made in step S1 because engine shutdown control is not being executed, a determination is made as to whether the state is immediately before engine shutdown control is executed (step S20). Specifically, a determination is made as to whether the virtual engine speed calculated by the virtual engine speed calculation unit 110 is less than a predetermined second speed, such as the idle speed. In other words, an affirmative determination is made in step S20 if the engine speed is greater than or equal to the first predetermined speed and less than the second predetermined speed.

[0067] If a negative determination is made in step S20, because the engine speed is above the second predetermined speed and the state is not immediately before engine shutdown control is executed, the routine is immediately terminated. Conversely, if an affirmative determination is made in step S20, because the engine speed is below the second predetermined speed and the state is immediately before engine shutdown control is executed, the behavior of the MT vehicle immediately before engine shutdown is reproduced (step S21), and the routine is temporarily terminated. Specifically, in step S21, the behavior of the MT vehicle immediately before engine shutdown is simulated to make the driver aware of the possibility of engine shutdown control being executed. By making the driver aware of the signs of engine shutdown control being executed, the driver is prompted to depress the accelerator pedal 12 or the clutch pedal 18, thereby avoiding execution of engine shutdown control. The behavior reproduction in step S21, for example, causes the engine sound emitted from the speaker into the vehicle cabin to change as the virtual engine speed decreases, generating vibrations in the front-rear direction, thereby outputting a stepwise torque from the motor 1.

[0068] As in the control example described above, when there is a possibility that engine shutdown control will be executed, the driver can be made aware of the possibility of execution of engine shutdown control by reproducing the behavior of the MT vehicle immediately before engine shutdown. By making the driver aware of the signs of execution of engine shutdown control in this way, the driver can be prompted to perform an operation such as depressing the accelerator pedal 12 or depressing the clutch pedal 18, thereby avoiding execution of engine shutdown control.

[0069] It should be noted that the present invention is not limited to the above-described embodiment. While the rotating electrical machine in the present invention is preferably a so-called electric generator having a power generation function, a configuration comprising a motor for outputting driving torque and a generator for generating electricity during regenerative braking is also possible. Furthermore, the rotational speed used to calculate the gear stage (speed ratio) need not be limited to the rotational speed of the above-described propeller shaft, but rather the rotational speed of an appropriate rotating component corresponding to the vehicle speed.

Claims

1. A control device for an electric vehicle comprising a rotating electric machine for transmitting torque to wheels and a braking device for applying braking torque to the wheels, and having no engine, a clutch mechanism, or a transmission connected to the engine, wherein: The control device of the electric vehicle comprises: an accelerator operation unit, operated by a driver to determine a driving request amount of the electric vehicle; a gear shift operating unit, operated by the driver to simulate the operation of the transmission; a clutch operating unit, operated by the driver to simulate the operation of the clutch mechanism; as well as a controller for controlling the braking device, The controller includes a virtual engine rotation speed calculation unit that calculates a virtual engine rotation speed based on operation amounts of the accelerator operation unit and the clutch operation unit. When the virtual rotational speed of the engine calculated by the virtual engine rotational speed calculation unit is lower than a predetermined rotational speed, the controller executes engine shutdown control for stopping the rotary electric machine to simulate shutdown of the engine. When the engine shutdown control is executed, the controller executes a holding assist control for applying a braking torque to the wheels via the braking device.

2. The control device of the electric vehicle according to claim 1, characterized in that: The controller is configured to determine the output torque of the rotary electric machine based on the operation amount of the accelerator operation unit. The controller prohibits the output of torque from the rotating electric machine based on the operation amount of the accelerator operation unit when the engine shutdown control is executed.

3. The control device for an electric vehicle according to claim 1 or 2, characterized in that: The controller performs a recovery notification for recovering from the engine shutdown when the engine shutdown control is executed.

4. The control device of the electric vehicle according to claim 3, characterized in that: The electric vehicle control device further includes a brake operating unit, which is operated by the driver to determine the braking torque of the braking device. The restoration notification includes an operation of the brake operating unit to increase the braking torque of the brake device and an operation of the clutch operating unit to simulate the release of the clutch mechanism.

5. The control device for an electric vehicle according to claim 4, wherein: The controller stops the engine shutdown control when the brake operating unit and the clutch operating unit are operated.

6. The control device for an electric vehicle according to any one of claims 1 to 5, wherein: The controller determines whether the driver's driving skills are low, The controller performs the holding assist control in a case where the driver's driving skill is low.

7. The control device of the electric vehicle according to claim 6, characterized in that: The controller performs the holding assist control in a case where the driver's driving skill is high and the electric vehicle is stopped on a slope.

8. The control device for an electric vehicle according to claim 6, wherein: The holding assist control is executed when the driver's driving skill is high and another vehicle exists in the moving direction of the electric vehicle.

9. The control device for an electric vehicle according to any one of claims 1 to 8, wherein: When the electric vehicle is capable of starting, the controller stops the holding assist control.

10. The control device for an electric vehicle according to any one of claims 1 to 9, wherein: The controller executes start assist control for suppressing re-execution of the engine shutdown control when the engine shutdown control is executed.

11. The control device of the electric vehicle according to claim 10, characterized in that: The start assist control includes setting a lower limit value of the virtual rotational speed of the engine calculated by the virtual engine rotational speed calculation unit to be equal to or higher than the predetermined rotational speed, thereby prohibiting execution of the engine shutdown control.

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