Electric vehicle

Abstract

To provide a technology that enables a vehicle to smoothly start while preventing the same from rolling backward or forward on a slope due to gravity.SOLUTION: An electric vehicle comprises an accelerator pedal, a pseudo shift operation member simulating a shift operation member in a manually shifted internal combustion engine vehicle, and a control device to control the electric vehicle. Upon selection by a driver, the control device executes a control mode to calculate driver demand torque for driving an electric motor based on an opening of the acceleration pedal and operation of the pseudo shift operation member. Additionally, when detecting that the electric vehicle is stopped on a sloped road surface, the control device executes hold assist. The hold assist includes outputting hold assist torque, drive wheel torque in a direction opposite to gravity. When the driver demand torque exceeds the hold assist torque, the control device stops outputting the hold assist torque and switches to outputting the driver demand torque.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a hold assist in an electric vehicle having a function of simulating an engine installation. By operating the brake by the hold assist, it is possible to prevent the vehicle from slipping down on a slope due to the action of gravity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The hold assist is a function for preventing the vehicle body from moving backward or forward due to the action of gravity when the vehicle stopped on a slope starts moving again. As a hold assist function, it is known to prevent backward or forward movement due to gravity by operating the brake on a slope. However, if the operation of the brake is suddenly terminated when the driving wheel torque required by the driver becomes sufficiently large, the driving wheel torque will change discontinuously, which is not comfortable for the driver. One object of the present disclosure is to provide a technique capable of enabling smooth starting while preventing backward or forward movement on a slope due to gravity.

Means for Solving the Problems

[0005] The present disclosure provides an electric vehicle having an electric motor as a drive source. The electric vehicle includes a driving operation member used for driving, a pseudo-shifting operation member imitating an operation member used for shifting operation of a manual transmission internal combustion engine vehicle, and a control device configured to control the electric vehicle according to an operation of the driving operation member. The driving operation member includes an accelerator pedal. The pseudo-shifting operation member includes a pseudo-H-type shifter imitating an H-type shifter of a manual transmission and a pseudo-clutch operation device imitating a clutch operation device. The control device is configured to execute a control mode for calculating a driver demand torque for driving the electric motor based on an opening degree of the accelerator pedal and an operation of the pseudo-shifting operation member by a driver's selection, and in the control mode, when it is detected that the electric vehicle is stopped on a sloped road surface, perform a hold assist for preventing backward or forward movement of the electric vehicle due to gravity acting on the electric vehicle. The hold assist includes outputting a hold assist torque which is a driving wheel torque in a direction opposite to gravity, and in response to the driver demand torque exceeding the hold assist torque, terminating the output of the hold assist torque and switching to the output of the driver demand torque.

Effect of the Invention

[0006] According to the electric vehicle of the present disclosure, a hold assist torque is output by a hold assist for preventing backward or forward movement of the vehicle on a slope. Further, the output of the hold assist torque ends when the driving wheel torque required by the driver exceeds the hold assist torque. And along with the end of the output of the hold assist torque, the driver demand torque is output. Thereby, the driving wheel torque to be output can be smoothly shifted from the hold assist torque to the torque required by the driver. In this way, it is possible to enable a smooth start while preventing backward or forward movement due to gravity during starting on a slope.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0008] Embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0009] 1. Configuration of the power train of an electric vehicle FIG. 1 is a diagram schematically showing the configuration of an electric vehicle 100 according to an embodiment of the present disclosure. First, the configuration of the power train of the electric vehicle 100 will be described with reference to FIG. 1.

[0010] The electric vehicle 100 is provided with two electric motors (M) 4F and 4R at the front and rear as a power source for running. The electric motors 4F and 4R are, for example, three-phase AC motors. The front electric motor 4F is connected to a front drive shaft 5F that drives the front wheels 6F. The rear electric motor 4R is connected to a rear drive shaft 5R that drives the rear wheels 6R. The front wheels 6F are suspended by an electronically controlled front suspension 7F with independent left and right sides. The rear wheels 6R are suspended by an electronically controlled rear suspension 7R with independent left and right sides.

[0011] An inverter (INV) 3F and 3R are respectively attached to the front electric motor 4F and the rear electric motor 4R. The front inverter 3F and the rear inverter 3R are respectively connected to the battery (BATT) 2. The battery 2 stores electrical energy for driving the electric motors 4F and 4R. That is, the electric vehicle 100 is a battery electric vehicle (BEV) that runs on the electrical energy stored in the battery 2. The inverters 3F and 3R are, for example, voltage source inverters, and control the torque of the electric motors 4F and 4R by PWM control.

[0012] 2. Configuration of the control system of the electric vehicle Subsequently, the configuration of the control system of the electric vehicle 100 will be described with reference to FIG. 1.

[0013] The electric vehicle 100 is equipped with a vehicle speed sensor 11. At least one of the wheel speed sensors (not shown) provided on each of the left and right front wheels 6F and the left and right rear wheels 6R is used as the vehicle speed sensor 11. Further, the electric vehicle 100 is equipped with an accelerator pedal stroke sensor 12. The accelerator pedal stroke sensor 12 is provided on the accelerator pedal 22 and outputs a signal indicating the depression amount of the accelerator pedal 22, that is, the accelerator opening. Furthermore, the electric vehicle 100 is equipped with a brake pedal stroke sensor 13. The brake pedal stroke sensor 13 is provided on the brake pedal 23 and outputs a signal indicating the depression amount of the brake pedal 23, that is, the brake opening.

[0014] The accelerator pedal 22 and the brake pedal 23 are driving operation members used for driving the electric vehicle 100. Separately from these driving operation members, the electric vehicle 100 is equipped with a pseudo-shift operation member that mimics the operation member used for the shift operation of a manual transmission internal combustion engine vehicle. The pseudo-shift operation member includes the following pseudo-H shifter 24 and pseudo-clutch pedal 25.

[0015] The pseudo H-type shifter 24 is a dummy different from the original H-type shifter. The pseudo H-type shifter 24 has a structure imitating the shift stick provided on the console and can move between shift positions along an H-shaped gate. However, since the electric vehicle 100 does not have an actual transmission, the shift positions of the pseudo H-type shifter 24 are virtual shift positions. A shift position sensor 14 is provided on the pseudo H-type shifter 24. The shift position sensor 14 outputs a signal indicating the shift position selected by the pseudo H-type shifter 24.

[0016] The pseudo clutch pedal 25 is a dummy different from the original clutch pedal. The pseudo clutch pedal 25 has a structure imitating the clutch pedal provided in a conventional manual transmission internal combustion engine vehicle. For example, the pseudo clutch pedal 25 is provided with a reaction force mechanism that generates a reaction force against the depression by the driver. The position when no stepping force is applied is the start position of the pseudo clutch pedal 25, and the position when it is depressed to the deepest is the end position of the pseudo clutch pedal 25. The driver can operate the pseudo clutch pedal 25 against the reaction force from the reaction force mechanism from the start position to the end position. A clutch pedal stroke sensor 15 is provided on the pseudo clutch pedal 25. The clutch pedal stroke sensor 15 outputs a signal indicating the depression amount of the pseudo clutch pedal 25. Since the electric vehicle 100 does not have an actual clutch, the operation amount of the pseudo clutch pedal 25, that is, the clutch opening degree, is a virtual clutch opening degree.

[0017] Note that although the pseudo clutch pedal 25 is a pedal-type operating device operated by the foot, a lever-type operating device or a dial-type operating device operated by the hand may be provided as a pseudo clutch operating device. The pseudo clutch operating device can be operated by the driver against the reaction force from the start position to the end position, and various structures can be adopted as long as the operating feeling similar to that of the clutch pedal provided in a conventional manual transmission internal combustion engine vehicle can be felt by the foot or hand.

[0018] In addition, the electric vehicle 100 is equipped with an inclination angle sensor 16. The inclination angle sensor 16 measures the inclination of the electric vehicle 100.

[0019] In addition, the electric vehicle 100 is equipped with a human machine interface (HMI) 20 as an interface with the driver and an in-vehicle speaker 21. The HMI 20 includes a touch panel display. The HMI 20 displays information on the touch panel display and receives input from the driver through a touch operation on the touch panel display. The in-vehicle speaker 21 can output sound and artificial sound, and can provide information to the driver by voice through the in-vehicle speaker 21.

[0020] The electric vehicle 100 is equipped with a control device 101. Sensors and devices to be controlled mounted on the electric vehicle 100 are connected to the control device 101 through an in-vehicle network. In addition to the vehicle speed sensor 11, the accelerator pedal stroke sensor 12, the brake pedal stroke sensor 13, the shift position sensor 14, the clutch pedal stroke sensor 15, and the inclination angle sensor 16, various other sensors are mounted on the electric vehicle 100.

[0021] The control device 101 is typically an electronic control unit (ECU). The control device 101 may be a combination of multiple ECUs. The control device 101 includes at least a processor 102 and a memory 103. The memory 103 includes a RAM for temporarily recording data, and a ROM for storing a program 104 executable by the processor 102 and various data 105 related to the program. The program 104 is composed of a plurality of instructions. The processor 102 reads the program 104 and the data 105 from the memory 103 and executes them, and generates a control signal based on the signals acquired from each sensor. The number of processors 102 included in the control device 101 may be one or more.

[0022] The control device 101 can control the electric vehicle 100 in a plurality of different control modes. The control mode can be selected by the driver himself / herself by touching the touch panel display of the HMI 20. Specifically, by touching the touch panel display of the HMI 20, one or more programs 104 associated with each touch operation are read from the memory 103 and executed by the processor 102. Hereinafter, the control modes of the electric vehicle 100 by the control device 101 that can be selected by the driver through the operation of the HMI 20 will be described.

[0023] 3. Control Modes of Electric Vehicles The control modes of the electric vehicle 100 selectable by the control device 101 include at least an automatic mode and a manual mode. The automatic mode is a control mode for driving the electric vehicle 100 as a normal BEV. In the automatic mode, the driver can basically drive the electric vehicle 100 only by operating the accelerator pedal 22, the brake pedal 23, and a steering wheel (not shown). In the automatic mode, the shift operation of the pseudo H-type shifter 24 and the clutch operation of the pseudo clutch pedal 25 are invalidated.

[0024] The manual mode is a control mode for operating the electric vehicle 100 like a manually shifted internal combustion engine vehicle. In the manual mode, a shift operation of the pseudo H-type shifter 24 and a clutch operation of the pseudo clutch pedal 25 are required. In the manual mode, the operation when the gear ratio of the manual transmission is switched is reproduced by the shift operation and the clutch operation.

[0025] The manual mode may further include a plurality of control modes. For example, the driver can operate the display of the HMI 20 and select a control mode in which options regarding engine characteristics, engine sound, suspension characteristics, etc. are appropriately combined, so as to determine the characteristics of the manually shifted internal combustion engine vehicle that the electric vehicle 100 is to simulate. The selected control mode is related to the driving control of the electric vehicle 100. Hereinafter, the driving control of the electric vehicle 100 will be described.

[0026] 4. Driving Control of Electric Vehicle Figure 2 is a diagram showing the configuration of a control device 101 related to the driving control of an electric vehicle 100. Specifically, Figure 2 shows the configuration related to torque control among the driving controls. When one or more driving control programs 104 stored in the memory 103 are executed by the processor 102, the processor 102 functions as a driving control device.

[0027] A control mode signal is input to the control device 101 as a driving control device from the HMI 20. The control mode signal includes information regarding the control mode selected by the driver. The control device 101 executes a process P110 based on the control mode signal. In the process P110, the control mode is switched according to the control mode signal. What particularly affects the driving control in the switching of the control mode is the switching between the automatic mode and the manual mode.

[0028] Hereinafter, the drive wheel torque based on the driver's request is referred to as the driver request torque. When the control mode is switched to the automatic mode, the control device 101 executes a process P120 for calculating the driver request torque in the automatic mode. In the process P120, the control device 101 obtains the vehicle speed from the signal of the vehicle speed sensor 11 and obtains the accelerator opening from the signal of the accelerator pedal stroke sensor 12. The control device 101 has a motor torque map using the accelerator opening and the vehicle speed as parameters. The torque obtained by the control device 101 inputting the vehicle speed and the accelerator opening into the motor torque map is the driver request torque.

[0029] When the control mode is switched to the manual mode, the control device 101 executes a process P130 for calculating the driver request torque in the manual mode.

[0030] In the calculation of the driving wheel torque in process P130, vehicle model MOD01 is used. Vehicle model MOD01 calculates the driver demand torque from the virtual transmission torque and the reduction ratio. Vehicle model MOD01 includes engine model MOD11, clutch model MOD12, and transmission model MOD13. The engine virtually realized by vehicle model MOD01 is called a virtual engine, the clutch virtually realized is called a virtual clutch, and the transmission virtually realized is called a virtual transmission. In engine model MOD11, the virtual engine is modeled. In clutch model MOD12, the virtual clutch is modeled. In transmission model MOD13, the virtual transmission is modeled.

[0031] Engine model MOD11 calculates the virtual engine speed and the virtual engine torque. The virtual engine speed is calculated from the vehicle speed, the overall reduction ratio, and the slip ratio of the virtual clutch. The virtual engine torque is calculated from the virtual engine speed and the accelerator opening. The vehicle speed is obtained from the signal of vehicle speed sensor 11. The accelerator opening is obtained from the signal of accelerator pedal stroke sensor 12. The overall reduction ratio is a numerical value obtained by multiplying the gear ratio of the virtual transmission by the reduction ratio determined by the mechanical structure from the virtual transmission to the driving wheels. In engine model MOD11, the relationship between the virtual engine speed and the virtual engine torque is defined for each accelerator opening. The engine characteristics of engine model MOD11 may also be selectable by the driver through the operation of HMI20.

[0032] The clutch model MOD12 calculates the torque transmission gain. The torque transmission gain is a gain for calculating the degree of torque transmission of the virtual clutch according to the clutch opening. The clutch opening is obtained from the signal of the clutch pedal stroke sensor 15. The clutch opening is 0% at the start position of the virtual clutch pedal 25 and 100% at the end position of the virtual clutch pedal 25. In the clutch model MOD12, the torque transmission gain is given for the clutch opening. The torque transmission gain is converted into the clutch torque capacity of the virtual clutch, that is, the virtual clutch torque capacity. Then, based on the comparison between the virtual clutch torque capacity and the virtual engine torque calculated by the engine model MOD11, the virtual clutch torque input from the virtual clutch to the virtual transmission is calculated. Also, in the clutch model MOD12, the value obtained by subtracting the torque transmission gain from 1 is calculated as the slip ratio. The slip ratio is used in the calculation of the virtual engine speed in the engine model MOD11.

[0033] The transmission model MOD13 calculates the virtual gear ratio. The virtual gear ratio is the gear ratio determined by the virtual shift position in the virtual transmission. The virtual shift position is associated one-to-one with the signal of the shift position sensor 14. The virtual gear ratio is set for each virtual shift position. The maximum virtual gear ratio is set for the first gear, and the virtual gear ratio is decreased in the order of the second gear, third gear, fourth gear, ···.

[0034] The transmission model MOD13 calculates the virtual transmission torque using the virtual gear ratio and the virtual clutch torque. The virtual transmission torque is the virtual torque output from the virtual transmission. The control device 101 controls the inverters 3F, 3R so that the output torques of the electric motors 4F, 4R change according to the virtual transmission torque. The virtual transmission torque changes discontinuously according to the switching of the virtual gear ratio. This discontinuous change in the virtual transmission torque generates a torque shock in the electric vehicle 100, producing the feel of a vehicle equipped with a stepped transmission.

[0035] When the driver required torque is calculated by process P120 or process P130, the control device 101 executes process P140. In process P140, the actual output torque is calculated. The actual output torque is the torque actually output to the drive wheels. When the hold assist control described later is not operating, the actual output torque is the driver required torque calculated by process P120 or process P130. The actual output torque when the hold assist control is operating will be described later.

[0036] The drive wheel torque calculated by process P140 is the sum of the torques acting on the left and right front wheels 6F and the left and right rear wheels 6R. The control device 101 controls the inverters 3F, 3R to generate the calculated torque in the electric motors 4F, 4R. Note that the torque distribution to the front wheels 6F and the rear wheels 6R may be fixed, or may be actively or passively variable.

[0037] The above describes the driving control of the electric vehicle 100. In addition to the driving control, the control of the electric vehicle 100 performed by the control device 101 includes sound control. The control device 101 as a sound control device can generate an artificially generated sound from the in-vehicle speaker 21. The artificial sound reproduced from the in-vehicle speaker 21 may include, for example, a pseudo engine sound imitating the engine sound in a conventional internal combustion engine vehicle. For example, when a control mode signal indicating that the manual mode has been selected is input from the HMI 20, the control device 101 generates a pseudo engine sound based on the virtual engine torque and the virtual engine speed, and generates the pseudo engine sound from the in-vehicle speaker 21. By reproducing the engine sound, a sense of reality can be given to the driver as if driving a real manual transmission internal combustion engine vehicle.

[0038] 5. Hill Hold Assist Regarding such an electric vehicle 100, consider a scenario where it stops on an uphill slope and then resumes moving forward. Since gravity acts on the electric vehicle 100, when the brake is turned off, the electric vehicle 100 will roll backward. However, when the automatic mode is selected, the driver can start the electric vehicle 100 simply by switching the brake pedal 23 to the accelerator pedal 22, so the electric vehicle 100 rarely rolls back significantly. On the other hand, when the manual mode is selected, in addition to operating the accelerator pedal 22, operations of the pseudo H-type shifter 24 and the pseudo clutch pedal 25 are required. After the driver releases the brake pedal 23, the time it takes for the driver-requested torque to exceed the torque required to start the electric vehicle 100 is longer than when the automatic mode is selected. Therefore, during the period until starting, the electric vehicle 100 may roll back significantly due to the action of gravity.

[0039] Therefore, when the control device 101 detects that the electric vehicle 100 is stopped on a road surface with an uphill slope, it executes hold assist control to prevent the electric vehicle 100 from rolling back due to the gravity acting on it. In the hold assist control, the control device 101 prevents the vehicle from rolling back by generating a torque in the same direction as the vehicle's traveling direction on the drive wheels. Hereinafter, the torque for preventing rolling back generated in the hold assist control is referred to as the hold assist torque.

[0040] FIG. 3 shows a time chart of the control flag, accelerator opening, clutch opening, vehicle speed, requested torque, and actual output torque when the manual mode is selected in the electric vehicle 100. Hereinafter, the hold assist control by the control device 101 and its effects will be described with reference to FIG. 3.

[0041] The control flag is the control flag for hold assist control, and when the control flag turns ON, the hold assist control activates. The clutch opening is a virtual clutch opening calculated based on the signal of the clutch pedal stroke sensor 15. The required torque is the drive wheel torque required by the driver and the drive wheel torque required as the hold assist torque. The solid line represents the hold assist torque, and the dotted line represents the driver required torque.

[0042] The time chart starts from time T0 when the electric vehicle 100 is stopped on an uphill slope. The driver is stepping on the brake pedal 23 and the pseudo clutch pedal 25. The virtual clutch is in a disengaged state, and the clutch opening is 100%. Between time T0 and T1, no drive wheel torque is output.

[0043] When the control device 101 detects that the driver has turned the brake OFF, it turns ON the control flag. The state where the driver has turned the brake OFF is a state where the side brake is not applied and the driver has removed their foot from the brake pedal 23. Although not shown in the time chart, at time T1, the driver removes their foot from the brake pedal 23 with the side brake released and turns the brake OFF. In response to this, the control device 101 turns ON the control flag for hold assist control. Then, it starts outputting the hold assist torque. The hold assist torque is a drive wheel torque in a magnitude that can stop the electric vehicle 100 and is output in the direction opposite to gravity, that is, in the traveling direction of the electric vehicle 100.

[0044] When the hold assist torque is being output, the control device 101 selects the larger of the driver required torque and the hold assist torque as the actual output torque. From time T1 to T2, since no driver required torque is output, the hold assist torque becomes the actual output torque.

[0045] At time T2, the driver switches the brake pedal 23 to the accelerator pedal 22, and the accelerator opening increases. Also, the driver starts the clutch operation and gradually decreases the clutch opening. As the clutch opening decreases, the torque transmission gain increases, and the driver-required torque gradually increases.

[0046] Between time T2 and time T3, the hold assist torque is selected as the actual output torque. During this period, the driver-required torque is not large enough to prevent the electric vehicle 100 from reversing on the slope, but since the hold assist torque is output as the drive wheel torque, the reverse of the electric vehicle 100 can be prevented.

[0047] At time T3, the driver-required torque becomes equal to the hold assist torque, and after time T3, the driver-required torque exceeds the hold assist torque. At time T3, in response to the driver-required torque exceeding the hold assist torque, the control device 101 turns off the control flag. The hold assist control ends, and the hold assist torque is no longer output. After time T3 when the output of the hold assist torque ends, the driver-required torque becomes the actual output torque. At this time, the magnitude of the driver-required torque exceeds the magnitude of the hold assist torque, which is the torque required to prevent the electric vehicle 100 from reversing. Therefore, the electric vehicle 100 starts to travel forward.

[0048] That is, when the control device 101 detects that the electric vehicle 100 has started moving on a slope, it activates the hold assist control. In the hold assist control, instead of activating the brake, the control device 101 outputs torque in the vehicle's traveling direction to prevent the vehicle from moving backward. The end condition of the hold assist control is that the driver-requested torque exceeds the torque output by the hold assist control. When the output of the hold assist torque ends, the actual output torque switches to the driver-requested torque, that is, the output of the driver-requested torque starts when the output of the hold assist torque ends. Since the hold assist torque and the driver-requested torque are equal at the end point, the drive wheel torque can be smoothly shifted to the driver-requested torque without discontinuously changing the actual output torque. In this way, the electric vehicle 100 can be smoothly started, and the comfort for the driver can be improved.

[0049] Note that the hold assist control may also be performed when the automatic mode is selected. By performing the hold assist control even in the automatic mode, it is possible to prevent the electric vehicle 100 from moving backward while the driver switches from the brake pedal 23 to the accelerator pedal 22. However, usually, the time from when the driver releases the brake pedal 23 until the driver-requested torque exceeds the hold assist torque is longer when the manual mode is selected, so the hold assist control is more effective when the manual mode is selected.

[0050] 6. Processing Example FIG. 4 is a flowchart showing the processing related to the hold assist control by the control device 101. The series of processes shown in FIG. 4 is realized by one or more programs 104 stored in the memory 103 being executed by the processor 102.

[0051] In step S101, the control device 101 determines whether the electric vehicle 100 is stopped. For example, the control device 101 may determine whether the electric vehicle 100 is stopped based on the signal obtained from the vehicle speed sensor 11. In this case, when the vehicle speed is 0, it is determined that the electric vehicle 100 is stopped. If the electric vehicle 100 is stopped (step S101; Yes), the process proceeds to step S102. On the other hand, if the electric vehicle 100 is not stopped (step S101; No), the series of processes ends.

[0052] In step S102, the control device 101 determines whether the place where the electric vehicle 100 is stopped is an uphill slope. The control device 101 can determine the inclination of the place where the electric vehicle 100 is stopped based on the information obtained from the inclination angle sensor 16. The inclination of the electric vehicle 100 obtained from the inclination angle sensor 16 is the inclination of the road surface. Note that the control device 101 may determine that there is a slope on the road surface when the inclination of the road surface where the electric vehicle 100 is stopped is greater than a predetermined value, and determine that the road surface is flat when the inclination of the road surface is less than or equal to the predetermined value. If the parking place of the electric vehicle 100 is an uphill slope (step S102; Yes), the process proceeds to step S103. On the other hand, if the parking place of the electric vehicle 100 is not an uphill slope (step S102; No), the series of processes ends.

[0053] In step S103, the control device 101 determines whether the brake has been turned off by the driver. If the brake has been turned off (step S103; Yes), the process proceeds to step S105. On the other hand, if the brake has not been turned off, that is, if the side brake is engaged or the brake pedal 23 is depressed (step S103; No), the determination in step S103 is repeated. Note that in step S103, the control device 101 may determine that the brake has been turned off when the amount of depression of the brake pedal 23 by the driver is less than or equal to a predetermined amount with the side brake released.

[0054] In step S105, the control device 101 starts to output the hold assist torque. The magnitude of the hold assist torque is set to be such that the electric vehicle 100 can resist the action of gravity and stop. Alternatively, the hold assist torque may be a torque slightly smaller than the torque required to completely stop the electric vehicle 100. Also, the magnitude of the torque may be calculated, for example, by feedback control using the vehicle speed as an output value such that the vehicle speed becomes equal to or lower than a threshold value. By using feedback control, even when there are changes in the weight of the vehicle body of the electric vehicle 100 or other disturbance factors, the exact magnitude of the required torque can be calculated. When the output of the hold assist torque is started, the process proceeds to step S106.

[0055] In step S106, the control device 101 determines whether the driver request torque exceeds the hold assist torque. If the driver request torque exceeds the hold assist torque (step S106; Yes), the process proceeds to step S107. On the other hand, if the driver request torque is equal to or less than the hold assist torque (step S106; No), the determination in step S106 is repeated again.

[0056] In step S107, the control device 101 ends the output of the hold assist torque. By ending the output of the hold assist torque, the actual output torque switches to the driver request torque. When the output of the hold assist torque ends, the series of processes ends.

[0057] Note that if the driver operates the brake after the control device 101 starts to output the hold assist torque and before the driver request torque exceeds the hold assist torque, the control device 101 may end the output of the hold assist torque. Thereby, unnecessary output of drive wheel torque can be prevented, and the power consumption of the battery 2 can be improved.

[0058] 7. Example of processing on a downhill slope When a driver attempts to reverse an electric vehicle 100 parked on a downhill slope, the vehicle may move forward due to gravity. Therefore, the hold assist control is also effective even when starting the electric vehicle parked on a downhill road surface in the reverse direction. FIG. 5 is a flowchart showing an example of processing related to hold assist control on a downhill road surface.

[0059] The process of step S201 is the same as the process of step S101 in FIG. 4. In step S202, the control device 101 determines whether the location where the electric vehicle 100 is parked is a downhill slope. Similar to step S102 in FIG. 4, the control device 101 can make a determination based on the information obtained from the inclination angle sensor 16. Also, when the inclination of the road surface where the electric vehicle 100 is parked is greater than a predetermined value, it can be determined that there is a slope on the road surface, and when the inclination of the road surface is less than or equal to the predetermined value, it can be determined that the road surface is flat. If the parking location of the electric vehicle 100 is a downhill slope (step S202; Yes), the process proceeds to step S203. On the other hand, if the parking location of the electric vehicle 100 is not a downhill slope (step S202; No), the series of processes ends.

[0060] The process of step S203 is the same as the process of step S103 in FIG. 4. However, when the brake is turned off (step S203; Yes), the process proceeds to step S204.

[0061] In step S204, the control device 101 determines whether the shift switch is set to reverse. When the manual mode is selected, based on the signal of the shift position sensor 14, it is determined whether the shift position of the pseudo H-type shifter 24 is in the reverse position. If the shift switch is set to reverse (step S204; Yes), the process proceeds to step S205. On the other hand, if the shift switch is not set to reverse (step S204; No), the series of processes ends.

[0062] In step 205, the control device 101 starts to output the hold assist torque. The torque output here is the drive wheel torque in the direction opposite to gravity, that is, in the direction opposite to the traveling direction of the electric vehicle 100. When the output of the torque starts, the process proceeds to step S206.

[0063] The process of step S206 is the same as that of step S106 in FIG. 4. However, both the output driver request torque and the hold assist torque are the drive wheel torques in the direction opposite to the traveling direction of the electric vehicle 100. The driver request torque in the direction opposite to the traveling direction of the electric vehicle 100 and the hold assist torque in the direction opposite to the traveling direction of the electric vehicle 100 are compared and a determination is made. When the driver request torque exceeds the hold assist torque, the process proceeds to step S207 and the output of the hold assist torque ends. Similar to the hold assist control on the uphill gradient, the hold assist switches to the driver request torque, and thereafter the driver request torque is output as the drive wheel torque.

[0064] Through the above processing, even on a downhill road surface, it is possible to prevent the electric vehicle 100 from moving forward unintentionally by the driver due to gravity. Also, since the hold assist torque and the driver request torque are equal at the end point, the drive wheel torque can be smoothly shifted to the driver request torque without discontinuously changing the actual output torque. In this way, the electric vehicle 100 can be smoothly started.

Description of Signs

[0065] 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 Pedal Stroke Sensor, 16 Inclination Angle Sensor, 21 In-vehicle Speaker, 22 Accelerator Pedal, 23 Brake Pedal, 24 Pseudo H-type Shifter, 25 Pseudo Clutch Pedal, 100 Electric Vehicle, 101 Control Device, 102 Processor, 103 Memory, 104 Program, 105 Data, MOD01 Vehicle Model, MOD11 Engine Model, MOD12 Clutch Model, MOD13 Transmission Model

Claims

1. An electric vehicle having an electric motor as a drive source, a driving operation member used for driving the electric vehicle, a pseudo-shift operation member imitating an operation member used for shift operation of a manual transmission diesel locomotive, and a control device configured to control the electric vehicle according to an operation of the driving operation member, wherein the driving operation member includes an accelerator pedal, the pseudo-shift operation member includes a pseudo-H-type shifter imitating an H-type shifter of a manual transmission and a pseudo-clutch operation device imitating a clutch operation device, the control device executes a control mode for calculating a driver demand torque for driving the electric motor based on an opening degree of the accelerator pedal and an operation of the pseudo-shift operation member by a selection of a driver, and in the control mode, when it is detected that the electric vehicle is stopped on a sloped road surface, performs a hold assist for preventing backward or forward movement of the electric vehicle due to gravity acting on the electric vehicle, the hold assist outputs a hold assist torque which is a drive wheel torque in a direction opposite to gravity, and includes ending the output of the hold assist torque and switching to the output of the driver demand torque in response to the driver demand torque exceeding the hold assist torque. An electric vehicle characterized by the above.

2. The electric vehicle according to claim 1, wherein the hold assist includes outputting the hold assist torque on condition that the sloped road surface is an uphill road surface. An electric vehicle characterized by the above.

3. The electric vehicle according to claim 1, wherein the hold assist includes outputting the hold assist torque on condition that the sloped road surface is a downhill road surface and the shift switch of the electric vehicle is set to reverse. An electric vehicle characterized by the above.

4. The electric vehicle according to claim 2 or 3, wherein the hold assist includes starting the output of the hold assist torque in response to a brake operation by the driver being turned off. An electric vehicle characterized by the above.

5. The electric vehicle according to claim 4, wherein the hold assist After starting the output of the hold assist torque and before the driver required torque exceeds the hold assist torque, when a braking operation is performed by the driver, including ending the output of the hold assist torque An electric vehicle characterized by the above

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