Electric automobile

Abstract

An electric vehicle is provided with a driving operation member including an accelerator pedal, a simulated shift operation member, and a control device. The control device is configured so as to execute a control mode for calculating a driver-requested torque for driving the electric motor on the basis of the opening degree of the accelerator pedal and the operation of the simulated shift operation member in accordance with the selection of the driver, and to perform holding assistance when it is detected that the electric vehicle is stopped on a gradient road surface. The holding assist includes: outputting a holding assist torque, which is a drive wheel torque in an opposite direction to gravity; and in response to the condition that the driver request torque exceeds the holding assist torque, ending the output of the holding assist torque, and switching to the output of the driver request torque.

Description

Technical Field

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

[0002] Japanese Unexamined Patent Application Publication No. 2023-107412 discloses holding assistance in an electric vehicle having a function of simulating engine shutdown. By using the holding assistance to operate the brake, it is possible to prevent the vehicle from sliding down on a slope due to the action of gravity. Summary of the Invention

[0003] Holding assistance is a function for preventing the vehicle body from moving backward or forward due to the action of gravity when a vehicle stopped on a slope starts again. As a holding assistance function, it is known to prevent backward and forward movement caused by gravity by operating the brake on a slope. However, if the operation of the brake is suddenly ended when the driver-requested drive wheel torque becomes large enough, the drive wheel torque changes discontinuously, which is not comfortable for the driver. The present disclosure provides a technique capable of preventing backward and forward movement on a slope caused by gravity and enabling a smooth start.

[0004] The present disclosure provides an electric vehicle having an electric motor as a drive source. The electric vehicle includes: a driving operation component for driving the electric vehicle; a simulated shift operation component that simulates an operation component used for a shift operation of a manual transmission type internal combustion locomotive; and a control device configured to control the electric vehicle according to an operation of the driving operation component. The driving operation component includes an accelerator pedal. The simulated shift operation component includes a simulated H-type shifter that simulates an H-type shifter of a manual transmission and a simulated clutch operation device that simulates a clutch operation device. The control device is configured to perform the following steps: according to a driver's selection, execute a control mode for calculating a driver-requested torque for driving the electric motor based on an opening degree of the accelerator pedal and an operation of the simulated shift operation component; and in this control mode, when it is detected that the electric vehicle is stopped on a sloped road surface, perform holding assistance for preventing backward or forward movement of the electric vehicle caused by gravity acting on the electric vehicle. The holding assistance includes: outputting a drive wheel torque in a direction opposite to gravity, that is, a holding assistance torque; and in response to a situation where the driver-requested torque exceeds the holding assistance torque, ending the output of the holding assistance torque and switching to the output of the driver-requested torque.

[0005] In the electric vehicle according to the aspect of the present disclosure, it may also be that the holding assistance includes outputting the holding assistance torque on the condition that the sloped road surface is an uphill road surface.

[0006] In the electric vehicle according to the aspect of the present disclosure, it is also possible that the holding assist includes outputting the holding assist torque on the condition that the sloped road surface is a downhill road surface and the shift switch of the electric vehicle is set to the reverse gear.

[0007] In the electric vehicle according to the aspect of the present disclosure, it is also possible that the holding assist includes starting to output the holding assist torque in response to the disconnection of the braking operation performed by the driver.

[0008] In the electric vehicle according to the aspect of the present disclosure, it is also possible that the holding assist includes ending the output of the holding assist torque when the driver performs a braking operation after the output of the holding assist torque has started and before the driver-requested torque exceeds the holding assist torque.

[0009] In the electric vehicle according to the aspect of the present disclosure, it is also possible that the control device is configured to calculate the driver-requested torque using a vehicle model, and the vehicle model includes an engine model that models a hypothetical engine, a clutch model that models a hypothetical clutch, and a transmission model that models a hypothetical transmission.

[0010] In the electric vehicle according to the present disclosure, a holding assist torque is output by a holding assist for preventing the vehicle from moving backward or forward on a slope. In addition, the output of the holding assist torque ends when the driver-requested driving wheel torque exceeds the holding assist torque. And, the driver-requested torque is output simultaneously with the end of the output of the holding assist torque. Thereby, it is possible to smoothly transfer the output driving wheel torque from the holding assist torque to the driver-requested torque. In this way, it is possible to prevent backward or forward movement caused by gravity when starting on a slope and to perform a smooth start. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Hereinafter, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the drawings, in which the same reference numerals denote the same elements, and:

[0012] Figure 1 is a diagram showing the structure of an electric vehicle according to an embodiment of the present disclosure.

[0013] Figure 2 is a diagram showing the structure of a control device related to the running control of the electric vehicle.

[0014] Figure 3 is a timing chart for explaining the holding assist control of the electric vehicle.

[0015] Figure 4 is a flowchart showing an example of processing related to the holding assist control for uphill driving.

[0016] Figure 5 This is a flowchart showing an example of a process related to the hold assist control for downhill driving. DETAILED DESCRIPTION

[0017] Embodiments of the present disclosure will be described with reference to the accompanying drawings. 1. Structure of the powertrain of an electric vehicle

[0018] Figure 1 This is a diagram schematically showing the structure of an electric vehicle 100 to which the embodiments of the present disclosure pertain. First, with reference to Figure 1 the structure of the powertrain of the electric vehicle 100 will be described.

[0019] The electric vehicle 100 is provided with two electric motors (M) 4F and 4R as power sources for driving at the front and rear. 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 left and right independent electronically controlled front suspensions 7F. The rear wheels 6R are suspended by left and right independent electronically controlled rear suspensions 7R.

[0020] Inverters (INV) 3F and 3R are respectively installed on the front electric motor 4F and the rear electric motor 4R. The front inverter 3F and the rear inverter 3R are respectively connected to a storage battery (BATT) 2. The storage 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 travels using the electrical energy stored in the storage battery 2. The inverters 3F and 3R are, for example, voltage source inverters, and control the torque of the electric motors 4F and 4R through PWM control. 2. Structure of the control system of an electric vehicle

[0021] Next, with reference to Figure 1 the structure of the control system of the electric vehicle 100 will be described.

[0022] The electric vehicle 100 is provided with a vehicle speed sensor 11. At least one of the unillustrated wheel speed sensors respectively provided on the left and right front wheels 6F and the left and right rear wheels 6R is used as the vehicle speed sensor 11. In addition, the electric vehicle 100 is provided 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. And, the electric vehicle 100 is provided 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.

[0023] The accelerator pedal 22 and the brake pedal 23 are driving operation components for driving the electric vehicle 100. In addition to these driving operation components, the electric vehicle 100 is also equipped with a simulated speed change operation component that simulates the operation component used for the speed change operation of a manual transmission type internal combustion engine vehicle. The simulated speed change operation component includes the following simulated H-type shifter 24 and simulated clutch pedal 25. The simulated clutch pedal 25 is an example of a simulated clutch operation device.

[0024] The simulated H-type shifter 24 is a virtual device different from the original H-type shifter. The simulated H-type shifter 24 has a structure similar to a shift lever provided on a console, and can move along an H-shaped gate between shift positions. However, since the electric vehicle 100 does not have a real transmission, the shift position of the simulated H-type shifter 24 is a virtual shift position. The simulated H-type shifter 24 is provided with a shift position sensor 14. The shift position sensor 14 outputs a signal indicating the shift position selected by the simulated H-type shifter 24.

[0025] The simulated clutch pedal 25 is a virtual one different from the original clutch pedal. The simulated clutch pedal 25 has a structure similar to the clutch pedal of the previous manual transmission type internal combustion engine vehicle. For example, the simulated clutch pedal 25 has a reaction force mechanism that generates a reaction force relative to the driver's stepping. The position when no stepping force is applied is the starting position of the simulated clutch pedal 25, and the position when stepped into the deepest position is the terminal position of the simulated clutch pedal 25. The driver can operate the simulated clutch pedal 25 from the starting position to the terminal position to overcome the reaction force from the reaction force mechanism. The simulated clutch pedal 25 is provided with a clutch pedal stroke sensor 15. The clutch pedal stroke sensor 15 outputs a signal indicating the amount of stepping on the simulated clutch pedal 25. The electric vehicle 100 does not have a real clutch, so the operation amount of the simulated clutch pedal 25, that is, the clutch opening, is a virtual clutch opening.

[0026] In addition, the simulated clutch pedal 25 is a pedal-type operating device operated by foot, but a lever-type operating device or a dial-type operating device operated by hand may also be provided as a simulated clutch operating device. The simulated clutch operating device allows the driver to overcome the reaction force and operate from the starting position to the end position. As long as the driver can feel the operating feeling of the clutch pedal of the conventional manual transmission type internal combustion engine vehicle with the foot or hand, various structures can be adopted.

[0027] Furthermore, the electric vehicle 100 includes a tilt angle sensor 16 . The tilt angle sensor 16 measures the tilt of the electric vehicle 100 .

[0028] In addition, the electric vehicle 100 is provided 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 accepts input from the driver based on a touch operation on the touch panel display. The in-vehicle speaker 21 can output sounds and artificial sounds, and can provide information to the driver in sound through the in-vehicle speaker 21.

[0029] The electric vehicle 100 is provided with a control device 101. The sensors mounted on the electric vehicle 100 and the devices to be controlled are connected to the control device 101 through 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, a clutch pedal stroke sensor 15, and an inclination angle sensor 16, various sensors are also mounted on the electric vehicle 100.

[0030] The control device 101 is typically an electronic control unit (ECU). The control device 101 may also be a combination of multiple ECUs. The control device 101 at least includes 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 associated with the program. The program 104 is composed of multiple instructions. The processor 102 reads the program 104 and data 105 from the memory 103 and executes them, and generates a control signal based on the signals obtained from the respective sensors. The number of processors 102 included in the control device 101 may be one or multiple.

[0031] 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 through a touch operation on the touch panel display of the HMI 20. Specifically, through a touch operation on the touch panel display of the HMI 20 by the driver, one or more programs 104 associated with the respective touch operations are read from the memory 103 and executed by the processor 102. Hereinafter, the control modes of the electric vehicle 100 that the control device 101 can select through the operation of the HMI 20 will be described. 3. Control Modes of Electric Vehicles

[0032] The control modes of the electric vehicle 100 that the control device 101 can select at least include 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 drive the electric vehicle 100 basically only through the operations of the accelerator pedal 22, the brake pedal 23, and a steering wheel (not shown). In the automatic mode, the shift operation of the simulated H-type shifter 24 and the clutch operation of the simulated clutch pedal 25 are invalidated.

[0033] The manual mode is a control mode for operating the electric vehicle 100 in the same manner as a manually shifted internal combustion engine vehicle. In the manual mode, it is necessary to perform a shifting operation of the simulated H-type shifter 24 and a clutch operation of the simulated clutch pedal 25. In the manual mode, the operations of shifting and clutching are performed to reproduce the actions when shifting the gear ratio of a manually shifted transmission.

[0034] The manual mode may also include multiple control modes. For example, it may be that the driver operates the display of the HMI 20 to select a control mode obtained by appropriately combining options related to engine characteristics, engine sound, suspension characteristics, etc., thereby being able to determine the characteristics of the manually shifted internal combustion engine vehicle that the electric vehicle 100 is desired 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. 4. Driving Control of Electric Vehicle

[0035] Figure 2 FIG. shows the structure of the control device 101 related to the driving control of the electric vehicle 100. Specifically, Figure 2 FIG. shows the structure related particularly to torque control in driving control. The processor 102 functions as a driving control device by executing one or more driving control programs 104 stored in the memory 103.

[0036] A control mode signal is input from the HMI 20 to the control device 101 which is a driving control device. The control mode signal contains information related to 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. The switching of the control mode particularly affects the driving control in the switching between the automatic mode and the manual mode.

[0037] Hereinafter, the drive wheel torque based on the driver's requirement will be referred to as the driver required torque. When the control mode is switched to the automatic mode, the control device 101 executes a process P120 for calculating the driver required 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 with 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 required torque.

[0038] When the control mode is switched to the manual mode, the control device 101 executes a process P130 for calculating the driver required torque in the manual mode.

[0039] The vehicle model MOD01 is used in the calculation of the drive wheel torque in P130. The vehicle model MOD01 calculates the driver demand torque based on the hypothetical transmission torque and the reduction ratio. The vehicle model MOD01 includes an engine model MOD11, a clutch model MOD12, and a transmission model MOD13. The engine hypothetically realized through the vehicle model MOD01 is called the hypothetical engine, the clutch hypothetically realized is called the hypothetical clutch, and the transmission hypothetically realized is called the hypothetical transmission. In the engine model MOD11, the hypothetical engine is modeled. In the clutch model MOD12, the hypothetical clutch is modeled. In the transmission model MOD13, the hypothetical transmission is modeled.

[0040] The engine model MOD11 calculates the hypothetical engine speed and the hypothetical engine torque. The hypothetical engine speed is calculated based on the vehicle speed, the overall reduction ratio, and the slip rate of the hypothetical clutch. The hypothetical engine torque is calculated based on the hypothetical engine speed and the accelerator opening. The vehicle speed is obtained from the signal of the vehicle speed sensor 11. The accelerator opening is obtained based on the signal of the accelerator pedal stroke sensor 12. The overall reduction ratio is a value obtained by multiplying the gear ratio of the hypothetical transmission by the reduction ratio determined by the mechanical structure from the hypothetical transmission to the drive wheels. In the engine model MOD11, the relationship between the hypothetical engine speed and the hypothetical engine torque is specified for each accelerator opening. The engine characteristics of the engine model MOD11 can also be selected by the driver through the operation of the HMI20.

[0041] The clutch model MOD12 calculates the torque transfer gain. The torque transfer gain is a gain used to calculate the torque transfer degree of the hypothetical clutch corresponding to the clutch opening. The clutch opening is obtained based on the signal of the clutch pedal stroke sensor 15. The clutch opening is 0% at the start position of the simulated clutch pedal 25 and 100% at the end position of the simulated clutch pedal 25. In the clutch model MOD12, the torque transfer gain is assigned to the clutch opening. The torque transfer gain is converted into the clutch torque capacity of the hypothetical clutch, that is, the hypothetical clutch torque capacity. And, based on the comparison between the hypothetical clutch torque capacity and the hypothetical engine torque calculated by the engine model MOD11, the hypothetical clutch torque input from the hypothetical clutch to the hypothetical transmission is calculated. In addition, in the clutch model MOD12, the value obtained by subtracting the torque transfer gain from 1 is calculated as the slip rate. The slip rate is used to calculate the hypothetical engine speed in the engine model MOD11.

[0042] The transmission model MOD13 calculates an imaginary gear ratio. The imaginary gear ratio is the gear ratio determined by an imaginary shift position in an imaginary transmission. The imaginary shift position is associated one-to-one with the signal of the shift position sensor 14. The imaginary gear ratio is set for each imaginary shift position. The maximum imaginary gear ratio is set for the first gear, and the imaginary gear ratio decreases in the order of the second gear, third gear, fourth gear, ….

[0043] The transmission model MOD13 uses the imaginary gear ratio and the imaginary clutch torque to calculate an imaginary transmission torque. The imaginary transmission torque is an imaginary torque output from the imaginary 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 imaginary transmission torque. The imaginary transmission torque changes discontinuously according to the switching of the imaginary gear ratio. This discontinuous change in the imaginary transmission torque causes a torque shock in the electric vehicle 100, obtaining an operating feeling similar to that of a vehicle equipped with a stepped transmission.

[0044] When the driver demand torque is calculated by the process P120 or the process P130, the control device 101 executes the process P140. In the process P140, the actual output torque is calculated. The actual output torque is the torque actually output to the drive wheels. In the case where the holding assist control described later is not operating, the actual output torque is the driver demand torque calculated in the process P120 or the process P130. The actual output torque in the case where the holding assist control is operating will be described later.

[0045] The drive wheel torque calculated by the 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 so that the electric motors 4F, 4R generate the calculated torque. It should be noted that the torque distribution to the front wheels 6F and the rear wheels 6R can be fixed, or can be changed actively or passively.

[0046] Above, the running control of the electric vehicle 100 has been described. In addition, in the control of the electric vehicle 100 performed by the control device 101, in addition to the running control, it also includes sound control. The control device 101 as the sound control device can generate an artificially generated sound from the in-vehicle speaker 21. The artificial sound played from the in-vehicle speaker 21 can also include, for example, a simulated engine sound similar to the engine sound in a conventional internal combustion locomotive. For example, when a control mode signal indicating that the manual mode has been selected is input from the HMI20, the control device 101 generates a simulated engine sound based on the imaginary engine torque and the imaginary engine speed, and generates the simulated engine sound from the in-vehicle speaker 21. By reproducing the engine sound, a sense of reality like driving a real manual transmission internal combustion locomotive can be given to the driver. 5. Holding Assist on a Slope

[0047] Regarding such an electric vehicle 100, consider a scenario where the electric vehicle 100 stops midway on an uphill slope and then starts again. Since gravity acts on the electric vehicle 100, the electric vehicle 100 moves backward when the brake is released. However, when the automatic mode is selected, the driver can start the electric vehicle 100 only by switching the brake pedal 23 to the accelerator pedal 22, so the electric vehicle 100 rarely moves backward significantly. On the other hand, when the manual mode is selected, in addition to the operation of the accelerator pedal 22, the operations of the simulated H-type shifter 24 and the simulated clutch pedal 25 are also required, and the time taken from when the driver releases the brake pedal 23 until the driver's required torque exceeds the torque required to start the electric vehicle 100 is longer than when the automatic mode is selected. Therefore, during the period before starting, the electric vehicle 100 may move backward significantly due to the action of gravity.

[0048] Therefore, when the control device 101 detects that the electric vehicle 100 has stopped on a road surface with an uphill slope, it executes hold assist control for preventing backward movement caused by the gravity acting on the electric vehicle 100. In the hold assist control, the control device 101 prevents the vehicle from moving backward by causing the drive wheels to generate a torque in the same direction as the vehicle's traveling direction. Hereinafter, the torque for preventing backward movement generated in the hold assist control will be referred to as the hold assist torque.

[0049] In Figure 3 , a timing chart shows the control flag, accelerator opening, clutch opening, vehicle speed, required torque, and actual output torque when the manual mode is selected in the electric vehicle 100. Hereinafter, with reference to Figure 3 the hold assist control of the control device 101 and its effects will be described.

[0050] The control flag is the control flag for the hold assist control, and when the control flag is turned on, the hold assist control operates. The clutch opening is a hypothetical 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 dashed line represents the driver's required torque.

[0051] The timing chart starts at time T0 when the electric vehicle 100 is in a state of having stopped on an uphill slope. The driver steps on the brake pedal 23 and the simulated clutch pedal 25. The hypothetical clutch is in a disengaged state, and the clutch opening is 100%. During the period from time T0 to T1, no drive wheel torque is output.

[0052] When the control device 101 detects that the driver has set the brake to the off state, it sets the control flag to on. The state where the driver turns off the brake 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 timing diagram, at time T1, the driver removed their foot from the brake pedal 23 while the side brake was released and turned off the brake. In response to this, the control device 101 turns on the control flag for maintaining the auxiliary control. And, it starts to output the holding auxiliary torque. The holding auxiliary torque is a driving wheel torque that is output in the direction opposite to gravity, i.e., the traveling direction of the electric vehicle 100, and is of a magnitude that can stop the electric vehicle 100.

[0053] When outputting the holding auxiliary torque, the control device 101 selects the larger of the driver-requested torque and the holding auxiliary torque as the actual output torque. Since no driver-requested torque is output from time T1 to T2, the holding auxiliary torque is the actual output torque.

[0054] At time T2, the driver switches the brake pedal 23 to the accelerator pedal 22, and the accelerator opening increases. In addition, the driver starts the clutch operation and gradually reduces the clutch opening. As the clutch opening decreases, the torque transmission gain increases, and the driver-requested torque gradually increases.

[0055] Between time T2 and time T3, the holding auxiliary torque is selected as the actual output torque. During this period, the driver-requested torque is not large enough to prevent the electric vehicle 100 from rolling back on the slope, but since the holding auxiliary torque is output as the driving wheel torque, the electric vehicle 100 can be prevented from rolling back.

[0056] At time T3, the driver-requested torque is equal to the holding auxiliary torque, and after time T3, the driver-requested torque exceeds the holding auxiliary torque. At time T3, in response to the driver-requested torque exceeding the holding auxiliary torque, the control device 101 sets the control flag to off. The holding auxiliary control ends, and the holding auxiliary torque is not output. After time T3 when the output of the holding auxiliary torque ends, the driver-requested torque becomes the actual output torque. At this time, the magnitude of the driver-requested torque exceeds the magnitude of the holding auxiliary torque, which is the torque required to prevent the electric vehicle 100 from rolling back. Therefore, the electric vehicle 100 starts to move forward.

[0057] That is, when the control device 101 detects that the electric vehicle 100 starts to move on a slope, it activates the holding assist control. In the holding assist control, the control device 101 does not operate the brake, but prevents the vehicle from moving backward by outputting torque in the traveling direction of the vehicle. In addition, the end condition of the holding assist control is that the driver-requested torque exceeds the torque output by the holding assist control. And when the output of the holding assist torque ends, the actual output torque is switched to the driver-requested torque, that is, the output of the driver-requested torque starts simultaneously with the end of the output of the holding assist torque. At the end moment, the holding assist torque is equal to the driver-requested torque, so the actual output torque does not change discontinuously, and the drive wheel torque can be smoothly changed to the driver-requested torque. In this way, the driving of the electric vehicle 100 can start smoothly, and the comfort for the driver can be improved.

[0058] In addition, the holding assist control can also be performed when the automatic mode is selected. By performing the holding assist control also in the automatic mode, it is possible to prevent the electric vehicle 100 from moving backward during the period when the driver switches from the brake pedal 23 to the accelerator pedal 22. However, generally, the time from when the driver releases the brake pedal 23 until the driver-requested torque exceeds the holding assist torque is longer when the manual mode is selected, so the holding assist control is more effective when the manual mode is selected. 6. Processing Example

[0059] Figure 4 is a flowchart showing the processing related to the holding assist control of the control device 101. Figure 4 The series of processes shown are implemented by the processor 102 executing one or more programs 104 stored in the memory 103.

[0060] In step S101, the control device 101 determines whether the electric vehicle 100 is in a stopped state. The control device 101 can also determine whether the electric vehicle 100 is in a stopped state based on, for example, a signal obtained from the vehicle speed sensor 11. In this case, it is determined that the electric vehicle 100 is in a stopped state when the vehicle speed is 0. When the electric vehicle 100 is in a stopped state (step S101; YES), the process proceeds to step S102. On the other hand, when the electric vehicle 100 is not in a stopped state (step S101; NO), the series of processes ends.

[0061] In step S102, the control device 101 determines whether the place where the electric vehicle 100 stops is an uphill slope. The control device 101 can judge the inclination of the place where the electric vehicle 100 stops 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. In addition, the control device 101 may also judge that there is a slope on the road surface when the inclination of the road surface where the electric vehicle 100 stops is greater than a specified value, and judge that the road surface is a non-sloped road surface when the inclination of the road surface is below the specified value. In the case where the place where the electric vehicle 100 stops is an uphill slope (step S102; yes), the process proceeds to step S103. On the other hand, in the case where the place where the electric vehicle 100 stops is not an uphill slope (step S102; no), a series of processes ends.

[0062] In step S103, the control device 101 determines whether the driver disconnects the brake. In the case where the brake is disconnected (step S103; yes), the process proceeds to step S105. On the other hand, in the case where the brake is not disconnected, that is, when the side brake is pulled up or the brake pedal 23 is depressed (step S103; no), the determination in step S103 is repeated again. It should be noted that in step S103, the control device 101 may also judge that the brake is disconnected when the amount of depression of the brake pedal 23 by the driver is below a specified amount in a state where the side brake is released.

[0063] In step S105, the control device 101 starts to output a holding assist torque. The magnitude of the holding assist torque is set to a magnitude such that the electric vehicle 100 can stop against the action of gravity. Alternatively, the holding assist torque may also be a torque slightly smaller than the torque required to completely stop the electric vehicle 100. In addition, the magnitude of the torque can also be calculated, for example, by feedback control with the vehicle speed as the output value so that the vehicle speed becomes below a threshold value. By using feedback control, even in the presence of changes in the weight of the body of the electric vehicle 100 and other disturbing factors, the magnitude of the required torque can be accurately calculated. When the output of the holding assist torque starts, the process proceeds to step S106.

[0064] In step S106, the control device 101 determines whether the driver-requested torque exceeds the holding assist torque. In the case where the driver-requested torque exceeds the holding assist torque (step S106; yes), the process proceeds to step S107. On the other hand, in the case where the driver-requested torque is below the holding assist torque (step S106; no), the determination in step S106 is repeated again.

[0065] In step S107, the control device 101 ends the output of the holding assist torque. By ending the output of the holding assist torque, the actual output torque switches to the driver-requested torque. When the output of the holding assist torque ends, a series of processes ends.

[0066] In addition, the control device 101 may also end the output of the holding assist torque when the driver operates the brake after starting the output of the holding assist torque and before the driver-requested torque exceeds the holding assist torque. Thereby, unnecessary output of drive wheel torque can be prevented, and the power consumption rate of the storage battery 2 can be improved. 7. Example of processing for downhill

[0067] When the driver wants to reverse the electric vehicle 100 stopped on a downhill slope, the vehicle may move forward due to gravity. Therefore, even when starting the electric vehicle stopped on a downhill road surface backward, the holding assist control is effective. Figure 5 is a flowchart showing an example of processing related to the holding assist control on a downhill road surface.

[0068] The processing of step S201 is the same as that of Figure 4 step S101. In step S202, the control device 101 determines whether the place where the electric vehicle 100 stops is a downhill slope. Similar to Figure 4 step S102, the control device 101 can make this determination based on the information obtained from the tilt angle sensor 16. In addition, the control device 101 may also determine that the road surface has a slope when the tilt of the road surface where the electric vehicle 100 stops is greater than a specified value, and determine that the road surface has no slope when the tilt of the road surface is below the specified value. If the place where the electric vehicle 100 stops is a downhill slope (step S202; yes), the processing proceeds to step S203. On the other hand, if the place where the electric vehicle 100 stops is not a downhill slope (step S202; no), a series of processes ends.

[0069] The processing of step S203 is the same as that of Figure 4 step S103. However, when the brake is disengaged (step S203; yes), the processing proceeds to step S204.

[0070] In step S204, the control device 101 determines whether the shift switch is set to the reverse gear. In the case of selecting the manual mode, based on the signal of the shift position sensor 14, it is determined whether the shift position of the analog H-type shifter 24 is in the reverse gear position. If the shift switch is set to the reverse gear (step S204; yes), the processing proceeds to step S205. On the other hand, if the shift switch is not set to the reverse gear (step S204; no), a series of processes ends.

[0071] In step S205, the control device 101 starts to output the assist torque. The torque output here is the driving 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 torque output starts, the process proceeds to step S206.

[0072] The process of step S206 is the same as Figure 4 step S106. However, both the output driver-requested torque and the maintained assist torque are the driving wheel torques in the direction opposite to the traveling direction of the electric vehicle 100. The driver-requested torque in the direction opposite to the traveling direction of the electric vehicle 100 and the maintained assist torque in the direction opposite to the traveling direction of the electric vehicle 100 are compared to make a determination. When the driver-requested torque exceeds the maintained assist torque, the process proceeds to step S207 and the output of the maintained assist torque ends. Similar to the maintained assist control on an uphill slope, the maintained assist is switched to the driver-requested torque, and then the driver-requested torque is output as the driving wheel torque.

[0073] Through the above processing, even on a downhill road surface, it is possible to prevent the electric vehicle 100 from advancing due to gravity in a manner not desired by the driver. In addition, at the end moment, the maintained assist torque is equal to the driver-requested torque, so the actual output torque does not change discontinuously, and the driving wheel torque can be smoothly changed to the driver-requested torque. In this way, the start of the electric vehicle 100 can be smoothly started.

Claims

1. An electric vehicle having an electric motor as a driving source, The electric vehicle is characterized by comprising: A driving operating component, used for driving the electric vehicle; Simulated speed change operating parts, simulating the operating parts used for speed change operation of manual speed change diesel locomotive; as well as a control device configured to control the electric vehicle according to the operation of the driving operation member, The driving operating components include an accelerator pedal, The simulated speed change operating component includes a simulated H-type shifter simulating an H-type shifter of a manual transmission and a simulated clutch operating device simulating a clutch operating device. The control device is configured to perform the following steps: executing a control mode for calculating a driver's required torque for driving the electric motor based on an opening degree of the accelerator pedal and an operation of the simulated shift operating member according to a driver's selection; as well as In the control mode, when it is detected that the electric vehicle is stopped on a sloping road surface, a holding assist is performed to prevent the electric vehicle from moving backward or forward due to gravity acting on the electric vehicle. The holding assist includes: outputting a drive wheel torque in a direction opposite to gravity, namely, a holding assist torque; and in response to the driver required torque exceeding the holding assist torque, ending the output of the holding assist torque and switching to the output of the driver required torque.

2. The electric vehicle according to claim 1, characterized in that: The holding assistance includes: The holding assist torque is output on the condition that the sloped road surface is an uphill road surface.

3. The electric vehicle according to claim 1, characterized in that: The holding assistance includes: The holding assist torque is outputted on the condition that the sloped road surface is a downhill road surface and a shift switch of the electric vehicle is set to a reverse gear.

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

5. The electric vehicle according to claim 4, characterized in that: The holding assist includes ending the output of the holding assist torque when the driver performs a brake operation after the output of the holding assist torque is started and before the driver required torque exceeds the holding assist torque.

6. The electric vehicle according to claim 1, characterized in that: The control device is configured to calculate the driver required torque using a vehicle model, The vehicle model includes an engine model that models a virtual engine, a clutch model that models a virtual clutch, and a transmission model that models a virtual transmission.

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