Electric vehicle

Abstract

To provide an electric vehicle capable of easily escaping from a stack during automatic driving travel.SOLUTION: An electric vehicle of the present invention is an electric vehicle that includes a rotating electric machine configured to generate a rotational driving force in each of a left driving wheel and a right driving wheel, and is capable of traveling by automatic driving, the electric vehicle including a control device configured to execute, when it is determined that at least one of the left driving wheel and the right driving wheel is stuck during traveling by automatic driving, driving force control for sticking in which torque generated by the rotating electric machine is increased or decreased to rotationally drive the left driving wheel and the right driving wheel.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electric vehicle. [Background technology]

[0002] Patent Document 1 discloses a technique for transmitting driving force in an electric vehicle by extending the suspension of the driving wheel on the slipping side to bring it into contact with the ground. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-161380 Summary of the Invention [Problem to be solved by the invention]

[0004] If an electric vehicle becomes stuck while traveling in autonomous driving, the technology disclosed in Patent Document 1 may not be able to free the vehicle from the stuck state simply by scraping the road surface.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide an electric vehicle that can easily escape from being stuck while traveling in an autonomous driving mode. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, the electric vehicle of the present invention is an electric vehicle that is equipped with a rotating electric machine that generates rotational driving force in each of the left and right drive wheels, and is capable of running in autonomous driving mode, and is characterized in that it is equipped with a control device that, when it is determined that at least one of the left and right drive wheels is stuck while running in autonomous driving mode, performs driving force control for sticking by increasing or decreasing the torque generated by the rotating electric machine to rotationally drive the left and right drive wheels.

[0007] This makes it easier to escape from being stuck during automatic driving by utilizing the recoil in addition to the rotational driving force of the left and right driving wheels.

[0008] In addition, in the above, the rotating electric machines may include a left-wheel in-wheel motor provided on the left driving wheel and a right-wheel in-wheel motor provided on the right driving wheel, and the control device may be configured to make the magnitude of torque generated by the left-wheel in-wheel motor and the right-wheel in-wheel motor different at the same timing during the driving force control for the stack.

[0009] This creates a sawing effect due to the difference in rotational drive force between the left and right drive wheels, improving the vehicle's ability to escape from a stuck vehicle. [Effects of the Invention]

[0010] The electric vehicle according to the present invention has the advantage of being able to easily escape from being stuck during autonomous driving by utilizing the recoil in addition to the rotational driving force of the left and right drive wheels. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a schematic configuration of an electric vehicle according to the first embodiment. [Figure 2] FIG. 2 is a block diagram showing an example of a schematic configuration of a control system in the electric vehicle according to the first embodiment. [Figure 3] FIG. 3 is a flowchart showing an example of stuck determination and driving force control performed by the control device while the electric vehicle according to the first embodiment is traveling in autonomous driving mode. [Figure 4] FIG. 4 is a timing chart relating to the drive force control for the stack in the first embodiment. [Figure 5] FIG. 5 is a diagram showing the state of the drive wheels when the drive force control for the stuck state is being executed. [Figure 6]FIG. 6 is a flowchart showing an example of stuck determination and driving force control performed by the control device while the electric vehicle according to the second embodiment is traveling in an autonomous driving mode. [Figure 7] FIG. 7 is a timing chart relating to the drive force control for the stack in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Embodiment 1) A first embodiment of an electric vehicle according to the present invention will be described below, although the present invention is not limited to this embodiment.

[0013] Fig. 1 is a schematic diagram showing an example of a schematic configuration of an electric vehicle 1 according to embodiment 1. Fig. 2 is a block diagram showing an example of a schematic configuration of a control system in electric vehicle 1 according to embodiment 1.

[0014] As shown in FIG. 1, an electric vehicle 1 according to the first embodiment includes a left front wheel 2FL, a right front wheel 2FR, a left rear wheel 2RL, and a right rear wheel 2RR. The left front wheel 2FL and the right front wheel 2FR are provided with a left wheel motor 4FL and a right wheel motor 4FR, respectively, as in-wheel motors serving as rotating electric machines. The left front wheel 2FL and the right front wheel 2FR are drive wheels that are rotated by the left wheel motor 4FL and the right wheel motor 4FR, respectively, to which power is supplied from an on-board battery or the like. The left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR are suspended relative to the vehicle body by a left front suspension 6FL, a right front suspension 6FR, a left rear suspension 6RL, and a right rear suspension 6RR, respectively. A control device 8 is capable of executing various controls related to the running of the electric vehicle 1. For example, in response to depression of accelerator pedal 14 (see FIG. 2) by the driver or an acceleration / deceleration request from automatic driving device 16, control device 8 controls left wheel motor 4FL and right wheel motor 4FR to rotate left front wheel 2FL and right front wheel 2FR. As a result, left front wheel 2FL and right front wheel 2FR apply driving force to the road surface, allowing electric vehicle 1 to move forward or backward. In electric vehicle 1 according to embodiment 1, control device 5 functions as a driving force control device.

[0015] In-wheel motors may be provided on all four left and right front and rear wheels, or only on the left rear wheel 2RL and the right rear wheel 2RR. Instead of using in-wheel motors, a single rotating electric machine (motor generator) may be used to generate torque, which is transmitted to the left front wheel 2FL and the right front wheel 2FR via a drive force transmission mechanism including a drive shaft or the like to rotate the wheels. The electric vehicle 1 is also equipped with a steering device (not shown) for controlling the steering angle of the wheels and a braking device (not shown) for generating braking force on each wheel. The steering device may be a power steering device that transmits the rotation of a steering wheel (not shown) operated by the driver to a tie rod (not shown) while amplifying the rotational torque, thereby steering the left front wheel 2FL and the right front wheel 2FR. The braking device may be of any type that applies braking force to each wheel 2FL, 2FR, 2RL, and 2RR in response to the driver's depression of a brake pedal (not shown).

[0016] The control device 8 receives inputs of detection values ​​from various sensors for detecting the state of the wheels, the vehicle's motion state, etc., such as the operation amount or depression amount of the accelerator pedal 14, and the wheel speed Vwi (i=FL, FR, RL, RR) from the wheel speed sensors 12i (i=FL, FR, RL, RR) of the respective wheels 2FL, 2FR, 2RL, 2RR. The control device 8 may also use GPS information from a GPS device 62 to detect the vehicle speed Vb.

[0017] Furthermore, various parameters required for various controls executed in the electric vehicle 1, such as various detection signals of the brake pedal depression amount, steering angle, yaw rate, longitudinal acceleration, and lateral acceleration, may be input to the control device 8, and various control commands may be output to corresponding devices. Then, for example, the control device 8 transmits control signals Cfl and Cfr to the left wheel motor 4FL and right wheel motor 4FR to adjust the torque generated by the left wheel motor 4FL and right wheel motor 4FR.

[0018] The control device 8 has an arithmetic processing unit 80, a left driving wheel control unit 82, and a right driving wheel control unit 84. The arithmetic processing unit 80 also has a torque determination unit 801 and a stuck determination unit 802. The torque determination unit 801 calculates and determines target values ​​Twfl, Twfr of torque to be generated by the left wheel motor 4FL and the right wheel motor 4FR based on the depression amount of the accelerator pedal 14 or an acceleration / deceleration request from the automatic driving device 16. The torque determination unit 801 then outputs signals of the target values ​​Twfl, Twfr of torque to be generated by the left wheel motor 4FL and the right wheel motor 4FR to the left driving wheel control unit 83 and the right driving wheel control unit 84. The left driving wheel control unit 83 and the right driving wheel control unit 84 output control signals Cfl, Cfr to the left wheel motor 4FL and the right wheel motor 4FR, respectively, to generate torque according to the received target values ​​Twfl, Twfr of torque.

[0019] The automatic driving device 16 may be a known device that can make the electric vehicle 1 travel autonomously (automatically drive) without the driver operating the accelerator, for example, by using the detection results of an external sensor such as a camera.

[0020] The stuck determination unit 802 of the calculation processing unit 80 determines whether at least one of the left front wheel 2FL and the right front wheel 2FR, which are drive wheels, has become stuck in a depression or the like. The stuck determination unit 802, for example, references the wheel speeds VwFL and VwFR of the left front wheel 2FL and the right front wheel 2FR and the vehicle speed Vb determined from the time change in the position information of the electric vehicle 1 obtained by the GPS device 10. Then, based on the wheel speeds VwFL and VwFR and the vehicle speed Vb, the stuck determination unit 802 determines that the electric vehicle 1 is stuck when the left front wheel 2FL and the right front wheel 2FR are rotating at a predetermined rotation speed or higher but are stopped in approximately the same position at a predetermined vehicle speed or lower. For example, the stuck determination unit 802 may determine that the electric vehicle 1 is stuck when the difference between the wheel speed Vwi and the vehicle speed Vb is equal to or greater than a predetermined threshold. Alternatively, the stuck determination unit 802 may perform the stuck determination based on the detection results of a longitudinal acceleration sensor provided on the electric vehicle 1.

[0021] In the electric vehicle 1 according to the first embodiment, when a stuck state is determined during automatic driving by the automatic driving device 16, the driving force control by the control device 8 is switched from normal driving force control to driving force control for stuck state. In this driving force control for stuck state, torque fluctuations are intentionally repeated to increase and decrease the torque generated by the left wheel motor 4FL and the right wheel motor 4FR.

[0022] Fig. 3 is a flowchart showing an example of stuck determination and driving force control performed by the control device 8 while the electric vehicle 1 according to the first embodiment is traveling in autonomous driving. Fig. 4 is a timing chart relating to the driving force control for stuck in the first embodiment. Fig. 5 is a diagram showing the state of the drive wheels 2 when the driving force control for stuck is being executed.

[0023] First, the control device 8 determines whether at least one of the left front wheel 2FL and the right front wheel 2FR is stuck during autonomous driving of the electric vehicle 1 (step S1). If the control device 8 determines that the wheels are not stuck (No in step S1), it ends the series of controls. On the other hand, if the control device 8 determines that the wheels are stuck (Yes in step S1), it switches the driving force control of the left wheel motor 4FL and the right wheel motor 4FR from normal driving force control to driving force control for stuck (step S2).

[0024] In the driving force control for getting stuck, as shown in Fig. 4, the control device 8 alternately switches the torque of the left wheel motor 4FL and the right wheel motor 4FR between 0 [Nm] and torque Tw1 [Nm] to increase or decrease the rotational driving force of the left front wheel 2FL and the right front wheel 2FR. As a result, the left front wheel 2FL and the right front wheel 2FR are fitted in the depression 20 as shown in Fig. 5. By increasing the motor torque to torque Tw1, the driving wheels 2 climb up the front slope 202 from the bottom 201 of the depression 20 as shown by arrow A in Fig. 5. Thereafter, the control device 8 reduces the motor torque from torque Tw1 to 0, so that the driving wheels 2 roll down from the front slope 202 to the bottom 201 as shown by arrow B in Fig. 5, and the momentum of this movement causes the driving wheels 2 to climb up the rear slope 203. Then, the control device 8 again increases the motor torque to torque Tw1, and the rotational driving force acting on the driving wheels 2 due to the torque Tw1 generated by the left wheel motor 4FL and the right wheel motor 4FR is added to the force acting on the driving wheels 2 as they roll down the rear slope 203 toward the bottom 201, in other words, the inertia of the forward moving electric vehicle 1, causing the driving wheels 2 to climb the forward slope 202 as shown by arrow C in Figure 5.

[0025] Next, the control device 8 determines whether the left front wheel 2FL and the right front wheel 2FR have escaped from the stuck state while executing the driving force control for the stuck state (step S3). If the control device 8 determines that the vehicle has not escaped from the stuck state (No in step S3), it continues to execute the driving force control for the stuck state and repeatedly executes the determination in step S3 until it determines that the vehicle has escaped from the stuck state (Yes in step S3). If the control device 8 determines that the vehicle has escaped from the stuck state (Yes in step S3), it returns to normal driving force control (step S4). Then, the control device 8 ends the example control.

[0026] As described above, in the electric vehicle 1 according to the first embodiment, when a stuck state is determined to be present during autonomous driving, the driving force control by the control device 8 is switched from normal driving force control to stuck driving force control. As a result, in the electric vehicle 1 according to the first embodiment, the recoil can be used in addition to the rotational driving forces of the left front wheel 2FL and the right front wheel 2FR to make it easier to escape from being stuck during autonomous driving.

[0027] Furthermore, in the electric vehicle 1 according to the first embodiment, it is possible to prevent excessive scraping of the road surface and to prevent the condition from worsening compared to when the left front wheel 2FL and the right front wheel 2FR are continuously driven to rotate forward by normal driving force control if the vehicle gets stuck during autonomous driving. Furthermore, in the electric vehicle 1 according to the first embodiment, the left wheel motor 4FL and the right wheel motor 4FR are not rotated at high rotation speeds when the vehicle gets stuck during autonomous driving, so the load on the left wheel motor 4FL and the right wheel motor 4FR is reduced and it is possible to prevent adverse effects on durability.

[0028] (Embodiment 2) An electric vehicle according to a second embodiment of the present invention will be described below. In the electric vehicle 1 according to the second embodiment, a left wheel motor 4FL and a right wheel motor 4FR, which are in-wheel motors, are provided only on the left front wheel 2FL and the right front wheel 2FR, as in the electric vehicle 1 according to the first embodiment shown in Fig. 1. Note that, for the other electric vehicle 1 according to the second embodiment, descriptions that are the same as those for the electric vehicle 1 according to the first embodiment will be omitted as appropriate.

[0029] Fig. 6 is a flowchart showing an example of stuck determination and driving force control performed by the control device 8 while the electric vehicle 1 according to the second embodiment is traveling in autonomous driving. Fig. 7 is a timing chart relating to the driving force control for stuck in the second embodiment.

[0030] First, the control device 8 determines whether at least one of the left front wheel 2FL and the right front wheel 2FR is stuck during autonomous driving of the electric vehicle 1 (step S11). If the control device 8 determines that the wheels are not stuck (No in step S11), it ends the series of controls. On the other hand, if the control device 8 determines that the wheels are stuck (Yes in step S12), it switches the driving force control from normal driving force control to driving force control for stuck, which changes the magnitude of the rotational driving force of the left front wheel 2FL and the right front wheel 2FR at the same timing (step S12).

[0031] In the drive force control for stuck state in the second embodiment, as shown in FIG. 7, the control device 8 alternately increases and decreases the torque of the right wheel motor 4FR between 0 and torque Tw2, thereby increasing and decreasing the rotational drive force of the right front wheel 2FR to drive the right front wheel 2FR for a certain period of time. The control device 8 also alternately increases and decreases the torque of the left wheel motor 4FL between 0 and torque Tw3 (>0) smaller than torque Tw2, thereby increasing and decreasing the rotational drive force of the left front wheel 2FL to drive the left front wheel 2FL for a certain period of time. The torque of the right wheel motor 4FR and the torque of the left wheel motor 4FL are increased and decreased at the same time, synchronized with each other. This allows the electric vehicle 1 to move forward while facing leftward due to the difference in rotational drive force between the left front wheel 2FL and the right front wheel 2FR. Then, the control device 8 alternately increases and decreases the torque of the right wheel motor 4FR between 0 and torque Tw3, increasing and decreasing the rotational drive force of the right front wheel 2FR to drive the right front wheel 2FR for a certain period of time. The control device 8 also alternately increases and decreases the torque of the left wheel motor 4FL between 0 and torque Tw2, increasing and decreasing the rotational drive force of the left front wheel 2FL to drive the left front wheel 2FL for a certain period of time. This allows the electric vehicle 1 to move forward while facing rightward due to the difference in rotational drive force between the left front wheel 2FL and the right front wheel 2FR. The control device 8 then alternately executes drive force control that allows the electric vehicle 1 to move forward while facing leftward and drive force control that allows the electric vehicle 1 to move forward while facing rightward, by varying the magnitude of the torque generated by the left wheel motor 4FL and the right wheel motor 4FR at the same timing, depending on the difference in rotational drive force between the left front wheel 2FL and the right front wheel 2FL.

[0032] Next, the control device 8 determines whether the left front wheel 2FL and the right front wheel 2FR have escaped from the stuck state while executing the driving force control for the stuck state (step S13). If the control device 8 determines that the vehicle has not escaped from the stuck state (No in step S13), it continues to execute the driving force control for the stuck state and repeatedly executes the determination in step S13 until it determines that the vehicle has escaped from the stuck state (Yes in step S13). If the control device 8 determines that the vehicle has escaped from the stuck state (Yes in step S13), it returns to normal driving force control (step S14). Then, the control device 8 ends the example control.

[0033] As described above, in the electric vehicle 1 according to the second embodiment, when a stuck determination is made during autonomous driving, the drive force control by the control device 8 is switched from normal drive force control to drive force control for stuck, which alternately changes the magnitude of the rotational drive force of the left front wheel 2FL and the right front wheel 2FR. As a result, in the electric vehicle 1 according to the second embodiment, a sawing effect (a drive force in the lateral direction) is produced by the difference in rotational drive force between the left front wheel 2FL and the right front wheel 2FR, making it easier for the left front wheel 2FL and the right front wheel 2FR to get caught on the slope of the depression, thereby improving the ability to escape from being stuck.

[0034] Furthermore, in the electric vehicle 1 according to the second embodiment, by implementing driving force control for getting stuck, it is not necessary to use a steering device to turn the electric vehicle 1 alternately left and right when escaping from being stuck, which makes it possible to improve the durability of the steering device. [Explanation of symbols]

[0035] 1 Electric vehicles 2FL left front wheel 2FR right front wheel 2RL Left rear wheel 2RR right rear wheel 4FL left wheel motor 4FR right wheel motor 6FL left front suspension 6FR Right front suspension 6RL left rear suspension 6RR right rear suspension 8 Control Device 10 GPS device 12i Wheel speed sensor 14 Accelerator pedal 16 Automatic driving device 20 depression 201 bottom 202 Slope ahead 203 Rear Slope

Claims

1. An electric vehicle that is capable of autonomous driving and includes a rotating electric machine that generates a rotational driving force on each of a left drive wheel and a right drive wheel, An electric vehicle characterized by comprising a control device that, when it is determined that at least one of the left drive wheel and the right drive wheel is stuck while traveling in autonomous driving mode, executes driving force control for sticking by increasing or decreasing the torque generated by the rotating electric machine to rotate the left drive wheel and the right drive wheel.

2. the rotating electric machine includes a left in-wheel motor provided on the left driving wheel and a right in-wheel motor provided on the right driving wheel, 2. The electric vehicle according to claim 1, wherein the control device causes the left in-wheel motor and the right in-wheel motor to generate different torques at the same timing during the stack driving force control.

Images