Vehicle control device

Abstract

Provided is a control device for a vehicle capable of facilitating drifting travel. A control device (10) is capable of independently controlling the braking force and driving force of front wheels (2a, 2b) and rear wheels (2c, 2d) of a vehicle (1). The control device (10) controls the braking force and the driving force of the front wheels (2a, 2b) so that the slip rate of the front wheels (2a, 2b) is kept constant in a state in which a drifting travel intention of a driver of the vehicle (1) is detected. As a result, the occurrence of slippage of the front wheels (2a, 2b) can be suppressed, and the vehicle (1) can also be controlled so as to suppress understeering, and drift travel can be facilitated.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control device of a vehicle. BACKGROUND

[0002] Patent Document 1 discloses a method in which, in a state where a drift mode is selected, if the vehicle enters a spin drive while being in a power-on state, a controller (control device of the vehicle) reduces the front wheel distribution torque ratio of AWD lower than in a case other than the drift mode.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENT

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-194060 A SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] In the existing method described in Patent Document 1 and the like, if the front wheels slip when the drift mode is selected, sometimes the steering is insufficient, and it is difficult to perform drift driving.

[0008] An object of the present disclosure is to provide a control device of a vehicle that can easily perform drift driving.

[0009] MEANS FOR SOLVING PROBLEMS

[0010] One aspect of the embodiment of the present invention relates to a control device of a vehicle that can independently control the braking force and driving force of the front wheels and the rear wheels, wherein in a state where a drift driving intention of a user is detected, the braking force and driving force of the front wheels are controlled to keep the slip ratio of the front wheels constant.

[0011] EFFECT OF THE INVENTION

[0012] According to the present disclosure, it is possible to provide a control device of a vehicle that can easily perform drift driving. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a schematic diagram showing a schematic structure of an example of a vehicle on which the control device of the embodiment is mounted.

[0014] Figure 2 is a flowchart of front wheel slip suppression control of the embodiment. DETAILED DESCRIPTION

[0015] Hereinafter, the embodiment will be described with reference to the drawings. For ease of understanding the description, the same reference numerals are given to the same constituent elements in each drawing as much as possible, and repeated description is omitted.

[0016] Figure 1is a schematic view showing an outline structure of a vehicle 1 on which the control device 10 of the embodiment is mounted. In addition, in Figure 1 , the left side in the drawing is a front direction of the vehicle 1, and the right side in the drawing is a rear direction of the vehicle 1.

[0017] The vehicle 1 is an electric vehicle that has a drive motor as a drive source and travels using torque output from the drive motor. In addition, Figure 1 The vehicle 1 shown is an example of a vehicle on which the control device 10 of the embodiment is mounted, and the structure of the vehicle is not limited to Figure 1 the example in

[0018] As shown in Figure 1 , the vehicle 1 is provided with front wheels 2a, 2b, rear wheels 2c, 2d, a front differential device 3f, a rear differential device 3r, a front-wheel drive motor 4f, a rear-wheel drive motor 4r, inverters 5f, 5r, a battery 6, a front-wheel motor rotation speed sensor 7f, a rear-wheel motor rotation speed sensor 7r, and a control device 10.

[0019] Hereinafter, without distinguishing between the front wheels 2a, 2b, the rear wheels 2c, and 2d, they will also be simply referred to as wheels 2. Without distinguishing between the front-wheel drive motor 4f and the rear-wheel drive motor 4r, they will also be simply referred to as drive motors 4. Without distinguishing between the inverters 5f and 5r, they will also be simply referred to as inverters 5. Without distinguishing between the front-wheel motor rotation speed sensor 7f and the rear-wheel motor rotation speed sensor 7r, they will also be simply referred to as motor rotation speed sensors 7.

[0020] The front-wheel drive motor 4f outputs torque that drives the front wheels 2a, 2b. The front wheel 2a corresponds to a right front wheel, and the front wheel 2b corresponds to a left front wheel.

[0021] The front-wheel drive motor 4f is driven using electric power supplied from the battery 6. The front-wheel drive motor 4f is connected to the front differential device 3f. The front differential device 3f is linked to the front wheels 2a, 2b via drive shafts, respectively. Torque output from the front-wheel drive motor 4f is transmitted to the front differential device 3f, and then distributed and transmitted to the front wheels 2a, 2b by the front differential device 3f.

[0022] The front-wheel drive motor 4f is, for example, a multiphase alternating-current motor, and is connected to the battery 6 via the inverter 5f. Direct current supplied from the battery 6 is converted into alternating current by the inverter 5f, and supplied to the front-wheel drive motor 4f.

[0023] The front-wheel drive motor 4f can have a function as a generator that uses kinetic energy of the front wheels 2a, 2b to generate electric power, in addition to outputting a drive torque of the front wheels 2a, 2b. In a case where the front-wheel drive motor 4f functions as a generator, electric power is generated by the front-wheel drive motor 4f and a braking force generated by regenerative braking is imparted to the vehicle 1. Alternating current generated by the front-wheel drive motor 4f is converted into direct current by the inverter 5f, and supplied to the battery 6. The battery 6 can be charged by the direct current supplied from the inverter 5f.

[0024] The rear-wheel drive motor 4r outputs a torque that drives the rear wheels 2c, 2d. In addition, the rear wheel 2c corresponds to a right rear wheel, and the rear wheel 2d corresponds to a left rear wheel.

[0025] The rear-wheel drive motor 4r is driven using electric power supplied from the battery 6. The rear-wheel drive motor 4r is connected to the rear differential device 3r. The rear differential device 3r is coupled to the rear wheels 2c, 2d via drive shafts, respectively. The torque output from the rear-wheel drive motor 4r is transmitted to the rear differential device 3r, and then distributed and transmitted to the rear wheels 2c, 2d by the rear differential device 3r.

[0026] The rear-wheel drive motor 4r is, for example, a multiphase alternating-current motor, and is connected to the battery 6 via the inverter 5r. Direct current supplied from the battery 6 is converted into alternating current by the inverter 5r, and supplied to the rear-wheel drive motor 4r.

[0027] The rear-wheel drive motor 4r can have a function as a generator that uses kinetic energy of the rear wheels 2c, 2d to generate electric power, in addition to outputting a drive torque of the rear wheels 2c, 2d. In a case where the rear-wheel drive motor 4r functions as a generator, electric power is generated by the rear-wheel drive motor 4r and a braking force generated by regenerative braking is imparted to the vehicle 1. Alternating current generated by the rear-wheel drive motor 4r is converted into direct current by the inverter 5r, and supplied to the battery 6. The battery 6 can be charged by the direct current supplied from the inverter 5r.

[0028] The front-wheel motor rotation speed sensor 7f detects a rotation speed of the front-wheel drive motor 4f and outputs a detection result. The rotation speed of the front-wheel drive motor 4f detected by the front-wheel motor rotation speed sensor 7f can correspond to information indicating a wheel speed of the front wheels 2a, 2b.

[0029] The rear-wheel motor rotation speed sensor 7r detects a rotation speed of the rear-wheel drive motor 4r and outputs a detection result. The rotation speed of the rear-wheel drive motor 4r detected by the rear-wheel motor rotation speed sensor 7r can correspond to information indicating a wheel speed of the rear wheels 2c, 2d.

[0030] The control device 10 communicates with each device mounted on the vehicle 1. For example, the control device 10 communicates with the inverter 5f, the inverter 5r, the front wheel motor rotation speed sensor 7f, the rear wheel motor rotation speed sensor 7r, and the like. The communication between the control device 10 and each device is implemented using, for example, CAN (Controller Area Network) communication.

[0031] The control device 10 is capable of independently controlling the braking force and the driving force of the front wheels 2a, 2b and the rear wheels 2c, 2d of the vehicle 1. In particular, in the present embodiment, the control device 10 controls the braking force and the driving force of the front wheels 2a, 2b so as to keep the slip ratio of the front wheels 2a, 2b constant in a state where the drift running intention of the driver (user) of the vehicle 1 is detected. In the following description, this control is sometimes referred to as "front wheel slip suppression control".

[0032] Here, the reason why the front wheel slip suppression control is implemented in the present embodiment is explained. As Figure 1 The vehicle 1 exemplified in the present embodiment is capable of, for example, implementing torque distribution control that freely changes the distribution of torque (braking force and driving force) between the front wheels 2a, 2b and the rear wheels 2c, 2d in accordance with various conditions such as the motion of the wheels 2 and the road surface conditions, in a vehicle in which the braking force and the driving force of the front wheels 2a, 2b and the rear wheels 2c, 2d can be independently controlled. In this torque distribution control, in a case where the maximum torque of the front wheels 2a, 2b is high (i.e., a case where the torque distribution of the front wheels 2a, 2b is greater than the torque distribution of the rear wheels 2c, 2d), if drift operation is performed, understeer can sometimes occur. When understeer occurs, the front wheels 2a, 2b slip, and the turning trajectory of the vehicle 1 can protrude outward from the target trajectory. As a result, a situation where it is not possible to transition to drift occurs.

[0033] Therefore, in the present embodiment, the front wheel slip suppression control is implemented in a case where understeer can occur. As a result, it is possible to suppress the slip of the front wheels 2a, 2b, and thus it is possible to control the vehicle 1 so as to be able to suppress understeer and to easily perform drift running. As a result, it is possible to cause the vehicle 1 to perform running that more closely matches the intention of the user.

[0034] The control device 10 can be physically configured as a computer system including a CPU (Central Processing Unit), a RAM (Random Access Memory) and a ROM (Read Only Memory) as main storage devices, an input device, an output device, a communication module, an auxiliary storage device, and the like. Each function of the control device 10 is realized by reading a prescribed computer software into the CPU, the RAM, and the like, causing the communication module, the input device, and the output device to act under the control of the CPU, and performing reading and writing of data in the RAM and the auxiliary storage device. In addition, the control device 10 can be installed as a part of an ECU (Electronic Control Unit) of the vehicle 1 on which the device is mounted.

[0035] In addition, the functions that the control device 10 of the embodiment has can be divided by a plurality of control devices, and a plurality of functions can be realized by one control device. In a case where the functions that the control device 10 has are divided by a plurality of control devices, the plurality of control devices can be connected to each other via a communication bus such as a CAN.

[0036] Figure 2 is a flowchart of the front wheel slip suppression control of the embodiment. Figure 2 Each process of the flowchart shown is implemented by the control device 10 in Figure 1 . Figure 2 The front wheel slip suppression control explained in the flowchart of

[0037] In step S10, it is determined whether or not the vehicle 1 on which the control device 10 is mounted is in the drift mode. In a case where a function capable of switching the operation of the drift mode on and off is provided at the driver's seat of the vehicle 1, the control device 10 can determine that the vehicle 1 is in the drift mode in a case where the drift mode is in the on state.

[0038] In a case where the vehicle is in the drift mode (Yes in step S10), the process proceeds to step S20. On the other hand, in a case where the vehicle is not in the drift mode (No in step S10), it is determined that the front wheel slip suppression control is not necessary to be implemented since it is a condition in which the drift running intention of the user (driver) is not detected, and the present control flow is ended.

[0039] In addition, the determination in step S10 is not implemented in a case where a function capable of switching the operation of the drift mode on and off is not provided at the driver's seat of the vehicle 1.

[0040] In step S20, it is determined whether the steering wheel angle of the vehicle 1 equipped with the control device 10 is greater than a predetermined threshold T1. The steering wheel angle corresponds, for example, to the steering angle of the front wheels 2a and 2b.

[0041] If the steering wheel angle is greater than the threshold T1 (yes in step S20), proceed to step S30. On the other hand, if the steering wheel angle is less than the threshold T1 (no in step S20), since no drifting intention of the user (driver) is detected, it is determined that front wheel slip suppression control is not required, and the control process ends.

[0042] In step S30, it is determined whether the front-to-rear acceleration (G) of the vehicle 1 equipped with the control device 10 is greater than a predetermined threshold T2. G is the acceleration generated by the vehicle 1 in the front-to-rear direction. In this control, drifting is the target, therefore the threshold T2 can be set to any positive value.

[0043] If the front and rear wheel slip ratio (G) is greater than the predetermined threshold T2 (yes in step S20), proceed to step S30. On the other hand, if the front and rear wheel slip ratio (G) is less than the predetermined threshold T2 (no in step S20), since no drifting intention of the user (driver) is detected, it is determined that front wheel slip suppression control is not required, and the control process ends.

[0044] In step S40, the results of each determination in steps S10, S20, and S30 indicate that a user's (driver's) intention to drift has been detected. Therefore, the braking force and driving force of the front wheels 2a and 2b are controlled to keep the slip ratio constant. In this step, the control device 10 can, for example, control the slip ratio (=(wheel speed - vehicle speed) / vehicle speed) of the front wheels 2a and 2b to remain constant by transmitting torque or braking force to the front wheels 2a and 2b.

[0045] By implementing Figure 2 The process of front wheel slip suppression control shown can suppress the slippage of the front wheels 2a and 2b, thereby suppressing understeer and making it easier for vehicle 1 to drift.

[0046] In addition, Figure 2 In the front wheel slip suppression control shown, based on the determination results of steps S10, S20, and S30, and limited to the state where the user's drifting intention is detected, the slip ratio control in step S40 can be implemented. Therefore, the front wheel slip suppression control can only be effective when the user performs a drifting operation while turning. As a result, vehicle 1 can drive in a manner more in line with the user's intention.

[0047] The above has been described with reference to the specific examples. However, the present disclosure is not limited to these specific examples. Modes obtained by applying appropriate design changes to these specific examples by those skilled in the art are also included in the scope of the present disclosure, as long as the features of the present disclosure are possessed. The elements, their arrangement, conditions, shapes, and the like possessed by the above-described specific examples are not limited to the illustrated content, and appropriate changes can be made. The elements possessed by the above-described specific examples can be changed to appropriate combinations, as long as no technical conflicts arise.

[0048] Legend of Reference Numerals

[0049] 1 vehicle

[0050] 2a, 2b front wheels

[0051] 2c, 2d rear wheels

[0052] 10 control device

Claims

1. A control device of a vehicle capable of independently controlling braking force and driving force of front wheels and rear wheels, wherein, in a state where a user's drift running intention is detected, the braking force and driving force of the front wheels are controlled so as to keep a slip ratio of the front wheels constant.

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