JP2021130361A - Control device - Google Patents

Abstract

To appropriately stabilize behaviour of a vehicle body.SOLUTION: A control device 100 of a vehicle 1 comprises a control part that when one driving wheel 15 of left and right driving wheels 15 of the vehicle 1 slips, executes brake LSD control of braking the slipped wheel, the slipped driving wheel, and when steering for swirling the vehicle 1 toward the slipped wheel is performed during execution of the brake LSD control, executes torque down control of making driving torque of the vehicle smaller than required torque.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control device.

For the purpose of stabilizing the vehicle body behavior, a technique for eliminating wheel slip has been proposed. For example, Patent Document 1 discloses a technique for eliminating a slip by reducing the driving torque of the vehicle when the wheel slips.

JP-A-2007-049825

By the way, as a technique for eliminating wheel slip, there is a brake LSD (Limited Slip Differential) control in addition to the technique using the control of the drive torque as described above. The brake LSD control is executed when one of the left and right drive wheels slips, and is a control for braking the slip wheels, which are the slipped drive wheels. For example, when one of the left and right drive wheels enters a low μ road surface (for example, a frozen road surface) and slips, the brake LSD control is used to cause the one drive wheel (that is, slip). The slip of the wheel) can be eliminated, and the driving force can be appropriately transmitted to the other driving wheel. However, if the drive wheel other than the slip wheel slips while the brake LSD control is being executed, the vehicle body behavior becomes unstable.

Therefore, in view of such a problem, an object of the present invention is to provide a control device capable of appropriately stabilizing the vehicle body behavior.

In order to solve the above problems, the control device of the present invention executes brake LSD control for braking the slip wheels, which are the slipped drive wheels, when one of the left and right drive wheels of the vehicle slips. However, when steering is performed to turn the vehicle toward the slip wheel side during execution of the brake LSD control, a control unit is provided that executes torque down control that makes the driving torque of the vehicle smaller than the required torque.

In the torque down control, the control unit may increase the amount of reduction of the drive torque with respect to the required torque as the required torque is larger.

In the torque down control, the control unit may increase the amount of reduction of the drive torque with respect to the required torque as the vehicle speed of the vehicle increases.

In the torque down control, the control unit may increase the amount of reduction of the drive torque with respect to the required torque as the steering angle in steering increases.

In the torque down control, the control unit may increase the amount of reduction of the drive torque with respect to the required torque as the braking force applied to the slip wheels by the brake LSD control is larger.

The control unit may stop the brake LSD control when the torque down control is executed.

The control unit does not have to execute the torque down control even when the steering is performed during the execution of the brake LSD control when the steering angle in the steering is smaller than the reference steering angle.

The control unit may stop the torque down control when both the left and right drive wheels enter a high μ road surface having a friction coefficient larger than the reference friction coefficient during the execution of the torque down control.

According to the present invention, it is possible to appropriately stabilize the vehicle body behavior.

It is a schematic diagram which shows the schematic structure of the vehicle which mounts the control device which concerns on embodiment of this invention. It is a block diagram which shows an example of the functional structure of the control device which concerns on embodiment of this invention. FIG. 5 is a schematic view showing a state in which the vehicle turns to the left from a state in which the right drive wheel of the vehicle according to the embodiment of the present invention is located on a high μ road surface and the left drive wheel is located on a low μ road surface. It is a flowchart which shows an example of the flow of the process for stabilizing the vehicle body behavior by the control device which concerns on embodiment of this invention. It is a schematic diagram which shows the relationship between a slip ratio and a grip force. In the comparative example, it is a figure showing an example of the transition of various state quantities when the vehicle turns to the left from the state where the right drive wheel is located on the high μ road surface and the left drive wheel is located on the low μ road surface. be. In the embodiment of the present invention, an example of the transition of various state quantities when the vehicle turns to the left from the state where the right drive wheel is located on the high μ road surface and the left drive wheel is located on the low μ road surface. It is a figure which shows.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. do.

<Vehicle configuration>
The configuration of the vehicle 1 on which the control device 100 according to the embodiment of the present invention is mounted will be described with reference to FIGS. 1 to 3.

FIG. 1 is a schematic view showing a schematic configuration of a vehicle 1 on which the control device 100 is mounted. As shown in FIG. 1, the vehicle 1 includes a motor 11, an inverter 12, a battery 13, a differential device 14, a drive wheel 15 (specifically, a left drive wheel 15L and a right drive wheel 15R). Brake pedal 21, master cylinder 22, hydraulic pressure control unit 23, brake device 24 (specifically, left drive wheel brake device 24L and right drive wheel brake device 24R), and wheel speed sensor 31 (specifically). Specifically, it includes a left drive wheel wheel speed sensor 31L and a right drive wheel wheel speed sensor 31R), an accelerator operation amount sensor 32, a steering angle sensor 33, a vehicle speed sensor 34, and a control device 100.

For example, the drive type of the vehicle 1 is front wheel drive, and the front wheels are drive wheels 15. In this case, the left front wheel corresponds to the left drive wheel 15L and the right front wheel corresponds to the right drive wheel 15R. In FIG. 1, the illustration of the rear wheel, which is a driven wheel, is omitted. The drive type of the vehicle 1 may be rear wheel drive (that is, the rear wheels may be drive wheels 15) or four-wheel drive (that is, both front wheels and rear wheels). May be the drive wheel 15).

The vehicle 1 is an electric vehicle that includes a motor 11 that is a drive motor as a drive source and travels by using the torque output from the motor 11. The vehicle 1 is merely an example of a vehicle equipped with the control device according to the present invention, and as will be described later, the configuration of the vehicle equipped with the control device according to the present invention is particularly limited to the configuration of the vehicle 1. Not done.

The motor 11 is a motor that outputs torque for driving the drive wheels 15. The motor 11 is driven by the electric power supplied from the battery 13. The motor 11 is connected to the differential device 14. The differential device 14 is connected to the left drive wheel 15L and the right drive wheel 15R via a drive shaft, respectively. The torque output from the motor 11 is transmitted to the differential device 14, and then distributed and transmitted to the left drive wheel 15L and the right drive wheel 15R by the differential device 14.

The motor 11 is, for example, a multi-phase AC motor, and is connected to the battery 13 via an inverter 12. The DC power supplied from the battery 13 is converted into AC power by the inverter 12 and supplied to the motor 11.

The motor 11 may have a function as a generator that generates electricity by using the kinetic energy of the drive wheels 15 in addition to the function of outputting the torque for driving the drive wheels 15. When the motor 11 functions as a generator, the motor 11 generates electricity and applies braking force by regenerative braking to the vehicle 1. The AC power generated by the motor 11 is converted into DC power by the inverter 12 and supplied to the battery 13. As a result, the battery 13 is charged.

The inverter 12 is a power conversion device that performs bidirectional power conversion. For example, the inverter 12 includes a three-phase bridge circuit. The inverter 12 can convert the DC power supplied from the battery 13 into AC power and supply it to the motor 11. Further, the inverter 12 can convert the AC power generated by the motor 11 into DC power and supply it to the battery 13.

The battery 13 is a battery capable of charging and discharging electric power. As the battery 13, for example, a lithium ion battery, a lithium ion polymer battery, a nickel hydrogen battery, a nickel cadmium battery or a lead storage battery is used, but batteries other than these may be used. The battery 13 stores the electric power supplied to the motor 11.

The brake pedal 21 accepts a brake operation (specifically, an operation of depressing the brake pedal 21) by the driver. The brake pedal 21 is connected to the master cylinder 22 via a booster (not shown).

The master cylinder 22 generates flood pressure according to the amount of brake operation, which is the amount of operation of the brake. The master cylinder 22 is connected to a brake device 24 provided on each wheel via a hydraulic pressure control unit 23. The flood pressure generated by the master cylinder 22 is supplied to each brake device 24 via the hydraulic pressure control unit 23.

The hydraulic pressure control unit 23 can adjust the hydraulic pressure supplied to each brake device 24 (that is, the brake hydraulic pressure of each brake device 24). Specifically, the hydraulic pressure control unit 23 has devices such as a pump and a control valve, and the brake hydraulic pressure of each brake device 24 is controlled by controlling the operation of these devices. Thereby, the braking force applied to each wheel is controlled. The hydraulic pressure control unit 23 may be able to individually adjust the hydraulic pressure supplied to each brake device 24. Further, the brake system may be two systems.

The braking device 24 applies a braking force to the wheels by using flood control. The total braking force applied to each wheel by each braking device 24 is the braking force applied to the vehicle 1. In the vehicle 1, the left drive wheel 15L is braked by the left drive wheel brake device 24L of the brake device 24, and the right drive wheel 15R is braked by the right drive wheel brake device 24R of the brake device 24.

The brake device 24 has, for example, a brake caliper (not shown) that includes a brake pad and a wheel cylinder. For example, a pair of brake pads are provided so as to face each other on both side surfaces of a brake disc that rotates integrally with a wheel. The wheel cylinder is formed in a brake caliper, and a piston is slidably provided in the wheel cylinder. The tip of the piston is provided so as to face the brake pad, and the brake pad moves toward each side surface of the brake disc as the piston slides. The flood pressure generated by the master cylinder 22 is supplied to the wheel cylinder of the brake device 24. As a result, the movement of the piston and the brake pad in the brake caliper causes both side surfaces of the brake disc to be sandwiched by the pair of brake pads, and the wheels are braked.

The wheel speed sensor 31L for the left drive wheel detects the wheel speed of the left drive wheel 15L and outputs the detection result.

The wheel speed sensor 31R for the right drive wheel detects the wheel speed of the right drive wheel 15R and outputs the detection result.

The accelerator operation amount sensor 32 detects the accelerator operation amount, which is the operation amount of the accelerator operation (specifically, the operation of depressing the accelerator pedal (not shown)) by the driver, and outputs the detection result.

The steering angle sensor 33 detects the steering angle, which is the amount of operation of steering (specifically, the operation of turning the steering wheel) by the driver using the steering wheel (not shown), and outputs the detection result.

The vehicle speed sensor 34 detects the vehicle speed (that is, the vehicle body speed) of the vehicle 1 and outputs the detection result.

The control device 100 includes a CPU (Central Processing Unit) which is an arithmetic processing unit, a ROM (Read Only Memory) which is a storage element for storing programs and arithmetic parameters used by the CPU, and parameters which are appropriately changed in the execution of the CPU. A RAM (Random Access Memory) or the like, which is a storage element for temporarily storing the above, is included.

The control device 100 communicates with each device mounted on the vehicle 1 (for example, an inverter 12, a hydraulic pressure control unit 23, a wheel speed sensor 31, an accelerator operation amount sensor 32, a steering angle sensor 33, and a vehicle speed sensor 34). Communication between the control device 100 and each device is realized by using, for example, CAN (Control Area Network) communication.

The function of the control device 100 according to the present embodiment may be divided by a plurality of control devices, or the plurality of functions may be realized by one control device. When the function of the control device 100 is divided by a plurality of control devices, the plurality of control devices may be connected to each other via a communication bus such as CAN.

FIG. 2 is a block diagram showing an example of the functional configuration of the control device 100. For example, as shown in FIG. 2, the control device 100 has an acquisition unit 110 and a control unit 120.

The acquisition unit 110 acquires various information used in the processing performed by the control unit 120 and outputs the information to the control unit 120. For example, the acquisition unit 110 acquires various information output from the wheel speed sensor 31, the accelerator operation amount sensor 32, the steering angle sensor 33, and the vehicle speed sensor 34.

The control unit 120 controls the operation of each device in the vehicle 1. For example, the control unit 120 includes a motor control unit 121 and a brake control unit 122.

The motor control unit 121 controls the operation of the motor 11. Specifically, the motor control unit 121 controls the supply of electric power between the battery 13 and the motor 11 by controlling the operation of the switching element of the inverter 12. Thereby, the torque output by the motor 11 is controlled. In this way, the motor control unit 121 can control the driving torque of the vehicle 1 (that is, the torque for driving the vehicle 1).

The brake control unit 122 controls the operation of the brake device 24. Specifically, the brake control unit 122 controls the brake hydraulic pressure of each brake device 24 provided for each wheel by controlling the operation of the hydraulic pressure control unit 23. Thereby, the braking force applied to each wheel is controlled.

As described above, the control unit 120 can control the braking force applied to the wheels. In particular, the control unit 120 executes brake LSD control for braking the slip wheels, which are the slipped drive wheels 15, when one of the left and right drive wheels 15 of the vehicle 1 slips. Slip means a phenomenon in which the slip ratio of a wheel (specifically, a value obtained by dividing the difference between the wheel speed and the vehicle speed by the vehicle speed) becomes excessively large and the wheel slips. When one of the left and right drive wheels 15 enters the low μ road surface and slips, the brake LSD control is executed to eliminate the slip of the one drive wheel 15 (that is, the slip wheel). However, the driving force can be appropriately transmitted to the other driving wheel 15. A low μ road surface is a road surface having a friction coefficient equal to or lower than the reference friction coefficient. Specifically, a low μ road surface is a road surface (for example, a frozen road surface) in which the possibility of wheel slippage is excessively high.

Here, when steering that turns the vehicle 1 toward the slip wheel side (hereinafter, also referred to as slip wheel side steering) is performed during execution of the brake LSD control, the drive wheel 15 that is not the slip wheel has a low μ road surface. There is a risk of entering. For example, when the slip wheel is the left drive wheel 15L, the steering that turns the vehicle 1 to the left in the state of facing the traveling direction (that is, the steering that rotates the steering wheel counterclockwise) is the slip wheel side steering. .. On the other hand, when the slip wheel is the right drive wheel 15R, the steering that turns the vehicle 1 to the right in the state of facing the traveling direction (that is, the steering that rotates the steering wheel clockwise) is the slip wheel side steering.

In FIG. 3, the vehicle 1 is on the left side (specifically, the traveling direction) from the state where the right drive wheel 15R of the vehicle 1 is located on the high μ road surface RS1 and the left drive wheel 15L is located on the low μ road surface RS2. It is a schematic diagram which shows the state of turning to the left side) in the state of facing.

FIG. 3 shows an example in which the region near the right end is the high μ road surface RS1 and the other region (the left region) is the low μ road surface RS2 in the traveling road on which the vehicle 1 is traveling. Has been done. The high μ road surface RS1 is a road surface having a friction coefficient larger than the reference friction coefficient. Specifically, unlike the low μ road surface RS2, the high μ road surface RS1 is a road surface (for example, an asphalt-paved and dry road surface) in which wheel slip is less likely to occur.

When the left drive wheel 15L enters the low μ road surface RS2 and slips, the brake LSD control is executed in order to eliminate the slip of the left drive wheel 15L. Then, while the vehicle 1 is traveling straight, the right drive wheel 15R is located on the high μ road surface RS1 and the left drive wheel 15L is located on the low μ road surface RS2, as shown by the solid line in FIG. It becomes a state. Here, when the vehicle 1 is steered to turn to the left drive wheel 15L side (that is, the left side) which is a slip wheel, the vehicle 1 turns to the left as shown by the arrow A1 in FIG. Then, as shown by the broken line in FIG. 3, the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface RS2. If the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface RS2 during execution of the brake LSD control, the right drive wheel 15R slips in the conventional technology, and the vehicle body behavior. May become unstable.

Therefore, in the present embodiment, when the control unit 120 of the control device 100 is steered to turn the vehicle 1 toward the slip wheel side (that is, the slip wheel side steering) during the execution of the brake LSD control, the vehicle 1 Torque down control is performed to make the driving torque of the vehicle smaller than the required torque (that is, the torque required as the driving torque). As a result, it becomes possible to appropriately stabilize the vehicle body behavior. The details of the processing for stabilizing the vehicle body behavior performed by the control device 100 will be described later.

<Operation of control device>
Subsequently, the operation of the control device 100 according to the embodiment of the present invention will be described with reference to FIGS. 4 to 7.

FIG. 4 is a flowchart showing an example of a processing flow for stabilizing the vehicle body behavior by the control device 100. Specifically, the control flow shown in FIG. 4 is executed by the control unit 120, and is repeatedly started after the control flow is completed.

When the control flow shown in FIG. 4 is started, first, in step S101, the control unit 120 determines whether or not one of the left and right drive wheels 15 has slipped. When it is determined that one of the drive wheels 15 has slipped (step S101 / YES), the process proceeds to step S102, and the control unit 120 starts the brake LSD control. On the other hand, when it is not determined that one of the drive wheels 15 has slipped (step S101 / NO), the control flow shown in FIG. 4 ends.

In the determination process of step S101, when the difference in wheel speed between the left drive wheel 15L and the right drive wheel 15R is, for example, the reference difference or more, the control unit 120 has the drive wheel 15 having the higher wheel speed. Is determined to be slipping. The reference difference is a value set so that it can be appropriately determined whether or not one of the left and right drive wheels 15 is slipping, and can be appropriately set according to the specifications of the vehicle 1. ..

The determination process in step S101 is not limited to the above example. For example, the control unit 120 specifies each slip rate of the left drive wheel 15L and the right drive wheel 15R, and based on the comparison result between each slip rate and the reference slip rate, whether or not one drive wheel 15 has slipped. May be determined. In this case, specifically, when the slip ratio of the drive wheels 15 is equal to or higher than the reference slip ratio, the control unit 120 determines that the drive wheels 15 are slipping. The reference slip ratio is a value set so that it can be appropriately determined whether or not the wheels are slipping, and can be appropriately set according to the specifications of the vehicle 1.

In the brake LSD control in step S102, the control unit 120 brakes the slip wheel, which is the slipped drive wheel 15. For example, when the left drive wheel 15L slips, the left drive wheel 15L is braked by the left drive wheel braking device 24L in the brake LSD control. On the other hand, when the right drive wheel 15R slips, the right drive wheel 15R is braked by the right drive wheel brake device 24R in the brake LSD control.

For example, in the brake LSD control, the control unit 120 controls the braking force applied to the slip wheels so that the slip rate of the slip wheels approaches a target slip rate greater than 0%. Here, the target slip ratio is preferably set to a value within a range in which the grip force of the tire of the slip wheel (that is, the frictional force generated between the tire and the road surface) is effectively recovered.

FIG. 5 is a schematic view showing the relationship between the slip ratio and the grip force. As shown in FIG. 5, in general, the vertical grip force, which is a traveling direction component of the grip force, increases in the process of increasing the slip ratio of the wheel from 0% to about 20%, and then the slip ratio of the wheel increases. It decreases in the process of doing. Further, in general, the lateral grip force, which is a component perpendicular to the traveling direction of the grip force, decreases as the slip ratio of the wheel increases. Therefore, in order to achieve both the vertical grip force and the horizontal grip force at a high level, it is preferable to adjust the slip ratio of the wheel within the target region of about 10% to about 20%. Therefore, the target slip ratio in the brake LSD control is preferably set to a value within the above target region, which is a range in which the grip force of the tire of the slip wheel is effectively recovered. Hereinafter, the control flow will be described by returning to FIG.

Following step S102, in step S103, the control unit 120 determines whether or not the slip wheel has entered the high μ road surface. When it is determined that the slip wheel has entered the high μ road surface (step S103 / YES), the process proceeds to step S109, the control unit 120 stops the brake LSD control, and the control flow shown in FIG. 4 ends. On the other hand, when it is determined that the slip wheel has not entered the high μ road surface (step S103 / NO), the process proceeds to step S104.

In the determination process of step S103, for example, the control unit 120 temporarily stops the braking of the slip wheels, and when the slip ratio of the slip wheels does not increase while the braking of the slip wheels is stopped, the slip wheels have a high μ. It is determined that the vehicle has entered the road surface.

The determination process in step S103 is not limited to the above example. For example, the control unit 120 may determine that the slip wheel has entered a high μ road surface when the slip ratio of the slip wheel drops to a value near 0%.

If NO is determined in step S103, in step S104, the control unit 120 determines whether or not steering for turning the vehicle 1 toward the slip wheel side (that is, steering on the slip wheel side) has been performed. When it is determined that the slip wheel side steering has been performed (step S104 / YES), the process proceeds to step S105, and the control unit 120 starts torque down control. On the other hand, when it is determined that the slip wheel side steering is not performed (step S104 / NO), the process returns to step S103.

In the torque down control in step S105, the control unit 120 makes the drive torque of the vehicle 1 smaller than the required torque. The control unit 120 can determine the required torque by using, for example, the accelerator operation amount and the vehicle speed. The details of torque down control will be described later.

Following step S105, in step S106, the control unit 120 stops the brake LSD control.

Next, in step S107, the control unit 120 determines whether or not both drive wheels 15 (that is, both the left and right drive wheels 15) have entered the high μ road surface. When it is determined that both drive wheels 15 have entered the high μ road surface (step S107 / YES), the process proceeds to step S108, the control unit 120 stops the torque down control, and the control flow shown in FIG. 4 ends. .. On the other hand, when it is determined that both drive wheels 15 have not entered the high μ road surface (step S107 / NO), the determination process of step S107 is repeated. If NO is continuously determined in step S107, and if a specific condition (for example, a condition that a predetermined time has elapsed) is satisfied, the process may proceed to step S108.

In the determination process of step S107, the control unit 120 determines that the two drive wheels 15 have entered the high μ road surface, for example, when the slip ratio of the two drive wheels 15 drops to a value near 0%.

The determination process in step S107 is not limited to the above example (that is, an example in which the slip ratio of each drive wheel 15 is used as a determination parameter). For example, in the control unit 120, each drive wheel 15 is high based on various parameters related to each drive wheel 15 (for example, the time change rate of the slip ratio, the tire grip force, the time change rate of the tire grip force, etc.). It may be determined whether or not the vehicle has entered the μ road surface.

In the above, an example of the flow of processing for stabilizing the vehicle body behavior by the control device 100 has been described with reference to the control flow of FIG. 4, but the control device 100 is other than those described above. Processing may be performed. For example, the control unit 120 executes torque down control when the steering angle in the slip wheel side steering is smaller than the reference steering angle even when the slip wheel side steering is performed during the execution of the brake LSD control. It is preferable not to do so. The reference steering angle is set to a small steering angle, for example, so that it can be determined whether or not the drive wheels 15 that are not the slip wheels are unlikely to enter the low μ road surface due to the steering on the slip wheel side. Will be done. That is, when the steering angle in the slip wheel side steering is smaller than the reference steering angle, it is determined that there is almost no possibility that the drive wheel 15 which is not the slip wheel enters the low μ road surface due to the slip wheel side steering. be able to. Therefore, it is possible to prevent the torque down control from being unnecessarily executed by not executing the torque down control when the steering angle in the slip wheel side steering is smaller than the reference steering angle.

Hereinafter, the vehicle 1 is on the left side (for example, the state shown by the solid line in FIG. 3 described above) from the state where the right drive wheel 15R is located on the high μ road surface and the left drive wheel 15L is located on the low μ road surface (for example, the state shown by the solid line in FIG. 3 described above). Specifically, the transition of various state quantities in the case of turning to the left side in the state facing the traveling direction will be described with reference to FIGS. 6 and 7 in comparison with each of the comparative examples and the cases of the present embodiment. .. In the comparative example, as in the present embodiment, when one of the left and right drive wheels 15 of the vehicle 1 slips, the brake LSD control for braking the slip wheels is executed. However, in the comparative example, unlike the present embodiment, the torque down control is not executed during the execution of the brake LSD control.

FIG. 6 shows various state quantities when the vehicle 1 turns to the left from the state where the right drive wheel 15R is located on the high μ road surface and the left drive wheel 15L is located on the low μ road surface in the comparative example. It is a figure which shows an example of the transition. Specifically, in FIG. 6, as various state quantities, each speed (vehicle speed VB, left wheel speed VL which is the wheel speed of the left drive wheel 15L, and right wheel speed VR which is the wheel speed of the right drive wheel 15R). , The drive torque of vehicle 1, the steering angle, and the brake LSD control execution flag are shown. In FIG. 6, the positive direction of the steering angle corresponds to the direction in which the vehicle 1 is turned to the right, and the negative direction of the steering angle corresponds to the direction in which the vehicle 1 is turned to the left. The brake LSD control execution flag is 1 when the brake LSD control is being executed, and is 0 when the brake LSD control is not being executed. The brake LSD control execution flag is rewritten and stored by the control device according to the comparative example.

In the example shown in FIG. 6, the vehicle 1 starts in the straight direction at time t10 from the state where the right drive wheel 15R is located on the high μ road surface and the left drive wheel 15L is located on the low μ road surface. .. After time t10, the vehicle speed VB increases as the drive torque increases. After that, at time t11, the left drive wheel 15L slips, and after time t11, the left wheel speed VL greatly increases (specifically, it increases at a speed higher than the vehicle speed VB). Here, at time t11, as the left drive wheel 15L slips, the brake LSD control execution flag is switched from 0 to 1, and the brake LSD control is started. As a result, the left drive wheel 15L, which is a slip wheel, is braked. Therefore, after the time t12, the left wheel speed VL decreases and the slip of the left drive wheel 15L is eliminated.

After that, at time t13, steering is performed to turn the vehicle 1 to the left side on the slip wheel side. As a result, the vehicle 1 turns to the left, and the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface. Then, at time t14, the right drive wheel 15R slips, and after time t14, the right wheel speed VR rises significantly (specifically, it rises at a speed higher than the vehicle speed VB). As described above, in the comparative example, during the execution of the brake LSD control, the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface and the right drive wheel 15R slips, thereby causing the vehicle body to slip. The behavior becomes unstable.

FIG. 7 shows various state quantities when the vehicle 1 turns to the left from the state where the right drive wheel 15R is located on the high μ road surface and the left drive wheel 15L is located on the low μ road surface in the present embodiment. It is a figure which shows an example of the transition of. Specifically, in FIG. 7, a torque down control execution flag is shown as various state quantities in addition to the state quantities shown in FIG. The torque down control execution flag is 1 when the torque down control is executed, and is 0 when the torque down control is not executed. In the present embodiment, the brake LSD control execution flag and the torque down control execution flag are stored in the storage element of the control device 100 and rewritten by the control unit 120.

In the example shown in FIG. 7, the right drive wheel 15R is located on the high μ road surface and the left drive wheel 15L is located on the low μ road surface, as in the example shown in FIG. In the vehicle 1, the vehicle 1 starts in the straight-ahead direction. After that, at time t21, the left drive wheel 15L slips and the brake LSD control is started. As a result, the left drive wheel 15L, which is a slip wheel, is braked. Therefore, the left wheel speed VL that has greatly increased after the time t21 decreases after the time t22, and the slip of the left drive wheel 15L is eliminated. Here, in the brake LSD control, as described above, the braking force applied to the slip wheels is controlled so that the slip ratio of the slip wheels approaches the target slip ratio greater than 0.

After that, at time t23, steering for turning the vehicle 1 to the left side on the slip wheel side (that is, steering on the slip wheel side) is performed. Here, at time t23, the torque down control execution flag is switched from 0 to 1 and the torque down control is started as the slip wheel side steering is performed. As a result, the drive torque of the vehicle 1 becomes smaller than the required torque TD.

Here, in the torque down control, the control unit 120 is such that the slip of the right drive wheel 15R is avoided when the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface. The drive torque of 1 is controlled. In order to properly control the drive torque, the control unit 120 reduces the drive torque of the vehicle 1 with respect to the required torque in the torque down control (that is, the required torque and the reduced drive torque due to the torque down control). It is preferable to control the difference) so as to change according to the following various parameters.

For example, in torque down control, it is preferable that the control unit 120 increases the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque as the required torque of the vehicle 1 increases. The larger the required torque, the easier it is for the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, to slip when the right drive wheel 15R enters the low μ road surface. Therefore, by increasing the amount of decrease in the drive torque as the required torque increases, slippage of the right drive wheel 15R can be appropriately avoided when the right drive wheel 15R enters a low μ road surface.

Further, for example, in torque down control, it is preferable that the control unit 120 increases the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque as the vehicle speed of the vehicle 1 increases. The higher the vehicle speed, the easier it is for the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, to slip when the right drive wheel 15R enters a low μ road surface. Therefore, by increasing the amount of decrease in the drive torque as the vehicle speed increases, slippage of the right drive wheel 15R can be appropriately avoided when the right drive wheel 15R enters a low μ road surface.

Further, for example, in torque down control, it is preferable that the larger the steering angle in steering on the slip wheel side, the larger the amount of decrease in the driving torque of the vehicle 1 with respect to the required torque of the control unit 120. The larger the steering angle in steering on the slip wheel side, the easier it is for the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, to slip when the right drive wheel 15R enters a low μ road surface. Therefore, it is possible to appropriately avoid slipping of the right drive wheel 15R when the right drive wheel 15R enters a low μ road surface by increasing the amount of decrease in the drive torque as the steering angle in the slip wheel side steering increases. can.

Further, for example, in torque down control, it is preferable that the greater the braking force applied to the slip wheels by the brake LSD control, the greater the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque. The greater the braking force applied to the slip wheels by the brake LSD control, the easier it is for the right drive wheels 15R to slip when the right drive wheels 15R, which are the drive wheels 15 that are not the slip wheels, enter the low μ road surface. Therefore, the larger the braking force applied to the slip wheels by the brake LSD control, the larger the amount of decrease in the drive torque, so that the slip of the right drive wheels 15R is appropriate when the right drive wheels 15R enter the low μ road surface. Can be avoided.

As shown in FIG. 7, at time t23, when the torque down control is started, the brake LSD control execution flag is switched from 1 to 0, and the brake LSD control is stopped. After time t23, although the brake LSD control is stopped, the torque down control is executed, so that the slip of the left drive wheel 15L located on the low μ road surface is avoided. FIG. 7 shows an example in which the slip ratio of the left drive wheel 15L is maintained at the same level as the target slip ratio of the brake LSD control even after the time t23 by executing the torque down control. As described above, in the torque down control, it is preferable that the drive torque is controlled so that the slip ratio of the drive wheels 15 becomes about the same as the target slip ratio of the brake LSD control.

As described above, in the present embodiment, the torque down control is executed at the time t23 when the slip wheel side steering is performed. Then, at the subsequent time t24, the right drive wheel 15R, which is the drive wheel 15 that is not the slip wheel, enters the low μ road surface in a state where the drive torque is controlled to be smaller than the required torque TD. Therefore, after the time t24, the right wheel speed VR increases and the slip ratio of the right drive wheel 15R increases, but the slip ratio of the right drive wheel 15R becomes about the same as the slip ratio of the left drive wheel 15L. As a result, slippage of the right drive wheel 15R is avoided, so that the vehicle body behavior can be appropriately stabilized.

<Effect of control device>
Subsequently, the effect of the control device 100 according to the embodiment of the present invention will be described.

In the control device 100 according to the present embodiment, when the control unit 120 is steered to turn the vehicle 1 toward the slip wheel side (that is, the slip wheel side steering) during execution of the brake LSD control, the control unit 120 of the vehicle 1 Torque down control is performed to make the drive torque smaller than the required torque. As a result, the drive torque of the vehicle 1 can be made smaller than the required torque before the drive wheel 15 which is not the slip wheel enters the low μ road surface due to the slip wheel side steering. Therefore, after the drive wheel 15 that is not the slip wheel has entered the low μ road surface, the slip of the drive wheel 15 can be avoided. Therefore, the vehicle body behavior can be appropriately stabilized.

Further, in the control device 100 according to the present embodiment, it is preferable that the control unit 120 increases the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque as the required torque of the vehicle 1 increases in the torque down control. As a result, the amount of decrease in the drive torque can be optimized according to the slipperiness of the drive wheels 15 after the drive wheels 15 that are not the slip wheels have entered the low μ road surface. Therefore, after the drive wheel 15 that is not the slip wheel has entered the low μ road surface, the slip of the drive wheel 15 can be appropriately avoided.

Further, in the control device 100 according to the present embodiment, it is preferable that the control unit 120 increases the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque as the vehicle speed of the vehicle 1 increases in the torque down control. As a result, the amount of decrease in the drive torque can be optimized according to the slipperiness of the drive wheels 15 after the drive wheels 15 that are not the slip wheels have entered the low μ road surface. Therefore, after the drive wheel 15 that is not the slip wheel has entered the low μ road surface, the slip of the drive wheel 15 can be appropriately avoided.

Further, in the control device 100 according to the present embodiment, it is preferable that the control unit 120 increases the amount of reduction of the drive torque of the vehicle 1 with respect to the required torque as the steering angle in the slip wheel side steering becomes larger in the torque down control. .. As a result, the amount of decrease in the drive torque can be optimized according to the slipperiness of the drive wheels 15 after the drive wheels 15 that are not the slip wheels have entered the low μ road surface. Therefore, after the drive wheel 15 that is not the slip wheel has entered the low μ road surface, the slip of the drive wheel 15 can be appropriately avoided.

Further, in the control device 100 according to the present embodiment, the control unit 120 reduces the driving torque of the vehicle 1 with respect to the required torque as the braking force applied to the slip wheels by the brake LSD control increases in the torque down control. It is preferable to increase the size. As a result, the amount of decrease in the drive torque can be optimized according to the slipperiness of the drive wheels 15 after the drive wheels 15 that are not the slip wheels have entered the low μ road surface. Therefore, after the drive wheel 15 that is not the slip wheel has entered the low μ road surface, the slip of the drive wheel 15 can be appropriately avoided.

Further, in the control device 100 according to the present embodiment, it is preferable that the control unit 120 stops the brake LSD control when the torque down control is executed. As a result, it is possible to prevent the brake LSD control from being unnecessarily continuously executed in a situation where the slip of the slip wheel located on the low μ road surface is avoided by the torque down control.

Further, in the control device 100 according to the present embodiment, the control unit 120 uses the steering angle in the slip wheel side steering as the reference steering angle even when the slip wheel side steering is performed during the execution of the brake LSD control. If it is smaller than, it is preferable not to execute the torque down control. As a result, it is possible to prevent the torque down control from being unnecessarily executed in a situation where there is almost no possibility that the drive wheel 15 which is not the slip wheel enters the low μ road surface due to the steering on the slip wheel side. be able to.

Further, in the control device 100 according to the present embodiment, when both the left and right drive wheels 15 enter the high μ road surface having a friction coefficient larger than the reference friction coefficient, the control unit 120 receives the torque down control. It is preferable to stop the torque down control. As a result, it is possible to prevent the torque down control from being unnecessarily continuously executed in a situation where there is almost no possibility that the drive wheels 15 slip even if the torque down control is not executed.

Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, and various modifications in the scope of claims are described. It goes without saying that the modified examples also belong to the technical scope of the present invention.

For example, although the configuration of the vehicle 1 has been described above with reference to FIG. 1, the configuration of the vehicle according to the present invention is not limited to such an example. The vehicle according to the present invention may be, for example, a vehicle 1 shown in FIG. 1 with some components deleted, added or changed. Further, the vehicle according to the present invention may be, for example, a vehicle provided with a drive motor for front wheels and a drive motor for rear wheels (that is, two drive motors are provided), and each wheel may be provided with a drive motor. On the other hand, the vehicle may be provided with a drive motor (that is, four drive motors are provided). A part or all of the drive source in the vehicle according to the present invention may be a drive source other than the drive motor (for example, an engine or the like).

Further, for example, the processes described by using the flowchart in the present specification do not necessarily have to be executed in the order shown in the flowchart. Further, additional processing steps may be adopted, and some processing steps may be omitted.

The present invention can be used in a control device.

1 Vehicle 11 Motor 12 Inverter 13 Battery 14 Differential device 15 Drive wheel 21 Brake pedal 22 Master cylinder 23 Hydraulic pressure control unit 24 Brake device 31 Wheel speed sensor 32 Accelerator operation amount sensor 33 Steering angle sensor 34 Vehicle speed sensor 100 Control device 110 Acquisition unit 120 Control unit 121 Motor control unit 122 Brake control unit

Claims (8)

When one of the left and right drive wheels of the vehicle slips, the brake LSD control for braking the slip wheel, which is the slipped drive wheel, is executed.
A control unit is provided that executes torque down control that makes the driving torque of the vehicle smaller than the required torque when steering is performed to turn the vehicle toward the slip wheel side during the execution of the brake LSD control.
Control device. In the torque down control, the control unit increases the amount of reduction of the drive torque with respect to the required torque as the required torque increases.
The control device according to claim 1. In the torque down control, the control unit increases the amount of decrease of the drive torque with respect to the required torque as the vehicle speed of the vehicle increases.
The control device according to claim 1 or 2. In the torque down control, the control unit increases the amount of reduction of the drive torque with respect to the required torque as the steering angle in the steering increases.
The control device according to any one of claims 1 to 3. In the torque down control, the control unit increases the amount of reduction of the drive torque with respect to the required torque as the braking force applied to the slip wheel by the brake LSD control increases.
The control device according to any one of claims 1 to 4. When the torque down control is executed, the control unit stops the brake LSD control.
The control device according to any one of claims 1 to 5. Even if the steering is performed during the execution of the brake LSD control, the control unit does not execute the torque down control if the steering angle in the steering is smaller than the reference steering angle.
The control device according to any one of claims 1 to 6. The control unit stops the torque down control when both the left and right drive wheels enter a high μ road surface having a friction coefficient larger than the reference friction coefficient during the execution of the torque down control.
The control device according to any one of claims 1 to 7.

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