JP2016111878A - Drive torque controller of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure stabilization of a vehicle behavior when shifting from yaw moment control to traction control.SOLUTION: A drive torque controller A of a vehicle comprises: a driving system capable of making driving torque transmitted to left and right drive wheels 5L, 5R different; a vehicle control module 1 for controlling a vehicle behavior by making the driving torque to the left and right drive wheels 5L, 5R different; and a motor controller 2 for starting control of reducing the driving torque to the drive wheels so that an actual slip value is converged to a TCS control target value when slip occurs in one of the left and right drive wheels 5L, 5R and the actual slip value is determined to be equal to or greater than a TCS (traction control of suppressing drive wheel slip) operation threshold value. In the driving torque controller A of the vehicle, when slip occurs during yaw moment control by left and right driving torque difference, the motor controller 2 sets the TCS operation threshold value and the TCS control target value to values smaller than a value when the left and right driving torque difference is zero.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drive torque control device for a vehicle that performs yaw moment control that gives a drive torque difference between left and right drive wheels and traction control that suppresses drive wheel slip.

  Conventionally, in an in-wheel motor electric vehicle, a drive control device capable of realizing 4WD control and traction / ABS equivalent control is known (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-295004

  However, for example, an in-wheel motor electric vehicle such as a vehicle that performs yaw moment control that gives a drive torque difference between left and right drive wheels, performs traction control (hereinafter referred to as “TCS”) that suppresses drive wheel slip. And When the TCS is operated, the TCS operation threshold value and the TCS control target value (both slip equivalent values such as slip amount and slip ratio) are set to the same value when there is a left / right driving torque difference and when there is no difference. In this case, there is a problem that the vehicle behavior is more likely to be disturbed when the TCS is operated in a traveling state with a left / right driving torque difference than when the TCS is operated in a traveling state without a left / right driving torque difference.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle driving torque control device that ensures stabilization of vehicle behavior when shifting from yaw moment control to traction control.

In order to achieve the above object, a vehicle drive torque control device of the present invention has a drive system capable of differentiating drive torque transmitted to left and right drive wheels, and includes a yaw moment control means and a traction control means. And comprising.
The yaw moment control means controls the vehicle behavior by making a difference in the drive torque to the left and right drive wheels.
The traction control means, when slip occurs on one of the left and right drive wheels and it is determined that the actual slip value is equal to or greater than the TCS operation threshold, the traction control means applies the drive wheel to the drive wheel so that the actual slip value converges to the TCS control target value. Control for reducing drive torque is started.
In this vehicle drive torque control device, the traction control means includes a TCS operation threshold value and a TCS control target when a slip occurs during yaw moment control by the left / right drive torque difference or during yaw moment control by the left / right drive torque difference. The value is made smaller than the value when the left-right driving torque difference is zero.

Therefore, when slip occurs during yaw moment control by the left / right drive torque difference or during yaw moment control by the left / right drive torque difference, the TCS operation threshold and TCS control target value are The value is made smaller than the value.
For example, when there is a left-right drive torque difference, and when using the TCS operation threshold and TCS control target value when there is no left-right drive torque difference, if drive wheel slip occurs due to the accelerator depressing operation, the slip will proceed sufficiently Transition to traction control. For this reason, generation | occurrence | production of a big driving wheel slip will be permitted and a vehicle behavior will become unstable.
On the other hand, when there is a left / right driving torque difference, the TCS operation threshold and the TCS control target value when there is no left / right driving torque difference are set to values smaller than those. For this reason, if a slip occurs in the drive wheel due to an increase in accelerator depression during the yaw moment control or the like, the TCS operation condition is satisfied with good response, and the traction control is started without causing an unnecessary slip. For this reason, driving wheel slip is quickly suppressed, and the stability of the vehicle behavior is ensured.
As a result, when shifting from yaw moment control to traction control, stabilization of vehicle behavior can be ensured.

1 is a schematic system diagram illustrating an in-wheel motor electric vehicle to which a drive torque control device according to a first embodiment is applied. FIG. 3 is a control system block diagram illustrating a control configuration of the motor controller according to the first embodiment. 4 is a flowchart illustrating a flow of a drive torque control process executed by the motor controller according to the first embodiment. It is a time chart which shows each characteristic of the slip amount, the 1st command torque, and the 3rd command torque at the time of normal running with basic driving fixed in a comparative example. 10 is a time chart showing characteristics of a slip amount, a first command torque, and a third command torque when an acceleration request due to increased accelerator depression intervenes during yaw moment control by torque hold in a comparative example. Time chart showing characteristics of slip amount, first command torque, second command torque FB torque down, and third command torque when an acceleration request due to an increase in accelerator pedal intervenes during yaw moment control by torque hold in the first embodiment It is.

  Hereinafter, the best mode for realizing a vehicle drive torque control apparatus according to the present invention will be described based on a first embodiment shown in the drawings.

First, the configuration will be described.
The configuration of the vehicle drive torque control apparatus according to the first embodiment will be described by dividing it into [overall system configuration], [drive torque control block configuration], and [drive torque control processing configuration].

[Overall system configuration]
FIG. 1 shows an in-wheel motor electric vehicle to which the drive torque control device A according to the first embodiment is applied. The overall system configuration will be described below with reference to FIG.

  The vehicle to which the drive torque control device A of the first embodiment is applied is an in-wheel motor electric vehicle by rear wheel drive in which left and right rear wheels are drive wheels 5L and 5R and left and right front wheels are driven wheels.

  As shown in FIG. 1, the drive torque control device A includes a vehicle control module 1 (yaw moment control means), a motor controller 2 (traction control means), inverters 3L and 3R, and in-wheel motors 4L and 4R. Drive wheels 5L and 5R.

  The vehicle control module 1 performs yaw moment control (DYC) for controlling the vehicle behavior by making a difference between the drive torques of the left and right drive wheels 5L and 5R based on predetermined input information. Specific yaw moment control includes steering response control, crosswind response control, acceleration / deceleration response control, steady lateral acceleration response control, and the like. The vehicle control module 1 includes a left front wheel speed sensor 11, a right front wheel speed sensor 12, a left rear wheel speed sensor 13, a right rear wheel speed sensor 14, an operation angle sensor 15, a yaw rate sensor 16, a lateral G sensor 17, and a front and rear G sensor. 18. A signal is input from the accelerator opening sensor 19 or the like. Then, according to the acquired information from the motor controller 2, when the slip amount exceeds the slip preliminary determination threshold value Jm during the yaw moment control, the increase in the left and right drive torque difference is stopped and the constant drive torque difference is maintained. When the slip amount exceeds the slip determination threshold value Jp (> Jm) in the state where the drive torque difference is constant, reduction of the left and right drive torque difference is started. The motor controller 2 is connected by a CAN communication line 6 so that slip amount information and the like can be exchanged bidirectionally. The slip rate may be used instead of the slip amount used as the actual slip value.

  When the motor controller 2 does not perform yaw moment control, slip occurs in the left and right drive wheels, and if it is determined that the slip amount is equal to or greater than the TCS operation threshold value, the motor controller 2 causes the slip amount to converge to the TCS control target value. Control (= TCS control) to reduce drive torque to the drive wheels is started. Here, the “TCS operation threshold value” is set to a value larger than the “slip determination threshold value Jp” on the yaw moment control side. The “TCS control target value” is set to a constant value smaller than the TCS operation threshold value. On the other hand, if a drive slip occurs during yaw moment control due to the difference between the left and right drive torques, and the slip amount exceeds the slip determination threshold value Jp, traction control that supports yaw moment control is possible without waiting for the slip amount to exceed the TCS operation threshold value. Is started (FIG. 2). The motor controller 2 acquires the final target values (right wheel first command torque, left wheel first command torque) of the yaw moment control and sensor information from the vehicle control module 1. Further, the motor rotation number signal from the resolvers 7L and 7R provided in the in-wheel motors 4L and 4R is input. Then, the left wheel final command torque and the right wheel final command torque are output to the inverters 3L and 3R, respectively.

  The inverters 3L and 3R convert the direct current from the in-vehicle battery 8 into three-phase alternating current during power running based on the right wheel final command torque and the left wheel final command torque from the motor controller 2, and drive output to the in-wheel motor 4 To do. Further, at the time of regeneration, the three-phase alternating current from the in-wheel motor 4 is converted into direct current, and the in-vehicle battery 8 is charged.

  The in-wheel motors 4L and 4R are provided independently for the left and right drive wheels 5L and 5R, respectively, and have a drive system that can vary the drive torque transmitted to the left and right drive wheels 5L and 5R. It is composed.

[Block configuration of drive torque control]
FIG. 2 shows a control configuration of the motor controller 2 of the first embodiment. Hereinafter, the block configuration of the drive torque control will be described with reference to FIG.

  As shown in FIG. 2, the motor controller 2 includes a driving wheel speed calculation unit 2a, a vehicle body speed calculation unit 2b, a slip amount calculation unit 2c, a slip determination unit 2d, a TCS operation threshold value determination unit 2e, A wheel command torque calculation unit 2f and a TCS control target value determination unit 2g are provided. The FB control operation unit 2h, the FB control stabilization flag generation unit 2i, the driver expected torque arrival flag generation unit 2j, and the TCS control target value inclination determination unit 2k are provided.

  The drive wheel speed calculation unit 2a calculates the drive wheel speed based on the motor rotation speed information from the resolvers 7L and 7R, and outputs it to the slip amount calculation unit 2c.

  The vehicle body speed calculation unit 2b calculates the vehicle body speed based on the wheel speed values from the wheel speed sensors 11, 12, 13, and 14 and the input information from the front / rear G sensor 18, and outputs the vehicle body speed to the slip amount calculation unit 2c.

  The slip amount calculation unit 2c calculates the slip amount based on the speed difference between the drive wheel speed from the drive wheel speed calculation unit 2a and the vehicle body speed from the vehicle body speed calculation unit 2b, and outputs the slip amount to the slip determination unit 2d.

  The slip determination unit 2d determines whether or not the slip amount from the slip amount calculation unit 2c exceeds the slip determination threshold value Jp. When the slip determination unit 2d determines that the slip amount has exceeded the slip determination threshold value Jp, the determination result is output to the TCS operation threshold value determination unit 2e and the left and right wheel command torque calculation unit 2f.

  When the TCS operation threshold value determination unit 2e receives the determination result that the slip amount exceeds the slip determination threshold value Jp from the slip determination unit 2d, the slip determination threshold value Jp set on the yaw moment control side is being controlled. It is determined as the TCS operating threshold. When the slip determination threshold value Jp that is smaller than the TCS operation threshold value during yaw moment non-control is determined as the TCS operation threshold value for starting the TCS control, the determination result and the slip amount are used as the TCS control target value determination unit 2g and the FB. Output to the control operation unit 2h.

When the left and right wheel command torque calculation unit 2f receives the determination result that the slip amount exceeds the slip determination threshold value Jp from the slip determination unit 2d, the right wheel first command torque, the left wheel first command torque, and the driver expected torque are used. The left and right wheel command torque with no torque difference is calculated and output to the FB control operation unit 2h. In the FB control operation unit 2h, the left and right wheel command torque having no torque difference is set as the FB control start torque (FB start torque).
Here, the FB start torque is determined as follows.
(a) Expected driver torque> First command torque (both left and right)
→ Make the left and right torques equal to the higher torque.
(b) Expected driver torque <first command torque (both left and right)
→ Make the left and right torques equal to the driver's expected torque.
(c) Right (left) first command torque <driver expected torque <left (right) first command torque → Left and right torques are made equal to driver expected torque.

  When the TCS control target value determining unit 2g inputs a determination result indicating that the slip determination threshold value Jp is set to the TCS operation threshold value from the TCS operation threshold value determining unit 2e, the initial value that is lower than the slip determination threshold value Jp is set as the TCS control target value. Determine the change to the target value. Then, based on inputs from the driver expected torque arrival flag generation unit 2j and the TCS control target value inclination determination unit 2k, the change of the TCS control target value is determined, and the determined TCS control target value is output to the FB control operation unit 2h. .

  The FB control operation unit 2h receives the determination result that the slip determination threshold value Jp is set to the TCS operation threshold value from the TCS operation threshold value determination unit 2e and the changed TCS control target value from the TCS control target value determination unit 2g. FB torque reduction (second command torque) is calculated by feedback control based on the deviation between the slip amount and the TCS control target value. Then, a third command torque (left and right equivalent final command torque, right wheel final command torque) is calculated by subtracting the second command torque from the first command torque by the left and right wheel command torque calculation unit 2f, and the inverter 3L , 3R.

  When the FB control operation unit 2h starts the FB control operation, the FB control stabilization flag generation unit 2i determines whether the FB control is stable. If the FB control is determined to be stable, the FB control stabilization flag generation unit 2i A control stabilization flag is generated and output to the left and right wheel command torque calculator 2f. The left and right wheel command torque calculation unit 2f receives the FB control stabilization flag and increases the first command torque from the start torque to the driver expected torque (torque corresponding to the accelerator opening).

  When the first command torque reaches the driver expected torque, the driver expected torque arrival flag generation unit 2j generates a driver expected torque arrival flag and outputs it to the TCS control target value determination unit 2g and the TCS control target value inclination determination unit 2k. To do.

  When the TCS control target value inclination determination unit 2k receives the driver expected torque arrival flag, the TCS control target value inclination determination unit 2k determines the inclination of the upward gradient to be increased from the initial target value toward the TCS control target value when there is no torque difference based on the road surface friction coefficient. And output to the TCS control target value determination unit 2g. When the TCS control target value determination unit 2g receives the generated driver expected torque arrival flag and the determined inclination, it maintains the initial target value until the driver expected torque arrival flag is generated. When the driver expected torque arrival flag is generated, it is determined from the initial target value toward the TCS control target value when there is no torque difference, depending on the road surface friction coefficient, the difference between the initial target value and the TCS control target value, etc. The TCS control target value is increased with the tilt.

  A reduction gear train 9L is provided between the in-wheel motor 4L and the drive wheel 5L, and a reduction gear train 9R is provided between the in-wheel motor 4R and the drive wheel 5R.

[Drive torque control processing configuration]
FIG. 3 shows a flow of drive torque control processing executed by the motor controller 2 of the first embodiment (traction control means). In the following, each step of FIG. 3 representing the drive torque control processing configuration will be described. This process is executed during the yaw moment control by the left and right driving torque difference.

  In step S1, input data processing such as rotation information, steering angle, yaw rate, lateral G, front / rear G, accelerator opening is performed, and the process proceeds to step S2.

  In step S2, following the input data processing in step S1, a slip amount (= drive wheel speed−vehicle speed) is calculated, and the process proceeds to step S3.

  In step S3, following the slip amount calculation in step S2, it is determined whether or not the slip amount is equal to or greater than the slip determination threshold value Jp. If YES (slip amount ≧ slip determination threshold value Jp), the process proceeds to step S4. If NO (slip amount <slip determination threshold value Jp), the process returns to step S1.

In step S4, following the determination that the slip amount in step S3 ≧ slip determination threshold value Jp, that is, the left / right drive torque difference is canceled in the yaw moment control, the left / right wheel command torque (first command Torque) is calculated, and the process proceeds to step S5.
Here, when the right and left wheel command torque is the right wheel torque> the left wheel torque, the left wheel torque is increased to the same torque as the right wheel torque so that the right wheel torque = the left wheel torque. When the right wheel torque is less than the left wheel torque, the right wheel torque is increased to the same torque as the left wheel torque so that the right wheel torque is equal to the left wheel torque.

In step S5, following the calculation of the left and right wheel command torque in step S4, it is determined that the slip determination threshold value Jp, which is the torque difference release threshold value of the yaw moment control based on the left and right driving torque difference, is set as the TCS operation threshold value, and then step S6 move on.
That is, the slip determination threshold value Jp set on the yaw moment control side is used as the TCS operation threshold value (left wheel start threshold value Jp or right wheel start threshold value Jp) for starting the TCS control as it is.

In step S6, following the determination of the TCS operation threshold value in step S5, an initial target value of the TCS control target value is determined, and the process proceeds to step S7.
Here, the initial target value is a value obtained by further subtracting a predetermined offset value from the slip determination threshold value Jp.

  In step S7, following the determination of the initial target value in step S6, the FB torque down amount (second command torque) is calculated by feedback control based on the deviation between the actual slip amount and the TCS control target value (initial target value). The FB control operation is started and the process proceeds to step S8.

In step S8, following the start of the FB control operation in step S7 or the determination that the FB control stabilization flag = 0 in step S9, an FB control stabilization flag is generated, and the process proceeds to step S9.
Here, the FB control stabilization flag indicates that the actual slip value is within the range of ± offset value from the initial target value, and the state where the value is within the range continues for a predetermined time or longer (integral term ≧ predetermined value) ), The FB control stabilization flag = 0 is rewritten to the FB control stabilization flag = 1.

  In step S9, following the generation of the FB control stabilization flag in step S8, it is determined whether or not the FB control stabilization flag = 1. If YES (FB control stabilization flag = 1), the process proceeds to step S10. If NO (FB control stabilization flag = 0), the process returns to step S8.

In step S10, following the determination that the FB control stabilization flag = 1 in step S9, the left and right wheel command torque (first command torque) calculated in step S5 starts to increase, and the process proceeds to step S11.
Here, when the first command torque is increased, the first command torque is gradually increased by applying a rate limiter (inclination limit).

In step S11, following the increase in the first command torque in step S10, a driver expected torque arrival flag is generated, and the process proceeds to step S12.
Here, the driver expected torque arrival flag is rewritten from the driver expected torque arrival flag = 0 to the driver expected torque arrival flag = 1 when the left wheel torque and the right wheel torque reach the driver expected torque that is the accelerator opening torque. .

  In step S12, following the generation of the driver expected torque reaching flag in step S11, it is determined whether or not the driver expected torque reaching flag = 1. If YES (driver expected torque arrival flag = 1), the process proceeds to step S13. If NO (driver expected torque arrival flag = 0), the process returns to step S11.

In step S13, following the determination that the driver expected torque attainment flag = 1 in step S12, an inclination for increasing the TCS control target value is determined, and the process proceeds to step S14.
Here, the inclination for increasing the TCS control target value is the initial target determined in step S6 toward the maximum allowable slip amount (for example, the TCS control target value when there is no drive torque difference) according to the road surface μ. Limit the ascending slope from the value. That is, when the road surface μ indicates a low μ road, the upward inclination is a gentle inclination, and the upward inclination is steep as the road surface μ indicates a high μ road.

  In step S14, following the determination of the rising slope of the TCS control target value in step S13, the TCS control target value is raised by the determined slope, and the process proceeds to step S15.

  In step S15, following the increase in the TCS control target value in step S14, it is determined whether or not the TCS control target value has reached an allowable target value (for example, a TCS control target value when there is no drive torque difference). To do. If YES (TCS control target value has reached the allowable target value), the process proceeds to the end. If NO (TCS control target value has not reached the allowable target value), the process returns to step S14.

Next, the operation will be described.
The operation of the drive torque control device A for the in-wheel motor electric vehicle of the first embodiment will be described separately for [Problem of comparative example], [Overall operation of drive torque control], and [Characteristic operation of drive torque control].

[Problems of comparative example]
First, when a slip occurs during yaw moment control using the left / right drive torque difference or during yaw moment control using the left / right drive torque difference, the TCS operation threshold value and TCS control target value remain unchanged from the yaw moment non-control values. What is not changed is a comparative example.

FIG. 4 is a time chart during normal running in which the basic drive is constant in the comparative example. Based on FIG. 4, the drive torque control action during normal running in the comparative example will be described.
In FIG. 4, time t1 is the start time of yaw moment control, time t2 is the time when the slip amount reaches the slip preliminary determination threshold value Jm, time t3 is the time when the slip amount reaches the slip determination threshold value Jp, and time t4 is the yaw moment The control end time, time t5, is the drive slip convergence time.

  When yaw moment control is started at time t1, the slip amount reaches the slip preliminary determination threshold value Jm at time t2, so that the torque limit is activated to the first command torque, and then the torque difference between the left and right wheel command torques. Is kept constant. After that, when the slip amount reaches the slip determination threshold Jp (> Jm) at time t3, the higher torque of the left and right wheel command torques is reduced toward the driver expected torque, and the lower torque is expected by the driver. Raise toward torque. Thereby, at time t4, the first command torque is unified with the driver expected torque and is maintained as it is. As for the slip amount, since the higher torque at which the drive slip has occurred is decreased toward the driver expected torque from time t3 when the slip determination threshold value Jp is reached, the slip amount converges at time t5. That is, during normal travel, after detecting that the slip amount has reached the slip determination threshold value Jp, the torque difference of the yaw moment control is made zero, so that slip is eliminated and the normal control is resumed.

  FIG. 5 is a time chart when an acceleration request by increasing the accelerator pedal intervenes during the yaw moment control by the torque hold in the comparative example. Based on this FIG. 5, the drive torque control action at the time of the acceleration request intervention in the comparative example will be described.

  In FIG. 5, time t1 is the start time of yaw moment control, time t2 is the time when the slip amount reaches the slip preliminary determination threshold Jm, time t3 is the time when the accelerator is stepped on, and time t4 is the slip amount reaches the slip determination threshold Jp. The time t5 is the TCS operation start time, the time t6 is the slip amount peak time, and the time t7 is the slip convergence time by TCS control.

  When yaw moment control is started at time t1, the slip amount reaches the slip preliminary determination threshold value Jm at time t2, so that the torque limit is activated to the first command torque, and then the torque difference between the left and right wheel command torques. Is kept constant. Thereafter, when the accelerator depression operation is performed at time t3, the driver expected torque increases with the accelerator depression operation. When the slip amount reaches the slip determination threshold value Jp (> Jm) at time t4, the left and right wheel command torque rapidly increases toward the driver expected torque due to a sudden release of the torque limit value. A large amount of slip occurs due to this sudden torque increase. When the slip amount exceeds the TCS operation threshold at time t5, TCS control is started, but the slip amount reaches a peak at time t6 due to overshoot. Then, after time t6, the slip amount gradually decreases toward the TCS control target value, and at time t7, the slip amount converges to the TCS control target value. That is, as indicated by the arrow B in FIG. 5, if an acceleration request by increasing the accelerator pedal is intervened during the yaw moment control by the torque hold, a large slip occurs due to a sudden release of the torque.

[Overall action of drive torque control]
First, the overall operation of the drive torque control will be described based on the flowchart shown in FIG.
When the yaw moment control based on the left / right driving torque difference is started, the process proceeds from step S1 to step S2 to step S3 in the flowchart of FIG. In step S2, the slip amount (= drive wheel speed−vehicle speed) is calculated. In step S3, it is determined whether or not the slip amount calculated in step S2 is equal to or greater than the slip determination threshold value Jp. While it is determined in this step S3 that the slip amount <the slip determination threshold value Jp, the flow of going from step S1 to step S2 to step S3 is repeated.

  On the other hand, if it is determined in step S3 that the slip amount ≧ the slip determination threshold value Jp, the process proceeds from step S3 to step S4 → step S5 → step S6 → step S7. In step S4, as the left and right wheel command torque (first command torque), not the driver expected torque, but the first command torque unified to the higher torque of the left and right wheels is calculated, and this first command torque is controlled by the FB control. This is the starting torque in operation. In step S5, the slip determination threshold value Jp is determined as a TCS operation threshold value for starting the TCS control. In step S6, the initial target value of the TCS control target value is determined by a value obtained by subtracting the offset value from the slip determination threshold value Jp. In step S7, the FB control operation for calculating the FB torque down amount (second command torque) is started by feedback control based on the deviation between the actual slip amount and the TCS control target value (initial target value).

  When the FB control operation is started, the process proceeds from step S7 to step S8 → step S9. In step S8, an FB control stabilization flag is generated, and in step S9, it is determined whether or not FB control stabilization flag = 1. While the FB control stabilization flag = 0, the flow from step S8 to step S9 is repeated. When the FB control stabilization flag = 1, the process proceeds from step S9 to step S10. In step S10, the left and right wheel command torque (first command torque) calculated in step S5 is multiplied by a rate limiter. The

  When the increase in the first command torque is started, in the next step S11, a driver expected torque arrival flag is generated, and in step S12, it is determined whether or not the driver expected torque arrival flag = 1. Then, when the left wheel torque and the right wheel torque reach the driver expected torque and the driver expected torque arrival flag is rewritten from “0” to “1”, the process proceeds from step S12 to step S13 → step S14 → step S15. In step S13, the rising slope of the TCS control target value is determined, and in the next step S14, the initial target value in step S6 is raised by the determined rising slope. In step S15, it is determined whether or not the initial target value has reached an allowable TCS control target value. When the initial target value does not reach the allowable TCS control target value, the flow of going from step S14 to step S15 is repeated. When the TCS control target value reaches the allowable TCS control target value, the traction control corresponding to the yaw moment control intervention is terminated.

  FIG. 6 is a time chart when an acceleration request due to an increase in accelerator pedal intervenes during yaw moment control by torque hold. Based on this FIG. 6, the drive torque control action at the time of the acceleration request intervention in the first embodiment will be described.

  In FIG. 6, time t1 is the start time of yaw moment control, time t2 is the time when the slip amount reaches the slip preliminary determination threshold Jm, time t3 is the time when the accelerator is stepped on, and time t4 is the slip amount reaches the slip determination threshold Jp. (= TCS operation start time). Time t5 is the generation time of the FB control stabilization flag, time t6 is the generation time of the driver expected torque arrival flag, and time t7 is the arrival time of the allowable TCS control target value.

  When yaw moment control is started at time t1, the slip amount reaches the slip preliminary determination threshold value Jm at time t2, so that the torque limit is activated to the first command torque, and then the torque difference between the left and right wheel command torques. Is kept constant. Thereafter, when the accelerator depression operation is performed at time t3, the driver expected torque increases with the accelerator depression operation. When the slip amount reaches the slip determination threshold value Jp at time t4, the torque difference control is canceled, and the first command torque is unified with the higher torque of the left and right drive wheels, and the FB control stabilization flag It is maintained until generation time t5.

  At time t4, as indicated by an arrow C in FIG. 6, the TCS operation threshold value for starting the traction control is determined from the value when there is no left-right driving torque difference (a value higher than the TCS control target value). Is switched to a lower slip determination threshold value Jp. At the same time, as indicated by an arrow D in FIG. 6, the initial target value of the TCS control target value is switched to a value smaller than the slip determination threshold value Jp at time t4. Then, traction control is started using the actual slip amount and the initial target value of the TCS control target value, the second command torque (FB torque down) is calculated, and the second command torque is subtracted from the first command torque. A third command torque (final command torque) is obtained. Then, the actual slip amount converges to the initial target value slightly later than time t4 when the traction control is started, and thereafter, the actual slip amount changes along the initial target value.

  Thereafter, when the FB control stabilization flag generation time t5 is reached, an increase in the first command torque that was maintained as the FB control start torque is started. At time t5, the second command torque (FB torque down) starts to decrease in accordance with the increase in the first command torque, and the third command torque (final command torque) remains constant from time t5 to time t6. Keep on. Furthermore, at time t6 when the driver's expected torque is reached due to the increase in the first command torque, the first command torque is maintained at a torque that matches the driver's expected torque. Then, at time t6, the TCS control target value rises with a rising slope determined from the initial target value from time t4 to time t6. The second command torque (FB torque down) starts increasing in accordance with the increase in the TCS control target value, and the third command torque (final command torque) is increased from time t6 to time t7. After that, when reaching the time T7 to reach the allowable TCS control target value, the TCS control target value is kept constant thereafter, the first command torque (= driver expected torque) is also kept constant, and the second command torque is reached. (FB torque down) is also kept constant. As a result, the third command torque (final command torque) is kept constant at a value obtained by subtracting the FB torque down from the driver expected torque.

  That is, the slip amount region indicated by hatching E in FIG. 6 becomes a reduction amount of the slip amount with respect to the comparative example when the acceleration request due to the accelerator depression increases during the yaw moment control by the torque hold, and the occurrence of the slip amount occurs. It can be suppressed.

[Characteristics of drive torque control]
In the first embodiment, during the yaw moment control based on the left / right driving torque difference, when a slip occurs and the slip amount exceeds the slip determination threshold value Jp (time t4 in FIG. 6), the TCS operation threshold value and the TCS control target value are set to the left / right drive. The configuration is such that the value is smaller than the value when the torque difference is zero.
For example, when there is a left-right drive torque difference, and when using the TCS operation threshold and TCS control target value when there is no left-right drive torque difference, if drive wheel slip occurs due to the accelerator depressing operation, the slip will proceed sufficiently Transition to traction control. For this reason, generation | occurrence | production of a big drive wheel slip will be permitted and a vehicle behavior will become unstable (FIG. 5).
On the other hand, when there is a left / right driving torque difference, values smaller than the TCS operation threshold and TCS control target value when there is no left / right driving torque difference are used (arrow C, arrow D in FIG. 6). For this reason, if a slip occurs in the drive wheels 5L and 5R due to an increase in accelerator depression during yaw moment control or the like, the TCS operation condition is satisfied with good response, and traction control is started without causing unnecessary slip. For this reason, driving wheel slip is quickly suppressed, and the stability of the vehicle behavior is ensured. As a result, when shifting from yaw moment control to traction control, stabilization of vehicle behavior can be ensured.

In the first embodiment, the TCS operation threshold value for starting the traction control is set to the slip determination threshold value Jp set on the yaw moment control side as a threshold value for canceling the left / right driving torque difference.
That is, since the TCS operation threshold value is set to the slip determination threshold value Jp on the yaw moment control side, the traction control is started without waiting time in accordance with the timing at which the yaw moment control side starts to release the left / right driving torque difference.
Therefore, if slip occurs during yaw moment control based on the left / right drive torque difference, the slip can be suppressed without a response delay by traction control that is started simultaneously with the release of the left / right drive torque difference.

In the first embodiment, when driving wheel slip is determined by the driver's accelerator depressing intervention during yaw moment control, the lower torque of the left wheel command torque and the right wheel command torque is increased to the higher torque. And it was set as the structure which makes the right-and-left wheel command torque without a torque difference the starting torque of traction control.
That is, when the target drive torque corresponding to the accelerator opening by the driver's accelerator operation is referred to as driver expected torque, both the current output torque and the torque closer to the driver expected torque are unified while observing the driver expected torque.
Therefore, by making the traction control start torque approach the driver expected torque earlier, it is possible to eliminate the driver's uncomfortable feeling and shift to another control without causing unnecessary slip.

In the first embodiment, as the TCS control target value, a value lower than the TCS operation threshold is set as the initial target value, and the initial target value is held until the left and right wheel command torque reaches the driver expected torque. When the driver expected torque is reached, the initial target value is increased toward the allowable TCS control target value.
That is, the initial target value in the traction control is temporarily held lower than the TCS operation threshold value, and when the left and right wheel command torque reaches the driver expected torque, the initial target value is gradually increased. Thus, by lowering the initial target value once lower than the TCS operation threshold value, the FB system is stabilized, and it is possible to shift to traction control without causing slipping quickly.
Therefore, it is possible to stabilize the FB system in the traction control and to reliably suppress the occurrence of a large slip.

In the first embodiment, as the left and right wheel command torque, the start torque is maintained from the start of the feedback control until the control stabilization is confirmed, and when the stabilization of the feedback control is confirmed, the configuration is increased from the start torque to the driver expected torque. did.
That is, after confirming the stabilization of the FB system, control is performed to gradually increase the left and right wheel command torque toward the driver expected torque.
Therefore, by maintaining the starting torque from the start of feedback control until control stabilization is confirmed, it is possible to shift to traction control in which the slip amount follows the initial target value without causing slip.

In the first embodiment, the rising slope when the left and right wheel command torque is increased from the starting torque to the driver expected torque is determined as a gentle slope slope when the road surface friction coefficient is low, and becomes a steep slope as the road surface friction coefficient increases. It was set as the structure to do.
With this configuration, on the low friction coefficient road, the progress of slip caused by increasing the left and right wheel command torque is suppressed. On the other hand, on the high friction coefficient road where slip is unlikely to occur, the left and right wheel command torque can be increased to the driver expected torque with good response.
Therefore, when driving on a low friction coefficient road, it is possible to bring the driving torque closer to the driver expected torque more quickly when driving on a high friction coefficient road without giving the driver a sense of incongruity.

Next, the effect will be described.
In the drive torque control device A for the in-wheel motor electric vehicle according to the first embodiment, the following effects can be obtained.

(1) having a drive system capable of differentiating the drive torque transmitted to the left and right drive wheels 5L, 5R;
A yaw moment control means (vehicle control module 1) for controlling the vehicle behavior by making a difference in the drive torque to the left and right drive wheels 5L, 5R;
When a slip occurs in one of the left and right drive wheels 5L, 5R and it is determined that the actual slip value is equal to or greater than the TCS operation threshold, the drive torque to the drive wheels so that the actual slip value converges to the TCS control target value. Traction control means (motor controller 2) for starting control to reduce
In a vehicle drive torque control device A comprising:
The traction control means (motor controller 2) sets the TCS operation threshold value and the TCS control target value to the left and right when slip occurs during yaw moment control based on the left / right drive torque difference or yaw moment control based on the left / right drive torque difference. The value is smaller than the value when the driving torque difference is zero.
For this reason, when shifting from yaw moment control to traction control, stabilization of vehicle behavior can be ensured.

(2) The traction control means (motor controller 2) is set on the yaw moment control side with the TCS operation threshold value that starts traction control when slip occurs during yaw moment control as the threshold value that releases the left-right drive torque difference. The slip judgment threshold Jp is set.
For this reason, in addition to the effect of (1), if slip occurs during yaw moment control due to the difference between the left and right drive torques, the slip can be suppressed without a response delay by traction control that is started simultaneously with the release of the left and right drive torque differences. .

(3) The traction control means (motor controller 2) increases the lower one of the left wheel command torque and the right wheel command torque when the driving wheel slip is determined by the driver's accelerator depressing step during yaw moment control. The left and right wheel command torque calculating section 2f uses the left and right wheel command torque with no torque difference as the starting torque for traction control.
For this reason, in addition to the effect of (1) or (2), by making the traction control start torque approach the driver expected torque earlier, it is possible to eliminate the driver's uncomfortable feeling and without causing unnecessary slip. It is possible to shift to another control.

(4) When the target driving torque corresponding to the accelerator opening by the driver's accelerator operation is called the driver expected torque,
The traction control means (motor controller 2) uses the value lower than the TCS operation threshold as the TCS control target value as the initial target value, and holds the initial target value until the left and right wheel command torque reaches the driver expected torque, When the driver expected torque is reached, the TCS control target value determination unit 2g that increases from the initial target value toward the allowable TCS control target value is provided.
For this reason, in addition to the effect of (3), as the TCS control target value, by setting the value lower than the TCS operation threshold as the initial target value, it is possible to stabilize the FB system in the traction control, Generation of large slips can be reliably suppressed.

(5) The traction control means (motor controller 2) has an FB control operation unit 2h that calculates an FB torque down amount by feedback control based on a deviation between the actual slip value and the TCS control target value.
The left and right wheel command torque calculation unit 2f maintains the start torque from the start of feedback control until the control stabilization is confirmed as the left and right wheel command torque excluding the FB torque down, and when the feedback control stabilization is confirmed. Increase from the starting torque to the driver expected torque.
For this reason, in addition to the effect of (3) or (4), maintaining the starting torque until control stabilization is confirmed, so that slip does not occur and the slip amount follows the initial target value. Can be migrated to.

(6) The left and right wheel command torque calculation unit 2f determines the upward slope when the left and right wheel command torque is increased from the start torque to the driver expected torque as a gentle slope slope when the road friction coefficient is low. The higher the value, the steep slope.
For this reason, in addition to the effect of (5), when driving on a low friction coefficient road, the driver does not feel uncomfortable due to the occurrence of slip, and when driving on a high friction coefficient road, the drive torque can be brought closer to the driver expected torque more quickly.

  The vehicle drive torque control device according to the present invention has been described based on the first embodiment. However, the specific configuration is not limited to the first embodiment, and the claims relate to each claim. Design changes and additions are allowed without departing from the scope of the invention.

  In the first embodiment, as a traction control means, when slip occurs during yaw moment control by the left and right driving torque difference, the TCS operation threshold is set to the slip determination threshold Jp set on the yaw moment control side. . However, as the traction control means, the TCS operation threshold value may be set to a value higher than the slip determination threshold value Jp as long as the TCS operation threshold value is set to a value smaller than the value when the left / right driving torque difference is zero.

  In the first embodiment, as the traction control means, when slip occurs during the yaw moment control by the left / right driving torque difference, the TCS control target value is set to a value smaller than the slip determination threshold value Jp. However, as the traction control means, the TCS control target value may be set to a value larger than the slip determination threshold value Jp as long as the TCS control target value is set to a value smaller than the value when the left / right driving torque difference is zero.

  In the first embodiment, as the traction control means, the switching timing of the TCS operation threshold value and the TCS control target value is set to the timing at which the slip amount in the time chart of FIG. 6 reaches the slip determination threshold value Jp (t4 in FIG. 6). showed that. However, as the traction control means, if the switching timing of the TCS operation threshold value and the TCS control target value is before time t4 in the time chart of FIG. 6, any timing from the yaw moment control start time t1 to time t4 is used. But it ’s okay. That is, the timing from the start to the end of the yaw moment control may be the timing for switching the TCS operation threshold value and the TCS control target value to a small value regardless of the occurrence of slip.

  In Example 1, the example which uses the slip amount by the difference of a wheel speed and a vehicle body speed as a slip value in traction control was shown. However, the slip value may be an example in which a slip ratio based on the ratio of the difference between the wheel speed and the vehicle speed relative to the vehicle speed is used.

  In the first embodiment, an example in which the drive torque control device of the present invention is applied to a rear wheel drive in-wheel motor electric vehicle is shown. However, the drive torque control device of the present invention is transmitted not only to the in-wheel motor electric vehicle but also to the left and right drive wheels like a vehicle that distributes the drive torque from one drive source to the left and right drive wheels by a clutch or the like. The present invention can be applied to a vehicle having a drive system that can vary the drive torque. Further, the vehicle is not limited to an electric vehicle, and can be applied to a hybrid vehicle, an engine vehicle, or the like capable of yaw moment control.

A Drive torque control device 1 Vehicle control module (yaw moment control means)
2 Motor controller (traction control means)
2a Drive wheel speed calculation unit 2b Car body speed calculation unit 2c Slip amount calculation unit 2d Slip determination unit 2e TCS operation threshold value determination unit 2f Left and right wheel command torque calculation unit 2g TCS control target value determination unit 2h FB control operation unit 2i FB control stabilization Flag generation unit 2j Driver expected torque attainment flag generation unit 2k TCS control target value inclination determination unit 3L, 3R Inverter 4L, 4R In-wheel motor 5L, 5R Drive wheel

Claims (6)

It has a drive system that can vary the drive torque transmitted to the left and right drive wheels,
Yaw moment control means for controlling the vehicle behavior by differentiating the drive torque to the left and right drive wheels;
If slip occurs on one of the left and right drive wheels and the actual slip value is determined to be equal to or greater than the TCS operation threshold, the drive torque to the drive wheel is reduced so that the actual slip value converges to the TCS control target value. Traction control means for starting control to perform,
In a vehicle drive torque control device comprising:
The traction control means sets the TCS operation threshold value and the TCS control target value to the left and right driving torque when slip occurs during the yaw moment control by the left and right driving torque difference or during the yaw moment control by the left and right driving torque difference. A drive torque control device for a vehicle, characterized in that the value is smaller than the value when the difference is zero. In the vehicle drive torque control device according to claim 1,
The traction control means sets the TCS operation threshold value, which starts traction control when slip occurs during yaw moment control, to a slip determination threshold value set on the yaw moment control side as a threshold value for canceling the left-right drive torque difference. A drive torque control device for a vehicle. In the vehicle drive torque control device according to claim 1 or 2,
The traction control means increases the lower torque of the left wheel command torque and the right wheel command torque to the higher torque when the drive wheel slip is determined by intervention by increasing the accelerator depression amount by the driver during the yaw moment control. A vehicle drive torque control device comprising: a left and right wheel command torque calculation unit that uses a right and left wheel command torque having no difference as a traction control start torque. In the vehicle drive torque control device according to claim 3,
When the target driving torque according to the accelerator opening by the driver's accelerator operation is called the driver expected torque,
The traction control means sets an initial target value that is lower than the TCS operation threshold value as the TCS control target value, and maintains the initial target value until the left and right wheel command torque reaches the driver expected torque, A vehicle drive torque control device comprising: a TCS control target value determining unit that increases the initial expected value toward an allowable TCS control target value when the driver expected torque is reached. In the vehicle drive torque control device according to claim 3 or 4,
The traction control means has an FB control operation unit that calculates an FB torque down amount by feedback control based on a deviation between an actual slip value and the TCS control target value,
The left and right wheel command torque calculation unit maintains the start torque as the left and right wheel command torque excluding the FB torque down amount until the control stabilization is confirmed from the start of the feedback control, and the feedback control is stabilized. If it is confirmed, the vehicle driving torque control device increases the starting torque to the driver expected torque. In the vehicle drive torque control device according to claim 5,
The left and right wheel command torque calculation unit determines an upward slope when the left and right wheel command torque is increased from the start torque to the driver expected torque as a gentle slope when the road surface friction coefficient is low, and the road surface friction coefficient is A drive torque control device for a vehicle, characterized by a steep slope as the height increases.