JP2016159815A - Drive power control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive power control device capable of normalizing lateral force due to the difference between left and right torque, and preventing unstable behavior of a vehicle, in a turning state where the margin of the lateral force in a friction circle of a driven wheel is reduced.SOLUTION: The drive power control device has a vehicle controller 11 for performing behavior control of a vehicle, in which driving torque of left and right rear wheels 1RL, 1RR is controlled independently by drive control of drive units WD, WD based on detection by sensors 40, and lateral force is applied to the left and right rear wheels 1RL, 1RR by the difference between left and right driving torque. The vehicle controller 11 controls the driving torque of the left and right rear wheels 1RL, 1RR during the turning, so that lateral force, obtained by adding lateral force caused by the turning and the lateral force due to the driving torque difference, is within the friction circle of the left and right rear wheels 1RL, 1RR.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a driving force control device that independently controls left and right driving wheels in a vehicle.

Conventionally, in a driving force control device that controls left and right driving forces independently, the driving force is controlled so as to suppress wheel slip independently, and the vehicle behavior during driving force control is stabilized. It is known (see, for example, Patent Document 1).
In this driving force control device, the torque of the driving wheels is controlled independently of the four wheels, and the wheel slip amount including locking is suppressed based on the driving torque, the vehicle speed, and the driving wheel speed.

Special table 2008-515372

  However, in the above-described conventional technology, when the vehicle travels in a direction in which lateral acceleration is applied during execution of a control that gives a left-right torque difference to the drive wheels, the lateral force is used to oppose the vehicle inertia, and the friction circle on the drive wheels There may be no room for lateral force within the range. In such a case, if the control that generates the lateral force due to the difference between the left and right torques is executed, the lateral force may exceed the margin of the friction circle, and the vehicle behavior may become unstable due to the generation of an unintended vehicle yaw moment. there were.

  The present invention has been made paying attention to the above problem, and in a turning state in which the margin of lateral force in the friction circle of the drive wheel is reduced, the lateral force is optimized by the difference between the left and right torques, and the vehicle behavior is stabilized. An object of the present invention is to provide a driving force control device capable of achieving the above.

In order to achieve the above object, the present invention provides:
Drive behavior of the drive unit based on detection of the driving state and traveling state of the vehicle, and the vehicle behavior that controls the drive torque of the left and right drive wheels independently on the left and right, and causes the vehicle to generate a yaw moment due to the difference between the left and right drive torques A driving force control device including a vehicle controller that executes control,
The vehicle controller controls the driving torque of the left and right driving wheels during turning in a direction in which a lateral force obtained by combining a lateral force generated by turning and a lateral force resulting from the difference in driving torque is contained in a friction circle of the left and right driving wheels. The driving force control device is characterized by this.

When the vehicle turns, a lateral force is generated in the left and right drive wheels in a direction opposite to the vehicle inertia. At the same time, when a drive torque difference is given to the left and right drive wheels by the vehicle behavior control, a lateral force for generating a vehicle yaw moment is generated in the left and right drive wheels.
Therefore, in the driving force control device of the present invention, during turning, the lateral force generated by turning and the lateral force resulting from the difference in driving torque is adjusted so that the lateral force of the left and right driving wheels is contained in the friction circle of the left and right driving wheels. Control drive torque.
Therefore, the lateral force that opposes the vehicle inertia and the lateral force due to the difference between the left and right driving torques are combined as compared with the case where the driving torque is not controlled in such a direction that the lateral force is contained in the friction circle of the left and right driving wheels. It is possible to suppress the lateral force from coming out of the friction circle of the left and right drive wheels, and to stabilize the vehicle behavior.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic system diagram showing an overall control system for an electric vehicle equipped with a driving force control apparatus according to Embodiment 1 of the present invention. 2 is a block diagram illustrating a control system of the driving force control apparatus according to Embodiment 1. FIG. 3 is a flowchart showing a flow of processing for obtaining a drive torque command value of the drive force control apparatus of the first embodiment. 4 is a flowchart illustrating processing for obtaining a left / right difference limit value in the driving force control apparatus according to the first embodiment; FIG. 4 is a left / right difference limiting gain setting characteristic diagram showing a map used to obtain a left / right difference limiting gain from lateral acceleration in the driving force control apparatus of the first embodiment. 6 is a time chart illustrating an example of an operation of a comparative example with the driving force control apparatus of the first embodiment. 3 is a time chart illustrating an example of the operation of the driving force control apparatus according to the first embodiment. It is an effect explanatory view showing a friction circle for explaining an effect of the driving force control device of Embodiment 1 of the present invention. 6 is a flowchart showing a flow of processing for obtaining a drive torque command value of the drive force control apparatus of the second embodiment. 6 is a time chart illustrating an example of the operation of the driving force control apparatus according to the second embodiment. 12 is a flowchart illustrating a flow of processing for obtaining a drive torque command value of the drive force control apparatus according to the third embodiment. 10 is a time chart illustrating an example of the operation of the driving force control apparatus according to the fourth embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing the driving force control apparatus of this invention is demonstrated based on embodiment shown in drawing.
(Embodiment 1)
First, the overall configuration of an electric vehicle provided with the drive control device of Embodiment 1 will be described.
FIG. 1 is an overall system diagram illustrating an electric vehicle including the drive control device according to the first embodiment.

  The electric vehicle includes left and right front wheels 1FL and 1FR and left and right rear wheels 1RL and 1RR. The left and right rear wheels 1RL, 1RR can be driven by the individual electric motors 3RL, 3RR (in-wheel motor IWM) built in the respective drive units WD as driving wheels, and the left and right front wheels 1FL, Steering is possible by turning 1 FR.

  Each of the electric motors 3RL and 3RR is a motor / generator that can also function as a generator, and can regeneratively brake the left and right rear wheels 1RL and 1RR that are motor-driven as described above in response to a predetermined power generation load.

  The electric vehicle shown in FIG. 1 includes a vehicle controller 11 that performs drive control and regeneration control of the electric motors 3RL and 3RR (in-wheel motor IWM). And the vehicle controller 11 performs vehicle behavior control. This vehicle behavior control is based on the drive control of the electric motors 3RL, 3RR (in-wheel motor IWM), causing the left and right rear wheels 1RL, 1RR to perform differential rotation and causing the vehicle to have a yaw moment (horizontal about the vertical axis). (Rotation of direction).

A detection signal is input to the vehicle controller 11 from a sensor group 40 as a detection unit that detects a driving state and a traveling state.
The sensor group 40 includes wheel speed sensors 41a, 41b, 41c, 41d, an accelerator opening sensor 42, a steering angle sensor 43, a yaw rate sensor 44, a longitudinal acceleration sensor 45, a lateral acceleration sensor 46, an oil temperature sensor 48, a motor temperature. A sensor 49 is included.
Wheel speed sensors 41a, 41b, 41c and 41d are wheel speeds of left and right front wheels 1FL and 1FR (left front wheel speed VFL and right front wheel speed VFR), which are driven wheels, and wheel speeds of motor driven left and right rear wheels 1RL and 1RR ( Left rear wheel speed VRL and right rear wheel speed VRR) are detected.

The accelerator opening sensor 42 detects an accelerator opening APO that is an accelerator pedal depression amount (not shown).
The steering angle sensor 43 detects the steering angle θ of the steering wheel.
The yaw rate sensor 44 detects a yaw rate φ that is a behavior around the vertical axis of the vehicle.
The longitudinal acceleration sensor 45 detects the longitudinal acceleration Gx of the vehicle.
The lateral acceleration sensor 46 detects the lateral acceleration Gy of the vehicle.
The oil temperature sensor 48 detects the lubricating oil temperature To in each drive unit WD.
The motor temperature sensor 49 detects a motor temperature Tmo that is the temperature of each electric motor 3RL, 3RR (in-wheel motor IWM).

  The vehicle controller 11 obtains the target motor torque (accelerator torque) of the electric motors 3RL and 3RR that drive the left and right rear wheels 1RL and 1RR based on the input information from the sensor group 40. Then, the vehicle controller 11 outputs the left torque command value and the right torque command value corresponding to these target motor torques to the inverter 20 that performs drive / regeneration control of the electric motors 3RL and 3RR. The left and right torque command values are determined based on the actual drive torque obtained in the drive unit WD.

  The inverter 20 supplies DC-AC converted power from the battery (not shown) to the electric motors 3RL and 3RR in accordance with the left and right torque command values. As a result, the left and right rear wheels 1RL, 1RR are driven or regenerated by the motor torques TmL, TmR formed in the electric motors 3RL, 3RR.

(Control by vehicle controller)
Next, control by the vehicle controller 11 will be described.
As described above, the vehicle controller 11 controls the driving of the electric motors 3RL and 3RR so as to obtain a target driving torque in the driving unit WD of the left and right rear wheels 1RL and 1RR.
In this drive control, in Embodiment 1, torque command values for the drive units WD and WD of the left and right rear wheels 1RL and 1RR that are drive wheels are independently controlled.
In this case, during straight running, control is basically performed so that the drive torques of the left and right rear wheels 1RL and 1RR are equal.

The vehicle controller 11 also executes control for intentionally making the driving torques of the left and right rear wheels 1RL and 1RR different and giving a driving torque difference between them in the known vehicle behavior control (yaw moment control).
As such vehicle behavior control, for example, during driving, a target yaw rate corresponding to a turning operation is calculated, and the difference between the driving torques of the left and right rear wheels 1RL and 1RR (right and left) is set so that the actual yaw rate of the vehicle matches the target yaw rate. Control that gives a drive torque difference) is known. Alternatively, as a vehicle behavior control, when a yaw moment is generated in the vehicle due to a road surface inclination or a crosswind during straight running, the yaw moment is set in a direction to suppress the yaw moment due to the drive torque difference between the left and right rear wheels 1RL and 1RR. The resulting control is known.

The left and right drive torque control including the vehicle behavior control (yaw moment control) described above will be described.
In this drive torque control, normally (in the case of non-vehicle behavior control such as when going straight), half of the vehicle target drive torque (accelerator torque) is set as the basic target drive torque of the left and right drive units WD, and according to this basic target drive torque. The left and right torque command values are output. The vehicle target driving torque is a driving torque or a braking torque requested by the driver, which is obtained based on information related to the accelerator opening, the vehicle speed, and the braking force, as is well known, This is the basic target drive torque.

  At the time of vehicle behavior control, one target drive torque of the left and right drive units WD is a value obtained by adding the vehicle behavior control torque to the basic target drive torque, and the other target drive torque is calculated from the basic target drive torque to the vehicle. The value is obtained by subtracting the behavior control torque.

(Limit value setting)
In the first embodiment, control is performed to set the left and right torque limit values, which are limit values based on the target slip value, to the left and right torque command values corresponding to the accelerator torque.
That is, the vehicle controller 11 obtains a target slip value that suppresses the slip (amount or rate) of the drive wheel to a predetermined value when the driver performs an acceleration operation, and based on the target slip value, the upper limit value of each of the left and right drive torques The left torque limit value and the right torque limit value are calculated. The left and right torque command values are limited based on the left and right torque limit values.

  Further, the vehicle controller 11 calculates a left / right difference limit value that limits the left / right drive torque difference within a predetermined range when the vehicle behavior control (yaw moment control) is executed, and the left / right drive torque difference uses the left / right difference limit value. Control not to exceed. Further, at the time of turning, the left / right difference limit value is set so that a lateral force obtained by combining the lateral force generated by the turning and the lateral force resulting from the difference in the left / right driving torque is within the friction circle of each of the left and right rear wheels 1RL, 1RR. To do. At this time, of the left and right torque command values, the torque command value on the high torque side is limited so that the left / right driving torque difference does not exceed the left / right difference limit value.

  Below, the structure which restrict | limits a right-and-left drive torque difference, and the flow of the process are demonstrated based on the control block diagram of FIG. 2, and the flowchart of FIG.

In the process of limiting the left / right driving torque difference, the first steps S1, S2, and S3, S4 shown in FIG. 3 calculate the left torque limit value and the right torque limit value in parallel, respectively.
Specifically, in step S1, a left target slip value that is a target slip amount or slip ratio of the left rear wheel 1RL that is the left driving wheel is calculated.
In the subsequent step S2, the left torque limit value is calculated by feedback control based on PID (Proportional-Integral-Derivative) control. That is, in step S2, the left target slip value obtained in step S1, the actual left slip value (amount or rate) obtained in the later-described actual slip value calculation unit 102, and the left obtained in step S9 described later. A left torque limit value is calculated based on the torque command value. The left torque limit value is an upper limit value for suppressing the slip state of the left rear wheel 1RL to the left target slip value.

In steps S3 and S4, the right torque limit value is obtained for the right rear wheel 1RR, which is the right wheel drive wheel, in the same manner as in steps S1 and S2.
That is, in step S3, a right target slip value that is a target slip amount or slip ratio of the right rear wheel 1RR is calculated.
In step S4, the right torque limit value is calculated by feedback control based on PID control. That is, in step S4, the right target slip value obtained in step S3, the actual right slip value (amount or rate) obtained in the actual slip value calculation unit 102, and the right torque command value obtained in step S9. To calculate the right torque limit value.

  The target slip value calculation unit 101, the actual slip value calculation unit 102, the left PID calculation unit 103, and the right PID calculation unit 104 in FIG. 2 execute the processes of steps S1 to S4. In addition, the start / end determination unit 105 determines whether to start and end the right / left driving torque difference limiting process.

  The target slip value calculation unit 101 determines the target slip values of the left and right rear wheels 1RL and 1RR, which are left and right drive wheels, based on the signal obtained from the sensor group 40, and the obtained left and right target slip values are set to the left PID. The data is output to the calculation unit 103 and the right PID calculation unit 104. Each of the left and right target slip values is a value set in advance according to the vehicle speed, and is set to a larger value at a low vehicle speed than at a high vehicle speed.

  The actual slip value calculation unit 102 calculates a left actual slip value and a right actual slip value based on each wheel rotation speed from the sensor group 40, and outputs them to the left PID calculation unit 103 and the right PID calculation unit 104, respectively. . This actual slip value is the difference between the vehicle body speed (vehicle speed V) obtained from the left and right driven wheel speeds (left and right front wheel speeds VFL and VFR) and the left and right driving wheel speeds (left and right rear wheel speeds VRL and VRR). Can be determined based on

Based on the left target slip value, the left actual slip value, and the left torque command value (previous value), the left PID calculation unit 103 calculates a left torque limit value for suppressing the actual slip value of the left rear wheel 1RL to the target slip value. Calculate.
Based on the right target slip value, the right actual slip value, and the right torque command value (previous value), the right PID calculation unit 104 calculates a right torque limit value for suppressing the actual slip value of the right rear wheel 1RR to the target slip value. Calculate.

  Next, returning to FIG. 3, the calculation process of the left / right difference limit value and the high torque side limit value after step S5a executed in parallel with the calculation of the left and right torque limit values will be described.

In step S5a, the lateral acceleration (Gy) generated in the vehicle detected by the lateral acceleration sensor 46 is read, and the process proceeds to step S5.
In step S5, a left-right difference limit value is calculated according to the lateral acceleration (Gy), and the process proceeds to step S8.

Here, the details of the process for obtaining the right / left difference limit value in step S5 will be described based on the flowchart of FIG.
First, in step S51, a left / right difference limit reference value is obtained. This left / right difference limit reference value is a value set in advance so as not to cause an unnecessarily large left / right driving torque difference in accordance with a necessary yaw moment in vehicle behavior control.
In the next step S52, the right / left difference limiting gain is set with reference to the map shown in FIG. 5 based on the lateral acceleration (Gy) read in step S5a. In this map, according to the lateral acceleration (Gy), the lateral difference limiting gain is set to 1 which is the maximum value in the case of a dead zone in the vicinity where the lateral acceleration (Gy) corresponding to the straight traveling state includes 0. Then, in a region where the lateral acceleration (Gy) is larger than the dead zone, the left / right difference limiting gain is set to be closer to 0 or a preset minimum gain as the lateral acceleration (Gy) increases.

In step S53, the right / left difference restriction reference value obtained in step S51 is multiplied by the left / right difference restriction gain obtained in step S52 to obtain a right / left difference restriction value. In the subsequent step S54, the right / left difference restriction value is obtained. The value is output to a high torque side limit value calculation unit 108 described later.
Here, the left / right difference limiting gain is obtained by adding a lateral force that is a sum of a lateral force that opposes the vehicle inertia when turning and a lateral force that generates a yaw moment in response to the left / right driving torque difference. It is set in advance so as to be within the friction circle of the left and right rear wheels 1RL and 1RR which are driving wheels.

  The processes in steps S51 to S53 (that is, the process in step S5) are performed by the left / right difference limit value calculation unit 106 shown in FIG. That is, the left / right difference limit value calculation unit 106 first obtains a left / right difference limit reference value based on the input from the sensor group 40 and the yaw moment by the vehicle behavior control. The left / right difference limit value calculation unit 106 multiplies the left / right difference limit reference value by the left / right difference limit gain calculated based on the lateral acceleration (Gy) of the inputs from the sensor group 40 to obtain the left / right difference limit value. Ask for.

  Returning to FIG. 3, the left accelerator torque and the right accelerator torque are calculated in step S <b> 6, which performs processing in parallel with the processing for obtaining the left and right torque control values and the processing for calculating the left / right difference limit value. Each of the left and right accelerator torques is a value corresponding to the driver acceleration request torque corresponding to the depression amount of the accelerator pedal (not shown) of the driver. That is, in step S6, first, an accelerator torque that is a driver requested acceleration is obtained from the accelerator opening (APO) and the vehicle speed V, and ½ of the accelerator torque is set as a left accelerator torque and a right accelerator torque. Then, during vehicle behavior control, the left / right driving torque difference obtained according to the required yaw moment is added to one of the left and right accelerator torques and subtracted to the other. Use accelerator torque.

In steps S7, S8, and S9, final left and right torque command values are obtained based on the left and right torque limit values, the left and right accelerator torques, and the left and right difference limit values.
Here, in step S7, the minimum value of the left and right accelerator torques obtained in step S6 and the left and right torque limit values obtained in steps S2 and S4 is set as the select low value.

  In the subsequent step S8, the left-right difference limit value obtained in step S5 is added to the select low value to obtain a high torque side limit value. That is, among the left and right accelerator torques, the upper limit value on the high torque side is the high torque side limit value obtained by adding the left / right difference limit value to the select low value.

In step S9, a left torque command value and a right torque command value are obtained based on the left and right torque limit values, the left and right accelerator torques, and the left and right difference limit values.
That is, the left torque command value is the minimum value among the left accelerator torque, the left torque limit value, and the high torque side limit value.
The right torque command value is the minimum value among the right accelerator torque, the right torque limit value, and the high torque side limit value.
In subsequent step S10, the left and right torque command values obtained in step S9 are output to each drive unit WD.

A configuration for determining the final left and right torque command values based on the above left and right torque limit values, left and right accelerator torques, and left and right difference limit values will be described with reference to FIG.
The left and right torque command values are calculated by an accelerator torque calculation unit 107, a high torque side limit value calculation unit 108, a left select low processing unit 109, and a right select low processing unit 110.
That is, in the accelerator torque calculation unit 107, as described above, each of the left and right sides is determined based on the accelerator torque corresponding to the driver requested acceleration obtained from the accelerator opening (APO) and the vehicle speed V, and the left and right drive torque difference necessary for vehicle behavior control. Find the accelerator torque.

  The high torque side limit value calculation unit 108 reads the left and right accelerator torques and the left and right torque limit values. Then, the left-right difference limit value is added to the lower value (select low) of the left accelerator torque and the left torque limit value to obtain the high torque side limit value.

The left select low processing unit 109 sets the minimum value among the left accelerator torque, the left torque limit value, and the high torque side limit value as the left torque command value.
In the right select low processing unit 110, the minimum value among the right accelerator torque, the right torque limit value, and the high torque side limit value is set as the right torque command value.

(Operation of Embodiment 1)
Next, the operation of the driving force control apparatus of the first embodiment will be described based on the time charts of FIGS.
FIG. 6 shows the operation of the comparative example of the driving force control apparatus of the first embodiment, that is, the operation when the left-right driving torque difference is not limited, and FIG. 7 shows the operation of the driving force control apparatus of the first embodiment. ing.
6 and 7, the operation when the left torque command value is controlled to a value larger than the right torque command value by the vehicle behavior control and the vehicle changes from the straight traveling state to the turning traveling state. Is shown.

First, the operation of the comparative example of FIG. 6 will be described.
In the straight running state from the time point t00 to the time point t01, the vehicle behavior control is executed, and the left torque command value is output as a value larger than the right torque command value. Such vehicle behavior control is performed, for example, when the traveling road surface is inclined in the vehicle width direction or when the vehicle receives an external force such as wind from the lateral direction and a yaw moment is generated despite the straight traveling state. Execute to suppress this yaw moment.

  At this time, the lateral force acting on the left and right rear wheels 1RL and 1RR which are drive wheels is a lateral force for generating a yaw moment due to a left and right drive torque difference by vehicle behavior control, and falls within the friction circle shown in FIG. , Have enough side force margin. The friction circle has a larger diameter as the road surface friction coefficient is larger, and a smaller diameter as the road surface friction coefficient is smaller.

  Thereafter, when turning is started from time t01 in FIG. 6, a lateral force is generated on the left and right rear wheels 1RL and 1RR to counter the vehicle inertia. In this case, the left and right rear wheels 1RL and 1RR have a lateral force obtained by adding a lateral force for generating a vehicle yaw moment due to a left and right driving torque difference by vehicle behavior control and a lateral force for countering vehicle inertia. Works. For this reason, the (rear) lateral force margin in the friction circle of the drive wheel is compared with the case where only one of the lateral force by the vehicle behavior control and the lateral force to oppose the vehicle inertia is generated as shown in FIG. It is narrowed as shown in

  When the lateral force that opposes the vehicle inertia continues to increase, the lateral force generated by the turn exceeds the lateral force margin due to the friction circle at time t02. In this case, the lateral force at the left and right rear wheels 1RL, 1RR is insufficient, and the vehicle behavior may become unstable.

The driving force control apparatus according to the first embodiment suppresses the behavior of the vehicle from becoming unstable due to the lateral force exceeding the lateral force margin of the friction circle. FIG. This will be described based on the time chart.
Even in the driving force control apparatus of the first embodiment, in the straight traveling state from the time point t0 to the time point t1, the left torque command value is set to a value larger than the right torque command value based on the vehicle behavior control. A lateral force is generated by the difference between the left and right drive torques.

Then, when turning is started at the time t1, the lateral acceleration (Gy) increases as in the operation example of FIG. 6, and accordingly, the lateral force to counter the vehicle inertia also increases.
However, in the driving force control apparatus of the first embodiment, when the lateral acceleration (Gy) increases, the left / right difference limiting gain decreases (see the map in FIG. 5), and the left / right difference limiting value calculated in step S5 is The value is smaller than that before the occurrence of the lateral acceleration (Gy). In other words, the left-right difference limit value added to the select low value in step S7 decreases as the lateral acceleration (Gy) increases, and the high torque side limit value decreases.

  Therefore, in the time chart of FIG. 7, the left-right difference limit value decreases from the time t2, and as a result, the high torque to be added to the select low value in step S7 (in this case, the value corresponding to the right torque command value). The side limit value also decreases as the lateral acceleration (Gy) increases. Due to the decrease in the high torque side limit value, the left torque command value is limited to a value lower than the left torque command value set based on the vehicle behavior control after time t3.

  As a result, the lateral force generated by the left-right drive torque difference can be reduced, and the lateral force generated by the left-right drive torque difference can be reduced. Lateral force margin can be expanded.

  For this reason, even if the lateral acceleration (Gy) due to turning increases and the lateral force against the vehicle inertia increases, the lateral force generated in the left and right rear wheels 1RL and 1RR is reduced within the range of the friction circle, that is, the lateral force. Therefore, the vehicle behavior can be stabilized within a margin range. In the figure, the dotted line that rises continuously from the solid line that indicates the lateral force that is the sum of the lateral force due to the difference between the left and right drive torques and the lateral force that is generated by turning is the lateral force that is generated when the left-right difference limit value is not reduced. (The lateral force of the comparative example) is shown. In this case, the lateral force exceeds the margin.

(Effect of Embodiment 1)
In the torque detection device of the first embodiment, the effects listed below can be obtained.
1) The driving force control apparatus of Embodiment 1 is
Drive units WD and WD capable of independently driving left and right rear wheels 1RL and 1RR as drive wheels on the left and right sides of the vehicle;
A sensor group 40 as a detection unit for detecting the driving state and the traveling state of the vehicle;
The drive torque of the left and right rear wheels 1RL and 1RR is independently controlled by the drive control of the drive units WD and WD based on the detection of the sensor group 40, and the yaw moment is applied to the vehicle by the left and right drive torque difference. A vehicle controller 11 for executing vehicle behavior control to be generated;
A driving force control device comprising:
The vehicle controller 11 uses the lateral force of the left and right rear wheels 1RL, 1RR as the driving force of the left and right rear wheels 1RL, 1RR during turning, which is the combined lateral force of turning and the lateral force of the driving torque difference. It is characterized by controlling in a direction to fit in the friction circle.
When vehicle behavior control is executed during a turn, a lateral force that opposes the vehicle inertia due to the turn and a lateral force that is generated by a difference in left and right drive torque act on the left and right rear wheels 1RL and 1RR. During such a turn, by controlling the direction in which the left and right rear wheels 1RL and 1RR are contained in the friction circle, it is possible to suppress the occurrence of a lateral force outside the range of the friction circle and to generate an unstable behavior of the vehicle. Can be suppressed.

2) The driving force control apparatus of Embodiment 1
The vehicle controller 11 sets a left / right difference limit value for restricting the generation of lateral force due to the left / right driving torque difference based on the lateral force generated by turning when controlling the driving torque of the left / right rear wheels 1RL, 1RR. And
Therefore, at the time of turning, by setting a left / right difference limit value for the driving torque of the left and right rear wheels 1RL, 1RR based on the lateral force generated by the turning, the generation of the lateral force due to the left / right driving torque difference is limited.
Therefore, when the lateral force against the vehicle inertia and the lateral force due to the left and right driving torque difference are applied to the left and right rear wheels 1RL and 1RR, the friction is reduced by the amount that the lateral force due to the left and right driving torque difference is limited. The margin of lateral force in the circle can be secured.
Thereby, generation | occurrence | production of the lateral force exceeding a friction circle can be suppressed, and generation | occurrence | production of the unstable behavior of a vehicle can be suppressed.

3) The driving force control apparatus of Embodiment 1
The vehicle controller 11 uses lateral acceleration (Gy) generated in the vehicle as lateral force generated by turning.
Therefore, when controlling the drive torque according to the lateral force generated by the turning, the drive torque control according to the lateral force can be executed at low cost by controlling according to the lateral acceleration (Gy). Further, by using the detection value of the existing lateral acceleration sensor 46 as the lateral acceleration, a driving force control device can be obtained at a lower cost.

(Other embodiments)
Next, a torque detection device according to another embodiment will be described.
Since the other embodiment is a modification of the first embodiment, the same reference numerals as those in the first embodiment are assigned to the same components as those in the first embodiment, and the description thereof is omitted. Only the differences will be described.

(Embodiment 2)
The driving force control apparatus according to the second embodiment calculates the steering angle detected by the steering angle sensor 43 in addition to the lateral acceleration (Gy) detected by the lateral acceleration sensor 46 as the lateral acceleration when calculating the left-right difference limit value. This is an example in which the steering angle converted lateral acceleration (Gyθ) obtained from θ) is used.

That is, as shown in the flowchart of FIG. 9, in the process of step S205a executed before step S5, the lateral acceleration (Gy) and the steering angle (θ) are read.
In step S5 for calculating the left / right difference limit value, the left / right difference limit value is calculated from the lateral acceleration (Gy) detected by the lateral acceleration sensor 46 and the steering angle converted lateral acceleration (Gyθ) calculated from the steering angle (θ). Calculate based on

That is, the first left / right difference limiting gain and the second left / right difference limiting gain are calculated as the left / right difference limiting gain multiplied by the left / right difference limiting reference value.
The first left / right difference limiting gain is calculated based on the lateral acceleration (Gy) as in the first embodiment. In parallel with this, the steering angle converted lateral acceleration (Gyθ) corresponding to the steering angle (θ) is calculated for the second left / right difference limiting gain.

  Note that the second left-right difference limiting gain is also obtained by using the steering angle conversion lateral acceleration (Gyθ) on the horizontal axis, as in the map shown in FIG.

  The left / right difference limit reference value is multiplied by the first left / right difference limit gain based on the lateral acceleration (Gy) and the second left / right difference limit gain based on the steering angle converted lateral acceleration (Gyθ). The difference limit value.

  Therefore, at the time of turning, the second left-right difference limiting gain based on the steering angle-converted lateral acceleration (Gyθ) at the time when the steering angle (θ) is generated by performing the steering before the actual lateral acceleration (Gy) is generated in the vehicle. The left / right driving torque difference can be limited by the left / right difference limit value calculated by multiplying by. Further, at the end of the turn, if the lateral acceleration (Gy) is actually generated in the vehicle even after the steering angle (θ) is returned to the straight traveling state, the left / right difference limit obtained by multiplying the first left / right difference limit gain is obtained. The left and right driving torque difference can be limited by the value.

(Operation of Embodiment 2)
The operation of the second embodiment will be described below based on the time chart of FIG.
Similarly to the time chart of the first embodiment, the time chart shown in FIG. 10 is already based on the vehicle behavior control from the time t20 to the time t21. Is giving a difference.
Then, turning is started at time t21, and turning is finished at time t27.

  During such travel, from the time point t20 to the time point t21, the vehicle is caused to generate a lateral force due to the difference between the left and right driving torques.

  Thereafter, when turning is started from the time t21, in the second embodiment, the lateral difference limit value is obtained by calculating the lateral acceleration (Gyθ) from the lateral acceleration (Gy) detected by the lateral acceleration sensor 46 and the steering angle (θ). ). That is, at the start of turning, first, a change occurs in the steering angle (θ) by the driver's steering, and then lateral acceleration (Gy) occurs in the vehicle. On the other hand, at the end of the turn, the driver performs steering to return the steering angle (θ) to the neutral position during straight traveling, and then the lateral acceleration (Gy) generated in the vehicle decreases.

In response to such changes in the steering angle (θ) and the lateral acceleration (Gy), first, at the time t22, the second left-right difference limiting gain decreases in accordance with the increase in the steering angle converted lateral acceleration (Gyθ). The left / right difference limit value decreases.
Thereafter, as the lateral acceleration (Gy) increases due to the increase in lateral acceleration (Gy) in the vehicle, the first left / right difference gain decreases and the left / right difference limit value further decreases.
As a result, the high torque limit value also decreases, and as shown in the drawing, the left torque command value on the high torque side is decreased from the value corresponding to the vehicle behavior control from the time t23b, and the left and right driving torque difference is reduced. Decrease.

  Therefore, it is possible to suppress the generation of the lateral force based on the left / right driving torque difference by the vehicle behavior control, and to suppress the lateral force within the range of the friction circle shown in FIG. In other words, the lateral force obtained by adding the lateral force due to the difference between the left and right drive torques and the lateral force generated by the turning can be suppressed within the margin of the lateral force margin in the friction circle. In FIG. 10, the dotted line continuous with the solid line indicating the resultant force of the lateral force due to the difference between the left and right driving torques and the lateral force generated by turning is the lateral force generated when the left / right difference limit value is not reduced (the lateral force of the comparative example). In this case, the lateral force exceeds the margin.

  In the operation example of FIG. 10, at the time t24, the increase of the steering angle (θ) is finished and held at a constant steering angle. At this time, the left and right torque command values are set to substantially the same value. The generation of yaw moment due to the difference between the left and right drive torque is suppressed.

  After the time t24, toward the end of the turn, the driver first decreases the steering angle (θ) from the time t25 toward the neutral position during straight traveling. As the steering angle (θ) decreases, the steering angle-converted lateral acceleration (Gyθ) decreases. On the other hand, at the time t25, the lateral acceleration (Gy) generated in the vehicle remains in this turn until the time t26. It is held at the maximum value and starts decreasing from time t26. As a result, the right / left difference limiting gain is maintained at a value close to 0 from the time point t25 to the time point t26, and then increases from t26 when the lateral acceleration (Gy) starts to decrease. Therefore, even if the steering angle (θ) starts to decrease at the time t25, the left-right difference limit value is maintained at a value close to 0 until the lateral acceleration (Gy) of the vehicle actually starts to decrease, and left-right driving is performed. Limit the lateral force due to torque difference.

  Then, as the lateral acceleration (Gy) starts decreasing at the time t26, the left / right difference limit value is increased by increasing the left / right difference limit gain, thereby generating a left / right driving torque difference. That is, as the lateral force against the vehicle inertia acting on the left and right rear wheels 1RL, 1RR decreases, the lateral force due to the left / right driving torque difference is increased again.

Thus, when the lateral acceleration (Gy) generated in the vehicle decreases, the lateral force against the vehicle inertia also decreases. Therefore, even if the lateral force due to the left / right driving torque difference is increased, The lateral force combined with the generated lateral force can be within the range of the friction circle.
Therefore, the lateral force generated in the left and right rear wheels 1RL and 1RR that are the left and right drive wheels can be kept within the range of the friction circle, and the vehicle behavior can be stabilized.

(Effect of Embodiment 2)
The driving force control apparatus according to Embodiment 2 has the following effects in addition to the effects 1) to 3).
2-1) The driving force control apparatus of Embodiment 2 is
The vehicle controller 11 uses, as the lateral acceleration, a steering angle converted lateral acceleration (Gyθ) obtained by converting a steering angle (θ) and a detected value (Gy) of a lateral acceleration actually generated in the vehicle. It is characterized by using.
Therefore, when starting the process of limiting the generation of the lateral force due to the left / right driving torque difference according to the lateral force generated by the turning, the steering angle conversion lateral acceleration (based on the steering angle (θ) detected by the steering angle sensor 43) Gyθ) can be used.
Therefore, before the lateral acceleration (Gy) is generated in the vehicle, it is possible to start the process of limiting the left / right driving torque difference, and control delay can be suppressed.
On the other hand, the process of limiting the left / right driving torque difference is completed based on the occurrence of the lateral acceleration (Gy), thereby ending the process of limiting the left / right driving torque difference at an early stage. Therefore, although the lateral force that opposes the vehicle inertia is acting, it is possible to suppress the occurrence of a problem that causes the lateral force due to the left-right drive torque difference.

(Embodiment 3)
The driving force control apparatus of the third embodiment is an example in which the left and right torque limit values are calculated by further limiting the target slip value according to the lateral acceleration (Gy).

Therefore, in the third embodiment, as shown in the flowchart of FIG. 11, the lateral acceleration (Gy) is read in steps S2a and S4a following steps S1 and S3.
In steps S2b and S4b, a limiting gain is obtained according to the lateral acceleration (Gy). This limiting gain is set to 1 in the dead zone when the lateral acceleration (Gy) is the dead zone, similarly to the left / right difference limiting gain set according to the lateral acceleration (Gy) based on the map shown in FIG. The smaller the value (Gy) exceeds the dead zone, the smaller the value.

  Further, in steps S2c and S4c, a left torque limit value and a right torque limit value are calculated. The left and right torque limit values are determined according to the corrected left and right target slip values obtained by multiplying the left and right target slip values (amount or rate) determined in steps S1 and S3 by the limit gain. That is, the left and right torque limit values are the upper limit values of torque in the left and right rear wheels 1RL and 1RR for obtaining a corrected target slip value limited in accordance with the lateral acceleration (Gy).

(Operation of Embodiment 3)
Next, the operation of the third embodiment will be described based on the time chart of FIG.
Similarly to the time chart of the first embodiment, the time chart shown in FIG. 12 has already been changed to the left and right driving torques at the time t30 based on the vehicle behavior control. Giving a difference. Then, the turning is started from the time t31.

When the lateral acceleration (Gy) increases from the time t31, the lateral force of the left and right rear wheels 1RL and 1RR that are the left and right drive wheels also increases against the vehicle inertia force.
For this reason, the margin of the lateral force for staying within the range of the friction circle shown in FIG. 8 gradually decreases from the time t31.

  On the other hand, in the third embodiment, when the lateral acceleration (Gy) increases, the limiting gain becomes a value smaller than 1, and the left and right target slip values are decreased, thereby decreasing the left and right torque limiting values ( (Based on the processing of steps S2a and S4a).

  Therefore, in the time chart of FIG. 12, the target slip value and the left and right torque command values decrease from the time point t32. Due to the decrease in the left and right torque command values, the margin of lateral force in the friction circle shown in FIG. 8 increases. For example, in FIG. 8, when the driving torque in the acceleration direction is decreased from T1 to T2, the lateral force allowed in the friction circle increases from Fy1 to Fy2, thereby increasing the margin of lateral force.

For this reason, the margin of lateral force increases from time t33, and even if the lateral force increases due to turning, the lateral force can be kept within the margin of margin (within the friction circle).
In other words, in the third embodiment, the limiting gain for the lateral acceleration (Gy) is set so that the lateral force generated by the turning can be within the range of the friction circle.

(Effect of Embodiment 3)
In addition to the effect 1) described in the first embodiment, the driving force control apparatus according to the third embodiment has the following effects.
3-1) The driving force control apparatus of Embodiment 3 is
The vehicle controller 11 sets a left and right torque limit value for suppressing the slip of the left and right rear wheels 1RL and 1RR to a target slip value as the drive torque, and controls the drive torque of the left and right drive wheels during the turning. The left and right torque limit values are set so as to further suppress the target slip value in accordance with a lateral acceleration (Gy) as a lateral force generated by the turning.
By setting the left and right torque limit values so as to suppress the target slip value, it is possible to increase the margin of lateral force of the left and right rear wheels 1RL and 1RR, and to keep the lateral force due to the left and right driving torque difference within the friction circle Thus, the vehicle behavior can be stabilized.

3-2) The driving force control apparatus of Embodiment 3 is
The vehicle controller 11 sets a limiting gain for further suppressing a target slip value according to a lateral force generated by turning, according to a lateral acceleration (Gy) generated in the vehicle.
Therefore, it is possible to set the target slip ratio according to the lateral force generated by the turn by using the existing lateral acceleration sensor 46, and a driving force control device can be obtained at a low cost.

(Embodiment 4)
The fourth embodiment is a modification of the first embodiment, in which the lateral acceleration is obtained from the yaw rate φ and the vehicle speed V.
That is, the left / right difference limit value calculation unit 106 shown in FIG. 2 obtains the lateral acceleration based on a value obtained by multiplying the yaw rate φ detected by the yaw rate sensor 44 and the vehicle speed V based on the detection of the wheel speed sensors 41a and 41b. The left / right difference limit value is determined according to the lateral acceleration.
In the fourth embodiment, since the lateral acceleration is obtained using the existing sensors of the yaw rate sensor 44 used for vehicle behavior control and the sensors (wheel speed sensors 41a and 41b) for detecting the vehicle speed, the lateral acceleration sensor 46 is used. The manufacturing cost can be reduced.

The driving force control device of the present invention has been described based on the embodiments. However, the specific configuration is not limited to these embodiments, and the invention according to each claim of the claims. Design changes and additions are permitted without departing from the gist of the present invention.
For example, in the embodiment, the drive unit is applied to an electric vehicle that drives the left and right rear wheels. However, the drive wheels driven by the drive unit and the number of wheels are not limited to this, and can be applied not only to driving left and right front wheels but also to driving four or more wheels.

In the second embodiment, the left / right difference limiting gain based on the lateral acceleration and the left / right difference limiting gain based on the steering angle are described as the map for calculating the left / right difference limiting gain. May have different settings.
In addition, although the example in which the lateral acceleration and the steering angle are used as the lateral force generated by turning to limit the generation of the lateral force due to the torque difference based on the lateral force generated by turning, the present invention is not limited to this. As shown in FIG. 2, the yaw rate or slip angle can also be used.

1RL Left rear wheel (drive wheel)
1RR Right rear wheel (drive wheel)
11 vehicle controller 40 sensor group (detection unit)
43 Steering angle sensor 46 Lateral acceleration sensor Gy Lateral acceleration WD Drive unit

Claims (6)

A drive unit capable of independently driving left and right driving forces of the left and right drive wheels of the vehicle;
A detection unit for detecting a driving state and a traveling state of the vehicle;
By controlling the drive of the drive unit based on the detection of the detection unit, the drive torque of the left and right drive wheels is independently controlled on the left and right, and the vehicle behavior control for causing the vehicle to generate a yaw moment by the difference in the drive torque on the left and right A vehicle controller to execute,
A driving force control device comprising:
The vehicle controller sets the driving torque of the left and right driving wheels during turning in a direction in which a lateral force obtained by combining the lateral force generated by the turning and the lateral force resulting from the driving torque difference is contained in the friction circle of the left and right driving wheels. A driving force control device characterized by controlling. The driving force control apparatus according to claim 1,
The vehicle controller sets a left / right difference limit value for limiting the generation of a lateral force due to the drive torque difference in accordance with a lateral force generated by the turn in controlling the drive torque of the left / right drive wheels during the turn. A driving force control device. The driving force control apparatus according to claim 1,
The vehicle controller sets, in the drive torque, a left-right torque limit value that suppresses slippage of the drive wheel to a target slip, and controls the drive torque of the left and right drive wheels during the turn. The driving force control apparatus characterized in that the left-right torque limit value is set so as to further suppress the target slip according to force. In the driving force control apparatus according to claim 2 or 3,
The vehicle controller uses a lateral acceleration generated in the vehicle as a lateral force generated by turning. The driving force control apparatus according to claim 4,
The vehicle controller uses a value obtained by converting a yaw rate of the vehicle as the lateral acceleration. The driving force control apparatus according to claim 4,
The vehicle controller uses, as the lateral acceleration, a lateral acceleration obtained by converting a steering angle and a detected value of the lateral acceleration actually generated in the vehicle.