JPH1086705A - Vehicle behavior controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve maneuverability and controllability in turning a vehicle. SOLUTION: A vehicle condition is presumed from a deviation of actual yaw acceleration from desired yaw acceleration corresponding to a steering operation (S120). When a vehicle tends to be under steer(US), an engine output correction value ΔTEUP and desired slip ratios λ17, λ07 of a drive wheels of turning outer and inner wheels are calculated (S160, S170) and a throttle opening and brak oil pressure of the drive wheel are controlled (S200, S210) to generate a torque difference between the left and right drive wheels, so that yaw moment necessary for turning is generated. Also, when the vehicle to be over steer(OS), ΔTEUP, λiT and λoT are calculated, while the desired slip ratio λoTF of a turning outer wheel side drive wheel is calculated (S160, S170), and the throttle opening and the break pressure of the drive wheel and the turning outer wheel side drive wheel are controlled (S200, S210) so that yaw moment necessary for turning is generated by the torque difference between the left and right drive wheels and a driving force added to the drive wheel. As a result, the maneuverabilit and controllability in the vehicle turning can be together ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle behavior control device for ensuring steering stability when turning a vehicle.

[0002]

2. Description of the Related Art Conventionally, yaw rate control has been known as a technique for improving the steering stability when turning a vehicle. In this yaw rate control, a target yaw rate is obtained from an occupant's steering operation or the like, and a torque distribution ratio to the left and right drive wheels and a torque distribution ratio so that the actual yaw rate of the vehicle becomes the target yaw rate.
This is a technique for controlling the engine output that gives a driving force to the left and right driving wheels.
As disclosed in Japanese Unexamined Patent Publication No. 4 (1995) -2014, when the target yaw rate is understeered larger than the actual yaw rate, the engine output is increased and the transmission torque distribution to the turning outer wheel side of the left and right driving wheels is increased to increase the left and right. The torque difference between the drive wheels is increased, and when the target yaw rate is smaller than the actual yaw rate, the engine output is reduced to put the drive wheels in the engine braking state, thereby reducing the torque difference between the left and right drive wheels.

[0003]

However, in such conventional yaw rate control, the actual yaw rate is controlled to the target yaw rate only by the torque difference between the left and right driving wheels.
In some cases, the stability of the vehicle could not be ensured.

That is, for example, in a rear-wheel drive vehicle, when the occupant steers the steering in the left and right directions in order to change lanes or run on an S-curve, first according to the yaw rate control, In response to the first steering operation (leftward steering), the torque difference between the drive wheels is increased to generate a turning moment in the vehicle, and in response to the next steering operation (rightward steering), the drive wheel Although the torque difference is increased in the opposite direction as before, during the yaw rate control associated with the second steering operation, the vehicle has an extremely large understeer tendency.
The torque difference between the driving wheels will be extremely large. As a result, after that, the steering is returned in the straight traveling direction, and even if an attempt is made to return the torque difference between the drive wheels to zero, the vehicle may spin in time.

[0005] In particular, the traveling path of the vehicle has a friction coefficient μ of the road surface.
Is a low μ road, the reaction force (road reaction force) received by the wheels from the road surface is small, and the yaw moment that can be generated by the drive torque difference is also small.
When traveling on the road, if a yaw moment for turning the vehicle quickly is given according to the steering operation of the occupant, then, when the steering is operated in the opposite direction and the yaw moment in the opposite direction is required, The necessary yaw moment cannot be generated, and the vehicle becomes extremely unstable, making the vehicle easier to spin.

That is, in the conventional yaw rate control, the steering performance can be improved, but the stability of the vehicle cannot be ensured. The present invention has been made in view of such a problem, and an object of the present invention is to provide a vehicle behavior control device that can ensure both steering performance and stability of a vehicle.

[0007]

In order to achieve the above object, in the vehicle behavior control device according to the first aspect,
When the vehicle is turning, the driving force increasing means increases the magnitude of the driving force applied to the driving wheels by the driving force generating means according to the degree of turning of the vehicle, and the control means determines whether the vehicle is actually turning. And the target turning state according to the steering operation of the occupant. The brake hydraulic pressure is applied to one of the braking force generating means provided on the left and right driven wheels so that the actual turning state approaches the target turning state. The brake fluid pressure from the source is applied to generate a braking force on one of the driven wheels.

In other words, when the vehicle turns, if the degree of turning increases, the driving force of the driving wheels loses the rolling resistance and the lateral force of the driving wheels decreases. By increasing the driving force of the driving wheels according to the degree of turning of the vehicle, a decrease in the lateral force of the driving wheels is prevented, lateral slippage occurring in the driving wheels is suppressed, and the behavior of the driving wheels is stabilized.

Further, since the turning state of the vehicle cannot be controlled to the target turning state only by stabilizing the behavior of the driving wheels, the present invention further provides a braking force to one of the driven wheels by the control means. By generating the yaw moment, a yaw moment necessary for controlling the turning state of the vehicle to the target turning state is generated.

Therefore, according to the present invention, it is possible to control the turning state of the vehicle to the target turning state without deteriorating the stability of the vehicle, and it is possible to secure both steering performance and stability. . Here, as the turning state and the target turning state used by the control means for controlling the brake fluid pressure, a yaw rate can be used as described in the above-mentioned conventional publication. In order to actually control the turning state of the vehicle to the target turning state by the control means, the control means is braked by the braking force generating means on the turning inner wheel side of the driven wheel during understeer. At least one of understeer control for applying hydraulic pressure and oversteer control for applying brake hydraulic pressure to the braking force generating means on the turning outer wheel side of the driven wheel during oversteer may be performed.

That is, when the yaw rate of the vehicle is understeer smaller than the target yaw rate corresponding to the steering operation of the occupant, the yaw rate can be increased by applying a braking force to the turning inner wheel side of the vehicle. In the case of understeer larger than the target yaw rate, the yaw rate can be reduced by applying a braking force to the turning outer wheel side of the vehicle. Therefore, if the control means is configured as described in claim 2, the control means may be configured to perform understeer or oversteer. Can be made closer to the target yaw rate requested by the occupant, and the steering performance of the vehicle can be improved.

In this case, in particular, the brake fluid pressure is applied to the braking force generating means on the turning outer wheel side during oversteering,
If a braking force is generated on the driven wheel on the turning side of the wheel, it is possible to prevent the vehicle from spinning, so that it is possible to further improve safety, which is preferable. If the yaw acceleration, which is a differential value of the yaw rate, is used as the turning state and the target turning state, the responsiveness of the control can be further improved.

Next, as described in claim 3, the control means not only generates the braking force of one of the driven wheels but also controls one of the braking force generating means provided on the left and right driving wheels. However, if the brake fluid pressure from the brake fluid pressure source is applied to generate a braking force on one of the drive wheels, the steerability and stability of the vehicle can be further improved.

That is, if the control means is configured as described in claim 3, the driving force can be moved between the left and right driving wheels by the braking force applied to one of the driving wheels. The yaw moment required to bring the actual turning state closer to the target turning state is more quickly and reliably generated by the torque difference between the left and right driving wheels caused by the movement and the braking force generated on one of the left and right driven wheels. This makes it possible to further improve the steerability and stability of the vehicle.

In particular, in this case, a yaw moment is generated in the vehicle by the torque difference between the left and right driving wheels, and the cornering force of the driven wheels is reduced by the braking force generated by the driven wheels to reduce the anti-spin moment. Can be generated, so that the stability of the vehicle can be further improved as compared with the conventional device that controls only the torque difference between the drive wheels.

When the yaw moment is controlled by applying a braking force to one of the drive wheels during the turning of the vehicle to thereby control the yaw moment by the torque difference between the left and right drive wheels, as described in claim 4, If the control means is configured to apply brake fluid pressure to the braking force generating means on the turning inner wheel side of the drive wheel during understeering, and to apply brake fluid pressure to the braking force generating means on the turning outer wheel side of the driving wheel during oversteering. Good.

According to the present invention, as described above, the driving force of the driving wheel is increased, and the braking force is applied to one of the driven wheels or one of the driven wheel and the driving wheel, so that the vehicle can be turned at the time of turning. The brake fluid pressure for generating a braking force on the driven wheel or the driven wheel and the driving wheel, which is controlled by the control means, improves the steerability and stability of the vehicle. It is desirable to determine so as to cancel the vehicle propulsion generated by the increase in the driving force by the driving force increasing means.

That is, the control means controls the driven wheels and the driven wheels so as to cancel the vehicle propulsion generated by the increase in the driving force of the driving wheels.
Alternatively, if the brake fluid pressure for generating the braking force on the driven wheel and the drive wheel is determined, the vehicle propulsion force does not increase or decrease against the intention of the occupant, and the occupant does not increase. It is possible to improve the maneuverability and stability during turning of the vehicle without giving a feeling of strangeness to the vehicle.

In order to improve the steerability and stability during turning of the vehicle without changing the vehicle propulsion force, for example, the control means may be provided as follows.
The required yaw moment required to control the actual turning state of the vehicle to the target turning state is calculated, and the amount of increase in the driving force by the driving force increasing means based on the required yaw moment and the brake fluid pressure applied to the braking force generating means May be determined respectively.

The required yaw moment can be obtained from the deviation between the yaw rate and the target yaw rate, or the deviation between the yaw acceleration and the target yaw acceleration. Then, if the required yaw moment is obtained from the deviation between the yaw acceleration and the target yaw acceleration, the turning state can be more quickly controlled by the target turning state,
preferable.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is a schematic configuration diagram illustrating an overall configuration of a vehicle behavior control device according to an embodiment to which the present invention is applied.
It should be noted that the vehicle behavior control device of the present embodiment uses a front engine / rear drive (F
Applicable to R) type vehicles.

As shown in FIG. 1, the intake passage 4 of the internal combustion engine 2
Is formed with a surge tank 4a for suppressing pulsation of intake air, and a throttle valve 12 which is opened and closed by a throttle drive motor 10 is provided upstream of the surge tank 4a. The throttle valve 12 is not opened and closed directly by the accelerator pedal 6 operated by the driver, but is a so-called linkless throttle.

The accelerator pedal 6 and the throttle valve 12 are provided with an accelerator opening sensor 14 and a throttle opening sensor 16 for detecting the opening of the accelerator pedal 6 and the throttle valve 12, respectively. It is input to the braking / driving force control circuit 20, which is a main part of the invention.

The intake passage 4 is provided with a fuel injection valve 24 that is opened by a fuel injection command from the internal combustion engine control circuit 26 and supplies fuel to the internal combustion engine 2.
The fuel injection command is based on the operating state of the internal combustion engine 2 (intake pipe pressure,
The rotational speed, the cooling water temperature, etc.) are determined in accordance with the fuel injection control program of the internal combustion engine control circuit 26 by using information from various sensors including the intake pressure sensor 28 for detecting the pressure in the surge tank 4a. It is created by processing based on.

Next, the braking / driving force control circuit 20 includes the accelerator opening sensor 14 and the throttle opening sensor 1 described above.
6, detection signals from the engine speed sensor 30, the driven wheel speed sensors 32FL and 32FR, the drive wheel speed sensors 32RL and 32RR, the yaw rate sensor 40, the steering angle sensor 44, and the like are also input.

Here, the engine speed sensor 30 detects the rotation speed (engine speed) of the crankshaft 2a of the internal combustion engine 2, and is also used for generating a fuel injection command by the internal combustion engine control circuit 26. You. The driven wheel speed sensors 32FL and 32FR are provided with left and right driven wheels (front wheels) 22F.
The left and right driven wheels 22FL and 22FR are provided on the rotation shafts of the left and right driven wheels 22FL and 22FR, respectively.

Further, drive wheel speed sensors 32RL, 32RR
Are sensors for detecting the rotational speeds of the left and right drive wheels (rear wheels) 22RL and 22RR, respectively. The rotation of the crankshaft 2a of the internal combustion engine 2 is transmitted via a transmission 38, a propeller shaft 34, and a differential gear 36. The transmitted right and left drive wheels 22RL, 22RR are provided on the rotating shafts of the respective wheels.

The braking / driving force control circuit 20 drives the throttle drive motor 10 on the basis of input signals from these sensors to control the opening of the throttle valve 12 (throttle opening), thereby achieving internal combustion. The driving force transmitted from the engine 2 to the left and right driving wheels 22RL, 22RR is controlled, and various solenoid valves provided in a hydraulic circuit 50 as a brake fluid pressure generation source are driven to control the respective wheels 22FL to 22FL.
By adjusting the pressure (brake oil pressure) applied to the wheel cylinders 51FL, 51FR, 51RL, and 51RR as braking force generating means provided on the RR, each of the wheels 22FL to 22FL is adjusted.
Controls the braking force applied to RR.

That is, the braking / driving force control circuit 20 controls the throttle opening to an opening corresponding to the accelerator operation of the driver based on the input signal from the accelerator opening sensor 14 during normal operation of the vehicle. Control, during vehicle acceleration,
By controlling the throttle opening (in other words, the driving force generated by the internal combustion engine 2) and the braking force of the left and right driving wheels 22RL and 22RR,
Traction control for suppressing the acceleration slip generated on the drive wheels 22RL and 22RR, anti-skid control for controlling the braking force of each wheel 22FL to 22RR when the vehicle is braked (when the brake pedal is depressed), and throttle opening when the vehicle turns. Degree (driving force generated by the internal combustion engine 2) and each wheel 22FL-2
By controlling the braking force of 2RR, turning control or the like for ensuring steering stability during turning of the vehicle is executed.

Next, the hydraulic circuit 50 used for such braking force control will be described. As shown in FIG.
The hydraulic circuit 50 includes a left driven wheel 22FL-a right drive wheel 22R.
R, right driven wheel 22FR-left drive wheel 22RL.

Of these pipe systems, a pipe 53A1 extending from the master cylinder 52 for pumping brake oil by a driver's brake operation to the wheel cylinders 51FL and 51RR of the left driven wheel 22FL and the right driving wheel 22RR is connected to a pipe 53A1.
A three-way switching valve 54A used for switching the hydraulic circuit (switched to two positions), a proportion valve 55A for applying high oil pressure to the wheel cylinder 51FL of the left driven wheel 22FL, and a range from the master cylinder 52 to the wheel cylinders 51RR and 51FL. Pressure increasing control valves 56 and 57 for controlling the opening and closing of the pipeline, and pressure reducing control valves 6 for controlling the opening and closing of the pipeline from the wheel cylinders 51RR and 51FL to the reservoir 66A.
1, 62, a reservoir 66A for storing the brake oil from the wheel cylinders 51RR and 51FL, and a pump 67A for pumping the brake oil from the reservoir 66A to the master cylinder 52 side. A pump 53A for increasing the brake oil pressure is provided in a pipe 53A2 extending from the master reservoir 69 to the three-way switching valve 54A.
A pressurization control valve 72A is provided for controlling the opening and closing of the pipeline between the downstream side of A and the master reservoir 69.

When the three-way switching valve 54A is switched to the position A, the three-way switching valve 54A controls the brake operation by a normal driver, the pressure increase control valves 56, 57,
Pressure reduction control valves 61 and 62, reservoir 66A, pump 67A
It is possible to perform well-known anti-skid control using, for example,. On the other hand, when the position is switched to the position B, traction control and turning behavior control can be performed by the high brake oil pressure by the pump 71A.

Similarly to the pipe 53A1, the other pipe 53B1 from the master cylinder 52 to the right driven wheel 22FR and the wheel cylinders 51FR and 51RL of the left drive wheel 22RL is connected to the other pipe 53B1. A three-way switching valve 54B, a proportion valve 55B,
Pressure increase control valves 58 and 59, pressure reduction control valves 63 and 64, a reservoir 66B, and a pump 67B are provided. Further, a conduit 53 extending from the master reservoir 69 to the three-way switching valve 54B.
B2 is provided with a pump 71B and a pressurization control valve 72B, similarly to the pipe 53A2.

The hydraulic circuit 50 includes first and second pressure sensors 75 and 76 for detecting the hydraulic pressure between the pumps 71A and 71B and the three-way switching valves 54A and 54B.
From the master cylinder 52 to the three-way switching valves 54A, 54B
And fourth pressure sensors 77 and 78 for detecting the hydraulic pressure during
The detection signals from these sensors 75 to 78 are also input to the braking / driving force control circuit 20. Based on these detection signals, the braking / driving force control circuit 20 controls the pressure increase control valves 56 to 59, the pressure reduction control valves 61 to 64,
Pressurization control valves 72A, 72B, 66A, 66B, pump 7
By controlling 1A and 71B, the brake hydraulic pressure applied to each wheel cylinder 51FL-51RR (that is, the braking force of each wheel 22FL-22RR) is controlled.

Next, of the control processes executed by the braking / driving force control circuit 20, a control process for turning behavior control, which is a main process related to the present invention (turning behavior control process).
Will be described. This process is a process for realizing the control means and the driving force increasing means of the present invention. In the braking / driving force control circuit 20, the steering angle of the steering obtained from the signal from the steering angle sensor 44 is equal to or larger than a predetermined angle. Is repeatedly executed in the braking / driving force control circuit 20 when the vehicle turns.

As shown in FIG. 3, when the turning behavior control process is started, first, in step S110 (S represents a step), the running state of the vehicle is detected by reading signals from the above-mentioned sensors. . Then, in the following S120,
Based on the detected running state of the vehicle, a vehicle state estimating process for estimating the vehicle state is executed.

This vehicle state estimating process is a process for estimating whether the running state of the vehicle is understeer (US), oversteer (OS), or in the optimum state (NS). Yes, and executed as shown in FIG. That is, in the vehicle state estimation process, first, in S310,
Using the following equation (1) with the steering angular velocity dma, vehicle speed (vehicle speed) V, wheel base L, steering gear ratio N, and stability factor Kh as parameters,
The target yaw acceleration dyro of the vehicle corresponding to the driver's steering operation is calculated.

Dyro = dma · V / L · N (1 + Kh · V ² ) (1) Since the steering angular velocity dma is a differential value of the steering angle, the input from the steering angle sensor 44 is used. The vehicle speed V is obtained based on the signals, for example, the left and right driven wheels 22FL, 2FL obtained by the driven wheel speed sensors 32FL, 32FR.
It is obtained by calculating the average value of the rotation speeds of 2FR (average driven wheel speed). The wheel base L, the steering gear ratio N, and the stability factor Kh are values unique to the vehicle, and are stored in the ROM in advance.

Next, when the target yaw acceleration dyro is calculated as described above, the actual yaw acceleration (actual yaw acceleration) dyr of the vehicle is obtained in step S320 based on the input signal from the yaw rate sensor 40, and the target yaw acceleration dyro is calculated. By subtracting the actual yaw acceleration dyr from the acceleration dyro, the yaw acceleration deviation △ d
yr (= dyro-dyr) is calculated.

Then, in subsequent S325, the actual yaw acceleration dyr
Is determined (positive / negative), and if dyr ≧ 0, S3
At 30, an OS in which the yaw acceleration deviation ＯＳdyr is set in advance
It is determined whether the value is smaller than a tendency determination value Kdyr1 (where Kdyr1 is a negative constant), and if △ dyr <Kdyr1,
At S340, the fact that the vehicle has an OS tendency is stored.

Conversely, if △ dyr ≧ Kdyr1, then S
In 350, it is determined whether or not the yaw acceleration deviation △ dyr is greater than a preset US tendency determination value Kdyr2 (where Kdyr2 is a positive constant). And △ dyr>
If it is Kdyr2, it is stored in S360 that the vehicle has a US tendency. Conversely, 逆 dyr ≦ Kdyr2, and the yaw acceleration deviation △ dyr is equal to or greater than the OS tendency determination value and equal to or less than the US tendency determination value. In this case, the fact that the vehicle is turning in an optimal state (NS) is stored in S370.

On the other hand, if it is determined in step S325 that dyr <0, it is determined in step S380 whether or not △ dyr> −Kdyr1, and if △ dyr> −Kdyr1, the vehicle tends to have an OS. Is stored (S340), and △ dyr ≦ −Kdyr1
If it is, in S390, it is determined whether or not −dyr <−Kdyr2. If △ dyr <−Kdyr2, the fact that the vehicle has a US tendency is stored (S360), and △ dyr ≧ −
If Kdyr2, the fact that the vehicle is turning in an optimal state (NS) is stored (S370).

Thus, the vehicle state estimating process (S120)
, The running state of the vehicle is estimated.
At 30, it is determined whether or not the vehicle has a US tendency based on the estimation result. If the vehicle has a US tendency, an engine output correction value ΔTEUP for increasing the output of the internal combustion engine 2 in accordance with the turning state of the vehicle (US tendency) is calculated in S160, and in S170. , Left and right drive wheels 2
2RL, each wheel 22RL for controlling the braking force of 22RR,
The target slip rates λiT and λoT of 22RR are calculated.

On the other hand, if it is determined in S130 that the vehicle does not have the US tendency, the process proceeds to S140, in which the aforementioned S12
Based on the estimation result at 0, it is determined whether or not the vehicle has an OS tendency. If the vehicle has an OS tendency, S18
0, an engine output correction value △ TEU for increasing the output of the internal combustion engine 2 according to the turning state of the vehicle (OS tendency)
P is calculated, and in S190, the left and right driving wheels 22RL, 22RR
And the target slip ratio λ of the wheels 22RL, 22RR, 22oF for controlling the braking force of the left and right driven wheels 22FL, 22FR, respectively, for controlling the braking force of one of the driven wheels 22oF, which is the turning outer wheel.
Calculate iT, λoT, λoTF.

The subscript "iT" given to the target slip ratio λ represents the target slip ratio for the turning inner wheel of the left and right drive wheels 22RL and 22RR, and the subscript "oT" represents the left and right drive wheels 22RL and 22RL. 22RR indicates the target slip ratio for the outer turning wheel, and the subscript “oTF” indicates the left and right driven wheels 22FL, 2FL.
Indicates the target slip ratio for the turning outer wheel in 2FR.

If it is determined in S140 that the vehicle does not have the OS tendency, the turning state of the vehicle is in an optimum state, and it is determined that the turning behavior control is unnecessary, and the control is performed. Is initialized, and the process returns to S110. Here, in the processing of S160 and S170, when the vehicle is in the US tendency, as shown in FIG. 5A, the yaw moment (indicated by a dotted line in the figure) applied to the position of the center of gravity of the vehicle is driven by the steering operation. Is smaller than the required yaw moment (represented by a solid line in the figure), the output torque from the internal combustion engine 2 is increased, and the left and right drive wheels 22 are increased.
A driving wheel serving as a turning inner wheel of the RTs 22RR (in the figure, a braking force is applied to the left driving wheel 22RL, and the left and right driving wheels 22RT, 22RR
By controlling the torque distribution ratio to the vehicle, the driving force of the turning outer wheel (the right driving wheel 22RR in the figure) is made larger than the driving force of the turning inner wheel (the left driving wheel 22RL in the figure), thereby reducing the yaw moment of the vehicle. This is a process for calculating a control amount for controlling to a required yaw moment corresponding to the steering operation of the driver.

Then, the processing of S160 is performed in S320.
Based on the yaw acceleration deviation 求 め る dyr and the moment of inertia I of the vehicle, the required yaw moment Mreq is obtained using the following equation (2), and Mreq = I △△ dyr (2) Engine speed sensor A current engine torque TE is obtained by using a map (not shown) using the engine speed detected at 30 and the throttle opening detected by the throttle opening sensor 16 as parameters. Left and right drive wheels 22RL, 22 from the internal combustion engine 2
Based on the total transmission efficiency η of the driving force in the power transmission system leading to RR and the total gear ratio i in the power transmission system, the driving torque of the current driving wheels 22RL and 22RR is calculated using the following equation (3). TN is determined, and TN = TE · i · η (3) Finally, the following equation (4) is used to calculate the engine torque correction value (that is, engine output correction value) 補正 TEUP. .

ΔTEUP = {(r / LT) · Mreq− (TN−Rt)} / i · η (4) In equation (4), r is the effective radius of the drive wheel, and LT is 2 of the tread. The value of 1 / Rt is the torque conversion value Rt of the rolling resistance. When the engine output correction value △ TEUP obtained as described above becomes a negative value, △ TEUP
Assuming UP = 0, guarding is performed with the value “0”.

On the other hand, the processing of S170 is based on the required yaw moment Mreq and the value LT of a half of the tread, and the target driving force difference between the left and right driving wheels 22RL and 22RR is calculated using the following equation (5). ΔDR is determined, and ΔDR = Mreq / LT (5) Next, this target driving force difference ΔDR and the wheel slip ratio λ
Based on the change rate of the braking / driving force K1 with respect to
, The slip ratio difference between the left and right drive wheels 22RL and 22RR.
SDLT is determined, ΔSDLT = ΔDR / K1 (6) Further, based on the slip ratio difference ΔSDLT and the current slip ratio λi of the driving wheel on the turning inner wheel side, using the following equation (7), ΛiT = λi− △ SDLT / 2 (7) Finally, based on the target slip rate λiT of the driving wheel on the turning inner wheel side and the slip rate difference △ SDLT, The target slip ratio λoT of the driving wheel on the turning outer wheel side is obtained using (8).

.Lambda.oT = .lambda.iT + .SIGMA.SDLT (8) The change rate K1 used to determine the slip rate difference .SIGMA.SDLT is, as shown in FIG. 6, a braking slip region where the vehicle speed V is lower than the wheel speed. (In the figure, the slip ratio λ
From the negative region) to the drive slip region where the wheel speed is higher than the vehicle speed V (the region where the slip ratio λ is suppressed in the figure), the braking / driving force is substantially proportional to the change in the slip ratio λ. It is a change ratio of the braking / driving force with respect to the slip ratio λ (in other words, a gradient of a straight section shown in FIG. 6) in a region where the change can be linearly approximated.

In this embodiment, as described above, the target slip ratio λiT of the turning inner wheel and the driving wheels serving as the turning inner wheel is set.
And λoT, a braking force is applied to the driving wheel on the turning inner wheel side, and a driving force is applied to the driving wheel on the turning outer wheel side.
The yaw moment of the vehicle having the S tendency is increased to the target yaw moment, and the turning state of the vehicle can be controlled to the target turning state corresponding to the steering operation of the driver.

As described above, in this embodiment, the change rate K
The target slip rates λiT and λoT of the driving wheels on the turning inner wheel side and the turning outer wheel side are obtained based on the above equation 1. In these target slip rates λiT and λoT, the change in the braking / driving force with respect to the slip rate λ can be linearly approximated. Deviates from the desired slip rate λiT because the desired yaw moment cannot be generated in the vehicle, and the vehicle behavior becomes rather unstable.
And λoT, upper and lower limit values λLimit are set corresponding to the above-mentioned regions, and the respective target slip rates λiT and λoT are respectively limited so that their absolute values do not exceed the upper and lower limit values λLimit. .

On the other hand, when the vehicle is in the OS tendency, the processes in S180 and S190 are performed as shown in FIG.
Since the yaw moment applied to the position of the center of gravity of the vehicle (indicated by a dotted line in the figure) is larger than the required yaw moment (indicated by a solid line in the figure) required by the driver through the steering operation, the output torque from the internal combustion engine 2 is increased. Along with
By applying a braking force to a driving wheel serving as a turning outer wheel (right driving wheel 22RR in the figure), a torque distribution ratio to the left and right driving wheels 22RT and 22RR is controlled, and a driven wheel serving as a turning outer wheel (right driving wheel 22RR in the figure) is further provided. By applying a braking force to the driving wheel 22FR), the driving force of the driving wheel on the turning outer wheel side is made smaller than the driving force of the driving wheel on the turning inner wheel side, and the lateral force of the driven wheel on the turning outer wheel side (right The process for calculating the control amount for controlling the yaw moment of the vehicle to the required yaw moment corresponding to the steering operation of the driver by reducing the horizontal arrow (the horizontal arrow given to the driving wheel 22FR) from the dotted line to the solid line shown in the figure. It is.

The processing in S180 is the same as that in S160.
The processing of S190 is performed in the same manner as described above. First, the required yaw moment Mreq obtained by using the above equation (2), the value LT of a half of the tread, and the rate of change Kf of the lateral force with respect to the braking force are obtained. , Based on the distance Lf between the axle on the driven wheel (front wheel) side and the position of the center of gravity of the vehicle, using the following equation (9),
The target driving force difference ΔDR of 2RL and 22RR is obtained, and ΔDR = Mreq / (LT · 1.5 + 0.5 · Kf · Lf) (9) Next, the target driving force difference ΔDR and wheel slip are calculated. Rate λ
Based on the change rate K1 of the braking / driving force with respect to
Using the equation (6), the slip ratio difference △ SDLT between the left and right drive wheels 22RL and 22RR is determined, and the slip ratio difference △ SDLT and the current slip ratios λi and λo of the drive wheels on the inner and outer turning wheels are determined. Based on the following equations (10) and (11), the target slip ratios λiT, λ of the drive wheels on the turning inner wheel side and the turning outer wheel side are calculated.
.omega.T respectively, .lambda.iT = .lambda.i + .SIGMA.SDLT / 2 (10) .lamda.oT = .lamda.o-.SIGMA.SDLT / 2 (11) Finally, the slip ratio difference .SIGMA.SDLT and the current slip ratio .lambda. Based on the above, the target slip ratio λoTF of the driven wheel on the turning outer wheel side is calculated using the following equation (12).

ΛoTF = λiT + △ SDLT (12) The target slip ratios λiT and λoT of each drive wheel are calculated in S17.
As in the calculation at 0, the absolute value is limited so as not to exceed the upper and lower limit values λLimit. Further, the arithmetic expression (9) for obtaining the target driving force difference ΔDR between the left and right driving wheels 22RL and 22RR is set as follows.

That is, the driving force difference generated between the left and right driving wheels is △ DR, and the braking force applied to the driven wheel on the turning outer wheel side is △ BF.
If the lateral force applied to the driven wheel on the turning outer wheel side is ΔFy, the value of a half of the tread is LT, and the distance between the axle of the driven wheel and the center of gravity is Lf, the required yaw moment Mreq is given by the following equation (1)
It can be described as 3).

Mreq = △ DR ・ LT + △ BF ・ LT + △ Fy ・ Lf (13) In equation (13), △ BF = △ DR / 2, △ Fy =
By approximating ΔBF · Kf, the above (13) can be described as the following equation (14). Mreq = △ DRＬLT + (△ DR / 2) ・ LT + (△ DR / 2) ・ Kf ・ Lf (14) From the equation (14), an arithmetic expression for obtaining the target driving force difference △ DR is obtained. By deriving, the above equation (9) is obtained.

As described above, S160 and 170,
Alternatively, at 180 and 190, the engine output correction value △ TE
After the UP and the target slip rates λiT, λoT, λoTF of each wheel are calculated, the process proceeds to S200 (see FIG. 3). Then, in S200, FIG. 7 showing the relationship between the engine speed, the shaft torque of the internal combustion engine 2, and the throttle opening degree
Using the map shown in FIG. 5, the shaft torque of the internal combustion engine 2 is calculated from the current torque by using the engine output correction value ΔTEU calculated above.
The throttle opening (target throttle opening) required to increase by P is calculated, and the throttle drive motor 10 is driven so that the throttle opening detected by the throttle opening sensor 16 becomes the target opening. Then, a process as driving force increasing means is performed.

Next, in S210, the slip ratio λi of the driving wheel on the turning inner wheel side of the left and right driving wheels 22RL and 22RR is set to the target slip ratio λiT, and the slip ratio λo of the driving wheel on the turning outer wheel side is set to the target slip ratio. When the target slip ratio λoTF of the driven wheel on the turning outer wheel side is set while controlling the respective ratios λoT, a hydraulic control process of controlling the slip ratio λoF of the driven wheel to the target slip ratio λoTF is executed. I do. Then, once the hydraulic control process is completed, the process returns to S110.

Next, the hydraulic control processing of S210 is performed for each wheel to be controlled (ie, the left and right driving wheels 22RL, 22RR,
And one of the left and right driven wheels 22FL and 22FR) according to the procedure shown in FIG. That is, first, S4
At 10, the slip ratio λW (λ
i, λo, or λoF), and then in S420, the target slip ratio λW0 (λiT, λoT, or λ
oTF).

In step S410, the wheel slip rate λW is calculated as follows: when the rotational speed of the wheel (wheel speed VW) is lower than the vehicle speed V (V> VW) and a braking slip occurs on the wheel. Conversely, when the wheel speed VW is higher than the vehicle speed V (V <VW) and an acceleration slip occurs on the wheels, calculation is performed using the following expression (16). If the wheel speed VW is equal to the vehicle speed V, the slip ratio .lambda.W = 0 is set.

ΛW = − (V−VW) / V (15) λW = (VW−V) / VW (16) Then, in S430, the slip ratio λW obtained in S410 is smaller than the target slip ratio λW0. Is determined to be larger than the target slip ratio λW0. If the slip ratio λW is larger than the target slip ratio λW0, the process proceeds to S440, and the control pattern for controlling the brake hydraulic pressure applied to the wheel cylinder of the wheel is changed to
The pressure increase control valve in the hydraulic circuit 50 is controlled to open and close to set a pressure increase pattern for increasing the brake oil pressure, and to increase the braking force applied to the wheel.

In this pressure increase pattern, the amount of increase in the brake oil pressure corresponds to the change rate K1 of the braking / driving force with respect to the slip ratio.
And the change rate K2 of the braking force with respect to the change of the brake oil pressure
, And the slip rate λW and the target slip rate λW0 are set as the following equation (17).

Pressure increase amount = (K1 / K2) × (λW−λW0) (17) On the other hand, when it is determined in S430 that the slip ratio λW is equal to or less than the target slip ratio λW0, the process proceeds to S450. Then, it is determined whether the slip ratio λW is smaller than the target slip ratio λW0. And the slip ratio λW
Is smaller than the target slip ratio λW0, S460
Then, the control pattern for controlling the brake oil pressure to the wheel cylinder of the wheel is set to a pressure reduction pattern for reducing the brake oil pressure by opening and closing the pressure reducing control valve in the hydraulic circuit 50, and is applied to the wheel. Decrease braking force.

In this pressure reduction pattern, the pressure reduction amount of the brake hydraulic pressure is determined by the change rate K1 of the braking / driving force with respect to the slip ratio.
And the change rate K2 of the braking force with respect to the change of the brake oil pressure
, And the slip rate λW and the target slip rate λW0 are set as the following equation (18).

Pressure increase amount = (K1 / K2) × (λW0−λW) (18) Further, when it is determined in S450 that the slip rate λW is equal to or larger than the target slip rate λW0 (that is, the slip rate λ
W can be controlled to the target slip ratio λW0)
The process proceeds to S470, and the control pattern for controlling the brake oil pressure to the wheel cylinder of the wheel is changed to a holding pattern for holding the brake oil pressure by controlling the pressure increasing control valve and the pressure reducing control valve in the hydraulic circuit 50 to the closed state. By setting, the braking force applied to the wheel is maintained at the current state.

During the execution of the hydraulic control process, the pump 71 in the hydraulic circuit 50 is controlled to control the brake hydraulic pressure of the wheel cylinder of the wheel to be controlled.
A and 71B are driven. Next, the operation of the above-described turning behavior control process will be described with reference to the explanatory diagram of FIG. FIG. 8 shows a case where the driver steers the steering in order to the left and right in order to change lanes or run on an S-shaped curve.

As shown in FIG. 8, when the driver steers the steering wheel to the left at time t1, the target yaw rate required by the driver increases in the + direction in accordance with the steering angle, and the steering angular velocity decreases. Accordingly, the target yaw acceleration requested by the driver also increases in the + direction. When the actual yaw acceleration is smaller than the target yaw acceleration, it is determined that the vehicle is in the US tendency, and the throttle opening is adjusted in response to the driver's accelerator operation in order to generate the necessary yaw moment for the vehicle. By opening the valve larger than the reference opening, the output torque of the internal combustion engine 2 is increased, and the brake hydraulic pressure PRL for the drive wheel on the turning inner wheel side, that is, the left drive wheel 22RL is increased, so that the braking force is applied to the left drive wheel 22RL. To the left and right drive wheels 2
A torque difference (driving force difference) is generated between 2RL and 22RR.

When the actual yaw acceleration of the vehicle reaches the target yaw acceleration by this control and the actual yaw acceleration becomes larger than the target yaw acceleration (time point t2), it is determined that the vehicle has the OS tendency. In order to suppress the yaw moment generated in the vehicle, the throttle opening is opened larger than the reference opening corresponding to the driver's accelerator operation to increase the output torque of the internal combustion engine 2 and to drive the turning outer wheel. By increasing the brake hydraulic pressure PRR for the wheels, that is, the right driving wheel 22RR, and applying a braking force to the left driving wheel 22RL, a torque difference (driving force difference) in the opposite direction to the left and right driving wheels 22RL, 22RR is reduced. And a brake hydraulic pressure PFR for the driven wheel on the turning outer wheel side, that is, the right driven wheel 22FR.
To reduce the lateral force of the driven wheel 22FR.

Therefore, according to the present embodiment, when the driver turns the vehicle by steering operation, the vehicle generates a yaw moment necessary for the turning to realize the turning state required by the driver. it can. Next, after the driver once steers the steering to the left as described above,
When the steering is switched to the right steering, the target yaw acceleration changes in the opposite direction (negative direction in the figure) as compared to the past.

When the target yaw acceleration changes in this way, it is determined that the vehicle is in the OS tendency until the actual yaw acceleration reaches "0", and the above control is continued, and the actual yaw acceleration is reduced. When it becomes the same direction (-direction) as the target yaw acceleration (time point t3), it is determined that the vehicle has the US tendency.

When it is determined that the vehicle has the US tendency, the throttle opening is set to a reference value corresponding to the driver's accelerator operation in order to generate a yaw moment necessary for turning the vehicle to the right. By opening the valve larger than the opening, the output torque of the internal combustion engine 2 is increased, and the brake hydraulic pressure PRR for the drive wheel on the turning inner wheel side, that is, the right drive wheel 22RR is increased.
(In this case, the increase in the brake hydraulic pressure PRR for the right drive wheel 22RR is continued), and a braking force is applied to the right drive wheel 22RR, so that the right and left drive wheels 22RL and 22RR are required to make a right turn. Generate a torque difference (driving force difference).

When the actual yaw acceleration of the vehicle reaches the target yaw acceleration by this control and the actual yaw acceleration becomes larger than the target yaw acceleration (time t4), it is determined that the vehicle is in the OS tendency. In order to suppress the yaw moment generated in the vehicle, the throttle opening is opened larger than the reference opening corresponding to the driver's accelerator operation to increase the output torque of the internal combustion engine 2 and to drive the turning outer wheel. By increasing the brake hydraulic pressure PRL for the wheels, that is, the left driving wheel 22RL, and applying a braking force to the left driving wheel 22RL, a torque difference (driving force difference) in the opposite direction to the left and right driving wheels 22RL, 22RR is reduced. And the brake hydraulic pressure PFL for the driven wheel on the turning outer wheel side, that is, for the left driven wheel 22FL.
To reduce the lateral force of the driven wheel 22FL.

Next, when the driver stops steering and returns the steering angle to “0”, the target yaw acceleration becomes
It changes again in the + direction. When the target yaw acceleration changes in this way, it is determined that the vehicle is in the OS tendency until the actual yaw acceleration reaches “0”, and the control is continued, and the actual yaw acceleration becomes the target yaw acceleration. When the vehicle moves in the + direction (time t5), it is determined that the vehicle has a US tendency.

When it is determined that the vehicle has the US tendency, the throttle opening is set to be larger than the reference opening corresponding to the driver's accelerator operation in order to generate a yaw moment required for the vehicle. By increasing the output torque of the internal combustion engine 2, the brake oil pressure PRL is increased for the drive wheel on the turning inner wheel side, that is, the left drive wheel 22RL (in this case, the brake oil pressure PRL is increased for the left drive wheel 22RL). Is continued), and a braking force is applied to the left driving wheel 22RL to generate a torque difference (driving force difference) required for the left and right driving wheels 22RL and 22RR.

When the actual yaw acceleration of the vehicle reaches the target yaw acceleration by this control and the actual yaw acceleration becomes larger than the target yaw acceleration (time t6), it is determined that the vehicle has the OS tendency. In order to suppress the yaw moment generated in the vehicle, the throttle opening is opened larger than the reference opening corresponding to the driver's accelerator operation to increase the output torque of the internal combustion engine 2 and to drive the turning outer wheel. By increasing the brake hydraulic pressure PRR for the wheels, that is, the right driving wheel 22RR, and applying a braking force to the right driving wheel 22RR, a torque difference (driving force difference) in the opposite direction to the left and right driving wheels 22RL and 22RR is reduced. And a brake hydraulic pressure PFR for the driven wheel on the turning outer wheel side, that is, the right driven wheel 22FR.
To reduce the lateral force of the driven wheel 22FR.

Therefore, according to the vehicle behavior control device of this embodiment, even when the steering is steered leftward and rightward in order to change lanes or run on an S-shaped curve, the torque of the left and right drive wheels is increased. Like a conventional device that generates the yaw moment necessary for turning a vehicle only by the difference, the vehicle becomes unstable due to the steering operation after the turning moment is once applied to the vehicle, and the vehicle spins. However, it is possible to improve the stability while ensuring the steering performance of the vehicle.

That is, the left and right driving wheels 22 indicated by dotted lines in FIG.
The change of the brake oil pressure PRL, PRR with respect to RL, 22RR is
As in the conventional device, the left and right driving wheels 22RL and 22RR are adjusted so that the yaw rate of the vehicle becomes the target yaw rate corresponding to the steering angle.
In order to generate a torque difference between the driving wheels 22RL and 22RL,
This shows the change in hydraulic pressure when a braking force is applied to RR. As described above, even if the steering stability during vehicle turning is to be ensured only by the torque difference between the left and right drive wheels 22RL and 22RR, the left and right drive wheels cannot be used. When a turning moment is generated in the vehicle by the torque difference between 22RL and 22RR, it takes time to change the yaw motion of the vehicle in accordance with the subsequent steering operation, and during that time, the vehicle becomes extremely unstable,
The vehicle is easier to spin (see the conventional yaw rate change indicated by the dotted line in the figure).

On the other hand, in the present embodiment, the yaw moment required for turning is generated by the torque difference between the left and right driving wheels 22RL and 22RR and the braking force applied to one of the driven wheels. At the time of turning the vehicle, not only the steerability but also the stability can be ensured.

In particular, in the present embodiment, the target yaw rate is not controlled in accordance with the difference between the target yaw rate and the actual yaw rate, and the braking force applied to the driven wheels is not controlled. Since the torque difference between the left and right driving wheels and the braking force applied to the driven wheels are controlled based on the difference between the acceleration and the actual yaw acceleration (yaw acceleration deviation), the responsiveness of control after steering can be improved, and the steering performance is improved. And the stability can be further improved.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can take various aspects. For example, in the above embodiment, the present invention is applied to a front engine / rear drive (FR)
Although the present invention has been described for a case where the present invention is applied to a vehicle of a vehicle type (in other words, a rear-wheel drive vehicle), the present invention can be applied to a vehicle of a front engine / front drive (FF) system (in other words, a front wheel drive vehicle). The same effects as in the above embodiment can be obtained.

In the above embodiment, not only the driving force of the driving wheels (ie, the output torque of the internal combustion engine) is increased but also a torque difference is generated between the left and right driving wheels during turning of the vehicle. Although a description has been given of a case in which a braking force is applied to the drive wheels described above, such control of the torque difference is not performed for the drive wheels, and the drive force of the drive wheels may be simply increased according to the degree of turning of the vehicle. Good. Then, when the vehicle turns, the lateral force on the driving wheel side is increased to secure the stability of the vehicle, and the turning force (i.e., the steering characteristic) of the vehicle is increased by the braking force applied to one of the driven wheels. ) Can be improved, so that the steering performance and stability during turning of the vehicle can be improved as compared with the conventional device.

Further, in the above-described embodiment, only when the vehicle is in the OS tendency, the braking force is applied to the driven wheel on the turning outer wheel side to prevent the vehicle from easily spinning. , When the vehicle tends to US,
If the braking force is applied to the driven wheels on the turning inner wheel side, the steerability of the vehicle can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vehicle behavior control device according to an embodiment.

FIG. 2 is an explanatory diagram illustrating a configuration of a hydraulic circuit according to an embodiment.

FIG. 3 is a flowchart illustrating turning behavior control processing executed in a braking / driving force control circuit.

FIG. 4 is a flowchart showing a vehicle state estimating process executed in S120 of FIG.

FIG. 5 is an explanatory diagram for explaining a control operation (a) in the US and a control operation (b) in the OS by turning behavior control.

FIG. 6 is an explanatory diagram for explaining a change characteristic of braking / driving force with respect to a slip ratio λ of a driving wheel and a procedure for setting a target slip ratio of left and right driving wheels.

FIG. 7 shows the relationship between the shaft torque of the internal combustion engine and the engine output correction value △.
FIG. 9 is an explanatory diagram showing a map for obtaining a throttle opening required to increase by TEUP.

FIG. 8 is a flowchart showing a hydraulic control process executed for each wheel in S210 of FIG.

FIG. 9 is an explanatory diagram illustrating an example of an operation by turning behavior control.

[Explanation of symbols]

2: Internal combustion engine 10: Throttle drive motor 12
... throttle valve 14 ... accelerator opening sensor 16 ... throttle opening sensor 20 ... braking / driving force control circuit 26 ... internal combustion engine control circuit 30 ... engine speed sensor 32FR, 32FL ... driven wheel speed sensor 32RL, 32RR ... driving wheel speed Sensor 40: Yaw rate sensor 44: Steering angle sensor 50: Hydraulic circuit 51FL to 51RR: Wheel cylinders 54A, 54B
... three-way switching valves 56 to 59 ... pressure increasing control valves 61 to 64 ... pressure reducing control valves 67A, 67B, 71A, 71B ... pump 72A,
72B ... Pressure control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 29/02 311 F02D 29/02 311A 41/04 301 41/04 301G

Claims (6)

[Claims] 1. A braking force generating means for generating a wheel braking force by a brake fluid pressure action on each of front, rear, left and right wheels of a vehicle, and a braking fluid pressure for the braking force generating means of each wheel. A brake fluid pressure source, a driving force source for providing a driving force using one of the front left and right wheels and the rear left and right wheels as a driving wheel, and A driving force increasing means for increasing the magnitude of the driving force applied to the driving wheels by the driving force generating means; and a turning state of the vehicle and a target turning state according to the steering operation of the occupant during turning of the vehicle. The brake hydraulic pressure is applied to one of the braking force generating means provided on the left and right driven wheels that do not receive the driving force from the driving force generation source so that the actual turning state approaches the target turning state. Brake from source Vehicle behavior control apparatus characterized by comprising: a control means for applying pressure, the. 2. The under-steer control for applying brake fluid pressure to the turning inner wheel-side braking force of the driven wheel during under-steering, and the turning outer wheel-side braking force of the driven wheel during over-steering. The vehicle behavior control device according to claim 1, wherein at least one of oversteer control for applying brake fluid pressure to the vehicle is executed. 3. The control means also applies a brake fluid pressure from the brake fluid pressure source to one of the braking force generating means provided on the left and right drive wheels, and controls the right and left by the brake fluid pressure. The actual turning state is made closer to the target turning state by a movement of the driving force between the left and right driving wheels due to a braking force generated on one of the driving wheels and a braking force generated on one of the left and right driven wheels. Claim 1 or Claim 2
The vehicle behavior control device according to claim 1. 4. The control means applies brake fluid pressure to braking force generating means on the turning inner wheel side of the drive wheel during understeering, and applies brake fluid pressure to braking force generating means on the turning outer wheel side of the drive wheel during oversteering. The vehicle behavior control device according to claim 3, wherein the vehicle behavior control device is added. 5. The vehicle control system according to claim 1, wherein the control means determines a brake fluid pressure applied to the braking force generating means so as to cancel a vehicle propulsion force generated by an increase in driving force by the driving force increasing means. The vehicle behavior control device according to any one of claims 1 to 4. 6. The control means calculates a required yaw moment required to control the actual turning state of the vehicle to the target turning state, and based on the required yaw moment, calculates the required driving force by the driving force increasing means. The vehicle behavior control device according to claim 5, wherein the amount of increase is determined, and the brake fluid pressure applied to the braking force generating means is determined.