JP3248397B2 - Vehicle behavior control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a behavior control device for suppressing and reducing undesired behaviors such as drift-out and spin during turning of a vehicle such as an automobile.

[0002]

2. Description of the Related Art As one of devices for controlling the behavior of a vehicle such as an automobile at the time of turning, for example, Japanese Unexamined Patent Publication No. Hei.
As disclosed in Japanese Patent Publication No. 56-56, a target yaw rate change speed is obtained from a steering amount change speed and a vehicle speed, and braking is performed on inner and outer wheels of the turning so that the detected yaw rate change speed matches the target yaw rate change speed. A known behavior control device is conventionally known.

According to such a behavior control device, the actual yaw rate change speed surely coincides with the target yaw rate change speed in any driving operation state, so that the yaw rate generation delay peculiar to the vehicle is eliminated, and the yaw rate is reduced. It is possible to eliminate a sense of discomfort caused by the delay in occurrence of, and to drive the vehicle at high speed without a sense of instability even on a mountainous road with continuous corners.

[0004]

Generally, the effect of the behavior control by controlling the braking force differs depending on the running state of the vehicle.
For example, when the driver counter-steers while the vehicle is in the oversteer state, the yaw moment (anti-spin moment) generated by applying the braking force to the front wheel on the outside of the turn is smaller than when the steering is not in the countersteer state. And the amount of decrease in the yaw moment increases as the steering angle of the counter steer increases. When the vehicle is in the understeer state, the understeer state can be reduced by not only giving the turning assist yaw moment to the vehicle but also decelerating the vehicle.

However, in the conventional behavior control device described in the above-mentioned publication, the effect of the behavior control by controlling the braking force is not taken into consideration as described above, which differs depending on the running state of the vehicle. There is a problem that an optimum behavior control effect cannot be exerted according to the running state of the vehicle, and thus the behavior cannot necessarily be controlled effectively and efficiently.

The present invention has been made in view of the above-mentioned problems in the conventional behavior control device, and a main object of the present invention is to obtain an optimal behavior control effect according to the running state of a vehicle. By controlling the braking force of each wheel so that
The purpose is to effectively and efficiently control the behavior of a vehicle.

[0007]

SUMMARY OF THE INVENTION According to the present invention, there are provided a main detecting means for detecting an oversteer state of a vehicle, and a braking force applied to at least a front wheel on the outer side of turning when the oversteer state of the vehicle is detected. Automatic braking means for applying, means for detecting a counter-steering state, and counter-steering when the counter-steering state is detected, the braking force applied to the wheels by the automatic braking means.
A vehicle behavior control device (means of claim 1) having means for increasing and increasing so as to increase as the degree of the vehicle increases ; means for detecting an oversteer state of the vehicle; Automatic braking means for applying a braking force to the front wheels, steering angle detecting means, and a large countersteer in which a yaw moment in a direction opposite to the turning direction of the vehicle is not generated even when a braking force is applied to the front outside wheel based on the steering angle. Means for determining whether or not the vehicle is in a state, and means for stopping application of the braking force by the automatic braking means when the large counter steer state is determined or applying the maximum braking force to all wheels by the automatic braking means. A vehicle behavior control device (configuration of claim 2) having:
A means for detecting an understeer state of the vehicle, an automatic brake means for applying a braking force to the wheels when the understeer state of the vehicle is detected, and the generation of a turning assist yaw moment rather than a deceleration at the start of operation of the automatic brake means. A braking force distribution control means for setting a priority braking force distribution, and a braking force distribution control means for prioritizing deceleration over turning assist yaw moment as time elapses from the start of the operation of the automatic braking means. The structure of claim 4) is achieved.

Further, according to the present invention, in order to effectively achieve the above-mentioned main problem, the means for controlling the driving force of the front wheels and the large counter steer state are determined. Thus, when the application of the braking force by the automatic braking means is stopped, a means for increasing the driving force of the front wheels is provided (the configuration of claim 3).

[0009]

When the vehicle is in an over-steering state, an anti-spin moment, that is, a yaw moment in the direction opposite to the turning direction is given to the vehicle by applying a braking force to the front wheel on the outside of the turning to reduce the over-steering state of the vehicle. be able to. However, when the driver performs counter-steering, the anti-spin moment becomes smaller than when counter-steering is not performed even if the braking force applied to the turning outer front wheel is the same.

[0010] For example, FIG. 14 (A) shows the situation where the counter steer is performed when the behavior of the vehicle turning left is oversteer, as shown the front outside wheel der
The braking force of the right front wheel is F and the steering angle of the countersteer is θ.
Assuming that the tread of the left and right front wheels is Tr, and the distance between the axles of the left and right front wheels and the center of gravity O of the vehicle is Lf, the yaw moment (anti-spin moment) M given to the vehicle by the braking force F is It is represented by Equation 1. As can be seen from Equation 1, the yaw moment M gradually decreases as the steering angle θ of the counter steer increases.

M = F ｛(Tr / 2) * cos θ−Lf * sin θ｝

According to the first aspect of the present invention, when an oversteer state of the vehicle is detected, a braking force is applied to at least the turning outer front wheel by the automatic brake means. In particular, when the countersteer state is detected, the automatic brake means is provided. The braking force applied to the wheels by the counter steer
The higher the degree, the higher the anti-spin moment is generated to control the behavior of the oversteer state, thereby effectively and efficiently reducing the oversteer state of the vehicle.

As can be seen from Equation 1, when the steering angle θ of the counter steer becomes a predetermined value, that is, when the direction of the braking force F of the turning outer front wheel passes through the center of gravity O of the vehicle, the yaw moment M becomes zero. In particular, as shown in FIG. 14B, the direction of the braking force F of the turning outer front wheel is determined by the center of gravity O of the vehicle.
When the steering angle of the counter steer becomes larger as the vehicle passes the front side of the vehicle, the yaw moment M becomes a negative value, and the vehicle is given a yaw moment in a direction that promotes turning by the braking force F. But rather increases.

According to the second aspect of the present invention, when a large counter steer state in which no yaw moment is generated in the opposite direction to the turning direction of the vehicle even when a braking force is applied to the turning outer front wheels, the automatic steering is determined. Since the application of the braking force by the braking means is stopped, the braking force is applied to the front wheels on the outside of the turning to reliably prevent the generation of a yaw moment in a direction to promote the oversteer state of the vehicle, or the automatic braking means prevents Since the maximum braking force is applied to the wheels,
The vehicle can be stopped as quickly as possible while avoiding generation of a large yaw moment in a direction that promotes the oversteer state.

According to the third aspect of the invention, when the application of the braking force by the automatic braking means is stopped due to the determination of the large counter steer state, the driving force of the front wheels is increased. The braking force is applied to the turning outer front wheel, and the yaw moment in the direction that promotes the oversteer state of the vehicle is reliably prevented from being generated, and the anti-spin moment is generated by the driving force of the front wheel,
As a result, the oversteer state of the vehicle is effectively suppressed as compared with the case where the application of the braking force by the automatic braking means is simply stopped.

In order to reduce the understeer state of the vehicle, both giving a turning assist yaw moment to the vehicle and decelerating the vehicle are effective. However, in the former case, the vehicle may be oversteered. The latter may promote an understeer state at the beginning of the behavior control.

According to the fourth aspect of the present invention, when the understeer state of the vehicle is detected, the braking force is applied to the wheels by the automatic braking means. By setting the braking force distribution to give priority to the generation of the moment, the turning performance of the vehicle is first improved, and the braking force distribution giving priority to the deceleration over the turning assist yaw moment over time from the start of the operation of the automatic brake means. As a result, the understeer state is reduced by deceleration, so that the understeer state of the vehicle is effectively and without the understeer state being promoted at the beginning of the behavior control or the vehicle being oversteered at the latter half of the behavior control. Controlled efficiently.

[0017]

According to one preferred embodiment of the present invention, the means for detecting an oversteer state of the vehicle according to the first to third aspects is such that the behavior of the vehicle is based on a physical quantity representing the skid of the vehicle. The means for detecting the understeer state of the vehicle is configured to determine whether the behavior of the vehicle is in the understeer state based on a physical quantity representing the yaw rate of the vehicle. You.

According to another preferred embodiment of the present invention, the means for determining whether or not the vehicle is in a large counter steer state in the configuration of claim 2 is characterized in that the means for determining whether or not the braking force of the front wheels on the outer side of the turning is lateral to the vehicle. A determination is made based on the steering angle as to whether or not the yaw moment in the turning direction due to the direction component is equal to or greater than the yaw moment in the direction opposite to the turning direction due to the component in the vehicle front-rear direction of the braking force of the turning outer front wheel.

According to another preferred embodiment of the present invention, the means for applying the maximum braking force to all the wheels by the automatic brake means in the structure of the second aspect is the coefficient of friction of the road surface and the Each wheel is configured to apply the maximum braking force that can be generated according to the load.

According to another preferred embodiment of the present invention, in the structure of the fourth aspect, the braking force distribution which gives priority to the generation of the turning assist yaw moment over the deceleration reduces the deceleration more than the turning assist yaw moment. The change of the braking force distribution to the priority braking force distribution includes: (1) decreasing the braking force distribution of the turning inner front wheel and increasing the braking force distribution of the turning outer front wheel; and (2) braking force distribution of the rear wheel side. And (3) a combination of (1) and (2) described above.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 1 is a schematic configuration diagram showing a braking device of a first embodiment of a behavior control device according to the present invention together with an electric control device.

In FIG. 1, a braking device 10 has a master cylinder 14 for pumping brake oil from first and second ports in response to a driver's depressing operation of a brake pedal 12, and a first port. Is connected to brake hydraulic control devices 18 and 20 for the front left and right wheels by a brake hydraulic control conduit 16 for the front wheels, and the second port is connected to the rear left and right wheels by a brake hydraulic control conduit 24 for the rear wheels having a proportional valve 22 in the middle. Brake hydraulic control devices 26 and 28. Further, the braking device 10 pumps up the brake oil stored in the reservoir 30 and supplies it to the high-pressure conduit 32 as high-pressure oil.
Four. The high-pressure conduit 32 is connected to each of the brake hydraulic control devices 18, 20, 26, 28, and an accumulator 36 is connected in the middle thereof.

Each of the brake hydraulic control devices 18, 20, 2
6, 28 are wheel cylinders 38FL, 38FR, 38RL, 38RR for controlling the braking force on the corresponding wheels, respectively.
And a 3-port 2-position switching type electromagnetic control valve 40FL,
The normally open electromagnetic on-off valves 44FL, 44FR, 44RL, 44RR provided between the 40FR, 40RL, 40RR and the low pressure conduit 42 and the high pressure conduit 32 connected to the reservoir 30 and the normally closed electromagnetic valve On-off valves 46FL, 46FR, 46RL, 46
RR. On-off valves 44FL, 44FR, 4 respectively
4RL, 44RR and open / close valve 46FL, 46FR, 46RL, 46RR
High-pressure conduit 32 between the connection conduits 48FL, 48FR, 48
Control valve 40FL, 40FR, 40RL, 40 by RL, 48RR
Connected to RR.

The control valves 40FL and 40FR are respectively a brake hydraulic control conduit 16 for the front wheels and a wheel cylinder 38FL.
And 38FR and wheel cylinder 38FL
, 38FR and the connection conduits 48FL and 48FR, the first position shown in the figure, the brake hydraulic control conduit 16 and the wheel cylinders 38FL and 38FR, and the wheel cylinders 38FL and 38FR and the connection conduit 48FL.
, And a second position for communicating and connecting with the 48FR. Similarly, 40RL and 40RR are respectively a brake hydraulic control conduit 24 for the rear wheel and a wheel cylinder 3
8RL and 38RR, and wheel cylinder 3
8RL and 38RR and the first position shown to cut off the communication between the connecting conduits 48RL and 48RR, and the brake hydraulic control conduit 2
4 to cut off the communication between the wheel cylinders 38RL and 38RR and connect the wheel cylinders 38RL and 38RR to the connecting conduit 4.
The position is switched to a second position for communicating and connecting 8RL and 48RR.

When the control valves 40FL, 40FR, 40RL, 40RR are in the second position, the on-off valves 44FL, 44FR,
44RL, 44RR and on-off valves 46FL, 46FR, 46RL, 4
When 6RR is controlled to the state shown in FIG.
8FL, 38FR, 38RL, 38RR are control valves 40FL, 40F
R, 40RL, 40RR and connecting conduit 48FL, 48FR, 48R
L and 48RR are connected to the high-pressure conduit 32 to increase the pressure in the wheel cylinder. Conversely, when the control valve is in the second position, the on-off valve 44FL,
4FR, 44RL, 44RR are closed and on-off valves 46FL, 46F
When R, 46RL, 46RR is opened, the wheel cylinder is connected in communication with the low pressure conduit 42 via the control valve and the connecting conduit, thereby reducing the pressure in the wheel cylinder. Further, when the control valve is in the second position, the on-off valves 44FL, 44FR, 44RL, 44RR and the on-off valves 46FL,
When the valves 6FR, 46RL, and 46RR are closed, the wheel cylinder is disconnected from both the high-pressure conduit 32 and the low-pressure conduit 42, so that the pressure in the wheel cylinder is maintained.

Thus, the braking device 10 includes the control valve 40FL,
When the 40FR, 40RL, 40RR is in the first position, the wheel cylinders 38FL, 38FR, 38RL, 38RR generate a braking force according to the amount of depression of the brake pedal 12 by the driver, and the control valves 40FL, 40FR, 40RL, 40RR.
When any of RR is in the second position, the on-off valves 44FL, 44FR, 44RL, 44RR and on-off valves 46FL,
By controlling the opening and closing of the wheels 46FR, 46RL and 46RR, the braking force of the wheel can be controlled irrespective of the amount of depression of the brake pedal 12 and the braking force of the other wheels.

Control valves 40FL, 40FR, 40RL, 40RR,
On-off valves 44FL, 44FR, 44RL, 44RR and on-off valves 46
FL, 46FR, 46RL, 46RR are controlled by an electric control device 50 as described in detail later. The electric control device 50 includes a microcomputer 52 and a drive circuit 54.
Although not shown in detail in FIG. 1, for example, it has a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output port device. May be of a general configuration connected to each other.

A signal indicating the vehicle speed V from the vehicle speed sensor 56, a signal indicating the lateral acceleration Gy of the vehicle from a lateral acceleration sensor 58 provided substantially at the center of gravity of the vehicle, and a yaw rate sensor 60 A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θ from the steering angle sensor 62, the wheel speed sensors 64FL, 64FR, 6
Wheel speed VFL, VFR, V of the corresponding wheel from 4RL, 64RR
Signals indicating RL and VRR are input. The lateral acceleration sensor 58 and the like detect lateral acceleration and the like with the left turning direction of the vehicle as positive.

The ROM of the microcomputer 52 stores a map corresponding to the control flow shown in FIG. 2 and the graph shown in FIG. 3 as described later, and the CPU executes the processing based on the parameters detected by the various sensors described above. Various calculations are performed as described below to determine whether or not the behavior of the vehicle is in an oversteer state, and whether or not the steering state is in a countersteer state. The target braking force is calculated, and the braking force of each wheel is controlled based on the calculation result to stabilize the turning behavior of the vehicle.

Next, the outline of the turning behavior control of the vehicle according to the first embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 2 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 10, the vehicle speed sensor 5
6, a signal indicating the vehicle speed V detected is read, and in step 20, the deviation Gy of the lateral acceleration Gy and the product V * γ of the vehicle speed V and the yaw rate γ is calculated as Gy−V * γ. That is, the lateral slip acceleration Vyd of the vehicle is calculated, and the deviation Vyd of the lateral acceleration is integrated to calculate the lateral slip speed Vy of the vehicle, and the longitudinal speed Vx of the vehicle is calculated.
(= Vehicle speed V) The ratio Vy of the side slip speed Vy of the vehicle body
The slip angle β of the vehicle body is calculated as / Vx. Further, a slip angular velocity βd of the vehicle body is calculated as a differential value of the slip angle β of the vehicle body.

In step 30, the linear sum a * β + b * βd (spin state quantity) of the slip angle β and the slip angular velocity βd of the vehicle body is calculated using a and b as positive constants, respectively. Is the reference value βc
(Positive constant) is determined, that is, it is determined whether the vehicle is in a spin state. If a negative determination is made, the process proceeds to step 140. If an affirmative determination is made, the process proceeds to step 140. Proceed to 40.

In step 40, for example, the lateral acceleration G
Whether the vehicle is turning left is determined by determining whether y or the yaw rate γ is positive. If the determination is affirmative, the coefficient S is set to 1 in step 50. When the negative determination is made, the coefficient S is set to -1 in step 60. In step 70, it is determined whether or not the product of the coefficient S and the steering angle θ is positive,
That is, it is determined whether or not the steering is in the steer state in the turning direction. When the determination is affirmative, the coefficient K is set to 1 in step 80.

When a negative determination is made in step 70, that is, when it is determined that the steering is in the counter steer state, in step 90, the absolute value θa of the steering angle θ is set to the reference value θc for determining the large counter steer state. It is determined whether or not the number has exceeded the threshold value.
Proceeding to 40, if a negative determination is made, step 10
At 0, the correction coefficient K is set according to the following equation (2). The determination of the large counter steer state in step 70 is made by determining whether the right side of the above equation (1) is negative, in other words, by determining whether tan θa> Tr / (2Lf). You may.

K = 1 / (cosθa− (2Lf / Tr) sinθa)

In step 110, the spin state quantity a
Based on the absolute value of * β + b * βd, a target slip ratio Rs is calculated from a map corresponding to the graph shown in FIG.
In step 120, the corrected target slip ratio Rsa
Is calculated as Rs * K, and in step 130, the braking force of the front outside wheel is controlled based on the corrected target slip ratio Rsa.

For example, the target wheel speed Vwt of the outside front wheel is calculated according to the following equation (3) using Vin as the wheel speed of the inside front wheel, and the duty ratio Dr is calculated according to the following equation (4). In the following equation (4), Vout is the wheel speed of the front wheel on the outside of the turn, and Kp and Kd are proportional constants of a proportional term and a differential term in the wheel speed feedback control.

[0038]

## EQU3 ## Vwt = (1-Rsa) * Vin

## EQU4 ## Dr = Kp * (Vout-Vwt) + Kd * d (V
out-Vwt) / dt

Further, in step 130, a control signal is output to the control valve 40FL or 40FR of the turning outer front wheel to switch the control valve to the second position, and the opening and closing of the turning outer front wheel is also performed. By outputting a control signal corresponding to the duty ratio Dr to the valve, the supply and discharge of the accumulator pressure to and from the wheel cylinder 38FL or 38FR of the turning outer front wheel is controlled, thereby controlling the braking pressure of the turning outer front wheel.

In this case, when the duty ratio Dr is a value between the negative reference value and the positive reference value, the upstream side open / close valve of the turning outer front wheel is switched to the second position and the downstream side open / close valve is set. Is held in the first position, the pressure in the corresponding wheel cylinder is held, and when the duty ratio is equal to or higher than the positive reference value, the on-off valves on the upstream and downstream sides of the turning outer front wheel are shown in FIG. The accumulator pressure is supplied to the corresponding wheel cylinder by controlling the position of the wheel cylinder, and the pressure in the wheel cylinder is increased. When the duty ratio is equal to or less than the negative reference value, the upstream of the turning outer front wheel is provided. When the open / close valves on the downstream and upstream sides are switched to the second position, the brake oil in the corresponding wheel cylinder is discharged to the low-pressure conduit 42, and Pressure eel in the cylinder is reduced.

In step 140, the application of the braking force to the front wheel on the outside of the turn is stopped, thereby terminating the behavior control. In this case, the corrected target slip ratio Rsa is 0.
If not, Rsa
Is gradually reduced to zero, whereby the braking force is gradually reduced.

Thus, in the first embodiment, the slip angle β and the slip angular velocity βd of the vehicle body are calculated in step 20, and it is determined in step 30 whether or not the vehicle is in a spin state based on these. When the behavior control is being performed when the vehicle is not in the spin state and the behavior control is terminated in step 140, the process returns to step 10. Therefore, in this case, steps 40 to 130
Is not executed, whereby the braking pressure of each wheel is controlled in accordance with the master cylinder pressure, that is, the amount of depression of the brake pedal 12.

On the other hand, when the vehicle enters the spin state, an affirmative determination is made in step 30 and
At 70, it is determined whether or not the steering is in a counter steer state. When the steering is in the counter steer state, the degree of the counter steer is high in step 100.
The correction coefficient K is calculated so as to become larger as
In step 20, the target slip ratio Rs is increased and corrected by the correction coefficient K, whereby the spin state of the vehicle is effectively and efficiently controlled even when the steering is in the countersteer state.

Further, when the vehicle is in the spin state and the driver performs steering in the large counter steer state, step 3 is executed.
When a positive determination is made at 0, a negative determination is made at step 70, an affirmative determination is made at step 90, and the behavior control is terminated at step 140. Is stopped, whereby the yaw moment in the turning assist direction caused by applying the braking force to the turning outer front wheel is reliably prevented from being applied to the vehicle.

FIG. 4 is a flowchart showing a behavior control routine according to the second embodiment. In FIG. 4, steps corresponding to the steps shown in FIG. 2 are given the same step numbers as those given in FIG.

In this embodiment, when it is determined in step 30 that the vehicle is not in the spin state, the routine proceeds to step 140, where the behavior control is terminated. That is, when it is determined that the steering state is in the large counter steer state, the maximum braking force is applied to the four wheels in step 150 to fully brake the four wheels. In this case, the friction coefficient μ of the road surface is calculated, for example, as the absolute value of the lateral acceleration Gy of the vehicle, or Gy ² + G, where the longitudinal acceleration of the vehicle is Gx.
is calculated as the square root of x ^2, also for example, calculating the load of each wheel from the lateral acceleration Gy and the longitudinal acceleration Gy of the vehicle, calculates the maximum braking force which each wheel may occur based on these, each wheel cylinder Is preferably controlled according to the maximum braking force thus calculated.

Thus, according to the second embodiment, when the driver performs steering in the large counter steer state in a situation where the vehicle is in the spin state, an affirmative determination is made in step 30 and a positive determination is made in step 70. A negative determination is made in step 90, and an affirmative determination is made in step 90, and the four wheels are fully braked in step 140. A yaw moment in the assisting direction is reliably prevented from being applied to the vehicle, and the vehicle is stopped as quickly as possible.

FIG. 5 is a schematic structural diagram showing a third embodiment of the behavior control device according to the present invention applied to a front wheel drive vehicle, and FIG.
FIG. 6 is a schematic configuration diagram showing the braking device of the embodiment shown in FIG. 5 together with an electric control device.

In FIG. 5, 2FL, 2FR, 2RL and 2RR denote left and right front wheels and right and left rear wheels, respectively. The braking force of these wheels is controlled by the hydraulic circuit 3 of the braking device 10 to control the wheel cylinders 38FL, 38FR, The control is performed by controlling the braking pressures of 38RL and 38RR.
As will be described later in detail, the hydraulic circuit 3 controls the braking pressure of the wheel cylinders 38FL, 38FR, 38RL, 38RR in response to the depression operation of the brake pedal 12 or by being controlled by the microcomputer 52 of the electric control device 50. I do.

Left and right front wheels 2FL which are both steering wheels and driving wheels
And 2FR are steered according to the rotation of a steering wheel not shown in the figure, and are driven by transmitting the output of the engine 4 to the drive shafts 6FL and 6FR via the transmission 5. The output of the engine 4 is controlled by controlling the throttle actuator 9 for driving the throttle valve 8 by the microcomputer 52 in accordance with the amount of depression of the accelerator pedal 7, thereby controlling the driving force of the left and right front wheels 2FL and 2FR. .

As shown in detail in FIG. 6, the braking device 10 is the same as the braking device in the first and second embodiments, but the microcomputer 52 of the electric control device 50 of this embodiment. A signal indicating the depression amount Accp of the accelerator pedal 7 is also input from the accelerator pedal sensor 66 to the input / output port device. Further, the ROM of the microcomputer 52 stores maps corresponding to the control flows of FIGS. 7 and 8 and the graph of FIG. 9 as described later, and the CPU performs the following based on the parameters detected by the various sensors described above. Perform various calculations to determine whether the behavior of the vehicle is in an oversteer state, and determine whether the steering state is a countersteer state,
Calculate the target braking force of each wheel according to the results of these determinations,
The turning behavior of the vehicle is stabilized by controlling the braking force of each wheel based on the calculation result and controlling the driving force of the left and right front wheels as necessary.

Next, the outline of the turning behavior control of the vehicle according to the third embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 7 is also started by closing an ignition switch (not shown), and is repeatedly executed at predetermined time intervals. Also, in FIG. 7, steps corresponding to the steps shown in FIG. 2 are given the same step numbers as those given in FIG.

In step 80 of this embodiment, the correction coefficient K is set to 1 and the throttle opening correction value Ts is set to 0, and in step 100, the correction coefficient K is set to And the correction value Ts of the throttle opening is set to zero. Step 14
At 0, the behavior control is terminated by stopping the application of the braking force to the turning outside front wheel, the corrected target slip ratio Rsa is gradually reduced to 0, and the throttle opening correction value Ts is set to 0. Is set to

Further, when an affirmative determination is made in step 90, that is, when it is determined that the steering is in the large counter steer state, the application of the braking force to the front wheel outside the turning is terminated in step 160, and in step 170 The correction value Ts of the throttle opening is set to the product of the absolute value of the spin state quantity a * β + * βd and the coefficient Ks using Ks as a positive constant.

Next, the outline of the throttle opening control in the third embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 8 is executed by interruption every predetermined time.

First, at step 210, a signal indicating the depression amount Accp of the accelerator pedal 7 detected by the accelerator pedal sensor 66 is read. At step 220, the signal is shown in FIG. 9 based on the depression amount Accp. Throttle opening Top from the map corresponding to the graph
Is calculated.

In step 230, step 220
The corrected throttle opening Top is calculated as the sum of the throttle opening Top calculated in step S1 and the correction value Ts of the throttle opening calculated by the behavior control routine shown in FIG. Then, the control signal is output to the throttle actuator 9 so that the opening of the throttle valve 8 is controlled to the corrected throttle opening Topa.

Thus, according to the third embodiment, when the driver performs the steering in the large counter steer state while the vehicle is in the spin state, an affirmative determination is made in step 30 and a positive determination is made in step 30. A negative determination is made in 70, an affirmative determination is made in step 90, and the application of the braking force to the turning outside front wheel is stopped in step 160, whereby the braking force is applied to the turning outside front wheel. It is reliably prevented that the yaw moment in the turning promotion direction caused by the application is given to the vehicle, and the correction value Ts of the throttle opening is set to the absolute value of the spin state amount a * β + * βd in step 170. The throttle opening is increased by the correction value Ts in step 230 of FIG. 8, and the drive of the left and right front wheels in the large counter steer state is set. Force is increased, the spin state of the vehicle is effectively and efficiently controlled even when Thereby steering is in large counter steer state.

FIG. 10 is a schematic configuration diagram showing a braking device according to a fourth embodiment of the behavior control device according to the present invention, which is configured to suppress drift-out, together with an electric control device.

As shown in detail in FIG. 10, the braking device 10 is the same as the braking device in the first to third embodiments, but the microcomputer 52 of the electric control device 50 of this embodiment. A signal indicating the lateral acceleration Gy of the vehicle body is not input to the input / output port device, and a signal indicating the master cylinder pressure Pm is input from the pressure sensor 68. The ROM of the microcomputer 52 stores the control flow of FIG. 11 and the maps corresponding to the graphs of FIGS. 12 and 13 as described later, and the CPU performs the following based on the parameters detected by the various sensors described above. Various calculations are performed to determine whether or not the behavior of the vehicle is in an understeer state, the target braking force of each wheel is calculated according to the determination result, and the braking force of each wheel is controlled based on the calculation result. This stabilizes the turning behavior of the vehicle.

Next, the outline of the turning behavior control of the vehicle according to the fourth embodiment will be described with reference to the flowchart shown in FIG. The control according to the flowchart shown in FIG. 11 is also started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

In step 310 of this embodiment, a signal indicating the vehicle speed V detected by the vehicle speed sensor 56 is read. In step 320, Kh is used as a stability factor, and L is used as a wheel base. The reference yaw rate γc is calculated according to the following equation 5, and
Using T as a time constant and s as a Laplace operator, the target yaw rate γt is calculated according to the following equation (6).

[0063]

Γ c = V * θ * (1 + Kh * V ² ) * L

Γt = γc / (1 + T * s)

In step 330, the yaw rate deviation Δγ, that is, the difference | γt | − | γ | between the absolute value of the target yaw rate γt and the absolute value of the actual yaw rate γ of the vehicle is calculated, and in step 340, the yaw rate deviation It is determined whether or not the deviation Δγ exceeds the reference value γc (positive constant), that is, whether or not the vehicle is in a drift-out state. When the determination is made, the process proceeds to step 350.

In step 350, the total braking force Ft is calculated from the map corresponding to the graph shown in FIG. 12 based on the yaw rate deviation Δγ, and in step 360, the braking force distribution for the inner wheel is calculated according to the following equation (7). Wi is calculated, and in step 370, the braking force distribution Wr for the rear wheels is calculated from the map corresponding to the graph shown in FIG. 13 based on the braking force distribution Wi for the inner wheels.

## EQU7 ## Wi = (Tct-Tc) / Tct

In step 380, the target braking force Fj (j = fo (turning front outside wheel) of the four wheels) is calculated according to the following equation (8).
fi (turn inside front wheel), ro (turn outside rear wheel), ri (turn inside rear wheel) are calculated.

Ffo = Ft * (1-Wi) * (1-Wr) Ffi = Ft * Wi * (1-Wr) Fro = Ft * (1-Wi) * Wr Fri = Ft * Wi * Wr

In step 390, the pressure sensor 68
The braking pressure Pi of the wheel cylinder 38i (i = FL, FR, RL, RR) of each wheel is estimated based on the master cylinder pressure Pm detected by the above and the control signal supplied to the opening / closing valve of each wheel. Based on the calculated target braking force of each wheel, the target braking pressure Pti of the wheel cylinder 38i of each wheel is calculated from a map not shown in the drawing, and the duty ratio Dri is calculated according to the following equation (9). You.
In the following equation 9, Kpp and Kpd are proportional constants of the proportional term and the differential term in the feedback control of the braking pressure.

Dri = Kpp * (Pi-Pti) + Kpd * d (Pi
−Pti) / dt

In step 390, a control signal is output to the control valve 40i of the wheel whose braking pressure is to be increased or decreased, so that the control valve is switched to the second position and the wheel is set to the second position. The control signal corresponding to the duty ratio Dri is output to the opening / closing valve of the turning outer wheel to control the supply / discharge of the accumulator pressure to / from the wheel cylinder 38i. Is controlled.

In step 400, the count value Tc of the timer is incremented by ΔT, and in step 440
In this case, it is determined whether or not the count value Tc exceeds the positive reference value Tct. If a negative determination is made, the process returns to step 310; When the target braking force Fj of the wheel is gradually reduced to zero, the behavior control is terminated, and the count value Tc is set to zero.

Thus, in the fourth embodiment, the yaw rate deviation Δγ is calculated in steps 320 and 330, and in step 340, it is determined whether or not the vehicle is in a drift-out state based on the yaw rate deviation Δγ. Is performed, and in step 350, the total braking force Ft is calculated in accordance with the yaw rate deviation Δγ, and in steps 360 and 3
At 70, the braking force distribution Wi of the inner wheel and the braking force distribution Wr of the rear wheel are calculated, and at step 380, the target braking force Fj of each wheel is calculated according to these distributions.
In step 390, the braking force of each wheel is set to the target braking force Fj.
Is controlled to be.

In particular, in the initial stage of the behavior control for the drift-out, the braking force distribution Wi for the inner wheels and the braking force distribution Wr for the rear wheels.
Is set high, a yaw moment in the turning direction due to the braking force of the inner wheel and a yaw moment in the turning direction due to a decrease in the lateral force of the rear wheel are generated, whereby the drift-out state can be reduced with good responsiveness. Also, in the latter half of the behavior control, the braking force distribution Wi for the inner wheels and the braking force distribution Wr for the rear wheels are set low, so that the oversteer state (spin state) due to excessive yaw moment is reliably prevented. The drift-out state can be appropriately reduced by decelerating the vehicle while driving.

Further, if the vehicle is not actually in the drift-out state, a negative determination is made in step 340, and therefore, the process returns to step 310 without executing steps 350 to 410, thereby braking each wheel. The pressure is controlled in accordance with the master cylinder pressure, that is, the amount of depression of the brake pedal 12.

In particular, according to the illustrated embodiment, the braking force distribution Wi for the inner wheels and the braking force distribution Wr for the rear wheels are gradually reduced with the passage of time. For example, the braking force is applied to the inner wheels at the beginning of the behavior control. In the latter half of the behavior control, unnatural changes in the behavior of the vehicle during behavior control are reliably prevented compared to when the braking force of the turning inner and outer wheels is controlled so that the braking force is applied to the outer wheel can do.

In the illustrated embodiment, both the braking force distribution Wi for the inner wheels and the braking force distribution Wr for the rear wheels are gradually reduced with the passage of time. Only the power distribution may be gradually changed, and the braking force of the left and right front wheels may be controlled such that the braking force is applied to the inner wheel at the beginning of the behavior control and the braking force is applied to the outer wheel in the latter half of the behavior control. Good.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the above-described first to third embodiments, whether or not the behavior of the vehicle is in the oversteer state is determined by determining the absolute value of the linear sum of the slip angle β and the slip angular velocity βd of the vehicle body. Although the determination is made based on whether or not the reference value is exceeded, whether or not the behavior of the vehicle is in the oversteer state may be determined based on an arbitrary state quantity indicating the oversteer state.

In the first to third embodiments, the braking force is applied only to the turning outer front wheel when the vehicle is in the spin state. However, the turning inner front wheel is also applied to the turning inner front wheel. A braking force may be applied, and an anti-spin moment may be applied to the vehicle by a difference between the braking force of the inner wheel and the braking force of the outer wheel.

In the fourth embodiment, the wheel cylinders 38i (i) of each wheel are based on the master cylinder pressure Pm detected by the pressure sensor 68 and the control signal supplied to the opening / closing valve of each wheel. = FL, FR, RL, RR) is estimated, and the target braking pressure Pti of the wheel cylinder of each wheel is estimated based on the target braking force of each wheel calculated according to Equation 8.
Is calculated, and the braking pressure of each wheel is controlled by the pressure feedback control. However, the braking pressure Pi of the wheel cylinder of each wheel may be detected by a pressure sensor. The ground vehicle speed may be detected by the ground vehicle speed sensor, the target slip ratio of each wheel may be calculated based on the ground vehicle speed, and the braking pressure of each wheel may be controlled based on the target slip ratio.

[0079]

As is apparent from the above description, according to the first aspect of the present invention, when an oversteer state of the vehicle is detected, a braking force is applied to at least the outer front wheel by the automatic braking means, In particular, when the counter-steering state is detected, the braking force applied to the wheels by the automatic braking means increases as the counter-steering degree increases.
Since the correction is made so as to become higher, an optimum anti-spin moment for controlling the behavior of the oversteer state is generated, whereby the oversteer state of the vehicle can be effectively and efficiently reduced.

According to the second aspect of the present invention, when it is determined that a large counter steer state in which no yaw moment is generated in a direction opposite to the turning direction of the vehicle even when a braking force is applied to the front wheels outside the turning direction, the automatic braking is performed. Since the application of the braking force by the means is stopped, it is possible to reliably prevent the generation of a yaw moment in a direction that promotes the oversteer state of the vehicle by applying the braking force to the turning outer front wheel, or Since the maximum braking force is applied to all the wheels by the automatic braking means, the vehicle can be stopped as quickly as possible while avoiding generation of a large yaw moment in a direction that promotes the oversteer state.

According to the third aspect of the present invention, when the application of the braking force by the automatic braking means is stopped due to the determination of the large counter steer state, the driving force of the front wheels is increased. By applying a braking force to the front wheels, it is possible to reliably prevent the generation of a yaw moment in a direction that promotes the oversteer state of the vehicle, and by applying a driving force to the front wheels in the large countersteer state. An anti-spin moment is generated, whereby the oversteer state of the vehicle can be effectively suppressed as compared with a case where the application of the braking force by the automatic braking means is simply stopped.

According to the fourth aspect of the present invention, when the understeer state of the vehicle is detected, the braking force is applied to the wheels by the automatic braking means. The braking force distribution prioritizes occurrence of the vehicle, so that the turning performance of the vehicle is first improved, and the braking force distribution prioritizes deceleration over the turning assist yaw moment as time elapses from the start of operation of the automatic braking means. As a result, the understeer state is reduced by deceleration, so that the understeer state is promoted effectively and efficiently without the understeer state being promoted at the beginning of the behavior control or the vehicle being oversteered at the latter half of the behavior control. Can be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a braking device of a first embodiment of a behavior control device according to the present invention together with an electric control device.

FIG. 2 is a flowchart illustrating a behavior control routine according to the first embodiment.

FIG. 3 is a graph showing a relationship between an absolute value of a spin state quantity a * β + b * βd and a target slip ratio Rs.

FIG. 4 is a flowchart illustrating a behavior control routine according to a second embodiment.

FIG. 5 is a schematic configuration diagram showing a third embodiment of the behavior control device according to the present invention applied to a front wheel drive vehicle.

FIG. 6 is a schematic configuration diagram showing a braking device of a third embodiment together with an electric control device.

FIG. 7 is a flowchart illustrating a behavior control routine according to a third embodiment.

FIG. 8 is a flowchart showing a throttle opening control routine in a third embodiment.

FIG. 9 is a graph showing a relationship between an accelerator pedal depression amount Accp and a throttle opening Top.

FIG. 10 is a schematic configuration diagram showing a braking device of a fourth embodiment of the behavior control device according to the present invention configured to suppress drift-out, together with an electric control device.

FIG. 11 is a flowchart illustrating a behavior control routine according to a fourth embodiment.

FIG. 12 is a graph showing the relationship between the absolute value of the spin state quantity a * β + b * βd and the total braking force Ft.

FIG. 13 shows the distribution of braking force Wi for inner wheels and the distribution of braking force W for rear wheels.
6 is a graph showing a relationship between r and r.

FIG. 14 is an explanatory diagram (A) showing a yaw moment in a turning suppression direction caused by a braking force applied to the turning outer front wheel when the left and right front wheels are in a counter steer state, and the left and right front wheels are in a large counter steer state. FIG. 7B is an explanatory diagram (B) showing the yaw moment in the turning promotion direction caused by the application of the braking force to the turning outer front wheel in the situation of FIG.

[Explanation of symbols]

 3. Hydraulic circuit 4. Engine 5. Transmission 10. Braking device 14. Master cylinder 18, 20, 26, 28. Brake hydraulic control device 34. Oil pump 38FL, 38FR, 38RL, 38RR Wheel cylinder 40FL, 40FR, 40RL, 40RR: Control valve 44FL, 44FR, 44RL, 44RR: On-off valve 46FL, 46FR, 46RL, 46RR: On-off valve 50: Electric control device 56: Vehicle speed sensor 58: Lateral acceleration sensor 60: Yaw rate sensor 62: Steering angle sensor 64FL 64RR: Wheel speed sensor 66: Accelerator pedal sensor 68: Pressure sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T 8/00 B60T 8/32-8/96

Claims (4)

(57) [Claims] A means for detecting an oversteer state of the vehicle; an automatic brake means for applying a braking force to at least a turning outer front wheel when the oversteer state of the vehicle is detected; a means for detecting a countersteer state; When the condition is detected, the braking force applied to the wheels by the automatic braking means is determined by the degree of counter steer .
And a means for performing an increase correction so as to increase as the vehicle height increases . Means for detecting an oversteer state of the vehicle, automatic braking means for applying a braking force to at least the outer front wheel when the oversteer state of the vehicle is detected, steering angle detection means, and turning based on the steering angle. Means for determining whether or not the vehicle is in a large counter steer state in which a yaw moment in a direction opposite to the turning direction of the vehicle is not generated even when a braking force is applied to the outer front wheel; Means for stopping the application of the braking force by the braking means or applying the maximum braking force to all the wheels by the automatic braking means. 3. The vehicle behavior control device according to claim 2,
Means for controlling the driving force of the front wheels, and means for increasing the driving force of the front wheels when the application of the braking force by the automatic braking means is stopped due to the determination of the large counter steer state. A behavior control device for a vehicle, comprising: A means for detecting an understeer state of the vehicle; an automatic brake means for applying a braking force to a wheel when the understeer state of the vehicle is detected; and a turning assist yaw rather than a deceleration when the automatic brake means starts operating. And a braking force distribution control means that prioritizes deceleration over turning assist yaw moment as time elapses from the start of operation of the automatic braking means. Behavior control device.