JP2877084B2 - Braking force 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 braking force control device, and more particularly, to a braking force control device for controlling a braking force when a vehicle turns.

[0002]

[Related Background Art] When a vehicle turns, the vehicle does not turn in accordance with the amount of steering depending on the driving state of the vehicle, tire characteristics, road conditions, load capacity, and the like. Overturning (oversteering)
It may be. When such understeer or oversteer occurs, the vehicle does not behave in accordance with the driver's intention, and the driver feels uncomfortable and the running stability is deteriorated, which is not preferable.

Therefore, an actuator capable of controlling the braking force independently of the operation of the brake pedal is provided for each wheel, and the actuator is automatically operated according to the turning state of the vehicle to apply the braking force to each wheel independently. Give this,
Japanese Patent Application Laid-Open No. 6-239216 discloses a braking force control technique for generating a desired turning yaw moment (understeer) or restoring yaw moment (oversteer) in a vehicle so as to appropriately re-establish and maintain the vehicle posture. Have been.

[0004]

By the way, when the vehicle is turned sharply or a turning yaw moment is generated in the vehicle as described above, a large centrifugal force acts on the vehicle. As described above, when the centrifugal force increases, the vehicle body is swung toward the outside of the turn. At this time, if the vehicle is a low-height passenger car or the like, there is no problem because the center of gravity is low.However, a vehicle such as a truck or a bus, which originally has a high center of gravity, has a relatively small height compared to a passenger car. Even with a small centrifugal force, a large moment acts on the position of the center of gravity.

[0005] Therefore, when making a sharp turn in such a truck or bus, the vehicle is greatly inclined due to an increase in centrifugal force and rolling occurs, and the vehicle is yawed based on the prior art disclosed in the above publication. When the control for giving the moment is performed, the rolling is promoted, and the running stability of the vehicle may be greatly impaired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a braking force control apparatus that always maintains a running stability during turning even in a vehicle having a high center of gravity. Is to provide.

[0007]

In order to achieve the above object, according to the present invention, a turning state detecting means for detecting a turning state of a vehicle, and a wheel for detecting wheel loads of at least a pair of left and right wheels, respectively. Load detection means, braking force control means capable of controlling the braking force of the wheels independently of the operation of the brake pedal, at least one of between the left and right wheels and between the front and rear wheels according to the output from the turning state detection means A first control mode in which the braking force control means is operated to control the turning behavior of the vehicle to a target turning characteristic by controlling a braking force difference, and an excessive roll index based on a detection output of the wheel load detection means is predetermined. Control means for operating the braking force control means to decelerate the vehicle when the value exceeds the control value, and performing the second control mode prior to the first control mode. It is characterized in that was example.

Accordingly, while the vehicle is turning, the braking force control means operates according to the output from the turning state detecting means,
Although the target turning characteristics can be obtained, when the excessive roll index based on the detection output of the wheel load detecting means exceeds a predetermined value, the braking force control means operates to decelerate the vehicle, and excessive rolling occurs. It is prevented beforehand. As a result, the turning characteristics of the vehicle can be controlled within a range in which the turning stability of the vehicle can be ensured.

According to a second aspect of the present invention, in the first control mode, when the vehicle is in an understeer state, the braking force difference is controlled so as to give a turning yaw moment to the vehicle. Therefore, when the vehicle is in the understeer state, the turning yaw moment is given and the vehicle is controlled in the turning direction.However, when the vehicle leans outside the turning direction and the excessive roll index exceeds a predetermined value, the turning control is prioritized. The braking force control means operates to decelerate the vehicle.
This makes it possible to reliably prevent a situation in which the running stability of the vehicle is degraded due to the rolling of the vehicle body due to the control of the turning direction, and the turning stability of the vehicle is ensured.

Further, in the invention according to claim 3, the excessive roll index is a small wheel load of the wheel, and the control means controls the second control when the wheel load of at least one wheel becomes equal to or less than a predetermined value. The mode is implemented. Therefore, during turning, the vehicle leans outward and at least one wheel on the inner wheel side tends to float, and when the wheel load falls below a predetermined value, the braking force control means operates to decelerate the vehicle, and the vehicle Satisfactorily secures turning stability.

Further, in the invention according to claim 4, the excessive roll index is a reduction speed of the wheel load of the wheel, and the control means determines that the reduction speed of the wheel load of at least one wheel becomes equal to or more than a predetermined value. The second control mode is performed. Therefore, during the turn, the vehicle is tilted outwardly of the turn, and at least one wheel on the inner wheel side tends to float,
When the wheel load reduction speed reaches a predetermined value or more and the wheel load rapidly decreases, the braking force control means operates to decelerate the vehicle, and the turning stability of the vehicle is secured early and well. You.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic configuration of a braking force control device according to the present invention mounted on a vehicle such as a truck or a bus. Hereinafter, the configuration of the braking force control device will be described with reference to FIG.

The vehicle 1 is provided with a pair of front wheels XFL, XFR and a pair of rear wheels XRL, XRR. As shown in FIG. 1, a steering wheel 8 is connected to the front wheels XFL and XFR via a knuckle arm 2, a relay rod 4, and a steering column shaft 6. Thus, when the steering wheel 8 is rotated, the front wheels XFL and XFR rotate around the fulcrum 10 in accordance with the operation amount, and the vehicle 1 is steered.

On the other hand, a propeller shaft 20 is connected to the rear wheels XRL and XRR via an axle shaft 14 and a differential 16. Further, the propeller shaft 20 is connected to an engine (for example, a diesel engine) 26 via a transmission 24. Thus, the output of the engine 26 is shifted by the transmission 24 and transmitted to the rear wheels XRL and XRR with an appropriate driving torque, so that the vehicle 1 can run.

Each of the wheels XFL, XFR, XRL and XRR is provided with a brake device 30 such as a hydraulic disc brake. The brake device 30 is, for example, an air-over-hydraulic brake. That is, as shown in the drawing, an air overhydraulic booster 32 for converting pneumatic pressure to hydraulic pressure is connected to each brake device 30.
Is connected to an air passage 34. Further, the normally open solenoid valve 45 and the double check valve 4
6, and an air tank 38 is connected via a relay valve 47 which opens and closes by supplying air pressure from an air brake valve 36 which opens and closes in conjunction with a brake pedal 40, thereby forming a service brake circuit. . Accordingly, when the driver of the vehicle 1 operates the brake pedal 40 and the air brake valve 36 is operated, the opening / closing valve 47 is opened according to the depression force of the brake pedal 40, and the air overhydraulic booster 3 is released from the air tank 38.
2 is supplied to the air. The air pressure is converted to hydraulic pressure in the air over hydraulic booster 32, and the hydraulic pressure activates the brake device 30 to cause the wheels XF
L, XFR, XRL and XRR braking are performed.

The air passage 34 is provided with an air passage 42 branching from the service brake circuit.
Normally closed solenoid valves (braking force control means) 4 corresponding to the respective brake devices 30 are provided in the air passages 42.
4 are interposed. The solenoid valve 44 is electrically connected to an electronic control unit (ECU) 50 together with the solenoid valve (braking force control means) 45. That is, when each of the solenoid valves 44 is opened in response to the operation signal from the ECU 50 and each of the solenoid valves 45 is individually closed, the respective brake devices 30 operate independently of the operation state of the air brake valve 36. , Corresponding wheels XFL, XFR, XRL,
XRR braking will be performed.

The wheels XFL, XFR, XRL,
The suspensions (not shown) supporting the XRR have loads acting on the respective wheels X, ie, wheel loads WFL, WFR, WRL,
A wheel load sensor (wheel load detecting means) 52 for detecting WRR is provided. As the wheel load sensor 52, a magnetostrictive sensor that is provided in the suspension device and detects distortion of the suspension device or a sensor that detects distortion of the axle is used, but an air spring of an air suspension (not shown) is used. What detects internal pressure may be used. Each wheel load sensor 52 is electrically connected to the ECU 50.

The vehicle 1 is equipped with a yaw rate sensor (turning state detecting means) 60 for detecting a change speed of yaw acting on the vehicle 1, that is, a yaw rate 、, and a steering column shaft 6 is provided with a steering wheel 8. The steering angle sensor 62 for detecting the steering angle θH based on the rotation angle of the steering wheel is attached. Further, each wheel is provided with a wheel speed sensor 64 for detecting the wheel speed. The yaw rate sensor 60, the steering angle sensor 62, and the wheel speed sensor 64 are connected to the ECU 50.

The engine 26 is provided with an electronic governor 70 for controlling fuel injection to the engine 26. The electronic governor 70 is provided with an electronic governor controller 51.
Is connected to the ECU 50 via the. Referring to FIG. 3, the electronic governor controller 51 is connected to an accelerator opening sensor 76 for detecting the amount of depression of an accelerator pedal 74, that is, the accelerator opening.
Controls the fuel injection amount to the engine 26 in accordance with the accelerator opening information from the accelerator opening sensor 76.

Hereinafter, the operation of the braking force control device configured as described above will be described. Referring to FIG. 2, there is shown a flowchart of a control mode switching routine (control means) of the braking force control of the vehicle 1 executed by the ECU 50. Hereinafter, a control procedure of the braking force control will be described based on this flowchart. In step S10, the detection values of the above sensors, that is, the wheel load information (excessive roll index) WFL, WFR, WRL, WRR from the wheel load sensor 52, the yaw rate information か ら from the yaw rate sensor 60, and the detection value from the steering angle sensor 62 The vehicle speed information V based on the steering angle information θH and the wheel speed information from the wheel speed sensor 64 is read.

In the next step S12, the steering angle information θH
Reference yaw rate (target turning characteristic) from vehicle speed information V
Find ψ0 by calculation. In step S14, a yaw rate deviation Δψ is obtained from the reference yaw rate {0 based on the above calculation and the yaw rate information 実 際 which is the actual value (Δψ = ψ
0-ψ). In step S16, each wheel X (XFL, XF
R, XRL, XRR) Wheel load W (WFL, WFR, WRL, WR)
R) change speed dW / dt, that is, wheel load change speed dWFL /
dt, dWFR / dt, dWRL / dt, dWRR / dt (decrease speed) are obtained.

In the next step S18, it is determined whether or not there is a wheel X having a wheel load W smaller than a predetermined value A. That is, the wheel loads WFL, WF of the wheels XFL, XFR, XRL, XRR
It is determined whether any of R, WRL, and WRR is less than a predetermined value AFL, AFR, ARL, or ARR that is set in advance for each wheel. The determination result of step S18 is false (No)
When it is determined that there is no wheel X whose wheel load W is less than the predetermined value A, for example, the vehicle 1 is traveling straight, and the load is equally applied to the wheels XFL, XFR, XRL, and XRR. If so, the process proceeds to step S20.

In step S20, the above-mentioned step S16
It is determined whether or not there is a wheel X such that the wheel load change speed dW / dt obtained in the step becomes smaller than the negative predetermined value B. That is, the wheel load change speed dWFL / d of each wheel XFL, XFR, XRL, XRR
t, dWFR / dt, dWRL / dt, and dWRR / dt, negative predetermined values BFL, BFR, BRL, and B preset for each wheel.
It is determined whether or not there is something below RR.

The determination result of step S20 is false (No)
If it is determined that there is no wheel X for which the wheel load change speed dW / dt is less than the predetermined value B, then step S
Proceed to 22. In step S22, it is determined whether the steering wheel 8 is operated and the vehicle 1 is in a turning state and the absolute value of the yaw rate deviation Δψ obtained in step S14 is larger than a predetermined value C (| Δψ |> C). I do. That is, here, it is determined whether or not the actual yaw rate ψ greatly deviates from the reference yaw rate ψ0 obtained from the steering angle θH and the vehicle speed V.

If the determination result in step S22 is true and the absolute value of the yaw rate deviation Δψ is larger than the predetermined value C,
Although the vehicle 1 is turning, it can be determined that the vehicle 1 is in the understeer state or the oversteer state for some reason. In this case, the process proceeds to step S24. In step S24, it is determined whether or not the yaw rate deviation Δψ is positive, that is, the actual yaw rate 小 さ く is smaller than the reference yaw rate ψ0 (Δψ = ψ0−ψ> 0), and the vehicle 1 tends to be understeer.

If the result of the determination in step S24 is true and the yaw rate deviation Δψ is positive, it can be determined that the vehicle 1 is slightly understeered, and the process proceeds to step S26. In step S26, the braking force control mode is set to the turning control mode (first control mode) in order to return the understeer state of the vehicle 1 to the normal turning state. In this case, the braking force control routine corresponding to the turning control mode, that is, each solenoid valve 44,
Forty-five control routines are separately provided (not shown), and the wheels XFL, XF are controlled based on the turning control routine.
The braking forces applied to R, XRL, and XRR are independently controlled. As a result, a turning yaw moment is generated to bring the vehicle 1 into a normal turning state, and the posture of the vehicle 1 is corrected.

Specifically, in the turning control, the braking force of the inner wheel during turning is larger than the braking force of the outer wheel, and a turning yaw moment is generated so that the vehicle 1 turns in the turning direction. It can be rebuilt. The difference between the braking force of the inner wheel and the braking force of the outer wheel is set in advance according to the magnitude of the yaw rate deviation Δψ. Therefore, each solenoid valve 4 is set so that the braking force of each wheel has these braking force differences.
4 and 45 are controlled independently. When braking is performed by the driver depressing the brake pedal 40 during cornering, the turning control is performed in addition to the braking performed by the driver.

In this turning control, control for increasing the braking force of the rear wheel to that of the front wheel may be performed instead of the control of increasing the braking force of the inner wheel to that of the outer wheel. The control and the control between the front and rear wheels may be performed simultaneously. On the other hand, when the determination result of step S24 is false and the yaw rate deviation Δψ is negative, it can be determined that the vehicle 1 is slightly oversteered.
Proceed to 8.

In step S28, the braking force control mode is set to the restoration control mode in order to return the oversteer state of the vehicle 1 to a normal turning state. In this case, similarly to the turning control mode, a braking force control routine corresponding to the restoration control mode is separately provided (not shown), and the braking force applied to each wheel X based on the restoration control routine is independent. Is controlled. As a result, similarly to the above, a restoring yaw moment is generated to bring the vehicle 1 into a normal turning state, and the posture of the vehicle 1 is corrected.

More specifically, in the restoration control, the braking force of the outer wheel during turning is larger than the braking force of the inner wheel, and a restoring yaw moment is generated such that the vehicle 1 is directed outward in a direction opposite to the turning direction. Thus, the posture of the vehicle 1 is reestablished. The difference between the braking force of the outer wheel and the braking force of the inner wheel is set in advance according to the magnitude of the yaw rate deviation Δψ, as described above. Therefore, the solenoid valves 44 and 45 are controlled such that the braking force of each wheel X has these braking force differences.

In this restoration control, instead of the control for increasing the braking force of the outer wheel than for the inner wheel, control for increasing the braking force of the front wheel than for the rear wheel may be performed. Alternatively, control between the inner and outer wheels and control between the front and rear wheels may be performed simultaneously. In addition, since the situation in which the vehicle 1 is in the oversteer state includes a large possibility that the vehicle 1 spins, in this restoration control, in addition to the braking by the brake device 30, the engine 2
The output of 6 is suppressed and the engine brake is also effective. That is, the ECU 50 calculates the yaw rate deviation Δψ
Is supplied to the electronic governor controller 51,
The electronic governor controller 51 supplies a signal corresponding thereto to the electronic governor 70. As a result, the amount of fuel injected into the engine 26 is reduced, and the engine brake operates (braking force control means).

If the result of the determination in step S22 is false and the absolute value of the yaw rate deviation Δψ is equal to or smaller than the predetermined value C, the vehicle 1 follows the reference yaw rate # 0 without understeer, oversteer, etc. Then, it can be considered that the vehicle is turning well, and in this case, the process proceeds to step S30, and the braking force control is not particularly performed. By the way, in a truck or a bus, the vehicle height is generally higher than that of a passenger car, and the position of the center of gravity P of the vehicle 1 is higher. Further, the center of gravity P is further increased in accordance with the increase in the load weight and the number of passengers.

Referring to FIG. 3, there are shown a top view (a) and a rear view (b) of a vehicle 1 such as a truck or a bus turning rightward. Running,
The center of gravity P in the figure is the lateral acceleration a calculated from the following equation (1).
Is acting, and centrifugal force is working. a = V ² / r (1) Here, r indicates a turning radius.

Therefore, during turning, a large moment due to centrifugal force acts on the center of gravity P of the vehicle 1 around the contact point of the outer ring, and the vehicle 1 is inclined outward. When the inclination becomes large in this way, the vehicle 1 rolls and running stability is extremely deteriorated. Therefore, in the braking force control device of the present invention, even in the case of such a vehicle 1 having a high position of the center of gravity P such as a truck or a bus, running stability is ensured by preventing excessive rolling from occurring during turning. I try to maintain sex.

As is apparent from FIG. 3, when the vehicle 1 is tilted during turning, a large wheel load (WL) is applied to the outer wheel, while a wheel load (WR) applied to the inner wheel is reduced (the size is indicated by an arrow). ). Therefore, in this case, in order to suppress the rolling of the vehicle 1 and maintain the running stability, the determination as to whether the vehicle 1 has reached the predetermined amount of inclination has already been described above, but the reduction of the wheel load W applied to the inner ring has been described above. It is determined whether or not the amount is less than a predetermined value A (step S18) or whether or not the reduction change amount of the wheel load applied to the inner ring is less than a predetermined value B (step S20).

During turning, the vehicle 1 tilts, and step S1 is executed.
8 or when the determination result of step S20 is true, the process proceeds to step S32. In step S32, step S28 is executed, and it is determined whether or not the restoration control mode is currently being executed. When the determination result is true and the vehicle is in the restoration control mode, as described above, the vehicle 1
, A restoring yaw moment is generated which is directed outward in the direction opposite to the turning direction. That is, in this case, the wheel load W (for example, WFL, WRL) applied to the wheel X corresponding to the outer wheel (for example, XFL, XRL for right turning) is reduced, while the wheel X (for the inner wheel side) is reduced. For example, for a right turn, XF
R, XRR) to increase the wheel load W (for example, WFR, WRR). Therefore, in the restoration control, the inclination of the vehicle 1 also tends to be restored, and it can be determined that the vehicle 1 will not lean any more.

Therefore, in this case, the process proceeds to step S22. At this time, if the attitude of the vehicle 1 is restored well and the absolute value of the yaw rate deviation Δψ is equal to or smaller than the predetermined value C, the process proceeds to step S30, where the restoration control mode is ended and the braking force control is not performed. On the other hand, the yaw rate deviation Δ
If the absolute value of ψ still exceeds the predetermined value C, the process proceeds to step S28 via step S24, and the restoration control mode is continued.

If the result of the determination in step S32 is false and the braking force control mode is not the restoration control mode, that is, if it is the turning control mode by executing step S26, or if there is no control by executing step S30. Then, the process proceeds to step S34. In step S34,
The braking force control is performed by setting the braking control mode to the anti-rolling mode (second control mode).

When the braking control mode is the turning control mode or no control, unlike the restoring control mode,
There is no element that restores the inclination of the vehicle 1. Conversely, in the turning control mode, a turning yaw moment is generated so as to decrease the turning radius r, and therefore, at the same vehicle speed V, the inclination of the vehicle 1 tends to be further increased (see equation (1)). Therefore,
In the anti-rolling mode, the vehicle speed V is reduced to reduce the lateral acceleration a (see equation (1)). That is, when the determination result of step S32 is false, the ECU 50 controls all the solenoid valves 44 and 45 to perform the predetermined drive regardless of whether the braking control mode is the turning control mode or the case where no control is performed. A signal is supplied to operate the brake device 30 to apply a braking force to each wheel X (XFL, XFR, XRL, XRR), thereby decelerating the vehicle 1 and reducing the centrifugal force acting on the center of gravity P. Thus, the inclination of the vehicle 1 is not deteriorated. Note that the braking force may be applied only to a specific wheel instead of all the wheels.

At the same time, the ECU 50 also supplies a signal to the electronic governor 70 via the electronic governor controller 51, whereby the amount of fuel injected into the engine 26 is reduced and the engine brake is also applied. As a result, the centrifugal force acting on the center of gravity P of the vehicle 1 is reduced, and even during turning, the inclination of the vehicle 1 is suppressed, rolling is prevented, and good running stability is maintained. .

Referring to FIG. 4, there is schematically shown a transition diagram of each braking force control mode described based on the flowchart of FIG. As shown in the figure, in the braking force control device of the present invention, the wheel load W is constantly monitored when the braking force control mode is the turning control mode or no control.
Accordingly, the braking force control mode is appropriately switched to the anti-rolling mode in accordance with the wheel load W, so that excessive lateral acceleration is reduced and the posture of the vehicle 1 recovers satisfactorily.
Thus, rolling is always reliably prevented even during turning.

As described in detail above, the braking force control device of this embodiment constantly monitors the wheel load W, and determines that the wheel load W decreases to less than the predetermined value A while the vehicle 1 is turning. When there is a wheel X, or when there is a wheel X in which the change speed of the wheel load W, that is, the wheel load change speed dW / dt is smaller than a predetermined negative value B, the braking force control mode is turned control mode or control. In the case where there is no vehicle, the braking force control mode is switched to the anti-rolling mode to apply the braking force to all the wheels X (XFL, XFR, XRL, XRR), or to decelerate the vehicle 1 by applying the engine brake. I have to.

Therefore, in the vehicle 1 such as a truck or a bus,
When the vehicle turns sharply or when the braking force control mode is set to the turning control mode during turning, the vehicle height is high and the center of gravity P is high.
Is high, the lateral acceleration a acts on the center of gravity P, and the vehicle 1 tends to greatly lean outward.
Is reduced, the posture of the vehicle 1 is appropriately maintained. As a result, the rolling of the vehicle 1 is prevented, the running stability is maintained well, and the yaw motion of the vehicle can be controlled within a range where the running stability of the vehicle is not impaired.

Further, since the switching to the anti-rolling mode is determined based on the detection value from the wheel load sensor 52, excessive rolling may occur regardless of fluctuations in the height of the center of gravity due to changes in loading conditions or the number of passengers. Can be accurately predicted, and it is ensured that the running stability of the vehicle is ensured. In the above embodiment, the yaw rate deviation Δψ
The turning control mode and the restoring control mode are executed based on the vehicle speed V. However, the present invention is not limited to this. For example, according to the deviation between the target lateral acceleration calculated from the vehicle speed V and the steering angle θH and the actual lateral acceleration, The turning control mode and the restoration control mode may be performed.

[0045]

As described above in detail, according to the braking force control apparatus of the first aspect of the present invention, the occurrence of an excessive roll is given priority over the first control mode for controlling the turning characteristics of the vehicle. Since the second control mode for preventing the vehicle is executed, it is possible to control the turning characteristics of the vehicle within a range where excessive rolling does not occur in the vehicle, and to secure running stability and realize good turning characteristics. Can be compatible. Further, by using the excessive roll index based on the wheel load, it is possible to accurately determine a situation in which the occurrence of excessive roll is predicted, and it is possible to reliably suppress excessive rolling.

According to the braking force control apparatus of the second aspect, the second control mode for decelerating the vehicle is performed prior to the first control mode for applying the turning yaw moment to the vehicle, so that the turning moment is applied. It is possible to reliably prevent a situation where the control promotes excessive rolling. According to the braking force control device of the third aspect, the second control mode is executed when the wheel load of at least one wheel becomes equal to or less than the predetermined value. Therefore, it is possible to reliably detect a situation in which excessive rolling occurs. It is possible to reliably prevent the occurrence of excessive rolling.

According to the braking force control device of the fourth aspect, the second control mode is executed when the reduction rate of the wheel load of at least one of the wheels becomes a predetermined value or more. Can be detected early,
Excessive rolling can be prevented more reliably.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a braking force control device of the present invention.

FIG. 2 is a flowchart showing a braking force control mode switching routine.

FIG. 3 is a schematic diagram illustrating a behavior of a vehicle during a turning operation.

FIG. 4 is a schematic diagram showing a transition of a braking force control mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle 30 Brake device 32 Air over hydraulic booster 34 Air passage 38 Air tank 42 Air passage 44 Solenoid valve (braking force control means) 45 Solenoid valve (braking force control means) 46 Double check valve 47 Relay valve 50 Electronic control unit (ECU) 51) Electronic governor controller 52 Wheel load sensor (wheel load detecting means) 60 Yaw rate sensor (turning state detecting means) 62 Steering angle sensor 64 Wheel speed sensor 70 Electronic governor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-108834 (JP, A) JP-A-3-239673 (JP, A) JP-A-7-117645 (JP, A) JP-A-2- 283555 (JP, A) JP-A-8-150908 (JP, A) JP-A-6-239216 (JP, A) JP-A-5-16699 (JP, A) JP-A-5-254406 (JP, A) Hira 5-46612 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60T 8/24 B60T 8/26 B60T 8/58 B60T 7/12

Claims (4)

(57) [Claims] 1. A turning state detecting means for detecting a turning state of a vehicle, a wheel load detecting means for detecting wheel loads of at least a pair of left and right wheels, and a braking force of a wheel independently of operation of a brake pedal. Controllable braking force control means, and controlling at least one braking force difference between the left and right wheels and between the front and rear wheels in accordance with an output from the turning state detection means, thereby setting the turning behavior of the vehicle to a target turning characteristic. A first control mode for activating the braking force control means, and activating the braking force control means for decelerating the vehicle when an excessive roll index based on a detection output of the wheel load detection means exceeds a predetermined value. A control device having a second control mode, comprising: control means for executing the second control mode in preference to the first control mode. 2. The control method according to claim 1, wherein the first control mode controls the braking force difference so as to give a turning yaw moment to the vehicle when the vehicle is in an understeer state.
The braking force control device according to any one of the preceding claims. 3. The excessive roll index is a value of a wheel load of a wheel, and the control means executes the second control mode when a wheel load of at least one wheel becomes a predetermined value or less. The braking force control device according to claim 1 or 2, wherein: 4. The excessive roll index is a reduction speed of a wheel load of a wheel, and the control means executes the second control mode when a reduction speed of a wheel load of at least one wheel becomes a predetermined value or more. The braking force control device according to claim 1 or 2, wherein: