JP2001018775A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the quality of ABS control by allowing a brake control device which effects ABS control to surely discriminate between a normal turning state on a high-μ road and an abnormal turning state such as a running state on a split-μroad or a spinning state. SOLUTION: In this brake control having a control means (d) which effects ABS control, the control means (d) is provided with a lateral acceleration estimating means (d1) for estimating lateral acceleration produced in a vehicle and a comparing and determining means d2 for comparing the lateral acceleration estimated by the lateral acceleration estimating means d1 with a detected lateral acceleration detected by a lateral acceleration sensor d2 included in a vehicle behavior detecting means (b) and for determining that normal turning matching steering angle is under way if the difference between the estimated and detected accelerations is less than a predetermined value and determining that abnormal turning is under way if the difference is greater than the predetermined value. The control means (d) is adapted to change the type of control whether normal turning or abnormal turning is determined to be under way during the ABS control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for performing control generally called anti-lock brake control (hereinafter referred to as ABS control) for controlling wheel brake pressure during braking to prevent wheel lock.

[0002]

2. Description of the Related Art Conventionally, a brake control device for executing ABS control calculates a pseudo vehicle speed Vi, and calculates the pseudo vehicle speed Vi.
Based on i, a pressure reduction threshold value (wheel speed) λ1 which is an optimal slip ratio for obtaining a large braking force at the time of braking is calculated, and when the detected wheel speed Vw falls below the pressure reduction threshold value λ1, the wheel is driven. The wheel cylinder pressure is reduced by determining that the vehicle is in the locked state. Thereafter, the wheel is returned from the wheel locked state by the reduced pressure, and when the wheel speed Vw returns to the vicinity of the pseudo vehicle body speed Vi, the pressure is increased again to recover the braking force. It is configured to be.

In the meantime, in pressure reduction / pressure increase during the ABS control, a control called four-wheel independent control is conventionally known. This is because the wheel speed of each wheel is obtained independently in executing the hydraulic pressure control of each wheel of the four wheels, and each wheel speed of each wheel is compared with a decompression threshold to control each wheel independently. Is what you do. In this control, the steering performance and the braking distance can be optimized.

As another control, a control called rear wheel select low is also known. This means that for the two front wheels, the wheel speed is determined for each wheel, and hydraulic control is executed independently for each wheel, but for the rear wheel, the hydraulic pressure suitable for the wheel with the lower wheel speed of the two wheels It is controlled by. That is, since the wheel having the lower wheel speed among the two rear wheels is in a rotating state in which the wheel is easily locked, the hydraulic pressure control suitable for the wheel is uniformly performed on the two wheels. This is suitable for an X-shaped brake pipe mainly used for a front wheel drive vehicle. It is to be noted that, for example, the above-mentioned prior art described in “Study on Automotive ABS” (1993, published by Sankaido Co., Ltd., pp. 82-83) is known.

[0005]

However, in the above-described four-wheel independent control, the friction coefficient of the road surface (hereinafter referred to as μ) differs between the left and right road surfaces (hereinafter referred to as split μ).
When the ABS control is executed while the vehicle is traveling on a road, the braking forces generated by the left and right wheels are different (high μ).
(A high braking force on the road side and a low braking force on the low μ road side), and a yaw moment is generated in the vehicle due to the difference between the left and right braking forces, and the vehicle posture may become unstable.

On the other hand, in the rear wheel select-low control described above, only the braking force suitable for the low μ road is generated on both the left and right rear wheels, so that the braking force is equal on the left and right sides and the vehicle posture is changed. Was stable. However, this technique has the following problems when the vehicle turns. That is, at the time of turning, a wheel speed difference (inner-outer wheel difference) occurs between the turning inner wheel and the turning outer wheel. However, when the turning inner wheel becomes slow, it is determined that there is an apparent tendency to lock. Become. Therefore,
Actually, the hydraulic pressure control of the left and right rear wheels is executed based on the wheel speed of the turning inner wheel as if it were a split μ road but not a split μ road, and as a result, the braking distance was increased. Put it. Incidentally, in the above-described four-wheel independent control, when turning, the optimal hydraulic control is performed for each wheel, so that the braking distance is short.

As described above, in the prior art, it has been impossible to achieve both stability of the vehicle posture on the split μ road and reduction of the braking distance during turning.
Therefore, as means for solving this problem, it is conceivable to execute the four-wheel independent control on a high μ road and the rear wheel select low control on a split μ road when turning. . However, conventionally, when the left and right wheel speeds are different, whether this is a turning traveling state,
It is difficult to accurately determine whether the vehicle is on the split μ road, and particularly, it is difficult to accurately determine that the vehicle is on the split μ road in the turning traveling state on the split μ road.

The present invention has been made in view of the above-mentioned conventional problems. In a brake control apparatus for executing ABS control, a normal turning state on a high μ road, a split μ road running state or a spin state, and the like are described. The purpose is to improve the control quality of the ABS control by reliably discriminating between the abnormal turning state and the split control by appropriately controlling the normal turning state and the abnormal turning state. The purpose is to achieve both stability of the vehicle posture on the μ road and shortening of the braking distance during turning.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention, as shown in the claim correspondence diagram of FIG. 1, independently controls brake fluid pressure for braking each wheel of a vehicle. A possible brake unit, a vehicle speed sensor b1 for detecting a wheel speed of each wheel, a vehicle behavior detecting means b for detecting a vehicle behavior, and an estimated vehicle speed based on an input from each wheel speed sensor b1. A brake comprising: pseudo vehicle speed calculating means c for obtaining a certain pseudo vehicle speed; and control means d for executing ABS control for operating a brake unit a to prevent wheel lock based on the pseudo vehicle speed and the wheel speed. In the control device, the control means d includes: a lateral acceleration estimating means d1 for estimating a lateral acceleration occurring in the vehicle; an estimated lateral acceleration by the lateral acceleration estimating means d1; Lateral acceleration sensor included in stage b b2
Is compared with the detected lateral acceleration, and if the difference between the two is less than a predetermined value, it is determined that the vehicle is turning normally in accordance with the steering angle, and if the difference is not less than the predetermined value, it is determined that the vehicle is turning abnormally. And a comparison determining unit d2, wherein the control unit d is configured to switch control between a normal turning determination and an abnormal turning determination during the ABS control.

In the present invention, the road surface μ of the left and right wheels
Is turning on a uniform high μ road and the vehicle is turning normally without spinning, the difference between the estimated lateral G corresponding to the turning radius and the vehicle speed and the lateral G actually detected is small. Therefore, the comparison and determination unit determines that the vehicle is turning normally, and the control unit executes the ABS control according to the normal turning. On the other hand, when the vehicle is turning on the split μ road or during an abnormal turn such as when the vehicle is spinning, the traveling direction of the vehicle and the steering angle are different. In particular, on the split μ road, one of the left and right wheel speeds becomes large. Therefore, the estimated lateral G based on the steering angle, the vehicle speed, etc.
Does not match the detected lateral G that is actually detected, and particularly when the vehicle state is in the spin direction, the detected lateral G is smaller than the estimated lateral G. Therefore, the comparison determination unit determines that the vehicle is turning abnormally, and the control unit performs control corresponding to the abnormal turning.

It should be noted that, as described in claim 2, claim 1
In the brake control device described in the above, the control means d includes:
At the time of the ABS control, when the normal turning is determined, the four-wheel independent control for performing the hydraulic control independently of the four wheels is executed, and at the time of the abnormal turning determination, the hydraulic control is independently performed for the front two wheels. The rear two wheels are preferably configured to execute a rear wheel select low control for performing a hydraulic control suitable for a wheel having a lower wheel speed among the two rear wheels.

Therefore, if the vehicle turns abnormally during the ABS control, the control means d executes the rear wheel select low control. As a result, in the rear wheels, the control suitable for the low-speed wheel is executed for the left and right wheels, and the left and right braking forces are generated evenly, and the vehicle posture is stabilized. Therefore, even on the split μ road, no spin occurs due to uneven braking force on the left and right.

On the other hand, when the vehicle is turning normally during the ABS control, the control means d executes four-wheel independent control. Therefore, in the case of the rear wheels, the maximum braking force is obtained for both the inner and outer wheels, and the braking distance can be reduced. During normal turning, the vehicle posture is unlikely to become unstable even if the braking force differs between the left and right. If the vehicle becomes unstable, the comparison and determination unit d2 determines that the vehicle is turning abnormally, and switches to the rear wheel select low control, thereby stabilizing the vehicle posture.

Further, as described in claim 3, claim 2
In the brake control device described in the above, the control means d includes:
When the vehicle is not turning, it is preferable to execute the rear wheel select low control.

Therefore, even when the vehicle is traveling straight, when the ABS control is performed on the split μ road, the braking forces on the left and right of the rear wheels are equalized, and the vehicle posture can be stabilized.

In addition, as described in claim 4, claim 1
4. The brake control device according to any one of claims 3 to 3, wherein the lateral acceleration estimating means d1 includes a steering angle detected by a steering angle sensor b3 included in the vehicle behavior detecting means b and a pseudo vehicle speed obtained by the pseudo vehicle speed calculating means c. It is preferable to provide a turning radius calculating means d11 for calculating a turning radius on the basis of the turning radius, and to estimate a lateral acceleration generated in the vehicle based on the turning radius. According to a fifth aspect of the present invention, in the brake control device according to the fourth aspect, the turning radius calculating means d11 calculates the vehicle mass as m, the wheelbase as L, and the distance between the vehicle center of gravity and the front axle as Lf. The distance between the center of gravity of the vehicle and the rear axle is Lr, the tire cornering force per front wheel is Kf, the tire cornering force per rear wheel is Kr, the running speed of the vehicle is V, the steering angle of the front wheels is δ, When the turning radius is ρ and the pseudo vehicle speed is Vi, ρ = ｛1− (m / 2L ² ) [(Lf · Kf−Lr · K)
r) / Kf · Kr] V ² ｝ × (L / δ), and the lateral acceleration estimating means d1
Is preferably configured to determine the estimated lateral acceleration YGS by an arithmetic expression of YGS = Vi ² / ρ. Therefore, in the devices according to the fourth and fifth aspects, the lateral acceleration can be easily estimated by the existing sensor.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a configuration diagram showing a main part of the brake device according to the embodiment, in which 1 is a master cylinder. The master cylinder 1 is configured to generate a hydraulic pressure when a driver operates a brake pedal (not shown).

The master cylinder 1 includes a brake circuit 2
Through the wheel cylinder 3. And
In the middle of the brake circuit 2, the upstream (master cylinder 1 side) and the downstream (wheel cylinder 3 side) of the brake circuit 2 communicate with each other to increase the brake fluid pressure of the wheel cylinder 3 (actually, the pressure increase state). Does not only increase the pressure, but also reduces the pressure when the master cylinder pressure decreases), releases the brake fluid from the wheel cylinder 3 to the drain circuit 4 to reduce the wheel cylinder pressure, A switching valve 5 is provided that can be switched to a holding state in which the brake fluid pressure of the wheel cylinder 3 is shut off by switching off.
Therefore, the hydraulic pressure of the wheel cylinder 2 can be arbitrarily increased or decreased based on the switching of the switching valve 5.

The drain circuit 4 is provided with a reservoir 6 capable of storing brake fluid. A pump 7 is provided for returning the brake fluid stored in the reservoir 6 to a position upstream of the switching valve 5 in the brake circuit 2.

In FIG. 2 described above, the configuration of the range surrounded by the dashed line is combined as one brake unit 11. Although FIG. 2 illustrates the configuration of one wheel, the overall configuration is as shown in FIG. 3, and the brake unit 11 includes four wheels FR, FL, R
The brake fluid pressure of each of the R and RL wheel cylinders 3 (not shown in FIG. 3) can be arbitrarily controlled.

The operation of the switching valve 5 and the pump 7 in the brake unit 11 is controlled by a control unit 12. The control unit 12 includes, as input means, wheel speed sensors 13, 13, 13, 13 for detecting rotation speeds of the wheels FR, FL, RR, RL; a steering angle sensor 14 for detecting a steering angle; A lateral G sensor 15 for detecting the generated lateral acceleration (hereinafter referred to as lateral G) is provided to execute ABS control for preventing wheel lock during braking.

Next, the ABS control according to the first embodiment will be described. FIG. 4 is a flowchart showing the flow of the ABS control according to the first embodiment. First, in step 101, after performing a predetermined initialization, step 10 is executed.
In step 2, a signal is read from each wheel speed sensor 13 to calculate a wheel speed Vw for each wheel.

In step 103, a pseudo vehicle speed Vi is calculated from the wheel speeds Vw of the four wheels. The details will be described later with reference to FIG. In the following step 104, the decompression threshold value λ1 is calculated. Incidentally, the pressure reduction threshold value λ1 is a value somewhat lower than the pseudo vehicle body speed Vi, and corresponds to the wheel speed at which the braking force can be obtained most efficiently.

In step 105, the steering angle δ and the lateral acceleration YG detected by the steering angle sensor 14 and the lateral G sensor 15 are fetched, and in step 106, the turning determination flag is set. This setting process will be described later with reference to the flowchart of FIG. 6, but it is determined whether or not the vehicle is turning normally, and if it is determined that the vehicle is turning normally, the turning determination flag is set to 1 and it is determined that the vehicle is turning abnormally. At times, the turning determination flag is reset to zero.

In the next step 107, a control switching process is executed. This control switching process is a process for selecting either the four-wheel independent control or the rear wheel select low control.
It will be described later based on the flowchart of FIG.

In step 108, a pressure increasing / decreasing process is executed. That is, based on whether the four-wheel independent control or the rear wheel select low, it is determined which of the pressure reduction, the holding, and the pressure increase is to be executed based on a comparison between each wheel speed Vw and the pressure reduction threshold value λ1, A process for outputting to the switching valve 5 is performed according to the determination result. Since the pressure increasing / decreasing process is a known control, a detailed description thereof will be omitted.

In step 109, it is determined whether or not 10 ms has elapsed, and the process returns to step 102 after 10 ms has elapsed. That is, in the present embodiment, the above flow is set to 10
This is executed every time ms elapses.

Next, based on the flowchart of FIG.
A method for obtaining the pseudo vehicle speed Vi in step 103 will be described. In step 1001, it is determined whether or not the ABS control is being executed based on whether or not the ABS flag AS has been set (= 1) last time (10 ms before). The selected wheel speed Vfs that selects the highest value from among the two wheel speeds Vw (select high) is defined as the pseudo vehicle body speed Vi. Note that the select wheel speed Vfs may be another value such as the second highest value instead of the select high (highest value). On the other hand, if the ABS control is being performed in step 1001, the process proceeds to step 1003, where
It is determined whether or not (A) is under non-ABS control. YES, that is, at the start of the ABS control, the routine proceeds to step 1004, where the pseudo vehicle speed Vi is set to the reference speed V0, and the timer is reset. In step 1005, the timer is counted for each control cycle. In step 1006, the branch judgment between the pseudo vehicle body speed Vi and the selected wheel speed Vfs is made based on whether or not FVP = 1. Step 100
7, the pseudo body speed Vi at that time is changed to the branch speed V
Let p.

Next, in steps 1008 to 1010, a pseudo vehicle acceleration / deceleration Vid is formed.
In step 1008, it is determined whether or not the first cycle of the ABS control or the second cycle or later is based on whether or not FCYCLE = 0. In the first cycle, since the deceleration is not known, the process proceeds to step 1010. The pseudo vehicle acceleration / deceleration Vid is set based on the value Vidp assuming the maximum acceleration / deceleration of the vehicle when the road surface μ is large. On the other hand, after the second cycle, the process proceeds to step 1009,
The deceleration Vid per control cycle is set using the values of the reference speed V0, branch speed Vp, and count timer T0 obtained in steps 1004, 1005, and 1007.

In the following step 1011, the pseudo vehicle speed Vi is calculated based on the pseudo vehicle speed Vi 10 ms before (10 ms before) and the pseudo vehicle acceleration / deceleration Vid. Further, in step 1012, the magnitude relationship between the pseudo vehicle speed Vi and the selected wheel speed Vfs is determined. If the selected wheel speed Vfs is larger, the process proceeds to step 101.
Proceeding to 3, the selected wheel speed Vfs is set to the pseudo vehicle speed Vi.

As described above, the pseudo vehicle speed Vi is determined by the ABS
When the control is not executed, it is formed from the selected wheel speed Vfs. In the ABS control, the first cycle is estimated based on a preset deceleration Vidp at the time of rapid deceleration. Estimation is performed based on an actual deceleration state based on T0 and the like. When the selected wheel speed Vfs is larger than the estimated value, the estimated wheel speed is formed by the selected wheel speed Vfs.

Next, the process of setting the turning determination flag in step 106 will be described with reference to FIG. First, in step 1061, it is determined whether or not the process is the first cycle of the ABS control. If YES, that is, if it is the first cycle, the process proceeds to step 1066 to execute the process of setting the turning determination flag = 0. When this turning determination flag is 0, the high μ
Indicates that the vehicle is turning normally on the road. On the other hand, when the turning determination flag is 1, it indicates that the vehicle is not turning normally, such as an oversteer state or a spin state, even when the vehicle is turning on a split road or on a high μ road.

Next, in step 1061, NO, ie, in the second and subsequent cycles of the ABS control, step 10
The program then proceeds to 62 to determine whether or not the absolute value of the steering angle detected by the steering angle sensor 14 is larger than a preset turning determination constant MANGL, that is, whether or not the turning operation is being performed. If so, step 1063
If the answer is NO, that is, if the vehicle is almost traveling straight, the process proceeds to step 1065.

In step 1063, the lateral acceleration occurring in the vehicle is estimated (this is estimated lateral acceleration YGS).

Here, the estimation of the lateral acceleration YGS will be described. First, the turning radius ρ is given by ρ = ｛1− (m / 2L ² ) [(Lf · Kf−Lr · K)
r) / Kf · Kr] V ² ｝ × (L / δ). Note that m is the vehicle mass, L is the wheelbase, Lf is the distance between the vehicle center of gravity and the front axle, Lr is the distance between the vehicle center of gravity and the rear axle, Kf is the tire cornering force per front wheel, and Kr is the rear. The tire cornering force per wheel, V is the running speed of the vehicle, and δ is the steering angle of the front wheels.

Then, when the turning radius ρ is obtained, the lateral acceleration can be obtained from Vi ² / ρ. Therefore, YGS = Vi ² / ρ.

Next, in step 1064, step 1
063, the estimated lateral acceleration YGS obtained in step 063 and the lateral G sensor 1
5 is compared with the detected lateral acceleration YG. If YG ≦ YGS, the routine proceeds to step 1066, where the turning determination flag = 0.
And if YG> YGS, step 1065
To set the turning determination flag = 1.

Next, the control switching process in step 107 will be described in detail with reference to the flowchart in FIG. Step 1
At 071, it is determined whether or not the turning determination flag is 0, that is, whether or not the vehicle is in an abnormal turning state. If YES, that is, if the turning is abnormal, the process proceeds to step 1072, and NO
That is, in the normal turning state, the process proceeds to step 1073 to execute the four-wheel independent control.
Let WC be the wheel speed VW detected by the wheel speed sensor 13 (in this document, the reference sign indicating each target wheel is omitted).

On the other hand, in the abnormal turning state, it is determined in step 1072 whether or not the wheel speed VWRL of the left rear wheel is equal to or higher than the wheel speed VWRR of the right rear wheel. If YES, that is, if VWRL ≧ VWRR, Proceeding to step 1074, the detected wheel speeds VWCFR and FL of the front wheels are set to the detected wheel speeds VWFR and FL of the respective wheels, but the control wheel speeds VWCRL and VWCRR of the rear wheels are all lower values. A process for setting the detected wheel speed VWRR of a certain right rear wheel is performed. On the other hand, if NO in step 1075, that is, if VWRL <VWRR, processing is performed to set the detected wheel speed VWRL of the left rear wheel, which is a lower value for the rear wheels, independent of the front wheels.

Next, the operation of the first embodiment will be described with reference to FIGS.
It will be described based on. A case where braking is performed during turning will be described. At the time of turning, as shown in FIG. 8, the wheel speed Vw of the turning inner wheel (indicated by a dotted line in the figure) is the wheel speed Vw of the turning outer wheel.
(Shown by a solid line in the figure). At this time, since the pseudo vehicle speed Vi is determined based on the select high value, it becomes equal to the wheel speed Vw of the turning outer wheel.

When the ABS control is executed, at the time of turning, the turning determination flag is set in step 107 based on the steering angle δ, the lateral acceleration YG, and the pseudo vehicle speed Vi, and the spin on the high μ road is performed. When the vehicle is turning normally without occurrence of oversteering, the turning determination flag is set to 1, and the four-wheel independent control is executed in the second and subsequent cycles from the start of the ABS control. This 4
In the wheel independent control, the decompression threshold λ is independently set for each wheel.
Since the ABS control is performed based on the comparison with the first wheel, the turning inner wheel is rotating at a lower speed than the turning outer wheel, so that the pressure is reduced frequently. Therefore, the wheel cylinder pressure Pw / c is In this figure, the pressure of the turning inner wheel indicated by the dotted line is lower than the pressure of the turning outer wheel indicated by the solid line in FIG.

By this four-wheel independent control, the maximum braking force is generated in each wheel, and the braking distance can be shortened.

On the other hand, when turning on the split μ road,
Alternatively, during an abnormal turn such as a spin state of the vehicle, the estimated lateral acceleration YGS based on the difference between the left and right wheel speeds Vw.
Is different from the detected lateral acceleration YG detected by the lateral G sensor 15. Specifically, as shown in FIG. 10, the value of the estimated lateral acceleration YGS becomes smaller than the detected lateral acceleration YG. . As a result, the turning determination flag is not set, and the control wheel speed VWC is formed for the two rear wheels in accordance with the low wheel speed. Therefore, pressure reduction and pressure increase are performed at the same timing on the left and right, and the wheel cylinder pressures Pw / c become equal. As a result, the same control is performed for different wheel speeds. As a result, the turning outer wheel that rotates at a high speed has a smaller braking force than the four-wheel independent control and has a value close to the pseudo vehicle speed Vi. Since the left and right braking forces are generated evenly, the vehicle posture does not become unstable due to the difference between the left and right braking forces.

Although the embodiment has been described with reference to the drawings, the present invention is not limited to the configuration of this embodiment, and any change in the configuration within the scope of the present invention is possible. It is possible. For example, in the embodiment, AB
Conventionally known control in which control is executed based on the pressure reduction threshold value λ1 during the S control has been described. However, a certain target value (a value close to the pressure reduction threshold value) is calculated, and the wheel speed converges to this target value. May be configured to execute the control as described above. in this case,
The braking distance can be shortened.

[0045]

As described above, according to the present invention,
When turning while the ABS control is being performed, when the road surface μ in the left and right wheels is turning normally without spinning on a uniform high μ road, the estimated lateral G and the lateral G that are actually detected.
Based on this, it is determined that the vehicle is turning normally, and control according to this can be accurately performed. On the other hand, when turning on a split μ road or during an abnormal turn such as when the vehicle is spinning, an abnormal turn is performed based on the estimated lateral G and the detected lateral G that is actually detected. Judgment can be made, and control according to this can be appropriately performed. As described above, it is possible to execute the control appropriately in accordance with the turning state, and it is possible to improve the control quality of the ABS control.

According to the second aspect of the present invention,
If the vehicle turns while the ABS control is being executed, and if it is determined that the vehicle is turning abnormally, the rear wheel select low control is executed to prevent spin due to uneven braking force on the left and right sides and stabilize the vehicle posture. On the other hand, in the case of a normal turn, the control means d can execute the four-wheel independent control to reduce the braking distance, to stabilize the vehicle posture on the split μ road, and And shortening of the braking distance can be achieved.

According to the third aspect of the present invention,
Even when the vehicle is traveling straight, when the ABS control is executed on the split μ road, the braking forces on the left and right of the rear wheels are equalized, and the vehicle posture can be stabilized.

According to the fourth and fifth aspects of the present invention, the lateral acceleration can be easily estimated by using the existing sensor.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims showing a brake control device of the present invention.

FIG. 2 is a configuration diagram showing a main part of the embodiment.

FIG. 3 is an overall view showing a brake control device according to the embodiment.

FIG. 4 is a flowchart of ABS control according to the embodiment.

FIG. 5 is a flowchart for obtaining a pseudo vehicle speed according to the embodiment;

FIG. 6 is a flowchart illustrating a setting process of a turning determination flag according to the embodiment;

FIG. 7 is a flowchart illustrating a control switching process according to the embodiment;

FIG. 8 is an explanatory diagram of an operation.

FIG. 9 is a time chart when four-wheel independent control is executed.

FIG. 10 is an explanatory diagram of an operation.

FIG. 11 is a time chart when the rear wheel select low control is executed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Master cylinder 2 Brake circuit 3 Wheel cylinder 4 Drain circuit 5 Switching valve 6 Reservoir 7 Pump 11 Brake unit 12 Control unit 13 Wheel speed sensor 14 Steering angle sensor 15 Lateral G sensor

Claims (5)

[Claims] 1. A brake fluid pressure for braking each wheel of a vehicle,
A brake unit that can be controlled independently of each other, a vehicle speed detecting unit that includes a wheel speed sensor that detects a wheel speed of each wheel, and a vehicle behavior detecting unit that detects a vehicle behavior; and an estimated vehicle speed based on an input from each wheel speed sensor. A brake control device comprising: pseudo vehicle speed calculating means for obtaining a pseudo vehicle speed; and control means for executing ABS control for operating a brake unit to prevent wheel lock based on the pseudo vehicle speed and the wheel speed. In the above, the control means may include a lateral acceleration estimating means for estimating a lateral acceleration occurring in the vehicle, a lateral acceleration estimated by the lateral acceleration estimating means, and a detection detected by a lateral acceleration sensor included in the vehicle behavior detecting means. If the difference between the two is less than a predetermined value, it is determined that the vehicle is turning normally in accordance with the steering angle. If the difference is equal to or more than a predetermined value, the vehicle is turning abnormally. And a comparison determining means for determining that the vehicle is in the middle. The control means is configured to switch control between a normal turning determination and an abnormal turning determination during the ABS control. apparatus. 2. The control means executes four-wheel independent control for performing fluid pressure control independently of each of the four wheels at the time of ABS control at the time of normal turning determination, and performs the preceding two at the time of abnormal turning determination.
The hydraulic pressure is controlled independently for each wheel,
2. The brake control device according to claim 1, wherein the brake control device is configured to execute a rear wheel select low control for performing a hydraulic control suitable for a wheel having a lower wheel speed among the rear two wheels. . 3. The brake control device according to claim 2, wherein the control means executes rear wheel select low control when the vehicle is not turning. 4. The vehicle control apparatus according to claim 1, wherein the lateral acceleration estimating unit is configured to calculate a steering angle based on a steering angle detected by a steering angle sensor included in the vehicle behavior detecting unit and the pseudo vehicle speed obtained by the pseudo vehicle speed calculating unit.
4. The brake control device according to claim 1, further comprising a turning radius calculating means for calculating a turning radius, wherein a lateral acceleration generated in the vehicle is estimated based on the turning radius. . 5. The turning radius calculation means includes a vehicle mass m, a wheel base L, a distance between the vehicle center of gravity and the front axle Lf, a distance between the vehicle center of gravity and the rear axle Lr, and a front wheel per wheel. Where Kf is the tire cornering force, Kr is the tire cornering force per rear wheel, V is the running speed of the vehicle, δ is the steering angle of the front wheels, ρ is the turning radius, and Vi is the pseudo vehicle speed. ｛1− (m / 2L ² ) [(Lf · Kf−Lr · K)
r) / Kf · Kr] V ² ｝ × (L / δ), and the lateral acceleration estimating means obtains the estimated lateral acceleration YGS by the following equation: YGS = Vi ² / ρ. 5. The brake control device according to claim 4, wherein the brake control is performed.