JP3275646B2 - Vehicle 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 suppresses and reduces undesirable behaviors such as drift-out and spin during turning of a vehicle such as an automobile equipped with an ABS (anti-lock brake system) by controlling braking force. The present invention relates to a braking force control device.

[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 Patent Application Laid-Open No. Hei 3-4545.
As disclosed in Japanese Patent Publication No. 3 (2003), a steering amount detecting means, a vehicle speed detecting means, a yaw rate detecting means, a limit vehicle speed detecting means for obtaining a tire grip limit vehicle speed according to the steering amount, a steering amount and a tire grip The vehicle has target yaw rate setting means for obtaining a target yaw rate corresponding to a limit vehicle speed, and braking means provided for each wheel. When the vehicle speed exceeds the tire grip limit vehicle speed, the yaw rate approaches the target yaw rate. 2. Description of the Related Art A behavior control device configured to control a braking force of a turning inner wheel and an outer wheel so that a vehicle speed decreases to a limit vehicle speed is conventionally known.

According to such a behavior control device, the vehicle can always be run in the grip area of the tires, and the yaw rate is prevented from exceeding the target yaw rate, thereby undesirably causing the vehicle to spin or drift out. Turning behavior can be prevented.

[0004]

Generally, a target slip ratio of a braking force control wheel is calculated based on a turning behavior of a vehicle, and a target wheel speed of the braking force control wheel is calculated based on the target slip ratio. When the wheel speed is controlled to be the target wheel speed, a reference wheel speed is required. Therefore, at least one wheel (reference wheel) does not control the braking force even during the behavior control, the wheel speed of the specific wheel is used as the reference wheel speed, and the control is performed based on the reference wheel speed and the target slip ratio.
Calculation of a target wheel speed of a power control wheel is performed.

However, in the case where the conventional braking force control device as described in the above publication is applied to an ABS-equipped vehicle, if the driver performs a relatively sharp braking operation during turning of the vehicle. Since the braking force of the reference wheel also increases relatively sharply, the reference wheel may be subjected to ABS control. Since the reference wheel is ABS control reference wheel velocity is disturbed, the reference wheel
The braking force of the braking force control wheel by the behavior control executed based on the speed is also disturbed, and especially when the reference wheel speed decreases rapidly, the actual slip ratio of the braking force control wheel rapidly increases and the braking force suddenly increases. There is a problem that the behavior control is not properly performed.

[0006] The present invention has been made in view of the in above-mentioned problems of the conventional braking force control-type behavior control apparatus, the main object of the present invention, reference wheel, i.e. the behavior control JP
If a certain non-braking force control wheel is subjected to ABS control ,
By limiting the reduction of the reference wheel speed calculated based on the wheel speed of a specific non-braking force control wheel, it is possible to prevent the braking force of the braking force control wheel from becoming excessive even when the reference wheel is subjected to ABS control. And control the turning behavior of the vehicle well.

[0007]

According to the present invention, there is provided an ABS control means for controlling a braking force of a wheel to prevent the wheel from locking when the wheel tends to lock. And a behavior control means for controlling the braking force of the control wheels when the turning behavior of the vehicle becomes unstable, thereby stabilizing the turning behavior of the vehicle. The behavior control means controls the braking force by the behavior control. Certain wheels not controlled
The reference wheel speed is determined based on the wheel speed of the reference wheel.
And the reference wheel based on a turning behavior state of the vehicle.
Means for determining a target slip rate of the braking force control wheel with respect to speed; means for determining a target wheel speed of the braking force control wheel based on the target slip rate and the reference wheel speed; Means for controlling the braking force to achieve the target wheel speed, a means for determining whether or not the braking force is controlled by the ABS control means for the reference wheel, Means for limiting a decrease in the reference wheel speed when it is determined that the braking force is controlled by the ABS control means for the reference wheel. Achieved.

[0008] According to the above configuration, the braking is performed by the behavior control.
A specific wheel whose force is not controlled is set as a reference wheel, it is determined whether or not the braking force is controlled by the ABS control means for the reference wheel, and it is determined that the braking force is controlled by the ABS control means for the reference wheel. In this case, the amount of decrease in the reference wheel speed is limited, so even if the wheel speed of the reference wheel suddenly decreases, the reference wheel speed does not decrease rapidly, and therefore the actual slip ratio of the braking force control wheel sharply increases. Thus, a sudden increase in the braking force is reliably prevented. According to the present invention,
Then, in the configuration of claim 1, the reference wheel speed
The means for limiting the amount of decrease is the AB for the reference wheel.
It is determined that the braking force is not controlled by the S control means.
The braking force is controlled by the ABS control means.
Of the reference wheel speed to be executed when it is determined that
It is configured not to limit the amount of reduction.

[0009]

According to a preferred aspect of the present invention, the behavior control means controls the braking force control wheel when the spin state amount indicating the turning behavior of the vehicle is equal to or larger than a reference value. The reference wheel is a turning inside front wheel, and the braking force control wheel includes at least a turning outside front wheel.

According to another preferred aspect of the present invention, the means for limiting the reduction amount of the reference wheel speed changes the vehicle speed when the reduction rate of the reference wheel speed exceeds the reference value. The lowering of the reference wheel speed is limited by correcting based on the estimated speed of the vehicle or the acceleration of the vehicle.

[0011]

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

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of one embodiment of a braking force control device according to the present invention.

In FIG. 1, a braking device 10 includes 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 an oil pressure in the master cylinder. And a hydraulic booster 16 for increasing the brake oil to a pressure (regulator pressure) corresponding to the pressure. Master cylinder 1
The first port 4 is a brake hydraulic control conduit 18 for the front wheels.
The second port is connected to a three-port two-position switching type for left and right rear wheels by a rear wheel brake hydraulic control conduit 26 having a proportional valve 24 on the way. It is connected to an electromagnetic control valve 28. The control valve 28 is connected by a conduit 30 to a brake hydraulic control device 32 for the left rear wheel and a brake hydraulic control device 34 for the right rear wheel.

The braking device 10 has an oil pump 40 that pumps up brake oil stored in the reservoir 36 and supplies it to the high-pressure conduit 38 as high-pressure oil. The high-pressure conduit 38 is connected to the hydro booster 16, and is also connected to a front-wheel switching valve 42 and a rear-wheel switching valve 44.
An accumulator 46 that accumulates high-pressure oil discharged from the accumulator as an accumulator pressure is connected. As shown, the switching valves 42 and 44 are also three-port two-position switching type electromagnetic switching valves.

The brake hydraulic control devices 20 and 22 for the front left and right wheels respectively include wheel cylinders 48FL and 48FR for controlling braking force on the corresponding wheels, electromagnetic control valves 50FL and 50FR of a three-port two-position switching type, and a reservoir. Low pressure conduit 5 as return passage connected to 36
The normally open solenoid-operated on-off valves 54FL and 54FR and the normally-closed electromagnetic on-off valves 56FL and 56FL provided in the middle of the regulator pressure supply conduit 53 connected between the hydraulic pump 2 and the discharge port of the hydro booster 16. 56FR. The regulator pressure supply conduit 53 between the on-off valves 54FL, 54FR and the on-off valves 56FL, 56FR respectively has connection conduits 58FL, 58
FR is connected to control valves 50FL and 50FR.

A brake hydraulic control device 32 for left and right rear wheels,
Reference numeral 34 denotes a normally-open electromagnetic on-off valve 60RL, 60 provided between the control valve 28 and the low-pressure conduit 52 in the middle of the conduit 30.
RR and normally closed solenoid-operated on-off valves 62RL, 62RR, and wheel cylinders 64RL, 64RR for controlling braking force on the corresponding wheels, respectively.
RL and 64RR are connected to the conduit 30 between the on-off valves 60RL and 60RR and the on-off valves 62RL and 62RR by connecting conduits 66RL and 66RR, respectively.

The control valves 50FL and 50FR are respectively a brake hydraulic control conduit 18 for the front wheels and a wheel cylinder 48FL.
And 48FR and wheel cylinder 48FL
, 48FR and the connection conduits 58FL and 58FR, the first position shown in the figure, the brake hydraulic control conduit 18 and the wheel cylinders 48FL and 48FR are disconnected, and the wheel cylinders 48FL and 48FR are connected to the connection conduit 58FL.
, And 58FR.

A regulator pressure supply conduit 68 for the left and right rear wheels is connected between the regulator pressure supply conduit 53 and the left and right rear wheel control valves 28, and the control valves 28 are respectively brake oil pressure control conduits for the rear wheels. 26 and on-off valve 60RL, 60RR
, And the first position shown in the drawing for interrupting the communication between the on-off valves 60RL, 60RR and the regulator pressure supply conduit 68, the brake hydraulic control conduit 26 and the on-off valves 60RL, 60RR.
And the switching to the second position where the on-off valves 60RL, 60RR and the regulator pressure supply conduit 68 are connected.

The control valves 50FL, 50FR, and 28 function as master cylinder pressure shutoff valves, and when these control valves are at the first position shown in the figure, the wheel cylinders 48FL, 48FR
FR, 64RL, 64RR are connected in communication with conduits 18, 26,
By supplying the master cylinder pressure to each wheel cylinder, the braking force of each wheel is controlled according to the amount of depression of the brake pedal 12 by the driver, and the control valves 50FL, 50FL
When 0FR, 28 is in the second position, each wheel cylinder is shut off from the master cylinder pressure.

The switching valves 42 and 44 have a function of switching the hydraulic pressure supplied to the wheel cylinders 48FL, 48FR, 64RL and 64RR between the accumulator pressure and the regulator pressure. Is switched to the second position and the on-off valves 54FL, 54FR, 60RL, 60
When the switching valves 42 and 44 are maintained at the illustrated first positions while the RR and the on-off valves 56FL, 56FR, 62RL, and 62RR are at the illustrated positions, the wheel cylinder 48FL,
By supplying the regulator pressure to the 48FR, 64RL, and 64RR, the pressure in each wheel cylinder is controlled by the regulator pressure, whereby the braking of that wheel is performed regardless of the amount of depression of the brake pedal 12 and the braking pressure of the other wheels. The pressure is controlled in a pressure increase mode by a regulator pressure.

Even if each valve is switched to the pressure increasing mode by the regulator pressure, when the pressure in the wheel cylinder is higher than the regulator pressure, the oil in the wheel cylinder flows backward, and the control mode is the pressure increasing mode. Nevertheless, the actual braking pressure decreases.

The control valves 50FL, 50FR, 28 are switched to the second position, and the on-off valves 54FL, 54FR, 60RL,
When the switching valves 42 and 44 are switched to the second position with the 60RR and the opening / closing valves 56FL, 56FR, 62RL, and 62RR in the illustrated positions, the wheel cylinders 48FL, 48F
By supplying the accumulator pressure to R, 64RL, and 64RR, the pressure in each wheel cylinder is controlled at an accumulator pressure higher than the regulator pressure, thereby affecting the amount of depression of the brake pedal 12 and the braking pressure of other wheels. Instead, the braking pressure of the wheel is controlled in the pressure increasing mode by the accumulator pressure.

Further, with the control valves 50FL, 50FR, 28 switched to the second position, the on-off valves 54FL, 54FR, 6
0RL and 60RR are switched to the second position, and the on-off valve 56F
When L, 56FR, 62RL, and 62RR are controlled to the state shown in the figure, the pressure in each wheel cylinder is maintained regardless of the positions of the switching valves 42 and 44, and the control valves 50FL, 50FR, 28
Are switched to the second position and the on-off valves 54FL, 5FL
4FR, 60RL, 60RR and open / close valve 56FL, 56FR, 62
When RL and 62RR are switched to the second position, the switching valve 42
The pressure in each wheel cylinder is reduced irrespective of the positions of and 44, whereby the braking pressure of the wheel is controlled in the reduced pressure mode regardless of the amount of depression of the brake pedal 12 and the braking pressure of the other wheels.

Switching valves 42 and 44, control valves 50FL, 50
FR, 28, on-off valves 54FL, 54FR, 60RL, 60RR and on-off valves 56FL, 56FR, 62RL, 62RR are controlled by an electric control device 70 as described later in detail. The electric control device 70 includes a microcomputer 72 and a drive circuit 74. The microcomputer 72 includes, for example, a central processing unit (CPU), a read-only memory (ROM), not shown in detail in FIG. , A random access memory (RAM), and an input / output port device, which may be connected to each other by a bidirectional common bus.

A signal indicating the vehicle speed V from the vehicle speed sensor 76, a signal indicating the lateral acceleration Gy of the vehicle body from a lateral acceleration sensor 78 provided substantially at the center of gravity of the vehicle body, a yaw rate sensor 80 A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θ from the steering angle sensor 82, a signal indicating the longitudinal acceleration Gx of the vehicle body from a longitudinal acceleration sensor 84 provided substantially at the center of gravity of the vehicle body, the wheel speed sensors 86FL From 86RR, the wheel speeds (peripheral speeds) VFL, VFR, VRL, V
A signal indicating RR is input. The lateral acceleration sensor 78, the yaw rate sensor 80, and the like detect lateral acceleration and the like with the left turning direction of the vehicle as positive, and the longitudinal acceleration sensor 84 detects longitudinal acceleration with the acceleration direction of the vehicle as positive.

The ROM of the microcomputer 72 stores the control flow shown in FIGS. 2 and 3 and the map shown in FIG. 4 as described later, and the CPU performs various operations based on the parameters detected by the various sensors as described later. And the spin value S for determining the turning behavior of the vehicle
V is obtained, the turning behavior of the vehicle is estimated and controlled based on the spin value, and the ABS control is performed on the braking force of each wheel.

The ABS control itself does not constitute the gist of the present invention, and is well known in the art as long as the wheels tend to lock, controlling the braking force of the wheels to prevent the wheels from locking. The control content may be any of the control contents described above, and therefore a detailed description of the ABS control will be omitted.

Next, the turning behavior control routine of the vehicle 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, at step 10, the vehicle speed sensor 7
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 spin value SV is calculated as a linear constant a * β + b * βd of the slip angle β and the slip angular velocity βd of the vehicle body using a and b as positive constants, respectively. Based on the absolute value of the value SV, a target slip ratio Rsfo of the front wheel on the outside of the turn with respect to a reference wheel speed Vb described later is calculated from a map corresponding to the graph shown in FIG.

In step 50, the target slip ratio R
It is determined whether or not sfo is 0, that is, whether or not the turning behavior of the vehicle is in a stable state and the behavior control is unnecessary. If the determination is affirmative, the process returns to step 10 and returns to the negative. When the determination is made, the process proceeds to step S60.
In step 60, the target wheel speed Vwt of the front wheel on the turning outer wheel side is calculated in accordance with the following equation 1 using Vb as the reference wheel speed calculated by the reference wheel speed calculation routine shown in FIG.

## EQU1 ## Vwt = Vb * (1-Rsfo)

In step 70, the duty ratio Dr
Is calculated according to the following equation (2). In the following equation 2, Vout is the wheel speed of the front wheel on the outside of the turn, and Kp and Kp
d is a proportional constant of a proportional term and a differential term in the wheel speed feedback control.

## EQU2 ## Dr = Kp * (Vout-Vwt) + Kd * d (V
out-Vwt) / dt

Further, in step 70, a control signal is output to the control valve 50FL or 50FR of the turning outer front wheel so that the control valve is switched 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 the wheel cylinder 48FL or 48FR 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 opening / closing valve of the turning outer front wheel is switched to the second position and the downstream side switching 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 upstream and downstream sides are switched to the second position, the brake oil in the corresponding wheel cylinder is discharged to the low-pressure conduit 52, thereby Pressure eel in the cylinder is reduced.

Next, the reference wheel speed calculation routine will be described with reference to the flowchart shown in FIG. FIG. 3
The control according to the flowchart shown in is also started by closing an ignition switch not shown in the figure,
It is repeatedly executed at a predetermined time interval.

First, in step 100, the turning inner wheel is specified from the sign of the yaw rate γ, and in step 110, the steering angle δ of the front wheel is calculated from the steering angle θ and the steering gear ratio, and Vfi is set to the inside of turning. The reference wheel speed Vb is calculated according to the following equation 3 with the front wheel speed as Tr and the tread as tread.

## EQU3 ## Vb = Vfi + γ * Tr * cos δ

In step 120, it is determined whether or not the inside front wheel is under ABS control based on a signal from an ABS control routine (not shown).
When a negative determination is made, the process returns to step 100, and when an affirmative determination is made, in step 130, the reference wheel speed Vb is corrected according to the following equation (4). In the following equation 4, MED means that an intermediate value between the three numerical values in parentheses is selected, and Vb _n-1 is the reference wheel speed calculated in step 130 one cycle before. , G
xy is (Gx ² + Gy ² ) ^1/2 .

[0038]

Vb = MED (Vb, Vbn _-1 + _αu , Vb)
_n-1 + α _d ) Here, Δt is a sampling time, G is a gravitational acceleration, and K is a constant of about 0.3, and α _u = (Gxy + G) * Δt α _d = (Gxy−K * G) * Δt. is there.

Thus, in the illustrated embodiment, the slip value β and the slip angular velocity βd of the vehicle body are calculated in step 20, the spin value SV is calculated as a linear sum of these in step 30, and the step 40 is performed.
In step 50, the target slip ratio Rsfo of the turning outer front wheel, which is the braking force control wheel, is calculated in accordance with the absolute value of the spin value SV, and in step 50, it is determined whether or not the turning behavior of the vehicle is stable. Will be

When the turning behavior of the vehicle is in a stable state, an affirmative determination is made in step 50 to return to step 10, and in this case, step 60
And 70, the braking pressure of each wheel is controlled according to the master cylinder pressure, and therefore the brake pedal depression amount, unless the driver depresses the brake pedal 12 excessively. Is excessive and the wheels tend to lock, ABS control is executed for the wheels.

When the turning behavior of the vehicle is in an unstable state such as spin, a negative determination is made in step 50, and in step 60, the target wheel speed Vwt of the front wheel outside the turning is calculated. In this case, the braking force is controlled so that the wheel speed of the turning outer front wheel becomes the target wheel speed Vwt.

In this case, the target wheel speed Vwt of the front outside wheel calculated at step 60 is calculated based on the reference wheel speed Vb obtained according to the routine of FIG. That is, in step 110, the reference wheel speed Vb of the turning outside front wheel is calculated based on the wheel speed Vfi of the turning inside front wheel which is the reference wheel, and in step 120, it is determined whether or not the turning inside front wheel is under ABS control. Is performed, and the inside front wheel of the turn is AB
If there is no danger that the wheel speed suddenly decreases, not during the S control, the wheel speed calculated in step 110 is set as it is as the reference wheel speed Vb.

On the other hand, when the turning inside front wheel is under the ABS control and there is a possibility that the wheel speed may decrease rapidly,
In step 120, the reference wheel speed Vb is Vb, Vb
decrease amount of the reference wheel speed by being corrected to an intermediate value among the _{n-1 + α u, Vb} n-1 + α d is limited, the front outside wheel target wheel thereby is calculated in step 60 It is reliably prevented that the speed Vwt is suddenly decreased and the braking force of the front wheel on the outside of the turn is controlled to be rapidly increased.

For example, FIG. 5 shows AB in a situation where the braking force control by the behavior control is executed for the front wheels outside the turning direction.
Wheel speed V of the front wheel inside the turn when S control is performed
9 is a graph showing an example of changes in fi, the wheel speed Vfo of the turning outer front wheel, and the target wheel speed Vwt of the turning outer front wheel in the case of the conventional braking force control device (A) and in the case of the embodiment (B). In FIG. 5, t1 indicates the time when the behavior control is started, and t2 indicates the time when the ABS control is started.

As shown in FIG. 5A, in the case of the conventional braking force control device, the wheel speed Vfi (=
Vb) drops sharply, the target wheel speed V of the front wheel on the outside of the turn
wt also sharply decreases, so that the braking force of the turning outer front wheel sharply increases and the wheel speed Vfo also sharply decreases. On the other hand, according to the illustrated embodiment, as shown in FIG. As described above, even if the wheel speed Vfi of the turning inside front wheel suddenly decreases, the reference wheel speed Vb changes gently, and accordingly, the target wheel speed Vwt of the turning outside front wheel also changes gently. It is possible to reliably prevent a sudden increase in the braking force and a sudden decrease in the wheel speed Vfo due to the sudden increase in the braking force.

Also, Japanese Patent Application No. Hei 6-63, filed by the present applicant.
As described in the specification of 246944 and the drawings,
When the turning inside front wheel is under the ABS control, the upper limit of the target slip rate of the turning outside front wheel may be set to be small. However, no matter how small the upper limit of the target slip rate is set, the turning inside which is the reference wheel is turned. When the wheel speed of the front wheels is significantly reduced, the target wheel speed of the turning outer front wheel, which is the braking force control wheel, is also reduced. Therefore, according to the method according to the above-described proposal, the braking force of the braking force control wheel becomes excessive. However, according to the illustrated embodiment, when the wheel speed of the front wheel on the inside of the turn sharply decreases, the amount of decrease in the reference wheel speed Vb is limited. It is possible to reliably and effectively prevent a sudden increase in the braking force of the turning outer front wheel.

According to the illustrated embodiment, the reference wheel speed Vb is corrected to an intermediate value among the three numerical values according to the above equation (4). Even when the speed increases relatively sharply, the amount of increase of the reference wheel speed Vb is limited, and therefore, it is possible to reliably and effectively prevent a sudden decrease in the braking force of the front wheels on the outside of turning.

In the illustrated embodiment, the reference wheel speed V
b is corrected according to the above equation 4,
The reference wheel speed Vb may be corrected according to Equation 5 below, where MAX means selecting the higher value of the two values in parentheses, and the estimated vehicle speed Vs, for example, four wheels The reference wheel speed Vb may be corrected according to the following equation (6), where Vxd is the differential value of the highest wheel speed among the wheel speeds and the lower limit of which is guarded by the longitudinal acceleration Gx.

[0049]

Vb = MAX (Vb, Vbn _-1 + _αu )

## EQU6 ## Vb = MAX (Vb, Vbn _-1 -Vsd * .DELTA.t)

In the illustrated embodiment, the target slip ratio Rs is calculated based on the spin value SV. When the target slip ratio Rs is not zero, a braking force is applied to the front wheel on the outer side of the turn, so that the anti-spin moment is applied to the vehicle. Is provided, whereby the turning behavior of the vehicle is stabilized. For example, a target yaw rate γt is obtained from the vehicle speed and the steering angle, and the inside of the turning is determined in accordance with a shortage of the actual yaw rate γ with respect to the target yaw rate γt. When the yaw moment in the turning assist direction is applied to the vehicle by applying the braking force to the front wheels, thereby controlling the drift-out as turning behavior, the reference wheel may be set to the turning outer front wheel.

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.

[0052]

As is apparent from the above description, according to the present invention, it is specified that the braking force is not controlled by the behavior control.
The wheels of the reference wheel, the braking force by the ABS control unit for the reference wheel is determined whether or not being controlled, the reference wheel velocity when it is determined that the braking force is controlled by the ABS control unit for the reference wheel Is limited, so that even if the reference wheel speed drops rapidly,
Does not decrease sharply, and therefore, it is possible to reliably prevent the actual slip ratio of the braking force control wheel from suddenly increasing and the braking force from increasing sharply, thereby controlling the behavior of the vehicle well. In addition, it is possible to reliably prevent an unnatural change in the behavior of the vehicle due to a sudden increase in the braking force of both the reference wheel and the braking force control wheel and a sudden decrease in the lateral force of these wheels at the same time. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of one embodiment of a braking force control device according to the present invention.

FIG. 2 is a flowchart showing a braking force control routine of the braking force control device according to the present invention.

FIG. 3 is a flowchart showing a reference wheel speed calculation routine of the braking force control device according to the present invention.

FIG. 4 is a graph showing a relationship between an absolute value of a spin value SV and a target slip ratio Rsfo.

FIG. 5 shows the wheel speed Vfi of the turning inside front wheel, the wheel speed Vfo of the turning outside front wheel, and the turning when ABS control is performed in a situation where the braking force control by the behavior control is performed on the turning outside front wheel. 6 is a graph showing an example of a change in the target wheel speed Vwt of the outer front wheel in the case of the conventional braking force control device (A) and in the case of the embodiment (B).

[Explanation of symbols]

 Reference Signs List 10 brake device 14 master cylinder 16 hydro booster 20, 22, 32, 34 brake hydraulic control device 28, 50FL, 50FR control valve 42, 44 switching valve 44FL, 44FR, 64RL, 64RR wheel cylinder 54FL 54FR, 60RL, 60RR ... open / close valve 56FL, 56FR, 62RL, 62RR ... open / close valve 70 ... electric control device 76 ... vehicle speed sensor 78 ... lateral acceleration sensor 80 ... yaw rate sensor 82 ... steering angle sensor 84 ... longitudinal acceleration sensor 86FL-86RR … Wheel speed sensor

Claims (2)

(57) [Claims] An ABS control means for controlling a braking force of a wheel when the wheel tends to lock to prevent the wheel from locking, and a braking force control wheel for behavior control when the turning behavior of the vehicle becomes unstable. by controlling the braking force and a behavior control means for stabilizing the turning behavior of the vehicle, the behavior control means ani
A specific wheel whose braking force is not controlled by dynamic control
Means for obtaining a reference wheel speed based on the wheel speed of the reference wheel
And the reference wheel speed based on the turning behavior of the vehicle.
Means for determining a target slip ratio of the braking force control wheel that,
Means for determining a target wheel speed of the braking force control wheels on the basis of prior SL target slip ratio and the reference wheel speed, the wheel speed of the braking force control wheel and means for controlling the braking force so that the target wheel speed A braking force control device for a vehicle including: a means for determining whether a braking force is controlled by the ABS control means for the reference wheel; and a braking force controlled by the ABS control means for the reference wheel. Means for restricting the amount of decrease in the reference wheel speed when it is determined that there is a vehicle braking force. (2) Means for limiting the amount of decrease in the reference wheel speed
Means the reference wheel is braked by the ABS control means.
When it is determined that the force is not controlled, AB
It is determined that the braking force is controlled by the S control means
Do not limit the amount of decrease in the reference wheel speed
The braking force control for a vehicle according to claim 1, wherein
apparatus.