JPH092234A - Braking force control device - Google Patents

Abstract

PURPOSE: To provide a braking force control device that can positively improve the traveling stability of a vehicle by accurately selecting and setting a wheel to apply braking force to among four wheels of the vehicle. CONSTITUTION: A yaw rate deviation computing part 15 subtracts a target yaw rate γ' computed by a target yaw rate computing part, from an actual yaw rate γ detected by yaw rate sensor 8. A braking wheel judging part 17 selects an inner rear wheel as a braking wheel in the case of the signs of the actual yaw rate γand yaw rate deviation Δγ being different and selects an outer front wheel as a braking wheel in the case of the signs of the actual yaw rate γ and yaw rate deviation Δγ being the same. This constitution can prevent such a state as to apply braking force to the rear wheel to increase a spin state in spite of having a spin tendency and to apply braking force to the front wheel to increase a drift-out state in spite of having a drift-out tendency.

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 for improving vehicle stability by applying braking force to appropriate wheels when cornering a vehicle.

[0002]

2. Description of the Related Art In recent years, a braking force control device has been developed which applies a braking force to appropriate wheels during cornering to improve vehicle stability in view of the force acting on the vehicle during cornering of the vehicle.

For example, Japanese Patent Application Laid-Open No. 2-70561 discloses a braking force control device which controls a rotational movement about a vertical axis passing through the center of gravity of a vehicle, that is, a yaw rate which is an angular velocity of yawing. This technique compares the target yaw rate with the actual yaw rate (actual yaw rate) to determine whether the vehicle's motion state is understeer or oversteer with respect to the target yaw rate. Power is added and corrected, and in the case of oversteer tendency, braking force is applied to the outer wheels to be corrected to improve the running stability of the vehicle.

[0004]

However, in the above-mentioned prior art, for example, when the vehicle has an understeer tendency during cornering and a braking force is applied to the inner front wheel, the wheel is locked due to a reduction in frictional resistance on the road surface. In the case of the tendency, there is a problem that the understeer tendency is increased.
On the contrary, if the steering wheel has an oversteer tendency and a braking force is applied to the outer rear wheel, the oversteer tendency is increased when the wheel has a lock tendency.

On the other hand, as another example showing the selection of the brake wheels,
Japanese Unexamined Patent Publication No. 4-372447 discloses that the braking wheel is selected depending on the steering state, but this technique does not solve the above problem.

The present invention has been made in view of the above circumstances, and it is possible to surely improve the running stability of a vehicle by appropriately selecting and setting the wheels to apply the braking force among the four wheels of the vehicle. An object is to provide a braking force control device.

[0007]

In order to achieve the above object, a braking force control device according to the present invention according to claim 1 is a braking force control device capable of independently controlling the braking force of each of four wheels of a vehicle. Vehicle speed detecting means for detecting, steering angle detecting means for detecting a steering angle, actual yaw rate detecting means for detecting an actual yaw rate of the vehicle, and target yaw rate calculating means for calculating a target yaw rate based on the vehicle speed and the steering angle. And a yaw rate deviation calculating means for calculating the yaw rate deviation by subtracting the target yaw rate from the actual yaw rate, a target braking force calculating means for calculating a target braking force based on the motion state of the vehicle and the yaw rate deviation, and an actual yaw rate and yaw rate deviation. Braking wheel discriminating means for selecting the braking wheel of the vehicle from the above, and the target braking force from the target braking force calculating means is selected by the braking wheel discriminating means. Characterized by comprising a braking signal output means for the signal output to the brake driving unit so as to apply to the wheels.

A braking force control device according to the present invention as defined in claim 2 is the braking force control device according to claim 1, wherein:
The braking wheel discriminating means selects the inner rear wheel as the braking wheel when the signs of the actual yaw rate and the yaw rate deviation are different, and selects the outer front wheel as the braking wheel when the signs of the actual yaw rate and the yaw rate deviation are the same. Characterize.

Further, the braking force control device according to the present invention according to claim 3 is the braking force control device according to claim 1 or 2, wherein the braking wheel discrimination means selects a braking wheel of the vehicle. It is characterized in that the range of the magnitude of the actual yaw rate at which the brake is not applied is preset.

A braking force control device according to a fourth aspect of the present invention is the braking force control device according to the third aspect.
It is characterized in that the range of the actual yaw rate at which the braking wheel of the vehicle is not selected by the braking wheel determination means and the braking is not performed is set to the range of the substantially straight motion state of the vehicle.

[0011]

According to the braking force control apparatus of the present invention, the vehicle speed detecting means detects the vehicle speed, the steering angle detecting means detects the steering angle, and the actual yaw rate detecting means detects the actual yaw rate of the vehicle, that is, the actual yaw rate. Further, the target yaw rate calculation means calculates a target yaw rate based on the vehicle speed from the vehicle speed detection means and the steering angle from the steering angle detection means, and the yaw rate deviation calculation means subtracts the target yaw rate from the actual yaw rate to calculate the yaw rate deviation. To calculate. The target braking force calculation means calculates the target braking force based on the vehicle motion state such as vehicle speed and steering angle and the yaw rate deviation. Further, the braking wheel discriminating means selects the braking wheel from the four wheels that can independently control the braking force based on the actual yaw rate and the yaw rate deviation. Then, the braking signal output means outputs a signal to the brake drive section so that the target braking force from the target braking force calculation means is applied to the braking wheel selected by the braking wheel determination means.

Next, in the braking force control device according to the second aspect, in the braking force control device according to the first aspect, the sign of the actual yaw rate and the yaw rate deviation are used when the braking wheel is selected by the braking wheel determination means. If the signs are different from each other, the inner rear wheel is selected as the braking wheel, and if the signs are the same, the outer front wheel is selected as the braking wheel.

Next, the braking force control device according to claim 3 is the braking force control device according to claim 1 or 2, wherein the actual yaw rate is within a preset range. No braking is selected and no braking is applied.

Next, in the braking force control device according to the fourth aspect, in the braking force control device according to the third aspect, when the magnitude of the actual yaw rate is within a preset range of substantially straight motion state of the vehicle. Does not select the braking wheel of the vehicle and does not brake.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention, FIG. 1 is a functional block diagram of a braking force control device, FIG. 2 is an explanatory diagram showing a schematic configuration of the braking force control device, and FIG. 3 is a braking force control device. FIG. 4 is a flowchart, FIG. 4 is an explanatory diagram of an example of the actual yaw rate and the target yaw rate, and the braking wheels, and FIG.

In FIG. 2, reference numeral 1 denotes a brake drive unit of a vehicle. A master cylinder 3 connected to a brake pedal 2 operated by a driver is connected to the brake drive unit 1, and the driver brakes. When the pedal 2 is operated, the master cylinder 3 causes the four wheels (left front wheel 4fl, right front wheel 4fr,
Left rear wheel 4rl, right rear wheel 4rr) wheel cylinders (left front wheel wheel cylinder 5fl, right front wheel wheel cylinder 5f)
r, the left rear wheel wheel cylinder 5rl, and the right rear wheel wheel cylinder 5rr), brake pressure is introduced to brake and brake the four wheels.

The brake drive unit 1 is a hydraulic unit equipped with a pressure source, a pressure reducing valve, a pressure increasing valve, etc., and each of the wheel cylinders 5fl, 5fr, 5 in response to an input signal.
The brake pressure can be independently introduced to rl and 5rr.

Each of the wheels 4fl, 4fr, 4rl, 4rr has a wheel speed sensor (wheel speed sensor 6fl left front wheel speed sensor 6fr right front wheel speed sensor 6rl left rear wheel speed sensor 6rl,
It is detected by the right rear wheel speed sensor 6rr). Further, a steering wheel angle sensor 7 for detecting a rotation angle of the steering wheel is provided in the steering wheel portion of the vehicle.

Reference numeral 10 indicates a control device formed by a microcomputer, and the control device 10 includes:
The wheel speed sensors 6fl, 6fr, 6rl, 6rr and the steering wheel angle sensor 7 are connected to a yaw rate sensor 8 as an actual yaw rate detecting means formed by combining an acceleration sensor, for example, and a drive signal is output to the brake drive unit 1. To do. The signal from the yaw rate sensor 8 is
For example, it is input to the control device 10 via a 7 Hz low-pass filter.

The control device 10 is, as shown in FIG.
From the vehicle speed calculation unit 11, the steering angle calculation unit 12, the yaw rate steady gain calculation unit 13, the target yaw rate calculation unit 14, the yaw rate deviation calculation unit 15, the target braking force calculation unit 16, the braking wheel discrimination unit 17, and the braking signal output unit 18, Is configured.

The vehicle speed detecting section 11 uses the wheel speeds ω1, ω2, ω from the wheel speed sensors 6fl, 6fr, 6rl, 6rr.
The signals of 3, ω4 are input, and these signals are calculated by preset mathematical expressions (for example, the average value of the speed signals from the wheel speed sensors 6fl, 6fr, 6rl, 6rr is calculated. The vehicle speed V is calculated and output to the yaw rate steady-state gain calculating section 13 and the target braking force calculating section 16 as a vehicle speed detecting means.

The steering angle calculator 12 receives the signal from the steering wheel angle sensor 7 and divides the steering wheel steering angle θ by the steering gear ratio N to obtain the actual steering angle δf (= θ /
N) is calculated and output to the target yaw rate calculation unit 14 and the target braking force calculation unit 16 as a steering angle detection unit.

Further, the yaw rate steady gain calculating section 13 obtains a yaw rate value (yaw rate steady gain Gγδf (0)) with respect to the actual steering angle δf when the vehicle makes a steady circle turn, based on a preset equation. Circuit part,
The calculated yaw rate steady-state gain Gγδf (0) is used as the target yaw rate calculation unit 14 and the target braking force calculation unit 16 described above.
Is output to Here, assuming that the wheel base is L and the stability factor determined by the specifications of the vehicle is A0, the yaw rate steady-state gain Gγδf (0) is calculated by the following equation. Gγδf (0) = 1 / (1 + A0 · V ² ) · V / L (1) Further, the stability factor A0 is defined by the vehicle mass m, the distance between the front axle and the center of gravity Lf, and the distance between the rear axle and the center of gravity. Where Lr is the distance, CPf is the front equivalent cornering power, and CPr is the rear equivalent cornering power. A0 = {- m · (Lf · CPf -Lr · CPr)} / (2 · L 2 · CPf · CPr) ... (2) Also, the target yaw rate calculating section 14, the real from the steering angle calculator 12 The steering angle δf and the yaw rate steady gain Gγδf from the yaw rate steady gain calculation unit 13
Based on (0), the target yaw rate γ ′ is calculated in consideration of the response delay of the vehicle, and the target yaw rate γ ′ is output to the yaw rate deviation calculation unit 15.
That is, the target yaw rate calculation means includes the yaw rate steady gain calculation unit 13 and the target yaw rate calculation unit 1.
4. The target yaw rate γ ′ can be calculated by γ ′ = 1 / (1 + T · s) · Gγδf (0) · δf (3) where T is the time constant and s is the Laplace operator. The above equation (3) is an equation that approximates the response delay of the vehicle expressed by the secondary system to the primary system, and T is a time constant, which is obtained by the following equation, for example. T = m · Lf · V / 2 · L · CPr (4) Further, in the yaw rate deviation calculation unit 15, the target yaw rate calculated by the target yaw rate calculation unit 14 is calculated from the actual yaw rate γ detected by the yaw rate sensor 8. γ '
To obtain the yaw rate deviation Δγ (= γ-γ '),
This is a circuit as a yaw rate deviation calculating means for outputting the yaw rate deviation Δγ to the target braking force calculating section 16 and the braking wheel discriminating section 17.

Further, the target braking force calculation unit 16 considers the vehicle specifications, and based on the vehicle motion state and the yaw rate deviation, the target braking force (front wheel target hydraulic pressure BF2f, rear wheel target hydraulic pressure BF2r). The calculated target hydraulic pressures BF2f and BF2r are output to the braking signal output unit 18 by a circuit as a target braking force calculation means for calculating. The target hydraulic pressure BF2f,
BF2r is calculated by the following equation, for example. BF2f = G1 · (ΔA · 4 · L 2 · CPf · CPr · V) / {(CPf + CPr) / df} · γ ... (5) BF2r = G1 · (ΔA · 4 · L 2 · CPf · CPr · V ) / {(CPf + CPr) / dr} γ (6) where G 1 is the gain, df is the front tread, dr
Indicates a rear tread, and ΔA is ΔA = {δf / (Gγδf (0) · δf + Δγ) −1 / Gγδf (0)} / L · V (7). Note that Δγ in the above equation (7) may be corrected in consideration of the sideslip angle β which is the angle formed by the traveling direction of the vehicle and the front-rear direction.

The braking wheel discriminating unit 17 is a circuit as a braking wheel discriminating means for selecting the braking wheel of the vehicle from the combination of the signs of the actual yaw rate γ and the yaw rate deviation Δγ.
The following combinations are set. The signs of the actual yaw rate γ and the target yaw rate γ ′ are both given by + for the left turning direction and − for the right turning direction of the vehicle.

(Case 1). γ> 0, Δγ <0 ... When the vehicle is turning left and there is an understeer tendency with respect to the target yaw rate γ '... Left rear wheel braking (Case 2). γ> 0, Δγ> 0 ... When the vehicle is turning to the left and there is an oversteer tendency with respect to the target yaw rate γ '... Right front wheel braking (Case 3). γ <0, Δγ <0 ... When the vehicle is turning right and there is an oversteer tendency with respect to the target yaw rate γ '... Left front wheel braking (Case 4). γ <0, Δγ> 0 ... When the vehicle is turning right and there is an understeer tendency with respect to the target yaw rate γ '... Right rear wheel braking (Case 5). When γ = 0 or Δγ = 0, no braking wheel is selected and no braking is applied (FIG. 5).

That is, when the signs of the actual yaw rate γ and the yaw rate deviation Δγ are different, the inner rear wheel is selected as the braking wheel, and the actual yaw rate γ and the yaw rate deviation Δγ are selected.
When the signs are the same, the outer front wheel is selected as the braking wheel. The result of the braking wheel discriminating unit 17 is output to the braking signal output unit 18.

With respect to the brake drive unit 1, the braking signal output unit 18 applies the front wheel target hydraulic pressure BF2f calculated by the target braking force calculation unit 16 to the braking wheel selected by the braking wheel determination unit 17, or It is a circuit as a braking signal output means for outputting a signal so as to apply the rear wheel target hydraulic pressure BF2r. The braking signal output unit 18 is also configured to determine the magnitudes of the values of the actual yaw rate γ and the yaw rate deviation Δγ in a predetermined manner, and also to determine whether or not the braking control is actually performed. Frequent braking is prevented.

Next, the braking force control of the first embodiment will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. This braking force control program is, for example, for a predetermined time (for example, 10 m
s) and the program starts, in step (hereinafter abbreviated as S) 101, from the steering wheel angle sensor 7 to the steering wheel steering angle θ, each wheel speed sensor 6fl, 6fr, 6
The wheel speeds ω1, ω2, ω3, ω4 are read from rl and 6rr, and the actual yaw rate γ is read from the yaw rate sensor 8, and the process proceeds to S102.

In step S102, the steering angle calculator 12 calculates the actual steering angle δf (= θ / N) from the steering wheel angle θ, and the vehicle speed detector 11 calculates the wheel speeds ω1, ω2, ω3, ω.
4, the vehicle speed V is calculated, and the yaw rate steady-state gain calculator 13 calculates the yaw rate steady-state gain Gγδf (0) according to the equation (1).

Next, in S103, the target yaw rate calculating unit 14 calculates the target yaw rate γ'from the equation (3), and in S104, the yaw rate deviation calculating unit 15
The yaw rate deviation Δγ (= γ−γ ′) is calculated at S1, and S1
In 05, the target braking force calculation unit 16 performs the above (5),
The front wheel target hydraulic pressure BF2f and the rear wheel target hydraulic pressure BF2r are calculated based on the equation (6), and the process proceeds to S106.

Hereinafter, steps S106 to S116 are procedures performed by the braking wheel discriminating unit 17. First, in step S106, it is determined whether or not the actual yaw rate γ is larger than 0 (a positive sign), that is, whether or not the vehicle is in a left turning state. If the actual yaw rate γ is 0 or less and the vehicle is not in the left turning state, the process proceeds to S107, and it is determined whether or not the actual yaw rate γ is smaller than 0 (a negative sign), that is, whether the vehicle is in the right turning state. Is determined.
In this S107, when the actual yaw rate γ which is determined not to be the right turning state is 0 (γ = 0), the vehicle is in the straight traveling state,
Proceed to S116.

When it is determined in S106 that the actual yaw rate γ is in the left turning state with a positive sign, the process proceeds to S108, it is determined whether the yaw rate deviation Δγ is 0 (Δγ = 0), and Δγ = If 0, the process proceeds to S116 and Δγ ≠ 0.
In case of, it progresses to S109.

In S109, the sign of the yaw rate deviation Δγ is determined, and if the sign of the yaw rate deviation Δγ is negative and different from the sign of the actual yaw rate γ, there is an understeer tendency with respect to the target yaw rate γ ', so that S110.
Then, the left rear wheel 4rl is selected as a braking wheel to be braked by the rear wheel target hydraulic pressure BF2r obtained in S105 (left rear wheel hydraulic pressure BRL = BF2r).

Further, in S109, the yaw rate deviation Δ
If the sign of γ is the same as the sign of the actual yaw rate γ and is positive,
Since there is an oversteer tendency with respect to the target yaw rate γ ', the routine proceeds to S111, where the right front wheel 4fr is selected as a braking wheel to be braked by the front wheel target hydraulic pressure BF2f obtained at S105 (right front wheel hydraulic pressure BFR = BF2f).

Further, in step S107, the actual yaw rate γ
Is determined to be a right turn state with a negative sign, S11
2, the yaw rate deviation Δγ is determined to be 0 (Δγ = 0), and if Δγ = 0, the process proceeds to S116.
If γ ≠ 0, the process proceeds to S113.

In S113, the sign of the yaw rate deviation Δγ is determined, and if the sign of the yaw rate deviation Δγ is positive and different from the sign of the actual yaw rate γ, there is an understeer tendency with respect to the target yaw rate γ ', so S114.
Then, the right rear wheel 4rr is selected as the braking wheel to be braked by the rear wheel target hydraulic pressure BF2r obtained in S105 (right rear wheel hydraulic pressure BRR = BF2r).

Further, in S113, the yaw rate deviation Δ
If the sign of γ is the same negative as the sign of the actual yaw rate γ, then
Since there is an oversteering tendency with respect to the target yaw rate γ ', the routine proceeds to S115, where the left front wheel 4fl is selected as a braking wheel to be braked by the front wheel target hydraulic pressure BF2f obtained at S105 (left front wheel hydraulic pressure BFL = BF2f).

On the other hand, when the process proceeds from S107, S108 or S112 to S116, no braking wheel is selected and no braking is performed.

Then, the above S110, S111, S11
After performing S4, S115, and S116, S11
7, the braking signal output unit 18 outputs a signal to the brake driving unit 1. That is, the above S11
When the signal of 0 is output, the brake drive unit 1 generates a braking force corresponding to the hydraulic pressure BRL = BF2r on the wheel cylinder 5rl, and when the signal of S111 is output, the brake drive unit 1 is output. Causes the wheel cylinder 5fr to generate a braking force corresponding to the hydraulic pressure BFR = BF2f, and when the signal from S114 is output,
The brake drive unit 1 is for the wheel cylinder 5rr,
When the braking force corresponding to the hydraulic pressure BRR = BF2r is generated and the signal from S115 is output, the brake drive unit 1 causes the hydraulic pressure BFL = B to the wheel cylinder 5fl.
A braking force corresponding to F2f is generated.

An example of the above control is shown in FIG. This figure shows an example of changes in the target yaw rate γ'and the actual yaw rate γ with the movement of the vehicle making a right turn after the left turn. The value of the actual yaw rate γ at the time t0 is delayed at the time t1. Appears.

Due to this delay, γ <γ 'holds until γ = γ' at time t2, and the yaw rate deviation Δγ (= γ-
γ ') <0. This is the case of the left turn (case 1) in FIG. 5, and in this case 1, the left rear wheel 4
The braking force is added to rl and the moment of the arrow is added to correct it, and drift-out is eliminated. In this state, for example, too much braking is applied to the left rear wheel 4rl, and the left rear wheel 4rl
Even when rl shows a lock tendency and loses the lateral force, the vehicle is in the oversteer direction and can generate the yaw rate in the same direction (arrow direction) as the original control law.

After that, until time γ = 0, γ
> Γ ′, and yaw rate deviation Δγ (= γ−γ ′)> 0
Becomes This case is the case of the left turn (case 2) in FIG. 5, and in this case 2, the braking force is applied to the right front wheel 4fr to correct it by adding the moment of the arrow, and the spin is eliminated. In this state, for example, even when the right front wheel 4fr is excessively braked and the right front wheel 4fr shows a locking tendency, and the lateral force is lost, the vehicle is in the understeer direction, which is the same as the original control law ( A yaw rate (arrow direction) can be generated.

Further, γ> γ 'holds until γ = γ' at time t4, and the yaw rate deviation Δγ (= γ-γ ')>
It becomes 0. This case is the case of the right turn (case 4) in FIG. 5, and in this case 4, the braking force is applied to the right rear wheel 4rr and the moment of the arrow is added to correct, and drift out is eliminated. . In this state, for example, even when the right rear wheel 4rr is excessively braked and the right rear wheel 4rr shows a locking tendency, and the lateral force is lost, the vehicle is in the oversteer direction and the original control law is satisfied. The yaw rate in the same direction (arrow direction) can be generated.

After that, until time γ = 0, γ
<Γ ′, and the yaw rate deviation Δγ (= γ−γ ′) <0
Becomes This case is the case of the right turn (case 3) in FIG. 5, and in this case 3, the braking force is applied to the left front wheel 4fl to add the moment of the arrow for correction to eliminate the spin. In this state, for example, even when the left front wheel 4fl is excessively braked and the left front wheel 4fl shows a locking tendency, and the lateral force is lost, the vehicle is in the understeer direction and the same direction as the original control law ( A yaw rate (arrow direction) can be generated.

As described above, according to the first embodiment, the turning direction of the vehicle is determined based on the actual yaw rate, and whether the traveling state is the understeer tendency or the oversteer tendency with respect to the target yaw rate is confirmed based on the actual yaw rate and the yaw rate deviation. Therefore, by selecting the most suitable wheel to be braked among the four wheels, it is possible to reliably prevent the drift-out and the spin. That is, despite the tendency to spin, the braking force is applied to the rear wheels to increase the spin, and the tendency to drift out is applied to the front wheels to increase the drift out. Can be prevented. Further, it is possible to prevent the braking force from being applied to the wheels in the direction of increasing the spin even during counter steering.

Next, FIGS. 6 and 7 show a second embodiment of the present invention, FIG. 6 is a flowchart of the braking force control, and FIG. 7 is an example of the actual yaw rate and the target yaw rate and an explanatory view of the braking wheels. In the second embodiment, in the configuration of the first embodiment, the range of the actual yaw rate in which the braking wheels of the vehicle are not selected and the vehicle is not braked is set in advance to the range of the substantially straight motion state of the vehicle. It is something that should be set.

That is, the following combinations of the actual yaw rate γ and the yaw rate deviation Δγ are set in the braking wheel discriminating section 17. As a set value, ε is a positive number obtained in advance by experiment or calculation, etc. (Case 1). γ> ε, Δγ <0 ... When the vehicle is turning to the left and there is an understeer tendency with respect to the target yaw rate γ '... Left rear wheel braking (Case 2). γ> ε, Δγ> 0 ... When the vehicle is overturning to the target yaw rate γ'in the left turning state ... Right front wheel braking (Case 3). γ <-ε, Δγ <0 ... When the vehicle is turning right and there is an oversteer tendency with respect to the target yaw rate γ '... Left front wheel braking (Case 4). γ <-ε, Δγ> 0 ... When the vehicle is turning right and there is an understeer tendency with respect to the target yaw rate γ '... Right rear wheel braking (Case 5). When ε ≧ γ ≧ −ε or Δγ = 0, no braking wheel is selected and no braking is performed.

That is, in the case of the motion state (substantially rectilinear motion state) indicated by ε ≧ γ ≧ −ε in (Case 5), the braking wheel is not selected and non-braking is performed.
, The actual yaw rate γ and the yaw rate deviation Δγ
If the signs of the two are different, the inner rear wheel is selected as the braking wheel, and if the signs of the actual yaw rate γ and the yaw rate deviation Δγ are the same, the outer front wheel is selected as the braking wheel.

Therefore, the flow chart shown in FIG. 3 of the first embodiment is similar to the flow chart shown in FIG.
After S106 is changed to S201 and S107 is changed to S202, the front wheel target hydraulic pressure BF2f and the rear wheel target hydraulic pressure BF2r are calculated in S105, and then the process proceeds to S201, whether or not the actual yaw rate γ is larger than ε, that is, It is determined whether or not the vehicle is in a left-turning state that is relatively large to some extent, and if the actual yaw rate γ is equal to or less than ε, the process proceeds to S202, and it is determined whether or not the actual yaw rate γ is smaller than −ε, that is, a slightly right-turning. It is determined whether or not the state. This S20
In the range of the actual yaw rate γ (ε ≧ γ ≧ −ε) which is determined not to be a right turn state to some extent in 2, the motion state is a substantially straight motion state, so the process proceeds to S116, and the braking wheel is selected. It will be non-braking without fail. Incidentally, in S201,
If γ> ε and it is determined that the vehicle is turning left to some extent, S
Proceeding to 108, control of the procedure described in the first embodiment is performed thereafter. Similarly, in S202, γ <−ε
Then, if it is determined that the vehicle is in a right turn state that is somewhat large, S112
Then, control of the procedure described in the first embodiment is performed thereafter.

An example of the above control is shown in FIG. This diagram corresponds to FIG. 4 of the first embodiment, and the value of the actual yaw rate γ at time t0 appears after the time t21.
After time t21, γ> ε at time t22, and until a certain amount of left turn is reached until γ = γ ′ at time t23.
<Γ ′, and the yaw rate deviation Δγ (= γ−γ ′) <0
Becomes This case corresponds to the case of the left turn (case 1) of FIG. 5 described in the first embodiment, and in this case 1, the braking force is applied to the left rear wheel 4rl to correct it by adding the moment of the arrow, Eliminate drift out. In this state, for example, braking too much on the left rear wheel 4rl,
Even when the left rear wheel 4rl exhibits a locking tendency and loses the lateral force, the vehicle is in the oversteer direction and can generate the yaw rate in the same direction (arrow direction) as the original control law.

Thereafter, until time t24, γ> γ ', and the yaw rate deviation Δγ (= γ-γ')> 0.
This case is the case of the left turn (case 2) in FIG. 5, and in this case 2, the braking force is applied to the right front wheel 4fr to correct it by adding the moment of the arrow, and the spin is eliminated. In this state, for example, even when the right front wheel 4fr is excessively braked and the right front wheel 4fr shows a locking tendency, and the lateral force is lost, the vehicle is in the understeer direction, which is the same as the original control law ( A yaw rate (arrow direction) can be generated.

Further, the period from time t24 to time t25 to time t26 is the case of the substantially straight-ahead movement state represented by ε ≧ γ ≧ −ε, and no braking wheel is selected and no braking is performed.

Next, γ <−ε at time t26, and γ> γ ′ until a certain right turn until γ = γ ′ at time t27, and the yaw rate deviation Δγ (= γ −γ ′
)> 0. This is the case of the right turn (case 4) in FIG. 5, and in this case 4, the right rear wheel 4rr
The braking force is added to and the moment of the arrow is added to correct it, and drift-out is eliminated. In this state, for example,
Even when the right rear wheel 4rr is excessively braked and the right rear wheel 4rr shows a locking tendency and loses the lateral force, the vehicle is in the oversteer direction and is in the same direction as the original control law (arrow direction). Can generate a yaw rate of.

Thereafter, until time t28, γ <γ ', and the yaw rate deviation Δγ (= γ-γ') <0.
This case is the case of the right turn (case 3) in FIG. 5, and in this case 3, the braking force is applied to the left front wheel 4fl to add the moment of the arrow for correction to eliminate the spin. In this state, for example, even when the left front wheel 4fl is excessively braked and the left front wheel 4fl shows a locking tendency, and the lateral force is lost, the vehicle is in the understeer direction and the same direction as the original control law ( A yaw rate (arrow direction) can be generated.

Further, from the time t28 to the time t30 from the time t29 to the time t30, there is a case where the vehicle is in a substantially linear motion state represented by ε ≧ γ ≧ −ε, and no braking wheel is selected and no braking is performed.

As described above, according to the second embodiment, when it is determined that it is not necessary to control by applying the braking force in the substantially straight traveling state, the brake is worn to reduce the wear of the brake. You can

[0058]

As described above, according to the present invention,
The actual yaw rate is used to determine the turning direction of the vehicle, and the yaw rate deviation from the actual yaw rate is used to determine whether the running condition is understeer or oversteer with respect to the target yaw rate, and the most appropriate wheel to brake is selected from the four wheels. By providing the braking wheel discrimination means to increase the spin by increasing the braking force to the rear wheels despite the tendency to spin, or applying the braking force to the front wheels to drift even if the tendency to drift out. It is possible to reliably prevent an increase in the out and improve the running stability of the vehicle.

Further, by setting the range of the actual yaw rate in which the braking wheel of the vehicle is not selected without selecting the braking wheel of the vehicle in advance, when it is not particularly necessary to apply the braking force for control, As non-braking, the wear of the brake can be reduced.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a braking force control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a braking force control device according to a first embodiment of the present invention.

FIG. 3 is a flowchart of braking force control according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an example of an actual yaw rate and a target yaw rate according to the first embodiment of the present invention, and a braking wheel.

FIG. 5 is an explanatory diagram of the operation of the vehicle by the braking force control according to the first embodiment of the present invention.

FIG. 6 is a flowchart of braking force control according to the second embodiment of the present invention.

FIG. 7 is an explanatory diagram of an example of an actual yaw rate and a target yaw rate according to a second embodiment of the present invention, and a braking wheel.

[Explanation of symbols]

 1 Brake drive unit 4fl, 4fr, 4rl, 4rr Wheels 5fl, 5fr, 5rl, 5rr Wheel cylinders 6fl, 6fr, 6rl, 6rr Wheel speed sensor 7 Handle angle sensor 8 Yaw rate sensor 10 Control device 11 Vehicle speed calculation unit 12 Steering angle calculation unit 13 steady-state yaw rate calculation unit 14 target yaw rate calculation unit 15 yaw rate deviation calculation unit 16 target braking force calculation unit 17 braking wheel determination unit 18 braking signal output unit δf actual steering angle V vehicle speed Gγδf (0) yaw rate steady-state gain γ actual yaw rate γ ' Target yaw rate Δγ Yaw rate deviation BF2f, BF2r Target braking force

Front Page Continuation (72) Inventor Munenori Matsuura 3-9-6 Osawa, Mitaka City, Tokyo Subaru Research Institute

Claims (4)

[Claims] 1. A braking force control device capable of independently controlling a braking force for each of four wheels of a vehicle, wherein a vehicle speed detecting means for detecting a vehicle speed, a steering angle detecting means for detecting a steering angle, and an actual yaw rate of the vehicle are displayed. An actual yaw rate detecting means for detecting, a target yaw rate calculating means for calculating a target yaw rate based on a vehicle speed and a steering angle, a yaw rate deviation calculating means for calculating a yaw rate deviation by subtracting the target yaw rate from the actual yaw rate, and a motion of the vehicle. Target braking force calculation means for calculating the target braking force based on the state and yaw rate deviation, braking wheel discrimination means for selecting the braking wheel of the vehicle from the actual yaw rate and yaw rate deviation, and the target from the target braking force calculation means A braking signal output means for outputting a signal to the brake drive unit so as to apply the braking force to the braking wheel selected by the braking wheel discrimination means is provided. Braking force control apparatus according to. 2. The braking wheel discrimination means selects the inner rear wheel as a braking wheel when the signs of the actual yaw rate and the yaw rate deviation are different, and the outer front wheel when the signs of the actual yaw rate and the yaw rate deviation are the same. The braking force control device according to claim 1, wherein 3. The braking wheel discriminating means is preset with a range of magnitudes of an actual yaw rate at which non-braking is performed without selecting a braking wheel of a vehicle. 2. The braking force control device described in 2. 4. The range of the actual yaw rate in which the braking wheels of the vehicle are not selected by the braking wheel discrimination means without selecting the braking wheels is set to the range of the substantially straight movement state of the vehicle. The braking force control device according to claim 3.