JPH04197858A - Braking force control device - Google Patents

Abstract

PURPOSE:To obtain satisfactory braking feeling at all times by providing a difference in braking force on right and left wheels and, when vehicle plane movements such as lateral movement, yawing movement, etc., are controlled, increasing pressure in either one of the right and left wheel cylinders in setting pressure difference and decreasing it in the other cylinder, from a reference value of the wheel cylinders. CONSTITUTION:A braking force control device is provided with a steering angle detection means (a), a target plane movement calculation means (c) for calculating a target plane movement of a vehicle plane movement by the output from a vehicle speed detection means (b), and a pressure difference setting means (d) for setting pressure difference between both right and left wheel cylinders by which a target plane movement can be obtained. In non- braking force difference control in which a target plane movement is set to zero, the pressure difference mentioned above is set to zero by the pressure difference setting means (d) and a reference value of wheel cylinder pressure reduced from a master cylinder pressure at a specified rate by the braking force control means (g) is given as a right and left wheel cylinder pressure. On the other hand, in braking force difference control in which a pressure difference between both right and left wheel cylinders is set, a right and left wheel cylinder pressure is given so that a setting pressure difference can be obtained by increasing a pressure of either one of both right and left wheel cylinders and reducing a pressure of the other wheel cylinder, from a reference value of the wheel cylinder pressure.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applied to vehicles, and optimizes vehicle planar motion such as lateral motion and yawing motion by providing a difference in braking force between left and right wheels during turning braking. The present invention relates to a braking force control device.

(Prior Art) As a braking force control device that optimally controls the yaw rate of a vehicle by creating a braking force difference between the left and right wheels during turning braking, the present applicant previously developed a braking force control device described in Japanese Patent Application No. 2-73121. We proposed a power control technology.

(Problem to be solved by the invention) However, in the above-mentioned prior braking force control device,
When the wheel cylinder differential pressure is set to zero during straight-line braking, etc., the master cylinder pressure is applied to the left and right wheel cylinders as is, and during turning braking, the wheel cylinder differential pressure is set according to the target yaw rate using braking force difference control. In this case, the master cylinder pressure is directly applied to one wheel cylinder, and the wheel cylinder pressure is reduced to the other wheel cylinder according to the set differential pressure, thereby creating a difference in braking force between the left and right sides.

Therefore, when comparing the total braking force of the vehicle during straight-line braking, etc. where braking force differential control is not performed, and the total braking force of the vehicle during turning braking, where braking force differential control is performed, The total vehicle braking force during power differential control is always low regardless of the magnitude of the set differential pressure, and the braking feel differs depending on whether or not braking force differential control is being performed.

The present invention has been made with attention to the above-mentioned problems, and is a braking force control device that controls vehicle plane motion such as lateral motion and yawing motion by creating a difference in braking force between left and right wheels. The objective is to make the braking feel almost the same regardless of the presence or absence of braking force difference control while optimally controlling planar motion.

(Means for Solving the Problems) In order to solve the above problems, the braking force control device of the present invention sets a pressure reduced by a predetermined ratio from the master cylinder pressure as a wheel cylinder pressure reference value, and sets a zero differential pressure. At times, a wheel cylinder pressure reference value is given to the left and right wheel cylinders, and when setting a differential pressure, one of the left and right wheel cylinders is increased from the wheel cylinder pressure reference value and the other is decreased, thereby obtaining the set differential pressure.

That is, as shown in the claim correspondence diagram of FIG. 1, when the steering angle detection means a detects the steering angle and the vehicle speed detection means detects the vehicle speed, the target plane motion of the vehicle is determined by the steering angle and the vehicle speed. A target planar motion calculating means C for calculating, a differential pressure setting means d for setting a differential pressure between left and right wheel cylinder pressures to obtain a target planar motion of the vehicle, and a master cylinder for detecting a master cylinder pressure generated based on a braking operation. A pressure detection means e, a wheel cylinder pressure reference value setting means f for setting a pressure subtracted from the master cylinder pressure at a predetermined rate as a left and right wheel cylinder pressure reference value, and a wheel cylinder pressure reference value setting means f for setting a pressure subtracted from the master cylinder pressure at a predetermined rate as a left and right wheel cylinder pressure reference value; The braking force control means 9 is provided with a braking force control means 9 which gives a pressure reference value and, when setting the differential pressure, increases the pressure in one of the left and right wheel cylinders from the wheel cylinder pressure reference value and reduces the pressure in the other to obtain the set differential pressure. Named Terateru.

(Function) During non-braking force differential control in which the target plane motion is set to zero for vehicle plane motion such as lateral motion or yawing motion, such as during straight-line braking, the differential pressure setting means d:
The differential pressure between the left and right wheel cylinder pressures is set to zero, and the braking force control means 9 applies a wheel cylinder pressure reference value, which is subtracted from the master cylinder pressure at a predetermined ratio, as the left and right wheel cylinder pressures.

During turning braking, etc., the target plane motion calculation means C calculates the target plane motion of the vehicle plane motion such as the lateral motion or yawing motion of the vehicle based on the steering angle from the steering angle detection means a and the vehicle speed from the vehicle speed detection means. is calculated, and the differential pressure setting means d sets the differential pressure between the left and right wheel cylinder pressures to obtain the target planar motion.During the braking force difference control, the braking force control means 9 calculates the pressure difference between the left and right wheel cylinder pressures at which the target plane motion is obtained. Control is performed to obtain a set differential pressure by increasing the left and right pressures and decreasing the other pressure from the reduced wheel cylinder pressure reference value.

Therefore, the total braking force of the vehicle during non-braking force differential control that does not control vehicle planar motion, and the vehicle total braking force during braking force differential control that controls vehicle planar motion by providing a braking force difference on the left and right sides. The braking force is the same within the pressure increase range set by the wheel cylinder pressure reference value, and even if it exceeds the pressure increase range set by the wheel cylinder pressure reference value, there is a small braking force due only to the exceeded amount. This can be suppressed by the difference in braking force of the total vehicle.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, the configuration will be explained.

FIG. 2 is an overall system diagram showing a braking force control device according to an embodiment of the present invention.

In Fig. 2, 1 is a steering angle sensor (steering angle detection means)
, 2 is a vehicle speed sensor (vehicle speed detection means), 3 is a flake pedal, 41J booster, 5 is a master cylinder, 6a, 6b
, 6c, and 6d are wheel cylinders of each wheel, 7a is a master cylinder pressure sensor (master cylinder pressure detection means) that detects the master cylinder pressure, and 7b, 7c, and γd are wheel cylinder pressures that detect the wheel cylinder pressure of each wheel. Sensor 8 is a flexible actuator that independently controls each wheel cylinder pressure.

The flake acticoator 8 is the same as the 3ch anti-skid actuator, and is 9a
, 9b, and 9c are solenoid valves that control the wheel cylinder pressure of the left front wheel, right front wheel, and rear wheel, respectively, and increase and maintain the pressure based on the current value.

Controlled at three levels of vacuum. Also, 70a, 11
b beam server, 1ob, 11a is accumulator, 12
a and 12b are recirculation pumps driven by a DC motor (not shown).

13 is a controller which inputs detection signals from the steering angle sensor 1, vehicle speed sensor 2, master cylinder pressure sensor 7a, wheel cylinder pressure sensors ab, 7c, 7d, and flake switch 14, and outputs detected values of vehicle speed and steering angle and the vehicle. The target yaw rate of the vehicle is calculated from the motion characteristics of the vehicle, and the left and right wheel cylinders 6a, 6 are adjusted so that the actual yaw rate caused by the front wheel steering and the left and right braking force difference matches the target yaw rate.
A differential pressure ΔP is set for the pressure applied to b.

On the other hand, the master cylinder pressure Pa. The pressure that decreases at a certain rate from 100 to 100 is set as the wheel cylinder pressure reference value PUCN, and when setting zero differential pressure, the wheel cylinder pressure reference value PuoN is applied to the left and right wheel cylinders 6a and 6b, and the differential pressure is set. Sometimes, one of the left and right wheel cylinders 6a, 6b increases the pressure from the wheel cylinder pressure reference value PVCN,
On the other hand, reduce the pressure from the wheel cylinder pressure reference values P and J.
A set differential pressure ΔP for optimally controlling the yaw rate is obtained by increasing and decreasing pressure differences.

Next, the effect will be explained.

When considering the motion of the vehicle as two degrees of freedom in the yaw and lateral directions shown in Figure 3, the equation of motion is as follows (+), (2
) can be expressed by the formula.

Iz ・i#(t) = Cf-Lf-Cr-Lrjut
-fBFL(t)-sr:R(t))/2
(+)M −Vy(t)=2 (CJ+Cr) −
M −Vx(t) ・*(t) (2
) However, Cf and Cr are the cornering forces of the front wheels and rear wheels, respectively, and can be expressed by equations (3) and (4).

(j= Kf −[e(t)/N−(Vy+Lf−φ
(t) /Vx(tll) (3) Cr=-Kr
・(Vy-Lr-φ(t) ＞/Vx (t)
(4) The meanings of other words are as follows.

TjJ(1): Yaw rate θ(t): Steering angle Vx(t): Vehicle longitudinal speed Vy(t): Vehicle lateral speed B FL(t): Left front wheel braking force B FR(t): Right front wheel brake Power △P: Target wheel cylinder differential pressure Pμ0: Master cylinder pressure* PFR: Target wheel cylinder pressure for right front wheel* PFt: u Target wheel cylinder pressure for front wheel Iz: Vehicle yaw moment of inertia Lf Distance between vehicle center of gravity and front axle Lr ・Distance between vehicle center of gravity and rear axle below f: Front wheel tread M: Vehicle weight N, steering gear ratio f: Front wheel cornering power r: Rear wheel cornering power (3), (4) equations (1), (2) If we consider this as a differential equation regarding the yaw rate ψ(t) and the lateral velocity Vy(t), it can be expressed as equations (5) and (6).

φ(t)=all−φ(t) +a12・Vy(t)+
bl−θ(t) +b discharge △Bf(t) (5) Vy(t
) = a21-φ(t) +a22-Vy(t)
+b2・θ(t) (6) However, 8 days f(t) = Day FL(t) - Day FL(t)
(7) a+I=-2(Kf-L
f・Lf+Kr"Lr-Lr)/(Iz-Vx)
(8) a12=72 (Kf-Lf-Kr-Lr)/
(Iz-Vx) (9) a21=-2(to f-
Lf-Kr-Lr・)/(M-Vx)-Vx (10
)a22=-2(Kf+Kr)/(M-Vx)
(II) bl=2・jLf/ (Iz−N
) b2-2・Kf/(M-N) bpl=T f/ (2・Iz) Here, front and rear wheel cornering power Kf, Kr are braking/
Changes when driving force is applied. Cornering forces Cf, Cr and braking/driving force are generally related to each other based on the concept of a friction circle as shown in FIG.

Taking the front wheels as an example, a method for calculating f when braking force is applied will be described below. Assuming that Cf is proportional to the wheel sideslip angle β, the maximum frictional force that the tire can produce (i.e. friction circle radius) is FO, β when Cf reaches the maximum value Cfmax is βmax, and cornering power when no braking force is applied. If fO is denoted by fO, then the relationship of equation (12) holds true.

Cfmax=FO=KfO・βmax
(12) If a braking force is applied when equation (12) holds true, Cfmax changes as shown in equation (13).

Therefore, Kf when the braking force Bf is applied is determined by equation (14).

Therefore, if the average value of the left and right wheels is Kf, then Kf when the braking forces BFL and BFR are applied to the left and right front wheels is (15)
is required.

Similarly, if the maximum frictional force that the rear wheels can produce is rO, the cornering power when FO1 braking force is not applied, then when braking force EIRR is added, r can be found by equation (16). .

ni,=ni,. r Next, the relationship between the steering angle input and the generated yaw rate will be described in (2). From equations (5) and (6), the relationship between the steering angle input θ(t)1 and the generated yaw rate Φ1(t) can be expressed as shown in equation (17) using the differential operator S.

, (bl"s+a12°b2-a22-
bl), θ(t)ψI (t) −8・−(a
ll+a22) s+, (all, all-a12.
a2+)=×(S)・θ(t)
(R) Transfer function of equation (17)×(S
) is in the form of (first order)/(second order), and the harder ■× becomes, the more oscillating the generated yaw rate in response to the steering angle input (t) becomes, and the vehicle maneuverability and stability may deteriorate. Recognize. Therefore, for example, if the target yaw rate φr (t) is a steering angle input (a first-order lag system with no over/undershoot), and the steady-state value is set equal to that of a normal vehicle, ψr(t) is (18 ) can be expressed as the formula.

ψr(t):H(Le(t)/(1+T S
) (18) However, HO is a steady yaw rate gain, which is defined by equation (19) using stability factor A.

H○=Vx/((1+A・Vx) 2・L−N
(19) A = -M (Lf-Kf-Lr
− to r) / (2−L ′ (Kf− to r)+
(20) Next, a method of matching the generated yaw of the vehicle and the rate Φ(t) to the target phase-rate ψr (t) using the braking force difference ΔBf(t) between the left and right front wheels will be described. (18
), the differential value of the target yaw rate φr(t)
is obtained using equation (21).

1r(t)=Ho・θ(t)/T-177r(t)/
T(21) Assuming that the generated yaw rate ψ(1) due to the steering angle input θ(1) and the front wheel left and right braking force difference input ΔBf(t) matches the target yaw rate φr(t), each differential The values ψ(t) and ψr (t) also match. Therefore, ψr
(t) = or (t), ψr (t) = φ(1), and when the above assumptions hold, Vy(t) is Vyr
(t) and substitute them into equations (5) and (6) to obtain equations (22) and (23).

1r(t) = a ++・φr(t)+a12− V
yr(t) +bl-e(t) +bpl-△Bf(t
)◇yr(t) =a21−ψr(t)+a22・Vy
r(t) +b2・θ(t) (23)
: Substituting equation (21) into equation (22), we get 8Bf(t)
is determined by equation (24).

△Bf(t)= +kar(t) −a II ・ψ(t
) a12・Vyr(t) −1)l−θ(t) /
In order to generate the front width left and right braking force difference determined by the bpH (24) formula, it is sufficient to generate a pressure difference between the wheel cylinder pressures of the left and right front wheels. Wheel cylinder pressure P and braking force B
The relationship of f is (2
5) It can be obtained using the formula.

Bf=2 ・up-Ap-rp-P/R=kp-P
(25) Mori dashi Kp=2・μp−Ap・rp/
Rup: Coefficient of friction between the flake pad and the disc rotor Ap Wheel cylinder area rp, disc rotor effective radius R: Tire radius Therefore, set the target pressure of the wheel cylinder pressure on the left and right front wheels as △
If P (t), then ΔP(t)=ΔB f(t)/k p
(26) Similarly, the relationship in equation (25) can be expressed as (15), (
By substituting into equation 16), f and Kr become (27) and (
28).

On the other hand, during normal braking, a certain percentage (
O: a = about 0.2)) (P ucN(t))
is controlled to be the wheel cylinder pressure. in this case,
The left and right wheel cylinder pressures have the same value.

PMCN(t)"(+-Q)IP'uC(t)
(29) P pp(t) = P FL(t
) = P ucN(t) ' (30) When performing control to create a differential pressure between the front, rear, left, and right wheel cylinders, in order to obtain a differential pressure of △p (t), each wheel cylinder pressure is calculated using the following formula. control to the value calculated by

PFR (t) = PucN (t) o, s books △P
(t)(l △P (t) l <2*a
*Puc(t)l i31,I) =P, c(t)' [-PIJC(t)≦△P
(t)≦−21a * puc(t)l (31,2
)=Puc(t) −△P(t)+PMC(t)
≧△p(t) ≧22nea * Puc(t)l
(31,3)=Puc(t) [△P (
t) < P, Jc(t)l (31,
4) 20 (△P (t) > p, c(t
)l (31,5)P FL (t)
= PIJCN (t) + 0.5 lines △P (t) f
l △P(t) l<2nea * Puc(t)
l @(32,I) = puc(t) +△P (t)f−PIJC(t)
≦△P (t) ≧-2ne a * Puc
(t)1(32,1) =Pvc(t)(Puc(t)≧△P (t)≧2Q
NeP Mc (t) ) (32,3)=0
(△P(t) <-P, C(t)+
(32,4)=puc(t) I△P(t)
>puc(t)l (32, 5) Therefore, the controller 13 executes the target wheel cylinder pressure calculation process shown in FIG. 5 and the braking force control process shown in FIG. 6 to control the braking force for the left and right front wheels. The yaw rate of the vehicle can be controlled to match the target yaw rate.

That is, the target wheel cylinder pressure calculation process shown in FIG. 5 is executed as a timer interrupt process every predetermined period ΔT (for example, 5 m5ec).

First, in step 2o, the speed detection value V8, the steering angle detection value 0, and the cylinder pressure P of the front wheel cylinders 6a and 6b are determined.
, P FR and rear wheel cylinders 6c, 6d
The cylinder pressure PRR is read, and then the process moves to step 21 to calculate the front wheel cornering power and the rear wheel cornering power K according to equations (21) and (28).
, and then proceed to step 22, where the following (33) to
Equation (36) is calculated to calculate a coefficient 8 + +v'' a 22V determined by the specifications of the vehicle.

Next, the process moves to step 23, where the above equations (8) to (11) are calculated from the detected vehicle speed value V and the preset specifications of the company vehicle.
The coefficient a II-822 is calculated by calculating the formula.

Next, the process moves to the steering wheel base 24, where the wheelbase is determined based on the detected vehicle speed value o, the stability factor calculated in advance based on the formula (20), and the specifications of the vehicle, and the steering gear is determined. Based on the ratio N (
19) Calculate the steady yaw rate gain H0 by calculating the steady yaw rate gain H0, and calculate the differential value φ2(n) of the target yaw rate by calculating the above formula (21) based on the calculated steady yaw rate gain H0. Then, the calculated differential value ψ, (n) and the previous value φ of the target yaw rate,
(n-1), the current target yaw rate ψ, (n) is calculated according to the following equation (37), and updated and stored in the target yaw rate storage area.

φ, (n) =・φ, (nl)+*, (n)△T
(37) Here, Δth is the timer interrupt period.

Next, the process moves to step 25 and the step 23 is performed.
The coefficient a2. and a22 and the above (+ 1a)
The coefficient b2 calculated in advance according to the formula and the step 24
Perform the calculation in (23) above from the target yaw rate φ, (n) calculated in and the previous value of lateral velocity V y, (n-1) to calculate the lateral acceleration ◇,, (n), From this calculated lateral acceleration ◇2, (n) and the previous value of lateral velocity V y, (n-1), the following equation (38) is calculated to obtain the current lateral velocity V, , (n ) is calculated and updated and stored in the lateral velocity storage area.

Vy, (n) −Vyr(n-1) +Vy, (n)Δ
T (38) Next, proceed to step 26,
The braking force difference ΔB between the left and right front wheels is calculated according to the above equation (24), and the above equation (26) is calculated based on the calculated braking force difference ΔB and the coefficient 2 previously calculated according to the equation (25). By performing the calculation, the target differential pressure ΔP is calculated.

Next, the process moves to step 27, and the master cylinder pressure P
A value obtained by subtracting a certain percentage a (a = about 0.2) from IJC is set as the wheel cylinder pressure reference value P, JoN (corresponding to the wheel cylinder pressure reference value setting means).

Next, the process proceeds to step 28, and whether the absolute value 1ΔP1 of the target differential pressure ΔP is within twice the difference between the master cylinder pressure PMc and the master cylinder pressure reference value PMCN, that is, if one wheel It is determined whether the cylinder pressure is within the pressure increase limit range, and when 1△Pl<2・O-P, Ac, the process moves to step 29, and the target cylinder pressure P18 for the front right wheel and the target cylinder pressure for the front left wheel are determined. Cylinder pressure PF is the above (3
11) and (32, 1), and the timer interrupt processing ends.

On the other hand, when it is determined in step 28 that 1△P1≧2・Q−PMo, it is determined whether the target differential pressure absolute value 1△P1 is less than or equal to the master cylinder pressure PLJC, and 1△Pl+<P.
, o, the process moves to step 31, and it is determined whether △P>O. At the time, the process moves to step 33, and the equation (31, 2) and (
The target cylinder pressure PFR*P, -1 is set by Equation 32,2), and the timer interrupt processing is ended.

Also, when 1△P1≧PL, o, the process moves to step 34, where it is determined whether △P>O, and when △P>0,
Proceeding to step 35, the formula (31,5) is set,
When △P≦○, the process moves to step 36 and the above (31
, 4) and (32, 4), the target cylinder is reached.

In the process shown in FIG. 5, steps 28 to 3
Process No. 6 corresponds to the braking force control means.

Therefore, in the case of I△P1〈2・o−P, jo,
The sum of the wheel cylinder pressures of the left and right wheels can be made equal to the sum of the wheel cylinder pressures of the left and right wheels during normal braking.

The braking force control process shown in FIG. 6 is executed individually on the left and right wheels as a timer interrupt process with six predetermined cycles, similar to the target cylinder pressure calculation process shown in FIG.

Note that FIG. 6 shows the braking force control process for the left wheel cylinder 6a.

That is, in step 40, it is determined whether or not the brake inch 14 is in the ON state, and when the brake inch 14 is in the OFF state, it is determined that the brake is not in the non-braking state, and the process proceeds to Step 41, where the output is performed. The variable Tp representing the holding time of the control signal is set to "1", and then the process moves to step 42, where the target cylinder pressure PFL and the actual cylinder pressure P are set.
, L is set to "1", and then the process moves to step 43.

In this step 43, whether the variable Tp is positive or “O”
If TP>O, the process proceeds to step 44, where the control signal CSF is set as a pressure increase signal of "0".

is output to the constant current circuit 20FL, and then the process moves to step 45 where "1" is subtracted from the variable below to create a new count Tp.
is calculated, updated and stored in the coefficient storage area, and then proceeds to step 46, where the value obtained by subtracting "1" from the variable m is stored as a new variable m, and updated and stored in the area. Finish the timer interrupt processing and return to the main block,
When the determination result in step 43 is Tp-○, the process proceeds to step 47 to output the control signal C3FL as a holding signal of the first predetermined voltage V5+, and then proceeds to step 46, and further the process proceeds to step 43. The result is Tp>
When the voltage is O, the process proceeds to step 48 to output the first predetermined voltage VS and the control signal CSF as a pressure reduction signal of the higher second predetermined voltage V52, and then step 49
The process moves to step 46, and the value obtained by adding "】" to the variable Tp is updated and stored in the variable register '1 area as a new variable Tp, and then the process moves to step 46.

Further, when the determination result of the steering wheel 40 is that the brake inch 14 is in the ON state, it is determined that the vehicle is in the braking state, and the process proceeds to step 50, where the target cylinder pressure calculated by the above-mentioned target cylinder pressure calculation process is determined to be in the braking state. Target cylinder pressure PFL
It is determined whether or not they match the master cylinder pressure P2°. If they match, the process moves to step 41, and if they do not match, the process moves to step 51.

In this step 51, it is determined whether the variable m is positive or not. If m>0, the process directly proceeds to step 43, and if m≦0, the process proceeds to step 52.

In this step 52, target cylinder pressure P4. and the current cylinder pressure detection value P2. After calculating the error P81 (=-*P-1P FL), the process moves to step 53.

In this step 53, the error p is set to the reference value Po
The variable TP is calculated according to the following formula (39), which rounds off the value divided by .

T P = I NT (P,,, /P o)
(39) Next, proceed to step 54 and set the variable m
is set to a predetermined value m0, and then the process proceeds to step 43.

For a detailed explanation of the operation of the braking force control process shown in FIG. 6, please refer to the specification of Japanese Patent Application No. 2-73721.

In this way, it is possible to generate a yaw rate that matches the optimum value of the target yaw rate according to the vehicle speed and steering angle by changing the cylinder pressures PF and PFR of each wheel cylinder 68 and 6b to the target cylinder pressure. Therefore, unstable behavior due to steering in a braking state can be prevented and steering stability can be improved, and transient yaw rate characteristics can be improved.

In addition, the lateral acceleration vy, (n) and the braking force difference ΔB,
Coefficient 82. required when calculating . .

a12+ 82e, ari2. b + and b2
Since the corner link power contained in It is possible to improve steering stability and transient yaw rate characteristics.

Furthermore, the total braking force of the vehicle during non-braking force differential control in which the vehicle yaw motion is not controlled, and the vehicle total braking force during braking force differential control in which the vehicle yaw motion is controlled by providing a 1-braking force difference between the left and right sides. The total braking force is within the range of pressure increase due to the wheel cylinder pressure reference value p and oN setting (1△P1〈2・O・P v
c) L: is the same, and even if the range of pressure increase due to the setting of the wheel cylinder pressure reference value is exceeded, the difference in the total vehicle braking force will be suppressed to a small difference only due to the exceeded amount, so the vehicle yawing movement will be suppressed. The braking feeling can be made almost the same regardless of the presence or absence of braking force difference control while optimally controlling the braking force.

In addition, by adopting this method, the braking force relative to the pedal depression force will be reduced in non-control situations such as straight-line braking, but this reduction in braking force can be easily compensated for by increasing the efficiency of the booster 4. It is possible to compensate.

Although the embodiment has been described above based on the drawings, the specific configuration is not limited to this embodiment.

For example, in the embodiment, the pressure (a*Puc) obtained by subtracting a certain percentage Q from the master cylinder pressure Puc is used as the wheel cylinder pressure reference value (PLJc)1). Master cylinder pressure P. 0 or above the set pressure (") The pressure obtained by subtracting a constant pressure from the master cylinder pressure P, Jo is the wheel cylinder pressure reference value (PIJcN), and when the master cylinder pressure P, Jc is below the set pressure, a certain percentage disappears. The pressure is set to the wheel cylinder pressure reference value (P,
oN).

Furthermore, instead of controlling the difference in braking force between the left and right front wheels as in the embodiment, it is also possible to control the difference in braking force between the rear wheels or the left and right wheels. It is also possible to detect and calculate wheel speed, vehicle longitudinal acceleration, etc. using one sensor.

(Effects of the Invention) As explained above, the present invention provides a braking force control device that controls vehicle planar motion such as lateral motion and yaw movement by providing a difference in braking force between left and right wheels. ,
The pressure subtracted from the master cylinder pressure at a predetermined rate is set as the wheel cylinder pressure reference value, and when the electrostrictive pressure is set, the wheel cylinder pressure reference value is given to the left and right wheel cylinders, and when the differential pressure is set, one of the left and right wheel cylinders is set. The set differential pressure is obtained by increasing the wheel cylinder pressure from the reference value and decreasing the other pressure, so the braking feeling is almost the same regardless of whether braking force differential control is used or not, while optimally controlling the vehicle's planar motion. The effect of being able to do this is obtained.

[Brief explanation of the drawing]

Fig. 1 is a tarem correspondence diagram showing the braking force control device of the present invention, Fig. 2 is an overall system diagram showing the braking force control device of the embodiment, and Fig. 3 is a vehicle motion with two degrees of freedom in yawing and lateral directions. Model diagram, Figure 4 is a diagram showing the concept of friction circle, Figure 5 is a flowchart for calculating the target wheel cylinder pressure for the left and right front wheels from the steering angle, vehicle speed, master cylinder pressure, and wheel cylinder pressure of each wheel, Figure 6 is a flowchart for determining a command signal to an actuator from target wheel cylinder pressure, wheel cylinder pressure, and master cylinder pressure. a...Steering angle detection means b...Vehicle speed detection means C...Target plane motion calculation means d--differential pressure setting means e...Master cylinder pressure detection means f--Wheel cylinder pressure reference value setting Means 9... - Braking force control means patent application Dainissan Motors Co., Ltd.

Claims (1)

[Scope of Claims] 1) Steering angle detection means for detecting a steering angle, vehicle speed detection means for detecting vehicle speed, and target planar motion calculation means for computing a target planar motion of the vehicle based on the steering angle and vehicle speed. , a differential pressure setting means for setting a differential pressure between left and right wheel cylinder pressures to obtain a target planar motion of the vehicle; a master cylinder pressure detecting means for detecting a master cylinder pressure generated based on a braking operation; wheel cylinder pressure reference value setting means that sets the pressure reduced by the ratio of A braking force control device comprising: braking force control means for obtaining a set differential pressure by increasing the pressure in one of the wheel cylinders from a wheel cylinder pressure reference value and decreasing the pressure in the other wheel cylinder.