JPH10297455A - Brake hydraulic control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the responsiveness of control and improve controllability by detecting the hydraulic fluid pressure of a master cylinder, calculating the braking force of front wheels based on this detected value, and setting the target braking force of rear wheels for the ideal braking force distribution based on the braking force of the front wheels. SOLUTION: For brake hydraulic control, the master cylinder pressure PMCF is read (S1), and the accurate braking force FF of front wheels is quickly calculated based on the master cylinder pressure PMCF and wheel velocities VwFL-VwR (S3). The target rear wheel braking force F*R attaining the ideal braking force distribution for the accurate and quick front wheel braking force FF is directly calculated and set (S6). The signal incrementally or decrementally controlling the rear wheel cylinder pressure based on the differential value between the target rear wheel braking force F*R and the rear wheel braking force FR is outputted (S7). The responsiveness of control is improved, and controllability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls, for example, at least the hydraulic pressure of a brake cylinder of a rear wheel of a vehicle by an actuator to control the hydraulic pressure of the brake cylinder so as to achieve an ideal braking force distribution. The present invention relates to a brake fluid pressure control device for a vehicle.

[0002]

2. Description of the Related Art The above-mentioned ideal braking force distribution means that the wheel load on the front wheel increases and the wheel load on the rear wheel decreases with braking, so that the frictional force of each wheel changes. For example, it is obtained by plotting a limit braking force at which each of the front and rear wheels is not locked, using the longitudinal acceleration acting on the vehicle as a parameter, for example. Japanese Patent Application Laid-Open No. 5-278585 discloses an example of a vehicle brake fluid pressure control device for achieving such an ideal braking force distribution.

In this conventional example, since the above-described ideal braking force distribution assumes that the front and rear wheels have the same wheel speed, the rotation speeds of the front and rear wheels are detected, and the rotation speed of the rear wheels is determined. When it is determined that the rotation speed of the front wheel is lower than the rotation speed of the front wheel, a control signal for reducing or maintaining the hydraulic pressure of the brake cylinder of the rear wheel is output to the actuator, and it is determined that the rotation speed of the rear wheel is higher than the rotation speed of the front wheel. At this time, a control signal for restoring (increasing) the hydraulic pressure of the braking cylinder of the rear wheel is output to the actuator, so that the rear wheel is decelerated at the same speed as the front wheel. Thereby, for example, the braking force of the front and rear wheels is changed regardless of a change in the vehicle weight when the vehicle is empty or when the vehicle is mounted or a change in the frictional force against the road surface or a change in the road surface reaction force torque caused by a change in the wheel load accompanying the change. This makes it possible to approach the ideal braking force distribution.

[0004]

By the way, the necessary and sufficient condition for minimizing the stopping distance is that the deceleration is limited to the limit at which the front and rear wheels are not locked and the speed is reduced at the same wheel speed, that is, the rotation speed. Therefore, the above-mentioned conventional example has a possibility of achieving this in principle.

However, controlling the braking force of each wheel while detecting the rotational speed of the wheel, or controlling the brake fluid pressure is a so-called feedback control, for example, controlling the brake fluid pressure. The validity of the control is evaluated only when the braking force changes and expresses it as the rotational speed of the wheel. Therefore, the responsiveness of the brake fluid pressure control is inferior, and a phenomenon similar to hunting, for example, in which the rotational speed of the rear wheel increases or decreases near the target value, is likely to occur. In order to detect the rotational speed of the wheel, it is general to calculate the rotational speed of the wheel, for example, by calculation. However, the rotational speed detected in this way includes a relatively large number of errors. . The factors include, for example, a change in the rolling radius of the tire due to a change in tire pressure or a change in wheel load, a change in the wheel rotational angular velocity according to a turning locus, or a rotational speed of a wheel rotating from low rotation to high rotation. And the effect of noise in response. Therefore, in order to suppress such an effect and obtain a high-precision wheel rotation speed, it is necessary to use, for example, a moving average value within a predetermined time or a value subjected to noise removal filtering. In order to determine the wheel rotation speed with such a value, it takes time to detect the wheel rotation speed, and as a result, there is a problem that the control timing is delayed.

The present invention has been developed in view of these problems, and calculates the braking force of the front wheels directly from the hydraulic pressure of the master cylinder or the hydraulic pressure of the brake cylinder for the front wheels. By setting the target rear-wheel braking force, the hydraulic fluid pressure in the rear-wheel braking cylinder is controlled so that the rear-wheel target braking force is achieved, improving control responsiveness. And calculate the vehicle weight and wheel load from the rotational angular acceleration of the wheels and the longitudinal acceleration acting on the vehicle,
An object of the present invention is to provide a vehicle brake fluid pressure control device that can reliably achieve an ideal braking force distribution according to a vehicle state at that time by setting a target braking force of a rear wheel using these. Things.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a vehicle brake hydraulic pressure control apparatus according to a first aspect of the present invention is to control at least a hydraulic pressure of a brake cylinder of a rear wheel of a vehicle. An actuator that can be adjusted according to a command signal;
Master cylinder hydraulic pressure detecting means for detecting the hydraulic pressure of the master cylinder; and a braking force for the front wheels based on the hydraulic pressure of the master cylinder detected by the master cylinder hydraulic pressure detecting means. Braking fluid pressure control means for setting a target braking force for the rear wheels to achieve an ideal braking force distribution based on the braking force and outputting a command signal for achieving the target braking force for the rear wheels to the actuator. It is characterized by the following.

In the present invention, generally, in this type of vehicle brake hydraulic pressure control system, only the hydraulic pressure of the rear wheel brake cylinder is controlled, and the front wheel brake cylinder is operated by the master cylinder. It is assumed that the hydraulic pressure is supplied as it is.

According to a second aspect of the present invention, there is provided a vehicle brake fluid pressure control device, comprising: an actuator capable of adjusting at least a hydraulic fluid pressure of a brake cylinder for a rear wheel of a vehicle according to a command signal; Front wheel brake cylinder hydraulic pressure detection means for detecting the hydraulic pressure of the brake cylinder, and front wheel braking control based on the front wheel brake cylinder hydraulic pressure detected by the front wheel brake cylinder hydraulic pressure detection means. Braking for calculating the power and setting a target braking force for the rear wheels to achieve an ideal braking force distribution based on the braking force for the front wheels, and outputting a command signal for achieving the target braking force for the rear wheels to the actuator. And a hydraulic pressure control means.

The brake fluid pressure control device for a vehicle according to a third aspect of the present invention includes a wheel rotational angular acceleration detecting means for detecting at least rotational angular acceleration of each of the front and rear wheels. The braking force of each of the front and rear wheels is calculated using the rotation angular acceleration of each of the front and rear wheels detected by the rotation angular acceleration detecting means, and the rear wheel is calculated using the vehicle weight calculated based on the braking force of each of the front and rear wheels. Is set.

The brake fluid pressure control device for a vehicle according to a fourth aspect of the present invention includes a longitudinal acceleration detecting means for detecting at least a longitudinal acceleration acting on the vehicle in a longitudinal direction. The vehicle weight is calculated using the longitudinal acceleration detected by the longitudinal acceleration detecting means and the calculated braking force of each of the front and rear wheels, and the wheel load of each of the front and rear wheels calculated based on the vehicle weight and the longitudinal acceleration is calculated. The target braking force of the rear wheel is set by using the target braking force.

[0012]

As described above, according to the brake fluid pressure control system for a vehicle according to the first aspect of the present invention, the hydraulic fluid pressure of the master cylinder is detected, and the detected hydraulic fluid pressure of the master cylinder is detected. By calculating the braking force of the front wheels based on the pressure, it is possible to accurately and quickly calculate the braking force of the front wheels, and to achieve the ideal braking force distribution based on the accurate and quick braking force of the front wheels. Since the target braking force is set and the command signal for achieving the target braking force of the rear wheel is output to the actuator, control responsiveness and controllability are improved as compared with the related art. can do.

According to the brake fluid pressure control device for a vehicle according to the second aspect of the present invention, the hydraulic fluid pressure of the front wheel brake cylinder is detected, and the detected hydraulic fluid pressure of the front wheel brake cylinder is detected. By calculating the braking force of the front wheels based on the pressure,
Accurate and quick braking force of the front wheels can be calculated, and based on the accurate and quick braking force of the front wheels, a target braking force for the rear wheels to achieve an ideal braking force distribution is set. Since a command signal for achieving power is output to the actuator, control responsiveness and controllability can be improved as compared with the related art.

According to the brake fluid pressure control device for a vehicle according to the third aspect of the present invention, the rotational angular acceleration of each of the front and rear wheels is detected, and the detected rotational angular acceleration of each of the front and rear wheels is used. By accurately calculating the braking force of each of the front and rear wheels, and by setting the target braking force of the rear wheel using the vehicle weight calculated based on the accurate braking force of each of the front and rear wheels, The controllability can be improved by setting the target braking force of the rear wheels closer to the ideal braking force distribution.

According to the brake fluid pressure control device for a vehicle according to the fourth aspect of the present invention, the longitudinal acceleration acting on the vehicle in the longitudinal direction is detected, and the detected longitudinal acceleration is accurately calculated. The vehicle weight can be calculated accurately by using the braking force of each of the front and rear wheels, and the wheel load of each of the front and rear wheels is calculated based on the accurate vehicle weight and the longitudinal acceleration. By setting the target braking force, the controllability can be improved by making the target braking force of the rear wheel closer to the ideal braking force distribution.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a vehicle brake fluid pressure control apparatus according to an embodiment of the present invention.

FIG. 1 shows an example in which the brake fluid pressure control device for a vehicle according to the present invention is applied to an anti-skid control device for a rear wheel drive vehicle based on an FR (front engine / rear drive) system.

In the figure, 1FL and 1FR are front left and right wheels, 1R
L, 1RR are rear left and right wheels, and rear left and right wheels 1RL, 1R.
The rotational driving force from the engine EG is transmitted to R via the transmission T, the propeller shaft PS, and the differential gear DG. Each of the wheels 1FL to 1RR has a wheel cylinder 2FL to a brake cylinder.
2RR, further mounted on the front wheels 1FL, 1FR are wheel speed sensors 3FL, 3FR for outputting sine wave signals corresponding to the rotational speeds of these wheels, and the propeller shaft PS has an average rotation of the two rear wheels. A wheel speed sensor 3R that outputs a sine wave signal corresponding to the speed is attached.
Each of the wheel cylinders 2FL to 2RR is a so-called disc brake which presses a pad against a disc rotor to perform braking.

Each front wheel wheel cylinder 2FL, 2FR
The hydraulic fluid pressure of one of the systems from the master cylinder 5 that generates two systems of master cylinder pressures on the front wheel side and the rear wheel side in response to the depression of the brake pedal 4 (hereinafter, also simply referred to as the front wheel master cylinder pressure). ) P _MCF front wheel side actuator 6FL as source pressure, is supplied separately via the 6FR, rear-wheel wheel cylinder 2RL, the 2RR, other hydraulic fluid pressure from the master cylinder 5 (hereinafter, simply rear wheel use also referred to as master cylinder pressure) P _MCR is configured to be supplied via a common rear wheel side actuator 6R as source pressure. Therefore, the anti-skid control device has a system configuration of three sensors and three channels as a whole. Incidentally, said one of the strains of the master cylinder 5 the front wheel actuator 6FL, a front wheel master cylinder pressure P _MCF supplied to 6FR, also after the other system is supplied to the rear-wheel actuators 6R wheel Sensor 1 that detects the master cylinder pressure P _MCR
3F and 13R are provided, respectively, and the brake pedal 4 is turned on when depressed, that is, the logical value "1".
The brake switch 14 for outputting the brake switch signal S _BRK is provided. The pressure sensors 13F and 13R convert the magnitudes of the front and rear wheel master cylinder pressures _PMCF and _PMCR into electric signals. In this embodiment, the two have a linear relationship with each other. . Therefore, the electric signal read by the microcomputer 20 of the control unit CR described later directly displays the front and rear wheel master cylinder pressures _PMCF and _PMCR . Before reading by the microcomputer 20, low-pass filter processing may be appropriately performed for noise removal processing or the like. Also, this vehicle, acceleration in the longitudinal direction that acts on the vehicle, the longitudinal acceleration sensor 15 for detecting a so-called longitudinal acceleration G _X is attached.

As shown in FIG. 2, each of the actuators 6FL to 6R has an electromagnetic inflow valve 8 interposed between a hydraulic pipe 7 connected to the master cylinder 5 and the wheel cylinders 2FL to 2RR. An electromagnetic outflow valve 9, a hydraulic pump 11, and a check valve 1 connected in parallel with the electromagnetic inflow valve 8.
1 and a accumulator 12 connected to a hydraulic line between the outflow valve 9 and the hydraulic pump 10. The electromagnetic inflow valve 8 shifts to a normally open state (pressure increasing state) at a normal position where power is not supplied and a closed state (pressure holding state) at a switching position due to power supply, due to operation compensation at the time of abnormality, that is, a relation of so-called fail-safe. The electromagnetic outflow valve 9 is normally closed at a normal position where power is not supplied (pressure holding state),
The state shifts to the open state (decompression state) at the switching position by energization.

The electromagnetic inflow valve 8, the electromagnetic outflow valve 9 and the hydraulic pump 10 of each of the actuators 6FL to 6R are provided with a wheel speed sine wave signal from the wheel speed sensors 3FL to 3R and a master of the pressure sensors 13F and 13R. Cylinder pressure P
_MCF and P _MCR and the brake switch signal S _BRK from the brake switch 14, the control unit lateral acceleration G _X from the lateral acceleration sensor 15 is inputted CR
, And are controlled by hydraulic pressure control drive signals EV, AV, and MR.

The control unit CR has a wheel speed.
Wheel speed sine wave signals from sensors 3FL to 3R are input.
And the rolling half of the tires of each of the wheels 1FL to 1RR.
The wheel speed (hereinafter simply referred to as the car speed)
Wheel speed) Vw_FL~ Vw_RTo calculate the wheel speed V
w_FL~ Vw_ROr the master cylinder pressure P_MCFAnd P_MCR
Or the lateral acceleration G_XAnti-skid based on etc
Control and arithmetic processing of rear wheel cylinder cylinder pressure control
And a microcomputer 20. This microphone
The computer 20 is used, for example, for anti-skid control.
The vehicle speed gradient V_XKAnd body speed V_XIs calculated,
And each wheel cylinder 2FL under anti-skid control
~ 2RR hydraulic fluid pressure (hereinafter simply referred to as wheel cylinder pressure)
Also write) P _FL~ P_RAnd calculate the target
From the wheel cylinder pressure and the PD (proportional-derivative) value.
Target wheel cylinder pressure increase / decrease amount ΔP^* _FL~ ΔP^* _RTo
The target wheel cylinder pressure increase / decrease amount ΔP^* _FL~
ΔP^* _RSo that the actuator 6F
Control signal S for L to 6R_EVFL~ S_EVR, S_AVFL~ S
_AVRAnd S_MRFL~ S_MRRIs output. Also this microphone
Computer 20 controls the rear wheel cylinder hydraulic pressure
, Each wheel cylinder pressure P of the front wheels_FL, P
_FRMaster cylinder pressure P equivalent to_MCFAnd the front wheel
Speed Vw_FL, Vw _FRAverage front wheel obtained by averaging the differential values of
Rotational angular velocity ω'w_FAnd the front wheel braking force F_FCalculate
And the current rear wheel cylinder pressure P_RAnd the rear wheel
Wheel speed Vw_RIs obtained by differentiating the rear wheel rotation angular velocity ω'w
_RFrom the rear wheel braking force F_RAnd calculate them accordingly.
Longitudinal acceleration G_XIs used to calculate the vehicle weight W,
And the longitudinal acceleration G_XFront and rear wheel load W_F, W_RTo
Calculate and aim to achieve ideal braking force distribution based on these
Rear wheel braking force F^* _RIs calculated, and the rear wheel braking force F at this time is calculated.
_RAnd the target rear wheel cylinder increase / decrease ΔP
^* _RAnd calculate the target rear wheel cylinder increase / decrease
ΔP^* _RSo that the actuator 6F
Control signal S for L to 6R_EVFL~ S_EVR, S_AVFL~ S
_AVRAnd S_{MR FL}~ S_MRRIs output. And like this
Control signal S output from the microcomputer 20
_EVFL~ S_EVR, S_AVFL~ S_AVRAnd S_MRFL~ S_MRRIs
22a for drive circuit_FL~ 22a_R, 22b_FL~ 22b_RPassing
And 22c_FL~ 22c_RThe drive signal as a command signal
EV_FL~ EV_R, AV_FL~ AV_RAnd MR_FL~ MR_RTo
The data is converted and supplied to the actuators 6FL to 6R.

Then, the microcomputer 20
Is an input interface having, for example, an A / D conversion function.
Circuit 20a and an arithmetic processing unit 2 such as a microprocessor
0b, a storage device 20c such as a ROM and a RAM,
Output interface circuit 20d having D / A conversion function
And Further, the microcomputer 20
Has a very high operating frequency,
Pulse width modulated digital data from
Data reference rectangular wave control signal S_EVFL~ S_EVR, S _AVFL~
S_AVRAnd S_MRFL~ S_MRROutput each drive
Circuit 22a_FL~ 22a_R, 22b_FL~ 22b_RAnd 22
c_FL~ 22c_RSimply apply it to each actuator
Drive signal EV_FL~ EV_R, AV_FL~ AV_RAnd MR
_FL~ MR_RIs configured to only convert and amplify
ing.

Next, the configuration of the brake fluid pressure control by the vehicle brake fluid pressure control device of the present embodiment will be described with reference to the arithmetic processing shown in the flowcharts of FIGS. This calculation process is executed as a timer interrupt process at every predetermined sampling time (for example, 10 msec) ΔT. In the subsequent arithmetic processing, any steps for communication are not particularly provided. However, programs and maps necessary for the arithmetic processing device 20b or necessary data are read from the storage device 20c at any time, and It is assumed that the data calculated by the arithmetic processing device 20b is updated and stored in the storage device 20c at any time.

First, in the arithmetic processing shown in FIG. 3, in step S01, for example, Japanese Patent Laid-Open No.
Calculating the estimated vehicle speed V _SP by the arithmetic processor as described in 50920 JP.

Then, the process proceeds to step S02 to
Anti-skid control is performed by uncalculated arithmetic processing
No anti-skid non-control condition is satisfied or not
Judgment, when anti-skid non-control condition is satisfied
To step S03, otherwise, to step S03.
The process proceeds to step S04. This anti-skid uncontrolled condition
Means, for example, the estimated vehicle speed V_SPFrom the wheel speed V
w_i(I = FL, FR, R) Estimated vehicle speed
V_SPThe ratio (percentage) to the slip ratio S of the wheel_i
And the slip ratio S of the wheel_iHas excellent steering effect
Predetermined reference slip ratio S₀Smaller or
The wheel speed Vw_iWheel (square) addition
(Reduced) speed V'w_i(<0) is a predetermined wheel load
Speed V'w ₀(<0)
What is necessary is just to employ | adopt the determination condition reverse to the start of skid control.

In step S03, the rear wheel cylinder pressure is controlled by the calculation process of FIG. 4 described later, and then the process returns to the main program. The step S
In step 04, the anti-skid control is performed by the arithmetic processing described in, for example, the above-mentioned Japanese Patent Application Laid-Open No. 8-150920, and then the process returns to the main program.

Next, step S0 of the arithmetic processing of FIG.
The minor program executed in Step 3 will be described with reference to the flowchart of FIG. In this operation process, first the pressure sensor 13F at step S1, the master cylinder pressure P _MCF from 13R, reads the P _MCR.

Next, the flow shifts to step S2, where the front-back
Longitudinal acceleration G from speed sensor 15 _XAnd the wheel speed control
Calculated based on the sine wave signals from the sensors 3FL to 3R.
Each wheel speed Vw_FL~ Vw_RRead. Note that the front and rear
The longitudinal acceleration G read from the speed sensor 15_XSlow down
Direction is positive.

Next, the process proceeds to step S3, in which the braking forces F _F and F _R of the front and rear wheels are calculated by a calculation process of FIG. Next, the process proceeds to step S4, and the vehicle weight W is calculated by the calculation process of FIG.

[0031] Next, the process proceeds to step S5, the front and rear wheel load W _F by the arithmetic processor of FIG. 7 to be described later, to calculate the W _R.
Next, the process proceeds to step S6, and the target rear wheel braking force F ^* _R is calculated by the calculation process of FIG.

Next, the flow shifts to step S7, in which a rear wheel cylinder pressure control signal is output by the arithmetic processing shown in FIG. Next, the minor program executed in step S3 of the arithmetic processing in FIG. 4 will be described with reference to the flowchart in FIG.

In this calculation process, first, in step S31
In, and calculates the wheel angular acceleration Omega'w _i further divided by the respective wheel tires rolling dynamic radius r _i of each wheel of the time differential value of the wheel speed Vw _i was written the read.

Next, the routine proceeds to step S32, where it is determined whether or not a rear wheel cylinder pressure control flag F _PROP described later is in a reset state of "0", and the rear wheel cylinder pressure control flag F _PROP is reset. If it is, the process proceeds to step S33; otherwise, the process proceeds to step S3.
Move to 4.

In step S33, the rear wheel master cylinder pressure P _{MCR is changed} to the current rear wheel cylinder pressure P _MCR.
After setting to _R , the process proceeds to step S35. In step S34, the in-wheel wheel cylinder pressure P _R after the last time in the storage unit 20c is updated and stored, rear wheel wheel cylinder pressure increase amount set by the arithmetic processing of the previous Figure 9 to be described later (hereinafter, Simply referred to as the rear wheel pressure increase / decrease amount) ΔP _R
The then sums moves after setting the wheel cylinder pressure P _R after the current to the step S35.

At step S35, the read front wheel master cylinder pressure _{PMCF is applied} to the front left and right wheel cylinder pressures P _FL and P _FR or simply the front wheel cylinder pressure P _F.
Set to.

[0037] Next, the process proceeds to step S36, the wheel angular acceleration Omega'w _FL of the front left and right wheels, calculates the average front wheel angular acceleration Omega'w _F from the average value of ω'w _FR. Next, the process shifts to step S37 to calculate a braking torque T _Bj (j = ForR) by the front and rear wheel cylinders according to the following equation.

T _Bj = μ _Pj・ P _j・ A _j・ r _rj・ 2 (1) where μ _Pj is a coefficient of friction between a disk brake pad of each wheel and a disk rotor. _j : The cross-sectional area of the wheel cylinder of the disc brake of each wheel r _rj : The effective radius of the disc rotor of the disc brake of each wheel. The reason why the braking torque is doubled is to consider the sum of the left and right wheels.

[0039] and then proceeds to step S38, the following 2 equations below, the transition from calculates a braking force F _j of the front and rear wheels in step S4 of the calculation processing of FIG. 4. F _j = (| I _j ω′w _j | + T _Bj ) / r _j (2) where I _j represents the moment of inertia of each wheel.

Here, the principle of deriving the braking force _Fj of each wheel will be briefly described. First, the braking force F _j of each wheel, appears in the form of the product of the wheel load W _j and the road surface friction coefficient μ at the time as described below 2-1 equations.

F _j = μ · W _j (2-1) On the other hand, the following equation 2-2 is obtained from the equation of motion of the wheel. | I _j · ω′w _j | = μ · W _j · r _j −T _Bj (2-2) Therefore, by substituting the wheel load W _{j of the} expression 2-1 into the expression 2-2, Solving with the braking force _Fj of the wheel gives the above two equations.

Next, step S4 of the calculation processing of FIG.
Will be described with reference to the flowchart of FIG. In this calculation process, first, step S
At 41, the brake switch signal _SBRK is "1"
It is determined whether or not the vehicle is in the N state. If the brake switch signal S _BRK is in the ON state, the _flow shifts to step S42; otherwise, the flow shifts to step S43.

In step S42, the vehicle weight W is calculated according to the following three equations, and then the flow shifts to step S5 in the calculation processing in FIG. W = m · g = (F _F + F _R ) · g / G _X (3) where g: gravitational acceleration.

Here, the principle of calculating the vehicle weight W will be briefly described. When the total braking force of the four wheels was F, the total braking force F is rather time to decelerate the vehicle mass m in the longitudinal acceleration X _G, obtaining the following 3-1 formulas.

F = m · X _G (3-1) Further, the total braking force F is the sum of the front wheel braking force _FF and the rear wheel braking force F _R (both have been calculated for the left and right wheels). From this, 3
After substituting into the left side of the equation (1) and solving it with the vehicle mass m,
The vehicle weight W is obtained by multiplying the gravitational acceleration g by the above equation (3).

In step S43, since the calculation principle of the vehicle weight W based on the above equation (3) cannot be applied, a predetermined value W ₀ set in advance is set as the vehicle weight W, and then the calculation processing of FIG. Move to step S5.

Next, step S5 of the calculation processing of FIG.
Will be described with reference to the flowchart of FIG. In this calculation process, first, step S
51, the following Equation 4, the wheel load W _F of the front and rear wheels in accordance with equation 5, the transition from to calculate the W _R to step S6 of the calculation process of FIG. 4.

W _F = W _F0 + W · G _X · H / L (4) W _R = W _R0 -W · G _X · H / L (5) where W _{F0 is the} front wheel static load. W _R0: rear wheel static load H: vehicle center-of-gravity height L: shows a wheel base, the longitudinal acceleration G _X is a positive value in the deceleration direction. The wheel load W _F, because calculation method of W _R is sufficiently well known,
A detailed description thereof will be omitted.

Next, step S6 of the calculation processing of FIG.
Will be described with reference to the flowchart of FIG. In this calculation process, first, step S
In step 61, the target rear wheel braking force F ^* _R is calculated according to the following six equations, and then the flow shifts to step S7 in the calculation processing in FIG.

[0050] ^{_{F * R = (| I F}} · ω'w F | + T BF) · W R / (W F · r F) ......... (6) Here, the calculation of the target rear-wheel braking force F ^* _R The principle will be briefly described. As described above, the ideal braking force distribution curve is obtained by plotting the limit braking force at which the front and rear wheels are not locked, for example, using the longitudinal acceleration acting on the vehicle as a parameter. Since it is the limit braking force that does not lock, it can be replaced with a parameter using the friction coefficient between the tire and the road surface, so-called road surface μ. When shown in figure 11, it is determined there road mu is under the front wheel braking force F _F, wheel braking force F _R is determined after achieving ideal braking force distribution in the road surface mu. These braking forces F _F and F _R are the wheel loads W of the front and rear wheels.
_Since the product is the product of _F , W _R and the road surface μ, the following equations 6-1 and 6-2 are obtained.

F _F = μ · W _F (6-1) F _R = μ · W _R (6-2) In the above equation (2), the subscript j is set to F in the expression 6-1. By substituting the equation and solving with μ, the following equation 6-3 is obtained.

[0052] _{μ = (| I F · ω'w} F | + T BF) / (W F · r F) ......... (6-3) by substituting the 6-3 expression on the 6-2 formula, That is, by setting the road surface μ generated at the front and rear wheels to be equal, the above-described equation (6) is obtained.

Next, step S7 of the calculation processing of FIG.
Will be described with reference to the flowchart of FIG. In this calculation process, first, step S
At 71, the rear wheel braking force deviation ΔF _R is calculated according to the following equation (7).

ΔF _R = F ^* _R− F _R (7) Next, the process proceeds to step S72, and the target rear wheel cylinder increase / decrease amount (hereinafter simply referred to as the target rear wheel increase / decrease amount) is calculated according to the following equation (8). Calculate ΔP ^* _R.

ΔP ^* _R = k ₁ · ΔF _R + k ₂ · (dΔF _R / dt) (8) Here, k _{1 represents a} proportional gain, and k ₂ represents a differential gain.

Next, the routine proceeds to step S73, where it is determined whether or not the target rear wheel pressure increase / decrease amount ΔP ^* _R is smaller than a pressure increase threshold ΔP ^* _RZ preset to, for example, about 0 MPa. If the wheel pressure increase / decrease amount ΔP ^* _R is smaller than the pressure increase threshold ΔP ^* _{RZ, the} flow shifts to step S74; otherwise, the flow shifts to step S75.

In step S74, the rear wheel
Cylinder pressure control flag F_PROPIs set to “1” and the next
Then, the process proceeds to step S76, where the target rear wheel pressure increase / decrease amount is set.
ΔP ^* _RIs set in advance to, for example, (−10 MPa).
Reduced pressure threshold ΔP^* _RGJudge whether it is greater than
Rear wheel increase / decrease ΔP^* _RIs the pressure reduction threshold ΔP^* _RGGreater than
If so, proceed to step S77; otherwise, proceed to step S77.
Move to step S78.

[0058] At step S78, clears the pressure increase interval counter CNT _INT-Z, then the process proceeds to step S79, clears the pressure increasing counter CNT _Z, then the process proceeds to step S80, the rear wheel pump drive The pulse width setting parameter W _MRR is set to “1”, and then step S
The process proceeds to 81 to increment the decompression interval counter CNT _INT-G , and then to step S82 to determine whether the decompression interval counter CNT _INT-G is equal to or greater than a predetermined count-up value CNT _INT-G0 . determines whether, step S8 when the vacuum interval counter CNT _INT-G is a predetermined count-up value CNT _{iN T-G0} or
The process proceeds to step S77, otherwise to step S77.

In step S83, the rear wheel pressure increase / decrease amount Δ
With P _R a preset reduced pressure predetermined value is set to (-ΔP _R0), then the process proceeds to step S84, the set "1" to the rear wheel inlet valve driving pulse width setting parameters W _EVR, the rear wheels Outflow valve drive pulse width setting parameter W _AVR
Is set to a predetermined pulse width predetermined value _WAVR0 , and then the flow shifts to step S85, where the decompression interval counter C
After clearing NT _INT-G , the routine goes to Step S86.

[0060] On the other hand, the in step S75, the determination whether the set state of the rear wheel cylinder pressure control flag F _{PR OP} is "1", the rear wheel cylinder pressure control flag F _PROP is set state If so, the process proceeds to step S87; otherwise, the process proceeds to step S88.
Move to

[0061] At step S87, clears the reduced pressure interval counter CNT _INT-G, then the process proceeds to step S89, increments the pressure increasing counter CNT _Z, then the process proceeds to step S90, the pressure increase counter CN
It is determined whether or not T _Z is equal to or greater than a predetermined count-up value CNT _Z0 . If the pressure increase counter CNT _Z is equal to or greater than the predetermined count-up value CNT _Z0 , the process proceeds to step S88. In this case, the flow shifts to step S91.

In step S91, the pressure increase interval counter CNT _INT-Z is incremented.
The process proceeds to 92, where it is determined whether the pressure increase interval counter CNT _INT-Z is equal to or greater than a predetermined count-up value CNT _INT-Z0 , and the pressure increase interval counter CNT is determined.
_{If INT-Z} is greater than or equal to the predetermined count-up value CNT _INT-Z0 , the process proceeds to step S93; otherwise, the process proceeds to step S77.

In step S93, the rear wheel increasing / decreasing amount Δ
P _R was set to a preset increased圧所value (+ ΔP _R0), then the process proceeds to step S94, the rear-wheel inlet valve driving pulse width setting parameters W _EVR a preset pulse width predetermined value W _EVR0 And the rear wheel outflow valve drive pulse width setting parameter _WAVR is set to "0", and then the process proceeds to step S95 to increase the pressure increase interval counter C
After clearing NT _INT-Z , the routine goes to the step S86.

In step S77, the rear wheel pressure increasing / decreasing amount ΔP _R is set to “0”, and then in step S96.
Step migrate, the rear wheel inlet valve driving pulse width setting parameters W _{EV R} and sets to "1", set to "0" to the rear wheel outlet valve driving pulse width setting parameters W _AVR in The process moves to S86.

[0065] In step S88, the later-wheel wheel cylinder pressure control flag F _{PR OP} is reset to "0", then the processing proceeds to step S97, the rear wheel pump drive pulse width setting parameters W _MRR The value is set to "0", and then the process proceeds to step S98 to set the rear wheel inflow valve drive pulse width setting parameter _WEVR to "0" and the rear wheel outflow valve drive pulse width setting parameter _WAVR.
Is set to “0”, and then the process proceeds to step S99.
After clearing the pressure increase interval counter CNT _INT-Z , the process proceeds to the step S86.

In step S86, the front left wheel pump drive pulse width setting parameter W _MRFL and the front right wheel pump drive pulse width setting parameter W _MRFR are both set to “0”, and the front left wheel inflow valve drive pulse width is set. The setting parameter W _EVFL and the front right wheel inflow valve drive pulse width setting parameter W _EVFR are both set to “0”, and the front left wheel outflow valve drive pulse width setting parameter W _AVFL and the front right wheel outflow valve drive pulse width The setting parameters W _AVFR are both set to “0”.

Then, the _flow shifts to step S100, where control signals _SEVi , _WAVi , and _WMRi corresponding to the above-described pulse width setting parameters W _EVi , _{WA Vi} , and W _MRi are calculated by a not-shown operation.
_EVi, S _AVi, to return from the creation output the S _MRi to the main program.

Next, step S1 of the calculation processing of FIG.
The outline of the arithmetic processing performed at 0 will be briefly described.
In this calculation process, when the inflow valve drive pulse width setting parameter W _EVi for each wheel is “0”, as shown in FIG. 10A, the sampling period ΔT of the calculation process of FIG.
, The inflow valve control signal S _{EV i} for each wheel which is always OFF.
Is output. Also, when the outflow valve drive pulse width setting parameter _WAVi for each wheel is "0", as shown in FIG.
The outflow valve control signal _SAVi for each wheel in the F state is output.

Further, the above-mentioned rear wheel inflow valve driving pulse width setting is performed.
Parameter W_EVRIs the pulse width predetermined value W_EVR0When
(For other wheels, the pulse width predetermined value W_EVR0Is applied
No), as shown in FIG.
The pulse width predetermined value at the beginning of the
W_EVR0OFF state for a predetermined time set corresponding to
After that, the rear wheel inflow valve control signal S which is turned on.
_EVRIs output. Also, the rear wheel outflow valve drive pulse
Width setting parameter W_AVRIs the pulse width predetermined value W _AVR0of
When (the other wheels have the pulse width predetermined value W_AVR0Is suitable
Not used), as shown in FIG.
At the beginning of the ring period ΔT,
Fixed value W_AVR0ON for a predetermined time set corresponding to
And after that, the rear wheel outflow valve control signal
No. S_AVRIs output.

When the inflow valve drive pulse width setting parameter _WEVi for each wheel is "1", as shown in FIG. 10e, the inflow valve control signal for each wheel which is always ON during the sampling period ΔT. S _EVi is output. Further, the outflow valve drive pulse width setting parameter W for each wheel
_{When AVi} is "1", as shown in FIG. 10f, the outflow valve control signal S _AVi for each wheel, which is always ON, is output during the sampling period ΔT.

When the wheel pump drive pulse width setting parameter W _MRi is "0", as shown in FIG. 10g, it is always OFF during the sampling period ΔT.
The pump control signal S _MRi for each wheel in the state is output. In addition, the above-described pump drive pulse width setting parameter W for each wheel is used.
_{When MRi} is “0”, as shown in FIG. 10h, the wheel pump control signal S _{MRi that} is always ON is output during the sampling period ΔT.

In order to facilitate understanding, some details of the arithmetic processing in FIG. 9 will be described in advance.
When the inlet valve driving pulse width setting parameters W _{EV R} for the rear wheel as described above is set to the pulse width predetermined value W _EVR0 the processing of FIG. 9 which is executed at step S7 in the arithmetic processing of Fig. 4 In steps S91 to S95
Or, from step S92 to step S77, step S9
6 is executed. In this flow, by setting the rear wheel inflow valve drive pulse width setting parameter W _EVR to the pulse width predetermined value W _EVR0 , the rear wheel inflow valve 8 for the rear wheel actuator 6R is _operated for a predetermined time as described above. In the OFF state, the hydraulic fluid pressure can be supplied to the rear wheel cylinders 2RL, 2RR. When the pressure increase interval counter CNT _INT-Z incremented in step S91 exceeds a predetermined count-up value CNT _INT-Z0 . Unless it becomes necessary, steps S92 to S77
Then, the process proceeds to step S96. During this time, the rear wheel inflow valve drive pulse width setting parameter W _EVR is “1” and the rear wheel outflow valve drive pulse width setting parameter W _AVR is “0”.
And the inflow valve 8 and the outflow valve 9 of the rear wheel actuator 6R are both closed, so that the rear wheel cylinder pressure P _R
Is retained. Then, the pressure increase interval counter CNT _INT-Z
Is greater than the predetermined count-up value CNT _INT-Z0 ,
The process proceeds from step S92 to steps S93 and S94, and for the first time, the rear wheel inflow valve driving pulse width setting parameter W _EVR is set to the predetermined pulse width value W _EVR0 , and the rear wheel outflow valve driving pulse width setting parameter W _EVR0 is set. _AVR is set to “0”, which causes the rear wheel actuator 6
While maintaining R outflow valve 9 of the closed, only the inflow valve 8 becomes short time opened state corresponding to the pulse width predetermined value W _EVR0, rear wheel wheel cylinder pressure P _R is the increase圧所value during this time The pressure is increased by (+ ΔP _R0 ). Note that after this manner rear wheel wheel cylinder pressure P _R is boosted stepwise, since the pressure increase interval counter CNT _INT-Z will be cleared in step S95, again the pressure increase interval counter CNT _INT-Z Is the predetermined count-up value CNT
Until it becomes _INT-Z0 or more, the rear wheel cylinder pressure P _R
Is not increased.

The rear wheel cylinder pressure P_RDecompression
Similarly, the rear wheel outflow valve drive pulse width setting parameter
TA W_AVRIs the pulse width predetermined value W_AVR0If set to
Steps S81 through S81 in the calculation process of FIG.
Step S85 or steps S82 to S77,
The flow of shifting to step S96 is executed. This flow
However, the value incremented in step S81 is
Pressure interval counter CNT _INT-GIs the predetermined count-up value C
NT_INT-G0Unless it becomes the above, the process from step S82
Since the process proceeds to step S96 after step S77,
Is between the inflow valve 8 and the outflow valve of the rear wheel actuator 6R.
9 are closed and the rear wheel cylinder pressure P_RIs
Will be retained. Then, the decompression interval counter CNT_INT-GBut
Predetermined count-up value CNT_INT-G0Each time
The process proceeds from step S82 to steps S83 and S84.
This is the first time the rear wheel outflow valve drive pulse width setting parameter
Meter W_AVRIs the pulse width predetermined value W_AVR0Is set to
Inlet valve drive pulse width setting parameter W for rear wheel_EVRIs
This is set to “1”, which causes the rear wheel actuator 6
While keeping the inflow valve 8 of R closed, only the outflow valve 9
The pulse width predetermined value W_{AV R0}Open for a short time corresponding to
And the driving pulse for the rear wheel has already been driven in step S80.
Width setting parameter W_MRRIs set to "1"
During this time, the rear wheel pump 10 is driven.
Eel cylinder pressure P_RIs the predetermined pressure reduction value (−ΔP_R0) Minutes
Only the pressure is reduced. In this case, the rear wheel
Cylinder pressure P_RAfter the pressure is reduced in steps,
In step S85, the decompression interval counter CNT_INT-GIs cleared
The pressure reduction interval counter CNT_INT-GBut
Predetermined count-up value CNT_INT-G0Until then,
Rear wheel cylinder pressure P_RIs not reduced.

Further, in particular, the rear wheel series as described above is used.
Pressure P_RIf the pressure is increased step by step, step S
From 87, the flow goes through the flow from step S90. here,
Passing through this flow is required after step S91.
And rear wheel cylinder pressure P _RPressure increase step by step
It is assumed that the
Increased pressure increase counter CNT_ZIs the prescribed count
Up value CNT_Z0If this is the case, that is,
Rear wheel cylinder pressure P_RStepwise pressure increase
Is repeated a predetermined number of times, step S90
Through steps S88 and S97 to step S9
Move to the flow to 8. This flow is described below.
Open the inflow valve 8 and outflow valve 9 of the rear wheel actuator 6R.
Maintain the closed state and adjust the rear wheel master cylinder pressure P_MCRIs straightforward
Sudden increase flowing into the rear wheel cylinders 2RL and 2RR
Pressure mode. That is, a controlled rear wheel wheel series
Pressure P_RStepwise pressure increase was repeated a predetermined number of times
Return to the normal braking state and secure the braking distance
It is intended to be.

Next, the overall operation of this embodiment will be described with reference to FIG.
This will be described with reference to the timing chart of FIG. This timing chart shows that the vehicle is traveling at a constant speed on a high μ good road before time t ₀₀ , and then shifts to a braking state from time t ₀₀ , whereupon the brake fluid pressure control of the rear wheel cylinders 2RL and 2RR is performed. This simulates the case where it is started. In this simulation, it is assumed that the anti-skid non-control condition is satisfied at any time in the arithmetic processing of FIG. 3 and the rear wheel cylinder pressure control in step S03 is continuously executed.

In the timing chart, first,
Time t₀₀Until the calculation process of FIG. 4 is executed,
The brake pedal has not yet been depressed, resulting in air
Master cylinder pressure P equivalent to pressure_MCF, P_MCRIs a step
It is read in S1 and then in step S2 the longitudinal acceleration G_X
And each wheel speed Vw_iIs read. In the next step S3
Executes the arithmetic processing of FIG. 5, and in the step S31
Is the wheel angular acceleration ω'w_iIs calculated. In this case,
Wheel speed Vw_iBecause the time derivative of is 0,
Wheel angular acceleration ω'w_iIs also "0", then the rear wheel
Cylinder pressure control flag F_PROPIs “0” reset status
To step S33, and as described above
Rear wheel master cylinder pressure P equal to atmospheric pressure_MCRThe rear wheel
Eel cylinder pressure P_R, Then step S35
And the front wheel master cylinder pressure P which is also equal to the atmospheric pressure_MCF
Is the front wheel cylinder pressure P_FAnd then step
In step S36, the average front wheel angular acceleration ω'w_FIs calculated, but before
Left and right wheel angular acceleration ω'w_FL, Ω'w _FRAre both "0"
From the average front wheel angular acceleration ω'w_FAlso becomes “0” and then
In step S37, the braking torque T of each of the front and rear wheel cylinders
_BjIs calculated, but also here, each wheel cylinder pressure P_j
Is equal to the atmospheric pressure (= 0MPa).
Brake torque T_BjAre all “0”,
Front and rear wheel braking force F calculated in the next step S38
_jAlso, each wheel angular acceleration ω'w_jIs "0"
Becomes "0". In the next step S4, the calculation shown in FIG.
Processing is executed, but in this case, the brake switch signal
S_BRKIs in the OFF state of “0”, the step S
From step 41, the process proceeds to step S43, where a predetermined location is set.
Fixed value W ₀Is set to the vehicle weight W for the time being. Also,
In the next step S5, the arithmetic processing of FIG. 7 is executed.
In this case, the longitudinal acceleration G detected_XIs "0"
Front and rear wheel load W_F, W_RIs the front wheel static load W_F0,Rear wheel
Static load W_R0Is equal to In the next step S6,
The arithmetic processing of FIG. 8 is executed, but the front wheel braking is performed as described above.
Force F_FIs "0", the target rear wheel braking force F^* _RAlso
It becomes “0”.

As described above, the target rear wheel braking force F ^* _R is "0".
In the non-braking state where the actual rear wheel braking force F _R is also “0”, the rear wheel braking force deviation Δ calculated in step S71 in the arithmetic processing of FIG. 9 executed in step S7.
Since F _R becomes "0", the target rear-wheel pressure increase amount ΔP calculated in step S72 ^* _R also becomes "0". When the target rear wheel pressure increase / decrease amount ΔP ^* _R becomes “0” in this manner, since it is equal to or greater than the pressure increase threshold ΔP ^* _RZ , the process proceeds from step S73 to step S75 in the calculation processing of FIG. Since the wheel cylinder pressure control flag F _PROP is in the reset state of “0”, the flow shifts to step S88, where the rear wheel cylinder pressure control flag F _{PROP is set.}
Is reset, and then steps S97 and S9 are performed.
8, the rear wheel pump drive pulse width setting parameter W _MRR ,
The rear wheel inflow valve drive pulse width setting parameter _WEVR and the rear wheel outflow valve drive pulse width setting parameter _WAVR are all set to "0", and the pressure increase interval counter CNT _INT-Z is cleared in the next step S99. Then, in step S86, the pump drive pulse width setting parameters W _MRFL and W _MR for the front wheels are set.
_FR and inflow valve drive pulse width setting parameters W _EVFL , W
_EVFR and outlet valve drive pulse width setting parameters W _AVFL , W
_AVFR is all set to "0", and in the next step S100, control signals S _EVi , S _AVi , S _MRi corresponding to each pulse width setting parameter W _EVi , _{WA Vi} , W _MRi are _generated and output, and then the main program is _executed. Return to. Here, all the control signals S _EVi , S _AVi , and S _{MRi generated} and _output are the same as those in FIG.
As described in 0, since all are in the OFF state, the hydraulic pumps 10 of the actuators 6FL to 6R are not driven, and the outflow valve 9 is closed and the inflow valve 8 is open. the master cylinder pressure P _MCF, P _MCR is directly supplied to the wheel cylinders 2FL～2RR, it is maintained in a state of so-called surge pressure. However, this condition, the actual wheel cylinder pressure P _F, not a state P _R are pressurized surge, indicated by a broken line that the wheel cylinder pressure control mode in FIG. 12 is a pressure increasing state.

On the other hand, at the time t₀₀Starts braking at
And the corresponding master cylinder pressure P_MCF, P_MCRBut
It gradually increases, and this is determined in step S1 of the arithmetic processing in FIG.
Read. In addition, before and after the deceleration direction (positive value) due to braking
Acceleration G_XAnd each wheel speed Vw gradually decelerating_iAnd the same
It is read in step S2. Is executed in the next step S3
In the calculation processing of FIG.
Speeding wheel speed Vw_iNegative wheel angular acceleration ω'w_iBut
Calculated, and then the rear wheel cylinder pressure control flag
F_PROPIs in the reset state of “0”.
Shift to S33 and gradually increase master cylinder for rear wheels
Pressure P_MCRIs the rear wheel cylinder pressure P_RSet to and then
In step S35, the master for the front wheels also increases gradually.
Cylinder pressure P_MCFIs the front wheel cylinder pressure P_FSet to
Then, in step S36, the front left and right wheel angular acceleration ω′w
_FL, Ω'w_FRNegative front wheel angular acceleration
ω'w_FIs calculated, and then gradually increases in step S37
Each wheel cylinder pressure P_jAccording to each front and rear wheel
Cylinder braking torque T_BjIs calculated and therefore the next step
In step S38, the braking torque T_BjAnd each negative wheel angle
Acceleration ω'w_jFront and rear wheel braking force F according to_jIs calculated
You. Next, in the calculation processing of FIG.
Is already in the braking state and the brake switch signal S_BRK
Is "1" in the ON state.
The process shifts to step S42, where the front and rear wheel braking force F_jAccording to
Further, the vehicle weight W at that time is accurately calculated. next,
In the calculation process of FIG. 7 executed in step S5, the vehicle
Both weights W and longitudinal acceleration G at that time_XAnd using
In step S51, the wheel loads W of the front and rear wheels_F, W_RIs calculated
Then, in the calculation processing of FIG.
Is used to calculate the front wheel braking force at that time.
F_FRear wheel braking force that satisfies the ideal braking force distribution
F ^* _RIs calculated.

However, the front wheel master cylinder pressure _PMCF has not yet increased, and therefore the front wheel braking force _FF is
The calculated target rear wheel braking force F ^* _R itself is also a small value because it is a small value that is far less than locking the wheels on the road surface, but the current rear wheel braking force F _R is still sufficient. In the calculation process of FIG. 9 executed in step S7, a relatively small positive rear wheel braking force deviation ΔF _R is calculated in step S71, and this rear wheel braking force deviation ΔF
_In step S72, a relatively small positive rear wheel pressure increase / decrease amount ΔP ^* _R is set based on _R. Therefore,
In the calculation process of FIG. 9, since the target rear wheel pressure increase / decrease amount ΔP ^* _R is equal to or greater than the pressure increase threshold ΔP ^* _RZ , the process proceeds from step S73 to step S75 in the same manner as described above, and the rear wheel wheel cylinder pressure Since the control flag F _PROP is in the reset state of “0”, the flow shifts to step S88 to reset the rear wheel cylinder pressure control flag F _PROP again, and then to steps S97, S98 and S98.
By moving to step S86 via 99, all the pulse width setting parameters W _EVi , _{WA Vi} , and W _MRi are _set to “0”.
And the pressure increase interval counter CNT _INT-Z is cleared.
The control signals S _EVi , S _AVi , and S _MRi in the F state are _generated and output, whereby the hydraulic pumps 10 of the actuators 6FL to 6R are not driven, and the inflow valve 8 is opened with the outflow valve 9 closed. and that state, that the master cylinder pressure P _MCF, is maintained in a state of surge pressure P _MCR is directly supplied to the wheel cylinders 2FL～2RR.

From this state, the master cylinder for the front and rear wheels is further moved.
Da pressure P_MCF, P_MCRGradually increases, the front and rear wheel
Cylinder pressure P_F, P_RAlso become bigger each braking torque
K T _BF, T_BRBefore it is in the deceleration direction
Rear wheel angular acceleration ω'w_F, Ω'w_RThe absolute value of
Front and rear wheel braking force F_F, F_RIncrease. However, this
Longitudinal acceleration G generated by the vehicle_XAlso gets bigger
From the calculation processing of FIG.
In step S42, a vehicle weight equivalent or substantially equivalent to the above
W is calculated. However, in step S5,
7, the longitudinal acceleration G_XTo increase
Accordingly, in step S51, the front wheel load further increases.
W_FAnd the rear wheel load W that further decreases_RIs calculated, and this
According to the calculation processing of FIG.
Is a target that gradually approaches a certain value in step S61.
Rear wheel braking force F^* _RIs calculated and set. Follow
And time t₀₁Thereafter, when the arithmetic processing of FIG. 4 is executed,
In the arithmetic processing of FIG. 9 executed in step S7 of FIG.
Calculated from step S71 to step S72
Target rear wheel pressure increase / decrease amount ΔP^* _RIs negative, that is,
Rear wheel increase / decrease ΔP^* _RIs the pressure increase threshold ΔP^* _RZLess than
And therefore, from step S73 to step S74.
Shift to rear wheel cylinder pressure control flag F_PROPBut
Set to "1". At this time, the target rear wheel pressure reduction
Quantity ΔP^* _RIs still the decompression threshold ΔP^* _RGTo be bigger
Then, the process proceeds from step S76 to step S77 to increase the rear wheels.
Decompression amount ΔP _RIs set to “0” and the next step
In S96, the rear wheel inflow valve drive pulse width setting parameter W
_EVRTo “1”, the rear wheel outflow valve drive pulse width setting parameter
TA W_{AV R}Are set to “0”, respectively. The next step
At S86, all the pulse widths for the front wheels are set as described above.
Parameter W_EVFL, W_EVFR, W_AVFL, W_AVFR, W_MRFL,
W_MRFRIs set to “0”. Therefore, the next step S
In 100, the front wheel actuators 6FL and 6FR
For each control signal S in the OFF state_EVi, S _AVi,
S_MRiThe master cylinder for front wheels
Da pressure P_MCFFor each front wheel cylinder 2FL, 2FR
Although it is maintained at a sudden increase in pressure supplied directly,
An inflow valve that is always ON for the actuator 6R
Control signal S _EVRAnd the outflow valve control signal S which is always OFF
_AVRWill be generated and output.
The tutor 6R is in a holding state to contain the hydraulic pressure.
Then, the rear wheel cylinders 2RL, 2RR
The working fluid pressure is maintained.

At this time, the front wheel speed Vw _F and the front wheel braking force F _F
From (∝ front wheel cylinder pressure P _F ), the target rear wheel speed V ^* w _R targeted using the wheel deceleration set by the ideal braking force distribution curve is indicated by a two-dot chain line in FIG. the time t ₀₁ after, the rear wheel cylinder 2RL, 2RR
For inner is in hydraulic fluid pressure holding state, the actual rear wheel speed Vw _R slightly faster than that the target rear wheel speed V ^* w _R continues slightly, by the reduction of the vehicle speed, immediately matched I do. In other words, the rear wheel cylinder pressure P _R without or depressurized or pressurized increased blindly, and contribute to reliably decelerate the vehicle speed at braking force ideal. This also hereafter, front wheel cylinder pressure P _F is equal to the front wheel master cylinder pressure P _MCF continued to increase slightly, as a result, the target to achieve the target rear wheel braking force F ^* _R to be ideal braking force distribution The rear wheel cylinder pressure P ^* _R also gradually increases, but the target rear wheel pressure increase / decrease amount ΔP ^* _R calculated from this is smaller than the pressure increase threshold ΔP ^* _RZ and larger than the pressure decrease threshold ΔP ^* _RG. As a result, the inside of the rear wheel cylinders 2RL, 2RR has been maintained in the hydraulic fluid pressure holding state for a while. Again,
The actual rear wheel speed Vw _R continued to match the target rear wheel speed V ^* w _R well, and the vehicle speed was reliably reduced without impairing the steering effect. During this time, the rear wheel pressure increase / decrease amount Δ
Since P _R continues to be set to “0” and the rear wheel cylinder pressure control flag F _PROP is set to “1”, the calculation process of FIG. proceeds from step S32 to step S34, the time t ₀₁ updates the stored rear wheel wheel cylinder pressure P _R is continuously thereafter retained.

Eventually, the target rear wheel braking which continues to increase gradually
Force F^* _R, The rear wheel cylinder pressure P_RConstant
Rear wheel braking force F_RIs also constant, so after the difference value
Wheel braking force deviation ΔF_RAlso gradually increased, then calculated
Target rear wheel pressure increase / decrease amount ΔP ^* _RIs the pressure increase threshold ΔP^*
_RZAt this point, the process of FIG.
In the arithmetic processing, steps S73 to S
75, proceed to step S87. This step S87
Then, as described above, the rear wheel cylinder pressure P_RNo
Decompression interval cow that is incremented during step decompression
CNT_{INT- G}Is cleared, and then in step S89
The pressure increasing counter CNT_ZIs incremented. Only
While the pressure boost counter has just been incremented
CNT_ZIs the predetermined count-up value CNT_Z0Over
From step S90 to step S91
, And here, the pressure increase interval counter CNT_INT-ZThe
And increments the predetermined count-up value CNT.
_INT-Z0Until the above, steps S92 to S92
The flow shifts to 77, and thereafter, this flow is repeated. Is
And time t₀₂The pressure increase interval counter CNT_INT-ZBut
Predetermined count-up value CNT_INT-Z0Once this is done,
From step S92 to step S94 via step S93
Transition. As a result, the flow of the rear wheel actuator 6R is reduced.
While the outlet valve 9 is kept closed, only the inlet valve 8 is
Loose width predetermined value W_EVR0Open for a short period of time
During this time, the rear wheel cylinder pressure P_RIs the booster station
Constant value (+ ΔP_R0) Minutes.

After this, the rear wheel braking force F_RIs ideal
Target rear wheel braking force F corresponding to braking force distribution^* _RApproaching
As a result, the target rear wheel pressure increase / decrease amount ΔP^* _RIs the pressure increase threshold Δ
P^* _RZAnd decompression threshold ΔP^* _RGBecause it stopped between
Similarly, the rear wheel cylinder pressure P_RIs kept
However, the vehicle speed can be reliably increased with the ideal braking force.
It helped to slow down.

On the other hand, FIG. 13 shows a simulation of brake fluid pressure control using a conventional wheel speed Vw _j as a control input. The assumption of this simulation is shown in FIG.
But are equivalent to those of, the rear wheel speed Vw _R set a target rear wheel speed V ^* w _R along the ideal braking force distribution from the actual rear wheel speed than the target rear-wheel speed V ^* w _R Vw _R Is small (slow)
And when it is determined, under reduced pressure or holding the rear wheel cylinder pressure P _R, is larger rear wheel speed Vw _R than (faster)
If it is determined that is obtained by such pressure increasing the rear wheel cylinder pressure P _R.

As described above, the wheel speed Vw_jFrom each hoi
Cylinder pressure P_jFeedback system that observes
In the embodiment, the actual braking force F_jEstimation is delayed,
Naturally, response delay and hunting occur in hydraulic control.
easy. Also in this simulation, the actual rear wheel speed Vw_R
Is the target rear wheel speed V^*w_RTime t below₁₁Then, FIG.
The rear wheel cylinder is already compared to the simulation of 2
Da pressure P_RIs correspondingly large, so that
Wheel speed Vw_RWill continue to decelerate greatly, so the time
t₁₂, T₁₃, T₁₄And rear wheel cylinder pressure P_RThe
The pressure must be reduced in a step-up manner. However, in this way
As a result of repeating the necessary decompression, this time t _FifteenAnd rear wheel speed Vw
_RIs the target rear wheel speed V^*w_R, And this time
Time t₁₆, T₁₇, T₁₈And rear wheel cylinder pressure P_RThe
I had to step up the pressure. In terms of results
Time t₁₉And the actual rear wheel speed Vw_RTarget rear wheel speed V^*w_RTo
Although they could be substantially matched, during this time, the rear wheel braking force F_R
Is not stable and eventually deviates from the ideal braking power distribution
The braking distance was long and the braking distance was most effectively secured.
Absent.

[0086] According to the brake fluid pressure control device of the present embodiment, to detect the front wheel master cylinder pressure P _MCF, precisely on the basis of the master cylinder pressure P _MCF or its equivalent front wheel cylinder pressure P _F a front wheel braking force F _F quickly calculated, because it is possible to directly set a target rear wheel braking force F ^* _R to be ideal braking force distribution on the basis of the accurate and rapid front wheel braking force F _F, the target Rear wheel braking force F ^* _R
The by outputting a command signal to the rear wheel wheel cylinder pressure P _R is obtained to achieve the responsiveness of the control as compared with the prior art can be improved controllability with improved.

Further, the rotational angular accelerations ω'w _F of the front and rear wheels,
By using ω'w _R , the braking forces F _F , F
_R can be calculated, and the target rear wheel braking force F ^* _R is set by using the vehicle weight W calculated based on the accurate braking force of each of the front and rear wheels. The controllability can be improved by setting F ^* _R closer to the ideal braking force distribution.

[0088] Further, front-rear braking force F _F, which is precisely calculated and longitudinal acceleration G _X, thereby enabling accurately calculate the vehicle weight W by using the F _R, the exact vehicle weight W and the longitudinal acceleration G _X, and the front and rear wheel loads W _F ,
By using a W _R sets the target rear wheel braking force F ^* _R, it is possible to improve the controllability of the target rear wheel braking force F ^* _R as a further close to the ideal braking force distribution.

As described above, the pressure sensors 13F, 13R
And step S1 of the arithmetic processing of FIG. 4 constitutes the master cylinder operating hydraulic pressure detecting means of the brake hydraulic pressure control device of the present invention,
Alternatively, step S35 of the arithmetic processing of FIG. 5 constitutes the front wheel braking cylinder operating hydraulic pressure detecting means, and similarly, the arithmetic processing of FIGS. Steps S31 and S36 of the arithmetic processing of FIG. 5 constitute the wheel rotational angular acceleration detecting means, and the longitudinal acceleration sensor 15 and the step S31 of the arithmetic processing of FIG.
2 constitutes the longitudinal acceleration detecting means.

[0090] In the above embodiment, front wheel cylinder 2FL, has been described in which the front wheel cylinder pressure P _F of 2FR be estimated from the master cylinder pressure P _MCF, is not limited thereto, Wheel cylinder pressure P of each wheel cylinder 2FL, 2FR
_F may be directly detected by a pressure sensor.

Further, in the above-described embodiment, only the case of the three-channel anti-skid control device in which the wheel speed of the rear wheel is detected by the common wheel speed sensor is described in detail. The present invention can also be applied to a so-called four-channel anti-skid control device in which wheel speed sensors are individually provided, and separate actuators are provided for the left and right wheel cylinders accordingly. Further, an independent control device may be used without using the anti-skid control device as the brake fluid pressure control device for the rear wheels.

The brake fluid pressure control device of the present invention can be applied to any vehicle such as a rear wheel drive vehicle, a front wheel drive vehicle, and a four wheel drive vehicle. In each of the above embodiments, a case has been described in which a microcomputer is applied as a control unit. Alternatively, electronic circuits such as a counter and a comparator may be combined.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vehicle showing an example in which a braking fluid pressure control device of the present invention is developed into an anti-skid control device.

FIG. 2 is a schematic configuration diagram illustrating an example of the actuator of FIG.

FIG. 3 is a flowchart showing an embodiment of an entire calculation process of braking force control executed by the control unit of FIG. 1;

FIG. 4 is a flowchart illustrating an example of a brake fluid pressure control calculation process executed in the overall calculation process of FIG. 3;

FIG. 5 is a flowchart illustrating an example of a calculation process for calculating a front and rear wheel braking force, which is performed in the brake fluid pressure control calculation process of FIG. 4;

FIG. 6 is a flowchart illustrating an example of a calculation process of a vehicle weight calculation performed in the brake fluid pressure control calculation process of FIG. 4;

FIG. 7 is a flowchart illustrating an example of a calculation process of front and rear wheel load calculation performed in the brake fluid pressure control calculation process of FIG. 4;

8 is a flowchart illustrating an example of a calculation process of calculating a target rear wheel braking force, which is performed in the brake fluid pressure control calculation process of FIG. 4;

FIG. 9 is a flowchart illustrating an example of a calculation process for outputting a control signal, which is performed in the brake fluid pressure control calculation process of FIG. 4;

FIG. 10 is an explanatory diagram of a control signal executed in the calculation processing of FIG. 9;

FIG. 11 is an explanatory diagram of ideal braking force distribution.

FIG. 12 is a diagram illustrating the operation of the brake fluid pressure control device according to the present embodiment.

FIG. 13 is an explanatory diagram of an operation of a conventional brake hydraulic pressure control device.

[Explanation of symbols]

 1FL to 1RR are wheels 2FL to 2RR are wheel cylinders (braking cylinders) 3FL to 3R are wheel speed sensors 4 are brake pedals 5 are master cylinders 6FL to 6R are actuators 8 are electromagnetic inflow valves 9 are electromagnetic outflow valves 10 are pumps 13F , 13R is a pressure sensor 20 is a microcomputer 22aFL-22cR is a drive circuit EG is an engine T is a transmission DG is a differential gear CR is a control unit

Claims (4)

[Claims] An actuator capable of adjusting at least a hydraulic pressure of a brake cylinder for a rear wheel of a vehicle in accordance with a command signal, a master cylinder hydraulic pressure detecting means for detecting a hydraulic pressure of a master cylinder, The braking force of the front wheels is calculated based on the hydraulic pressure of the master cylinder detected by the cylinder hydraulic pressure detecting means, and the target braking force of the rear wheels is set based on the braking force of the front wheels. And a brake fluid pressure control means for outputting a command signal for achieving the target braking force of the rear wheel to the actuator. 2. An actuator capable of adjusting at least a hydraulic pressure of a brake cylinder of a rear wheel of a vehicle in accordance with a command signal, and a hydraulic fluid pressure detection of a front wheel brake cylinder for detecting a hydraulic pressure of a brake cylinder of a front wheel. Means for calculating the front wheel braking force based on the hydraulic pressure of the front wheel braking cylinder detected by the front wheel braking cylinder hydraulic pressure detecting means, and an ideal braking force distribution based on the front wheel braking force. Brake fluid pressure control means for setting a target braking force for the rear wheels and outputting a command signal for achieving the target braking force to the rear wheels to the actuator. Control device. 3. Wheel rotational angular acceleration detecting means for detecting at least rotational angular acceleration of each of the front and rear wheels, wherein the control means uses the rotational angular acceleration of each of the front and rear wheels detected by the wheel rotational angular acceleration detecting means. The braking force of each of the front and rear wheels is calculated by using the vehicle weight calculated based on the braking force of each of the front and rear wheels, and the target braking force of the rear wheel is set. A brake fluid pressure control device for a vehicle according to any one of the preceding claims. 4. A longitudinal acceleration detecting means for detecting at least a longitudinal acceleration acting on the vehicle in a longitudinal direction, wherein the control means comprises: a longitudinal acceleration detected by the longitudinal acceleration detecting means; The vehicle weight is calculated using the braking force of the vehicle, and the target braking force of the rear wheel is set using the wheel loads of the front and rear wheels calculated based on the vehicle weight and the longitudinal acceleration. Item 3
4. The brake fluid pressure control device for a vehicle according to claim 1.