JPH11208438A - Vehicle behavior control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent slippage of a travelling line easy to be caused on a low μroad surface and to secure a braking distance demanded on a high μ road surface by vehicle behavior control by braking force control. SOLUTION: Slippage prevention of a travelling line and security of a braking distance are doubly carried out by setting a braking force reduction (pressure reduction) priority mode to acquire front and rear wheel braking force differences ΔFF*, ΔFR* to provide a target moment M required for correction of vehicle behavior by prior reduction of braking force, a braking force increase (pressure increase) priority mode to provide them by prior increase of braking force and a braking force simultaneous increase and reduction (pressure increase and reduction moderate) mode which is in the middle of the above two and total braking force of which does not change and selecting each of the modes for example, along with a road surface μ substituted by lateral acceleration and longitudinal acceleration and a will of a driver recognized from operation of the driver.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention controls the braking force of each wheel based on vehicle behavior information such as a yaw rate, a sideslip angle or a sideslip speed, and a target value of the vehicle behavior calculated based on a vehicle model. The present invention relates to a vehicle behavior control device that generates a vehicle behavior correction moment such as an anti-spin moment.

[0002]

2. Description of the Related Art Various types of vehicle behavior control devices of this type have been proposed. Among them, for example, JP-A-6-9
No. 9800 discloses a method of calculating a target value of a vehicle behavior such as a yaw rate, a side slip angle or a side slip speed based on a vehicle model, and a vehicle behavior such as a yaw rate, a side slip angle or a side slip speed generated in the vehicle. The braking force of each wheel, that is, the braking fluid pressure to the braking cylinder, is obtained in accordance with the deviation between the two values, in order to obtain, for example, a force that matches the actual value of the vehicle behavior to the target value. Control. In addition, such a force is referred to as a vehicle behavior correction moment such as an anti-spin moment, for suppressing (in some cases accelerating) the rotation of the vehicle plane behavior. According to such a vehicle behavior control device, for example, when the vehicle enters a turning state that exceeds the limit of the grip of the tire such as extreme oversteer or understeer, for example, the actual value of the yaw rate is set to the target value. As a result, the vehicle behavior correction moment is generated by controlling the braking force of each wheel so that the vehicle can always be driven in the grip area of the tire, and at the same time, such as extreme oversteer or understeer, etc. This makes it possible to prevent undesirable turning behavior from being suppressed.

[0003]

In the prior art, for example, when an oversteer state occurs with respect to the target vehicle behavior, for example, the braking force of the front turning outer wheel is increased to increase the anti-steering force. Spin moment,
That is, a vehicle behavior correction moment for suppressing the oversteer state is generated. That is, the braking force difference between the wheels required to generate the vehicle behavior correction moment is obtained by increasing the braking force. However, if the control is performed only in the direction of increasing the braking force, for example, on a low μ road surface having a low friction coefficient state (hereinafter also simply referred to as μ), the oversteer state is certainly prevented from being suppressed, but the braking force increases. In some cases, the cornering force of the front turning outer wheel is reduced, and the traveling line of the vehicle is shifted outward.

[0004] The present invention has been developed in view of these problems, and provides a braking force reduction priority control in which the braking force difference between the wheels required to generate a vehicle behavior correction moment is reduced by reducing the braking force. By providing this, unnecessary reduction in grip force and cornering force can be avoided, and the road surface μ
A vehicle behavior control device capable of securing a braking distance by giving priority to an increase in braking force, or stabilizing a traveling line by giving priority to a reduction in braking force, depending on the running conditions of a vehicle. It is intended for.

[0005]

In order to achieve the above object, a vehicle behavior control apparatus according to the present invention detects a vehicle behavior and controls a braking force of each wheel to control the vehicle behavior. The vehicle behavior control device that generates a correction moment includes a braking force reduction priority control unit that gives priority to a reduction in the braking force in order to obtain a braking force difference between the wheels required to generate the vehicle behavior correction moment. It is characterized by having.

According to a second aspect of the present invention, in the vehicle behavior control device according to the first aspect of the present invention, the braking force reduction priority control means controls the braking force of the wheel whose priority has been reduced to zero. , The braking force of the other wheels is increased.

According to a third aspect of the present invention, in the vehicle behavior control apparatus according to the first or second aspect, the braking force difference between the wheels required to generate the vehicle behavior correction moment is determined. In order to obtain, the braking force increase priority control means for giving priority to the increase of the braking force, the vehicle traveling state detecting means for detecting the traveling state of the vehicle, and the vehicle traveling state detected by the vehicle traveling state detecting means. Accordingly, a braking force increase / decrease rate control means for controlling a rate of reduction of the braking force by the braking force reduction priority control means and an increase rate of the braking force by the braking force increase priority control means is provided. .

According to a fourth aspect of the present invention, there is provided a vehicle behavior control apparatus according to the third aspect of the present invention for obtaining a braking force difference between wheels required to generate the vehicle behavior correction moment. A braking force simultaneous increase / decrease control means for simultaneously increasing and decreasing the braking force so that the total sum of the braking forces does not change, wherein the braking force increase / decrease rate control means includes a vehicle detected by the vehicle running state detection means. In accordance with the running condition of the vehicle, the priority of the braking force reduction by the braking force reduction priority control means, the braking force increase by the braking force increase priority control means, and the simultaneous increase / decrease of the braking force by the braking force simultaneous increase / decrease control means are set. It is characterized by being.

According to a fifth aspect of the present invention, in the vehicle behavior control device according to the fourth aspect of the present invention, as the vehicle traveling state detecting means, a road surface friction coefficient state detecting means for detecting a road surface friction coefficient state is provided. Wherein the braking force increase / decrease rate control means gives priority to the reduction of the braking force by the braking force reduction priority control means when the road friction coefficient state detected by the road friction coefficient state detection means is low, and the road surface friction When the coefficient state is high, priority is given to the increase of the braking force by the braking force increase priority control means or the simultaneous increase and decrease of the braking force by the simultaneous braking force increase / decrease control means.

According to a sixth aspect of the present invention, in the vehicle behavior control device according to the fourth or fifth aspect of the present invention, as the vehicle traveling condition detecting means, a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle. Means, wherein the braking force increase / decrease rate control means gives priority to the reduction of the braking force by the braking force reduction priority control means when the lateral acceleration detected by the lateral acceleration detection means is small, and when the lateral acceleration is large, It is characterized in that priority is given to an increase in braking force by the braking force increase priority control means or a simultaneous increase and decrease in braking force by the braking force simultaneous increase / decrease control means.

According to a seventh aspect of the present invention, in the vehicle behavior control device according to the sixth aspect, the braking force increase / decrease rate control means includes a change in a lateral acceleration detected by the lateral acceleration detection means. When the amount is large, the reduction of the braking force by the braking force reduction priority control means is prioritized.

The vehicle behavior control device according to claim 8 of the present invention is characterized in that, in the invention according to any one of claims 4 to 7, the vehicle running condition detecting means detects longitudinal acceleration that occurs in the vehicle. Means, wherein the braking force increase / decrease rate control means gives priority to the reduction of braking force by the braking force reduction priority control means when the longitudinal acceleration detected by the longitudinal acceleration detecting means is small, and when the longitudinal acceleration is large, It is characterized in that priority is given to an increase in braking force by the braking force increase priority control means or a simultaneous increase and decrease in braking force by the braking force simultaneous increase / decrease control means.

According to a ninth aspect of the present invention, in the vehicle behavior control device according to the eighth aspect, the braking force increase / decrease rate control means includes a change in the longitudinal acceleration detected by the longitudinal acceleration detecting means. When the amount is large, priority is given to increasing the braking force by the braking force increase priority control means or to simultaneously increasing and decreasing the braking force by the braking force simultaneous increase / decrease control means.

According to a tenth aspect of the present invention, there is provided a vehicle behavior control apparatus according to the fourth to ninth aspects.
As the vehicle running state detecting means, a steering state detecting means for detecting whether the actual vehicle behavior is an oversteer state or an understeer state with respect to a target value of the vehicle behavior,
The braking force increase / decrease rate control means gives priority to the reduction of the braking force by the braking force reduction priority control means when the vehicle behavior detected by the steering state detection means is in the oversteer state, and controls the braking force when the vehicle behavior is understeer. It is characterized in that priority is given to an increase in the braking force by the power increase priority control means or a simultaneous increase and decrease in the braking force by the simultaneous braking force increase / decrease control means.

According to a eleventh aspect of the present invention, in the vehicle behavior control device according to the fourth to ninth aspects of the present invention, as the vehicle traveling state detecting means, a brake pedal depressing operation for detecting a brake pedal depressing operation is performed. An increase detection means, wherein the braking force increase / decrease rate control means prohibits a decrease in braking force by the braking force reduction priority control means when an increase in brake pedal operation is detected by the brake pedal increase detection means; or It is characterized in that priority is given to an increase in braking force by the braking force increase priority control means or a simultaneous increase / decrease in braking force by the simultaneous braking force increase / decrease control means.

According to a twelfth aspect of the present invention, there is provided a vehicle behavior control device according to the fourth to eleventh aspects, wherein the vehicle running condition detecting means detects a turning operation of a steering wheel. An increase detection means, wherein the braking force increase / decrease rate control means comprises:
When the steering wheel turning-up detecting means detects the turning operation of the steering wheel, the reduction of the braking force by the braking-force-decreasing priority controlling means is prioritized, or the braking force is increased or the braking force by the braking-force increasing priority controlling means. The simultaneous increase / decrease control means prohibits simultaneous increase / decrease of the braking force.

[0017]

According to the vehicle behavior control apparatus according to the first aspect of the present invention, the vehicle behavior correcting the actual vehicle behavior toward the target vehicle behavior, such as the anti-spin moment, In order to obtain the braking force difference between the wheels required to generate the correction moment, the braking force reduction priority control means for giving priority to the reduction of the braking force is provided. If the required braking force difference between the wheels is obtained with priority given to the reduction of the vehicle, it is possible to obtain a vehicle behavior correction moment while avoiding a decrease in tire grip force and cornering force. Undesirable turning behavior can be suppressed and prevented without shifting the line.

Further, according to the vehicle behavior control device of the second aspect of the present invention, when the braking force of the preferentially reduced wheel becomes zero, the braking force of the other wheels is increased. For example, even if the braking force difference between the wheels required to generate the vehicle behavior correction moment cannot be obtained by simply reducing the braking force, the vehicle behavior correction moment is generated by reliably obtaining the braking force difference between the wheels. be able to.

According to the vehicle behavior control device of the third aspect of the present invention, the ratio of the braking force decrease priority control and the increase priority control of the braking force is controlled in accordance with the running condition of the vehicle. If the road surface friction coefficient state is low, priority is given to the braking force reduction control so that the traveling line is not shifted, and if the road surface friction coefficient state is high, priority is given to the braking force increase control and the braking distance is secured, Unwanted turning behavior can be prevented and suppressed.

According to the vehicle behavior control device of the present invention, the priority of the braking force reduction priority control, the increase priority control, and the simultaneous increase / decrease control is set according to the running condition of the vehicle. For example, if the road surface friction coefficient state is low, the braking force reduction control is prioritized so as not to shift the traveling line, and if the road surface friction coefficient state is high, the braking force increase control is prioritized to increase the braking distance. In addition, when the road surface friction coefficient state is moderate, the traveling line can be made as intended by the driver while securing the braking distance without changing the total braking force.

According to the vehicle behavior control device of the present invention, when the road surface friction coefficient state is low, priority is given to the braking force reduction control, and when the road surface friction coefficient state is high, the braking force reduction control is performed. Since the increase control or the simultaneous increase / decrease is prioritized, it is possible to achieve both control modes such as keeping the traveling line from being shifted and securing the braking distance in accordance with the road surface friction coefficient state.

According to the vehicle behavior control apparatus of the present invention, when the lateral acceleration equivalent to the road surface friction coefficient state is small, the braking force reduction control is prioritized, and when the lateral acceleration is large, the braking force is controlled. , Control is given priority to increase control or simultaneous increase / decrease control, so that control modes such as keeping the running line stable and securing a braking distance can be compatible according to the friction coefficient state on each road surface. .

According to the vehicle behavior control device of the present invention, when the change amount of the lateral acceleration is large, the control for decreasing the braking force is prioritized. The braking force can be controlled in a decreasing direction in accordance with the operation of emphasizing the turning traveling line, so that the traveling line is not shifted.

Further, according to the vehicle behavior control apparatus of the present invention, when the longitudinal acceleration equivalent to the road surface friction coefficient state is small, the braking force reduction control is given priority, and when the longitudinal acceleration is large, the braking force is reduced. , Control is given priority to increase control or simultaneous increase / decrease control, so that control modes such as keeping the running line stable and securing a braking distance can be compatible according to the friction coefficient state on each road surface. .

According to the vehicle behavior control device of the ninth aspect of the present invention, when the change amount of the longitudinal acceleration is large, the reduction control of the braking force is prioritized. The braking force can be controlled in the decreasing direction to secure the braking distance in accordance with the driver's operation that emphasizes the braking distance, such as adjusting.

According to the vehicle behavior control apparatus of the present invention, when the vehicle behavior is in the oversteer state, the braking force reduction control is prioritized, and when the vehicle behavior is in the understeer state, the braking force increase control or Since the simultaneous increase / decrease control is prioritized, the oversteer state is controlled so that the turning traveling line is not shifted without lowering the grip force and cornering force of the important front turning outer wheel, and the understeer state can be suppressed and prevented in the understeer state. Power can be controlled in the increasing direction to reduce the vehicle traveling speed.

Further, according to the vehicle behavior control apparatus of the present invention, when the operation of increasing the brake pedal is detected, the control of decreasing the braking force is prohibited or the control of increasing the braking force or simultaneous increase and decrease are performed. Since the control is prioritized, the braking force can be controlled in the increasing direction to secure the braking distance in response to the driver's operation with emphasis on the braking distance.

According to the vehicle behavior control apparatus of the twelfth aspect of the present invention, when the turning operation of the steering wheel is detected, the braking force decreasing control is prioritized, or the braking force increasing control or simultaneous increase / decrease is performed. Since the control is prohibited, it is possible to control the braking force in the decreasing direction and not to shift the traveling line in accordance with the driver's operation with emphasis on the traveling line.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a vehicle behavior control device according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a brake fluid pressure / electric system diagram showing an outline of a brake fluid pressure control device as a vehicle behavior control device of the present embodiment. In the figure, reference numerals 1FL and 1RR indicate a front left wheel and a rear right wheel, respectively, and 1FR and 1RL indicate a front right wheel and a rear left wheel, respectively. Then, wheel cylinders 2FL to 2RR corresponding to the respective wheels 1FL to 1RR are mounted as braking cylinders. 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.

The master cylinder 5 generates two systems of master cylinder pressure in response to the depression of the brake pedal 4.
The connection structure with each of the wheel cylinders 2FL to 2RR is such that the front left wheel cylinder 2FL and the rear right wheel cylinder 2RR are connected to one system of the master cylinder 5,
A piping structure called the diagonal split piping or X piping, which connects the front right wheel cylinder 2FR and the rear left wheel cylinder 2RL to the other system. In this embodiment, the rear left and right wheel cylinders 2RL,
Proportioning valves 20RL and 20RR are interposed between 2RR and master cylinder 5. The proportioning valves 20RL, 20RR are used to increase the rate of increase of the braking force on the front wheels, especially on the rear wheels, in order to make the distribution of the braking forces of the front and rear wheels closer to the so-called ideal braking force distribution with respect to changes in the wheel load during braking. It is smaller than that on the side, and the existing one can be used.

On the other hand, for each system of the master cylinder pressure of the master cylinder 5, master cylinder disconnection valves 6A and 6B for connecting and disconnecting the master cylinder 5 and the wheel cylinders 2FL and 2RR or 2FR and 2RL are interposed. Also,
A pressure boosting pump 3 for pressurizing the brake fluid of the master cylinder reservoir 5a is separately provided, and the discharge pressure of the pressure boosting pump 3 is branched into two, and the two systems of master cylinder pressure from the master cylinder 5 are Master cylinder intermittent valve 6
A, 6B downstream, that is, each wheel cylinder 2FL
Merge on the ２2RR side. Further, between each of the confluence points and the pressure-intensifying pump 3, pressure-increasing pump interrupting valves 7A and 7B for intermittently connecting the pressure-increasing pump 3 and the wheel cylinders 2FL and 2RR or 2FR and 2RL are interposed.

Then, one system of the master cylinder 5 or one system branched from the pressure increasing pump 3 is regarded as one system of the braking fluid pressure source, and the wheel cylinders 2FL, 2RR or 2FR, 2RL connected thereto are regarded as one system. Pressure increase control valves 8FL, 8RR or 8 corresponding to the respective upstream sides of
FR, 8RL is interposed. The brake fluid pressure at the brake fluid pressure source is also referred to as a line pressure for convenience. Further, these pressure increase control valves 8FL, 8RR or 8FR, 8
RL includes check valves 9FL and 9RR in respective bypass passages.
Or, 9FR, 9RL is provided, and when the depression of the brake pedal is released, the brake fluid in the wheel cylinders 2FL, 2RR or 2FR, 2RL is quickly transferred to the master cylinder 5RL.
To be reduced to the side.

The discharge sides of the individual decompression pumps 11A and 11B are connected to the respective systems of the braking fluid pressure sources, and their suction sides are connected to the wheel cylinders 2FL and 2RR.
Alternatively, the pressure reduction control valve 10FL, 10
RR or 10FR, 10RL is interposed. The two pressure reducing pumps 11A and 11B also serve as one pump motor. In addition, reservoirs 18A and 18B for preventing interference are connected between the decompression control valves 10FL and 10RR or 10FR and 10RL and the decompression pumps 11A and 11B.

Each of these pressure control valves is controlled by a control described later.
Switchable by drive signal from roll unit
Position switching valves, which are fail safe,
For example, master cylinder intermittent valves 6A and 6B are always open,
Pump shut-off valves 7A and 7B are always closed, and pressure increase control valve 8F
L, 8RR or 8FR, 8RL is always open, pressure reducing control valve 1
0FL, 10RR or 10FR, 10RL is normally closed.
Each solenoid 6 is driven by the drive signal.
A_SOL, 6B_SOL, 7A_SOL, 7B_SOL, 8FL_SOL,
8RR_SOL, 8FR_SOL, 8RL_SOL, 10FL_SOL,
10RR_SOL, 10FR _SOL, 10RL_SOLIs excited
Then, the state is switched to the opposite open / close state. In addition, the pressure boosting pon
Control unit 3 and decompression pumps 11A and 11B
The drive is controlled by a drive signal from the unit.

Therefore, in this braking fluid pressure circuit, when controlling the braking force for performing the vehicle behavior control described later, the braking fluid pressure (hereinafter also referred to as wheel cylinder pressure) of each of the wheel cylinders 2FL to 2RR is increased. In this case, for example, the pressure increasing pump 3 is driven with the master cylinder on-off valves 6A and 6B closed and the pressure-increasing pump on-off valves 7A and 7B open, and the generated pressure is reduced by the pressure reduction control valves 10A and 6B.
With the FL-10RR closed, the pressure increase control valves 8FL-8RR
Is controlled to open and supply to each of the wheel cylinders 2FL to 2RR.

Each of the wheel cylinders 2FL-2FL
When each wheel cylinder pressure is to be reduced after the RR wheel cylinder pressure is increased, for example, the master cylinder disconnection valves 6A and 6B are closed, and the pressure increase pump disconnection valves 7A and 7B are closed. , 11B, and while the pressure increase control valves 8FL to 8RR are closed, the pressure reduction control valves 10FL to 10RR are controlled to open to discharge the brake fluid in the wheel cylinders 2FL to 2RR.

The opening control of each of the pressure increase control valves 8FL to 8RR and the pressure reduction control valves 10FL to 10RR will be described later. Further, in order to reduce the reaction force to the brake pedal 4, when the brake pedal 4 is depressed, the master cylinder on-off valves 6A and 6B may be opened. Also, increasing the braking force and increasing the braking fluid pressure (wheel cylinder pressure), and decreasing the braking force and decreasing the braking fluid pressure (wheel cylinder pressure) are the same meaning. Hereafter, both will be treated synonymously.

On the other hand, as shown in FIG. 1, each of the wheels 1FL to 1RR has a wheel speed (hereinafter also referred to as a wheel speed) corresponding to the rotation speed of the wheel. Wheel speed sensor 12F that outputs a sinusoidal signal
L to 12RR are attached.

In the vehicle, a yaw rate sensor 13 for detecting the actual yaw rate ψ 'generated in the vehicle, a steering angle sensor 14 for detecting the steering angle θ of the steered wheels from the steering angle of the steering wheel, and a steering angle sensor 14 for the vehicle. and an acceleration sensor 15 for detecting a lateral acceleration and longitudinal acceleration, the two systems and a line pressure sensor 16 for detecting the line pressure P _MC of, if necessary by detecting the state of depression of the brake pedal 4 detects a brake pedal stroke η Brake stroke sensor 19
The detection signal of each sensor and switch is input to a control unit 17 described later.
The actual yaw rate ψ ′ from the yaw rate sensor 13 and the steering angle θ from the steering angle sensor 14 have, for example, positive and negative directions, but between them, for example, when the steering wheel is turned right. The steering angle is set so that the directionality of the clockwise yaw rate generated at that time matches, and in the present embodiment, the steering angle θ> 0 and the yaw rate ψ ′> 0 are set in the left turn. I have. The brake pedal stroke η from the brake stroke sensor 19 is, for example, a logical value “0” indicating an OFF state when the brake pedal is not depressed, and is a digital signal that increases stepwise as the brake pedal stroke increases. And

The control unit 17 receives a detection signal from each of the aforementioned sensors and switches and outputs a control signal to each of the switching valves.
And a drive circuit for converting a control signal output from the microcomputer into a drive signal for each control valve solenoid including an electromagnetic switching valve as described above. The microcomputer includes an input interface circuit having an A / D conversion function, an output interface circuit having a D / A conversion function, an arithmetic processing device including a microprocessor unit MPU, a ROM, an R
It has a storage device such as an AM. Since the operating frequency of the microcomputer is very high, the microcomputer outputs a reference rectangular wave control signal of pulse width modulated digital data, and each drive circuit simply outputs the control signal to each actuator. It is configured to only convert and amplify a drive signal suitable for the device. Further, in the microcomputer,
It is responsible not only for generating and outputting the main control signals necessary for the various controls as described above, but also, for example, for controlling the drive of the pressure reducing pump required for the pressure reduction control in the vehicle behavior control and for supplying power to the actuator itself. It goes without saying that the control signal to the switch element of the actuator relay is also generated and output in parallel.

Next, the arithmetic processing of the brake fluid pressure control executed by the microcomputer in the control unit 17 to control the yawing momentum of the vehicle will be described with reference to the flowcharts in the accompanying drawings. Although no particular communication step is provided in this arithmetic processing, programs and maps stored in the ROM of the storage device in the microcomputer or various data stored in the RAM are always subjected to arithmetic processing. Each calculation result transmitted to a buffer or the like of the device and calculated by the arithmetic processing device is also stored in the storage device at any time.

First, FIG. 2 shows an overall flow of the braking force control, a so-called general flow. This calculation process is executed as a timer interrupt every predetermined sampling time ΔT, for example, 10 msec. First, in step S1, each wheel is calculated by a calculation process (not shown) based on the sine wave signals from the wheel speed sensors 12FL to 12RR. Speed Vw
_i (i = FL, FR, RLorRR) is calculated. More specifically,
In the case where the wheel speed sensors 12FL to 12RR are, for example, those described in Japanese Patent Laid-Open No. 7-329759 previously proposed by the present applicant, the sine signals from the wheel speed sensors 3FL to 3R are previously determined. wave signals leave waveform shaping into a rectangular wave signal, Nde read a Lo / Hi of the rectangular wave signal with a short sampling period determined pulse width of the square wave signal, calculates the wheel speed Vw _i from the pulse width. That is,
Pulse width of the waveform-shaped rectangular wave signal the larger the wheel speed Vw _i is the shorter, the pulse width becomes longer the smaller the wheel speed Vw _i. The pulse width of this square wave signal is
Since it is equivalent to the time required for a tooth of a predetermined length to pass through the sensor as described above, it is inversely proportional to the rotational angular velocity of each wheel. Therefore, if the pulse width of this rectangular wave signal is obtained, each wheel rotational angular velocity of a demand, the wheel speeds Vw _i multiplied by the dynamic rolling radius tire to the rotating angular velocity is calculated. Of course, it is possible to calculate similarly the wheel speed Vw _i be a conventional method of obtaining the wheel rotational angular velocity by several pulses within a predetermined time is counted.

Next, the process proceeds to step S2, where the detection signals from the respective sensors are read by an arithmetic process (not shown). At the next step S3, for example the applicant to calculate the estimated vehicle speed V _X by the are not shown processing described in Japanese Patent Laid-Open No. 8-150920 previously proposed. Incidentally, the operation processing is the described in this publication, without using the longitudinal acceleration, but is configured for calculating the estimated vehicle speed V _X of only the wheel speed Vw _i, the longitudinal acceleration by the acceleration sensor 15 in this embodiment Since the detection has been performed, the correction may be performed using the value.

Next, the processing shifts to step S4, not shown.
Calculation processing, for example, from the acceleration sensor 15
Lateral acceleration Y_GAnd the estimated vehicle speed V_XAnd Yawley
From the actual yaw rate ψ 'from the sensor 13
Therefore, the side slip acceleration β of the vehicle _ddIs calculated.

Β _dd = Y _G −V _X · ψ ′ (1) Next, the process proceeds to step S5, and the vehicle is subjected to an arithmetic operation (not shown) such as a low-pass filter process in which the phase is appropriately set. calculating the sideslip speed beta _d of side-slip acceleration beta _dd time integration to.

Next, the process proceeds to step S6 to calculate a side slip angle β of the vehicle from a ratio β _d / V _X between the side slip speed β _{d of the} vehicle and the estimated vehicle speed V _X by a calculation process (not shown).

Next, the process proceeds to step S7, in which a target yaw rate ψ ^{′ *} is calculated by a not-shown calculation process using a vehicle model described in, for example, Japanese Patent Application Laid-Open No. Hei 5-24528 previously proposed by the present applicant. . Note that the target yaw rate ψ ^{′ *} is a yaw rate achieved when a predetermined cornering force is obtained at each wheel, and as a result, the vehicle is turning in a neutral steer state. In calculating the target yaw rate ψ ^{′ *,} a value obtained by dividing the steering angle by the steering gear ratio may be used as the steering angle θ. In addition, the estimated vehicle speed V _X and the steering angle θ
May be obtained from the map. In either case,
The basis is a vehicle model based on the equation of motion of the vehicle, and its derivation is detailed in, for example, "Motion and Control of Vehicles" (Masato Abe, Sankaido).

Next, the process proceeds to step S8, where the deviation between the target yaw rate ψ ^'* and the actual yaw rate ψ', ie, the target yaw rate deviation Δψ
The target moment M ^* for correcting the vehicle behavior is calculated from ^{'* and the} like. This target moment M ^* is, as shown in FIG.
The oversteer state (OS in the figure) where the actual yaw rate ψ ′ is larger than the target yaw rate ψ ^{′ *} and the side slip angle β and the side slip velocity β _d are small, or the actual yaw rate ψ ′ is smaller than the target yaw rate ψ ^{′ *} and the side slip angle β or side slip speed β _d
Is a vehicle rotation suppression or acceleration moment for correcting vehicle behavior such as a large understeer state (US in the figure). For example, the actual yaw rate ψ ′ is made to coincide with a target yaw rate ψ ^{′ *} , or the sideslip angle β And to generate a braking force difference between the front and rear left and right wheels necessary to set the side slip speed β _d to a predetermined target value, for example, the target yaw rate deviation Δψ ^{′ *} , the side slip angle deviation or the side slip speed deviation. It is obtained from a linear sum to which a control gain is added.

Next, the process proceeds to step S9, and in order to generate the target moment M ^* obtained in step S8, an oversteer state (for example, as shown in FIG. 3) as shown in FIG. OS) and understeer state (U.S. in the figure), etc., to determine the braking force difference between the inner and outer (left and right) wheels and / or front and rear wheels required for correcting the vehicle behavior,
It is allocated to each wheel to calculate a target braking force F _i ^* of each wheel.

Next, the process proceeds to step S10, where the wheel cylinders 2FL of the wheels 1FL to 1RR required for generating the target braking force F _i ^* are calculated according to a not-shown calculation process.
The target wheel cylinder pressure P ^* _i of .about.2RR is calculated.
The target wheel cylinder pressure P ^* _i can be obtained from the effective radius of the disk rotor, the coefficient of friction between the disk rotor and the pad, the effective area of the pad, the effective radius of the wheel cylinder, and the like in the disk brake of this embodiment. Can be easily derived.

[0052] and then proceeds to step S11, the not shown operation processing to calculate the current estimated wheel cylinder pressure P _i. Specifically, in step S11,
When the control of the wheel cylinder pressure has already been started for the vehicle behavior control, the control amount, that is, the wheel cylinder pressure increase / decrease amount is grasped in the microcomputer as described later, and is shown in FIG. As described above, since the pressure increasing / decreasing characteristics of the wheel cylinder pressure (= valve opening time) are known in advance, for example, the master cylinder pressure (= line pressure) when the vehicle behavior control is started is set as an initial value, and What is necessary is just to accumulate and track the wheel cylinder pressure increase / decrease amount of the previous control time.

Next, the flow shifts to step S12, where the target wheel cylinder pressure P ^{* is} calculated by a calculation process (not shown) ^.
_The target wheel cylinder pressure increase / decrease amount ΔP ^* _i is calculated from the deviation between _i and the current estimated wheel cylinder pressure P _i .

Next, the process proceeds to step S13, where the pressure increase control valves 8FL to 8RR or the pressure decrease control valve 10F are provided for each wheel according to the target wheel cylinder pressure increase / decrease amount ΔP ^* _i.
Calculate the solenoid excitation drive pulse duty ratio for L to 10RR. Specifically, the pressure increase control valves 8FL to 8RR or the pressure decrease control valves 10FL to 10RR are provided for each wheel.
To control the opening and closing of any of the solenoids 8FL
_A solenoid excitation drive pulse duty ratio such as which time ratio of _{SOL to} 8RR _SOL or 10FL _{SOL to} 10RR _SOL to excite (or set to a non-excitation state) is calculated. That is, one of the pressure-increasing control valves 8FL to 8RR or the pressure-reducing control valves 10FL to 10RR is controlled to open for each wheel so that the achieved wheel cylinder pressure-increasing / decreasing amount ΔP ^* _i is obtained at the current control timing. Is calculated as the duty ratio of the drive pulse.

Then, the flow shifts to step S14 to generate and output a solenoid excitation drive pulse control signal corresponding to the duty ratio by a not-shown calculation process, and then returns to the main program. The generation of the drive pulse signal according to the duty ratio is performed by using a conventional PWM (Pulse Pulse).
Width Modulation) control is the same as that of FIG.

Next, step S9 of the arithmetic processing of FIG.
The calculation processing of FIG. In this operation process, first in step S91, the following two equations below and 3 wherein said target moment M ^* front and rear wheel target braking force difference for generating a [Delta] F _F ^*, and calculates the [Delta] F _R ^*. Note that the front and rear wheel target braking force differences ΔF _F ^* and ΔF _R ^* are the differences in the magnitude of the braking force between the front left and right wheels or between the rear left and right wheels required to generate the target moment M ^*. .

ΔF _F ^* = M ^* / (T _rF / 2) (2) ΔF _R ^* = M ^* / (T _rR / 2) (3) where T _rF : before Left and right wheel tread _TrR : Indicates the rear left and right wheel tread.

Next, the flow shifts to step S92, where
And the line pressure P _MCFront and rear wheel base
Final braking force F_BiIs calculated. F_BFL= F_BFR= K_b・ P_MC ……… (4) F_BRL= F_BRR= K_b・ P_MC・ K_PV ……… (5) where K_b: Conversion coefficient K_PV: Indicates the proportioning valve rear wheel distribution ratio.

Next, the flow shifts to step S93, in which an increase / decrease control mode for each wheel cylinder pressure is set in accordance with the arithmetic processing shown in FIGS. Next, step S94
The control proceeds to step S93 to determine the pressure increase / decrease control mode of each wheel cylinder pressure set in step S93. If the set control mode is the pressure decrease priority control mode, the flow proceeds to step S95, and the control proceeds to step S95. If it is the control mode, the process proceeds to step S96, and if it is the pressure increase priority control mode, the process proceeds to step S97.

In step S95, FIG.
After calculating the target braking force F _i ^* in the pressure-decreasing priority control mode according to the calculation process, the process proceeds to step S98. In step S96, the target braking force F _i ^* in the increased / decreased moderate control mode is calculated in accordance with the calculation process of FIG. 11 described later, and then the process proceeds to step S98.

In step S97, the target braking force F _i ^* in the pressure-increasing priority control mode is calculated according to the calculation process of FIG.
Move to

In step S98, FIG.
After calculating the tire braking / driving stiffness coefficient K _Si in accordance with the calculation processing of (1), the flow shifts to step S99. Step S9
In step 9, the target slip ratio S _i ^* is calculated according to the following equation (6), and then the process proceeds to step S10 of the calculation processing in FIG.

Next, step S9 of the calculation processing of FIG.
The case where the arithmetic processing of the control map search of FIG. 6 is executed in 3, will be described. In the control map of FIG. 6, for example, the increasing / decreasing control mode of each wheel cylinder pressure is set using the lateral acceleration or the longitudinal acceleration detected by the acceleration sensor 15.

That is, the lateral acceleration or longitudinal acceleration generated in the vehicle is an evaluation index obtained by turning or accelerating and decelerating and equivalent to the road surface μ at that time. Therefore, the lateral acceleration or longitudinal acceleration is used as the road surface μ. Then, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is equal to or less than a relatively small predetermined value, it is regarded as a low μ road surface (snow in the figure) such as a frozen road surface, and the traveling line is not shifted as described above. In this case, the pressure reduction priority (braking force reduction priority) mode is selected. That is, in such a low μ road surface, the target moment M ^* of the braking force difference required generating [Delta] F _F ^*, delta
When trying to obtain F _R ^* by increasing the pressure (increasing the braking force), the grip force and cornering force of the tire are likely to decrease,
Since the running line of the vehicle is likely to shift, it is possible to prevent the running line from shifting by preferentially controlling each wheel cylinder pressure in the direction of pressure reduction, that is, in the direction of decreasing the braking force. On the other hand, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is a relatively large predetermined value or more, it is regarded as a high μ road surface (dry in the figure) such as a dry concrete road surface, and the braking distance is secured as described above. Pressure priority (braking force increase priority) mode. In other words, on such a high μ road surface, even if the wheel cylinder pressure is increased to increase the braking force, the gripping force of the tire and the cornering force do not readily decrease, so that the running line of the vehicle is less likely to shift, and rather positively It is desirable to increase the braking force and reduce the vehicle speed to secure a braking distance.

In the middle area between the two areas, that is, in the area (wet in the figure) where the road surface μ or the lateral acceleration or the longitudinal acceleration is less than the relatively large predetermined value and more than the relatively small predetermined value, the braking distance Mode is selected so as not to shift the traveling line while maintaining the pressure. In addition, in addition to these or individually, for example, when the change amount of the lateral acceleration per unit time is larger than a preset value, the pressure reduction priority (braking force reduction priority) mode is selected. Is also good. That is, a large amount of change in the lateral acceleration per unit time means that, for example, there is a high possibility that the driver is operating the steering wheel largely to correct the deviation of the traveling line or to prevent the deviation of the traveling line. From
In such a case, the pressure reduction priority mode may be selected so that the traveling line does not shift. When the amount of change in the longitudinal acceleration per unit time is larger than a preset value, the pressure reduction priority (braking force reduction priority) mode is prohibited, or the pressure increase / decrease medium (braking force simultaneous increase / decrease) mode or The pressure increase priority (braking force increase priority) mode may be forcibly selected. In other words, the fact that the amount of change in the longitudinal acceleration per unit time is large means that the driver actively steps on the brake pedal to reduce the vehicle speed, including, for example, improving the understeer state by overspeed described later. Therefore, in such a case, the pressure increase priority mode or the pressure increase / decrease medium mode may be selected so as to reduce the vehicle speed or secure the braking distance.

Next, in addition to or independently of the control map search of FIG. 6, when the arithmetic processing of FIG. 7 is executed in step S93 of the arithmetic processing of FIG. 5, first, in FIG. For example, it is determined whether the vehicle is in an oversteer state (OS in the figure) or an understeer state (US in the figure) with respect to the target vehicle behavior by an arithmetic process that is not performed. In step S9302, the process proceeds to step S9303. If the vehicle is in the understeer state, the process proceeds to step S9303. More specifically, as described above, the actual yaw rate ψ ′ is a positive value and the target yaw rate 左^{′ *} is also a positive value when turning left, and the yaw rate error Δψ ′ is changed from the actual yaw rate ψ ′ to the target yaw rate ψ ′.
^When defined as a value obtained by subtracting ^'* , Δψ'> 0 and ψ '> 0
For oversteer, Δψ ′ <0 and ψ ′> 0 for understeer, Δψ ′> 0 and ψ ′ <0 for understeer, Δψ ′ <
0 and 見 な ′ <0 can be regarded as oversteer.

In step S9302, the depressurization priority (braking force reduction priority) mode is forcibly selected according to a not-shown calculation process, and then the flow shifts to step S94 in the calculation process of FIG. That is, as described above, the front turning outer wheel generates the highest cornering force during turning, and it is necessary to relatively increase the braking force of the front turning outer wheel to correct the oversteer state. However, if the control is performed only in the direction of increasing the braking force of the front turning outer wheel, the cornering force of the front turning outer wheel is reduced according to the principle of the friction circle, and the traveling line may be shifted outward. Therefore, in such an oversteer state, by giving priority to the control for reducing the braking force in the pressure reduction priority mode, it is possible to prevent the traveling line from shifting.

In step S9303, the medium pressure increase / decrease mode (simultaneous increase / decrease in braking force) mode or the pressure increase priority (braking force increase priority) mode is forcibly selected in accordance with a calculation process (not shown). The process moves to step S94 of the calculation process. That is, contrary to the above, in order to correct the understeer state, the braking force of the front turning inner wheel or the rear wheel is relatively increased to generate the target moment M ^* for correcting the understeer state. Although it is possible to do so, on the other hand, the main cause of the understeer state is a so-called overspeed in which the vehicle speed is too high. Therefore, in the understeer state, the vehicle speed can be reduced or the braking distance can be secured by controlling the braking force in the pressure increasing priority mode or the pressure increasing / decreasing medium mode so as to increase the braking force.

Next, in addition to or independently of the above, when the arithmetic processing of FIG. 8 is executed in step S93 of the arithmetic processing of FIG. 5, first in step S9311, the brake is performed according to an arithmetic processing (not shown). It is determined whether the pedal is being depressed or not. If the brake pedal is being depressed, the flow shifts to step S9312; otherwise, the flow shifts to step S94 of the calculation processing in FIG.
Specifically, for example, when the increase amount of the brake pedal stroke η per unit time from the brake pedal stroke sensor 19 is larger than a preset value, it is determined that the brake pedal is being depressed. Instead of the brake pedal stroke eta, the line pressure P _MC from the line pressure sensor 16 may be used as well.

In step S9312, the pressure reduction priority (braking force reduction priority) is given in accordance with a calculation process (not shown).
After prohibiting the mode, or forcibly selecting the medium pressure increase / decrease mode (simultaneous increase / decrease in braking force) mode or the pressure increase priority (braking force increase priority) mode, step S9 of the calculation processing in FIG.
Move to 4. In other words, when the driver is stepping on the brake pedal, it is highly likely that the driver wants to reduce the vehicle speed or shorten the braking distance, or is trying to correct the vehicle behavior by the braking force.
The pressure reduction priority mode in which the braking force is reduced is prohibited, and the pressure increase priority mode in which the braking force is increased or the pressure increase / decrease mode in which the braking force controllability is excellent is selected.

Next, in addition to or independently of the above, when the arithmetic processing of FIG. 9 is executed in step S93 of the arithmetic processing of FIG. 5, first, in step S9321, the steering operation is performed according to an arithmetic processing (not shown). It is determined whether the wheel is being turned or not. If the steering wheel is being turned, the process proceeds to step S9322. Otherwise, the process proceeds to step S94 of the calculation process in FIG.
Move to More specifically, if the amount of increase in (the absolute value of) the steering angle θ per unit time from the steering angle sensor 14 is larger than a preset value, it is determined that the steering wheel is being turned.

In step S9322, the pressure reduction priority (braking force reduction priority) is given in accordance with a not-shown calculation process.
After selecting the mode, step S of the arithmetic processing of FIG.
Move to 94. In other words, when the steering wheel is being turned up, the driver is unlikely to want to shift the traveling line, and therefore, the pressure reduction priority mode in which the braking force is reduced so as not to shift the traveling line is selected.

Next, step S9 of the arithmetic processing of FIG.
The arithmetic processing of FIG. This
First, in step S9501, the calculation
Front wheel braking force difference ΔF_F ^*Determines if is positive
And the front wheel braking force difference ΔF_F ^*Is positive if
Proceed to step S9502, and if not, step S9502.
The process moves to step S9503.

In step S9502, the calculated front right wheel basic braking force F _BFR is equal to the front wheel braking force difference ΔF _F.
^* Is determined to be less than the front right wheel basic braking force F
_{If the BFR} is less than the front wheel braking force difference ΔF _F ^* , the process shifts to step S9504; otherwise, the process proceeds to step S9504.
The process proceeds to 9505.

[0075] as well as set in the step S9504, the front wheel braking force difference [Delta] F _F ^* from the front right wheel base braking force F front wheel braking force increment the value obtained by subtracting the _BFR ΔF F _(+), the front right wheel base braking force F _BFR the front wheel braking force reduction amount [Delta] F F _(-) is set to the process proceeds to step S9506 from.

In step S9505, the front wheel braking force increase amount ΔF _{F (+)} is set to “0”, and the front wheel braking force difference ΔF _F ^{* is set} to the front wheel braking force reduction amount ΔF _{F (−)} . Then, the flow shifts to the step S9506.

In step S9506, the front wheel braking force reduction amount ΔBFR is calculated from the front right wheel basic braking force F _BFR.
The value obtained by subtracting _{FF (-)} is set to the front right wheel target braking force _FFR ^* , and the value obtained by adding the front wheel braking force increase amount ΔFF ₍₊₎ to the front left wheel basic braking force _FBFL is used for the front left wheel. After the target braking force F _FL ^* is set, the flow shifts to step S9507.

[0078] On the other hand, in step S9503, the calculated front-left wheel base braking force F _BFL absolute value of the front wheel braking force difference | [Delta] F _F ^* | determines whether less than a either, the front left wheel base system Power F _BFL is the absolute value of front wheel braking force difference | ΔF
If it is less than _F ^* |, the flow shifts to step S9508; otherwise, the flow shifts to step S9509.

At step S9508, the absolute value of the front wheel braking force difference | ΔF _F ^* |
The value obtained by subtracting the _BFL and sets the front wheel braking force increment ΔF F _(+), the front left wheel base braking force F _BFL front wheel braking force reduction amount [Delta] F F _- transition from set to the step S9510 ₍₎ .

In step S9509, the front wheel
Braking force increase ΔF_{F (+)}Is set to “0”, and
Absolute value of front wheel braking force difference | ΔF_F ^*| Is the front wheel braking force reduction
ΔF _{F (-)}And then proceed to step S9510.
I do.

Then, in step S9510, the front wheel braking force increase ΔF is added to the front right wheel basic braking force F _BFR.
The sum of _{F (+)} is set as the front right wheel target braking force F _FR ^*, and the value obtained by subtracting the front wheel braking force reduction amount ΔF _{F (−)} from the front left wheel basic braking force _FBFL is used as the front left wheel target braking force. After setting the braking force F _FL ^* , the flow shifts to the step S9507.

In step S9507, it is determined whether or not the calculated rear wheel braking force difference ΔF _R ^* is a positive value. If the rear wheel braking force difference ΔF _R ^* is a positive value, the process proceeds to step S9507. The process moves to S9511; otherwise, the process moves to step S9512.

In step S9511, the calculated rear right wheel basic braking force F _BRR is equal to the rear wheel braking force difference ΔF _R.
^* To determine whether the rear right wheel basic braking force F
_{If BRR} is less than the rear wheel braking force difference ΔF _R ^* , the process shifts to step S9513; otherwise, the process proceeds to step S9513.
The process proceeds to 9514.

[0084] At step S9513, it sets a value obtained by subtracting the rear right wheel base braking force F _BRR from the rear wheel braking force difference [Delta] F _R ^* in the rear wheel braking force increment ΔF R _(+), the right rear transition from set to the step S9515 _- the wheel base braking force F _BRR rear wheel braking force reduction amount [Delta] F R _().

In step S9514, the rear wheel braking force increase amount ΔF _{R (+)} is set to “0” and the rear wheel braking force difference ΔF _R ^{* is set} to the rear wheel braking force reduction amount ΔF _{R (− )} , And then proceeds to step S9515.

In step S9515, the rear wheel braking force reduction amount ΔB is calculated from the rear right wheel basic braking force F _BRR.
The value obtained by subtracting F _{R (-)} is set as the rear right wheel target braking force F _RR ^* , and the value obtained by adding the rear wheel braking force increase ΔF _{R (+)} to the rear left wheel basic braking force F _BRL is used as the rear braking force. After setting the left wheel target braking force F _RL ^* , the process proceeds to step S98 of the calculation processing in FIG.

[0087] On the other hand, in step S9512, the absolute value of the left wheel base braking force F _BRL After the calculated said rear wheel braking force difference | [Delta] F _R ^* | determines whether less than a either, the rear left wheel base The braking force _FBRL is the absolute value of the rear wheel braking force difference | ΔF
If it is less than _R ^* |, the flow shifts to step S9516; otherwise, the flow shifts to step S9517.

In step S9516, the rear left wheel basic braking force F is calculated from the absolute value | ΔF _R ^* | of the rear wheel braking force difference.
And sets the rear wheel braking force increment ΔF R ₍₊₎ a value obtained by subtracting the _BRL, the rear left wheel base braking force F _BRL rear wheel braking force reduction amount [Delta] F R _(-) from the set to the step S9518 Transition.

In step S9517, the rear wheel
Braking force increase ΔF_{R (+)}Is set to “0”, and
Absolute value of rear wheel braking force difference | ΔF_R ^*| Is the amount of reduction in rear wheel braking force
ΔF _{R (-)}And then go to step S9518.
I do.

In the step S9518, the rear wheel braking force increase ΔF is added to the rear right wheel basic braking force F _BRR.
The sum of _{R (+)} is set as the rear right wheel target braking force F _RR ^*, and the value obtained by subtracting the rear wheel braking force reduction amount ΔF _{R (−)} from the rear left wheel basic braking force _FBRL is the value of the rear left wheel. After setting the target braking force F _RL ^* , the process proceeds to step S98 of the calculation processing in FIG.

Next, step S9 of the calculation processing of FIG.
The arithmetic processing of FIG. This
First, in step S9601, the calculation process
Front wheel braking force difference ΔF_F ^*Determines if is positive
And the front wheel braking force difference ΔF_F ^*Is positive if
Proceed to step S9602; otherwise, step S9602.
The process moves to step S9603.

[0092] In step S9602, the calculated front-right wheel base braking force F _BFR is determined whether the front wheel braking force difference half value (ΔF _F ^* / 2) less than the either, the front right wheel The basic braking force F _BFR is half of the front wheel braking force difference (ΔF _F
If it is less than ( ^* / 2), the flow shifts to step S9604; otherwise, the flow shifts to step S9605.

[0093] as well as set in the step S9604, the front wheel braking force difference [Delta] F _F ^* from the front right wheel base braking force F front wheel braking force increment the value obtained by subtracting the _BFR ΔF F _(+), the front right wheel base braking force F _BFR the front wheel braking force reduction amount [Delta] F F _(-) is set to the process proceeds to step S9606 from.

In step S9605, the half value (ΔF _F ^* / 2) of the front wheel braking force difference is set as the front wheel braking force increase ΔF _{F (+)} and the front wheel braking force decrease ΔF _{F (−)} , respectively. After that, the flow shifts to the step S9606.

In the step S9606, the front wheel braking force reduction amount ΔB is calculated from the front right wheel basic braking force F _BFR.
The value obtained by subtracting _{FF (-)} is set to the front right wheel target braking force _FFR ^* , and the value obtained by adding the front wheel braking force increase amount ΔFF ₍₊₎ to the front left wheel basic braking force _FBFL is used for the front left wheel. After the target braking force F _FL ^* is set, the flow shifts to step S9607.

[0096] On the other hand, in step S9603, the pre-calculated left wheel base braking force F _BFL is the absolute value of the half value of the front wheel braking force difference | determines whether less than a either not, | [Delta] F _F ^* / 2 the absolute value of the front left wheel base braking force F _BFL half value of the front wheel braking force difference | ΔF _F ^* / 2 | if less than proceeds to step S9608, otherwise proceeds to step S9609.

[0097] In the step S9608, the absolute value of the front wheel braking force difference | ΔF _F ^* | from the front left wheel base braking force F
The value obtained by subtracting the _BFL and sets the front wheel braking force increment ΔF F _(+), the front left wheel base braking force F _BFL front wheel braking force reduction amount [Delta] F F _- transition from set to the step S9610 ₍₎ .

In step S9609, the absolute value | ΔF _F ^* / 2 | of the half of the front wheel braking force difference is used as the front wheel braking force increasing amount ΔF _{F (+)} and the front wheel braking force decreasing amount ΔF _{F (− )}
Then, the flow shifts to the step S9610.

[0099] Then, in step S9610, the front right wheel base braking force F _BFR in the front wheel braking force increment ΔF
_The sum of _{F (+)} is set as the front right wheel target braking force F _FR ^*, and the value obtained by subtracting the front wheel braking force reduction amount ΔF _{F (−)} from the front left wheel basic braking force _FBFL is used as the front left wheel target braking force. After setting the braking force F _FL ^* , the flow shifts to the step S9607.

[0100] Step If at the step S9607, the calculated rear wheel braking force difference [Delta] F _R ^* is equal to or a positive value, the rear wheel braking force difference [Delta] F _R ^* is positive The process moves to S9611; otherwise, the process moves to step S9612. In the step S9611, the right wheel base braking force F _BRR After the calculated is equal to or less than half value of the rear wheel braking force difference (ΔF _R ^* / 2), the rear right wheel base system If the power F _BRR is less than half of the rear wheel braking force difference (ΔF _R ^* / 2), step S
Move to step 9613, otherwise, step S96
Go to 14.

[0102] At step S9613, it sets a value obtained by subtracting the rear right wheel base braking force F _BRR from the rear wheel braking force difference [Delta] F _R ^* in the rear wheel braking force increment ΔF R _(+), the right rear After the wheel basic braking force F _{BRR is set} to the rear wheel braking force reduction amount ΔF _{R (−)} , the flow shifts to step S9615.

In step S9614, the half value (ΔF _R ^* / 2) of the rear wheel braking force difference is calculated by increasing the rear wheel braking force ΔF _{R (+)} and decreasing the rear wheel braking force ΔF _{R (−).} Then, the flow shifts to the step S9615.

Then, in step S9615, the rear wheel braking force reduction amount Δ is calculated from the rear right wheel basic braking force F _BRR.
The value obtained by subtracting F _{R (-)} is set as the rear right wheel target braking force F _RR ^* , and the value obtained by adding the rear wheel braking force increase ΔF _{R (+)} to the rear left wheel basic braking force F _BRL is used as the rear braking force. After setting the left wheel target braking force F _RL ^* , the process proceeds to step S98 of the calculation processing in FIG.

[0104] On the other hand, in step S9612, the absolute value of the left wheel base braking force F _BRL After the calculated half value of the rear wheel braking force difference | ΔF _R ^* / 2 | determines whether less than a either If the rear left wheel basic braking force F _BRL is smaller than the absolute value | ΔF _R ^* / 2 | of the half value of the rear wheel braking force difference, the flow shifts to step S9616; otherwise, the flow shifts to step S9617. .

In step S9616, the absolute value of the rear wheel braking force difference | ΔF _R ^* |
And sets the rear wheel braking force increment ΔF R ₍₊₎ a value obtained by subtracting the _BRL, the rear left wheel base braking force F _BRL rear wheel braking force reduction amount [Delta] F R _(-) from the set to the step S9618 Transition.

In step S9617, the absolute value | ΔF _R ^* / 2 | of the half value of the rear wheel braking force difference is calculated by increasing the rear wheel braking force ΔF _{R (+)} and decreasing the rear wheel braking force ΔF _{R. After} setting each to _(-) , the flow shifts to the step S9618.

Then, in step S9618, the rear wheel braking force increment ΔF is added to the rear right wheel basic braking force F _BRR.
The sum of _{R (+)} is set as the rear right wheel target braking force F _RR ^*, and the value obtained by subtracting the rear wheel braking force reduction amount ΔF _{R (−)} from the rear left wheel basic braking force _FBRL is the value of the rear left wheel. After setting the target braking force F _RL ^* , the process proceeds to step S98 of the calculation processing in FIG.

Next, step S9 of the arithmetic processing of FIG.
The arithmetic processing of FIG. 12 executed in Step 7 will be described. This
First, in step S9701, the calculation processing
Front wheel braking force difference ΔF_F ^*Determines if is positive
And the front wheel braking force difference ΔF_F ^*Is positive if
Proceed to step S9702, otherwise, step
The process moves to step S9703.

In the step S9702, the calculated
Front right wheel basic braking force F_BFRThe front right wheel target braking as it is
Force F_FR ^*And the calculated front left wheel basic braking
Force F _BFLThe front wheel braking force difference ΔF_F ^*To the left
Wheel target braking force F_FL ^*And then step S9704
Move to

On the other hand, in the step S9703, the value obtained by adding the absolute value | ΔF _F ^* | of the front wheel braking force difference to the calculated front right wheel basic braking force F _BFR is used as the front right wheel target braking force F.
_FR ^* , and the calculated front left wheel basic braking force F
_{After BFL is set} to the front left wheel target braking force F _FL ^* , the flow shifts to step S9704.

[0111] Step If at the step S9704, the calculated rear wheel braking force difference [Delta] F _R ^* is equal to or a positive value, the rear wheel braking force difference [Delta] F _R ^* is positive The process moves to S9705; otherwise, the process moves to step S9706.

In the step S9705, the calculated
Right wheel basic braking force F_BRRRear right wheel target braking as it is
Force F_RR ^*And the calculated rear left wheel basic braking
Force F _BRLThe rear wheel braking force difference ΔF_R ^*To the left
Wheel target braking force F_RL ^*And then the processing of FIG.
The process moves to step S98.

On the other hand, in step S9706, the value obtained by adding the absolute value | ΔF _R ^* | of the rear wheel braking force difference to the calculated rear right wheel basic braking force F _BRR is used as the rear right wheel target braking force F.
_RR ^* and the calculated rear left wheel basic braking force F
After setting _{BRL as it is} to the rear left wheel target braking force F _RL ^* , the flow shifts to step S98 of the calculation processing in FIG.

Next, step S9 of the arithmetic processing of FIG.
8 will be described. This operation process, first in step S9801, calculates, for example, the estimated vehicle from the speed V _X by dividing further the value obtained by subtracting the wheel speed Vw _i estimated vehicle speed V _X of the wheel slip ratio S _i.

Next, the flow shifts to step S9802 to calculate
Absolute value of wheel slip ratio | S _i| Is set in advance
Predetermined value S₀Or not, that is,
Whether the wheels are slipping due to braking / driving force
The absolute value of the wheel slip ratio | S_i| Is the specified value
S₀If it is the above, the flow shifts to step S9803,
If not, the process moves to step S9806.

In step S9803, the total wheel braking / driving force F applied to each wheel is calculated in accordance with a calculation process (not shown).
_After calculating _TOTAL-i , the flow shifts to step S9804. Specifically, for example, the engine output is obtained from the engine speed and the throttle opening, and the output is multiplied by the transmission ratio (reduction ratio) of the transmission and divided by the number of driving wheels to calculate the driving force to each driving wheel. And the estimated wheel cylinder pressure P _i
, The braking force applied to each wheel is calculated, and the total braking / driving force F _TOTAL-i applied to each wheel is calculated from the difference between the two.

In step S9804, each of the wheels
Value of the total wheel braking / driving force | F _TOTAL-i|
Set value F₀Whether or not, that is, a predetermined value
With the above-mentioned braking / driving force, the wheels may slip.
Is determined, and the absolute value of the total wheel braking / driving force |
F_TOTAL-i| Is the predetermined value F₀If yes, step
Proceed to S9805; otherwise, return to the previous step.
The process moves to S9806.

In step S9805, a value obtained by dividing the wheel total braking / driving force F _TOTAL-i by the wheel slip ratio S _i is set as a tire braking / driving stiffness coefficient K _Si , and then the processing in step S99 of FIG. Move to

[0119] In step S9806, the wheel load W _i basic tire braking-driving stiffness coefficient k consisting of a function of
_The value obtained by multiplying _Si by a correction coefficient f (β), which is a function of the road surface μ and the side slip angle β of the vehicle, is used as a tire braking / driving stiffness coefficient K.
_After setting to _Si , step S99 of the arithmetic processing of FIG.
Move to The basic tire braking / driving stiffness coefficient k _Si, which is a function of the wheel load W _i , is the wheel load W up to a certain point.
It is a function that increases linearly with the increase of _{i, and} the rate of increase gradually decreases from the point and saturates.

Next, the operation of the present embodiment will be described. Before the overall operation of the vehicle behavior control of the present embodiment,
The operation of each braking force (wheel cylinder pressure increase / decrease) control mode by the arithmetic processing of FIGS. 10 to 12 will be described.

Since the target yaw rate ψ ^{′ *} calculated in step S7 of the calculation processing in FIG. 2 is a yaw rate generated when the vehicle achieves neutral steering within the grip range of the tire, as described above, it is simple. Is the actual yaw rate (absolute value) ψ 'is the target yaw rate (absolute value)
小 さ If it is smaller than ^'* , it can be said that it is in the understeer state, and if it is larger, it is in the oversteer state. Therefore, the target moment M ^{* also} calculated in step S8 of the calculation processing of FIG.
For example, in an understeer state, an anti-spin moment in the oversteer direction (which should be accurately described as a spin moment) is given to the vehicle. Conversely, for example, in an oversteer state, an antispin moment in the understeer direction is given to the vehicle. Therefore, if the target wheel cylinder pressure is achieved while feeding back the yaw rate, extreme oversteer and understeer are corrected, and neutral steer within the grip range of the tire is obtained.

The braking force differences ΔF _F ^* and ΔF _R ^* of the front and rear wheels required to generate the target moment M ^* are calculated in step S92 of the calculation processing in FIG. The way of applying the braking force differences ΔF _F ^* , ΔF _R ^* differs in the following steps S95 to S97. By the way, depending on the setting of the braking force difference ΔF _F ^* , ΔF _R ^* between the front and rear wheels, the braking force difference may be made between the inner and outer turning wheels, ie, the left and right wheels,
It is possible to make a difference in braking force between the front and rear wheels, and these should be tuned variously in view of the steering stability required of the vehicle.

Therefore, if the pressure-decreasing priority mode is selected in step S93 of the calculation processing of FIG.
Then, the process proceeds from S4 to step S95, where the calculation processing of FIG. 10 is performed. Here, for example, considering a case where an oversteer state occurs during a left turn, and a clockwise target moment M ^* is required to correct the oversteer state, first in step S9501, in the arithmetic processing of FIG. determining the difference [Delta] F _F ^* is whether positive, i.e. from the front left wheel braking force F _FL and the front right wheel or larger than the braking force F _FR or front right wheel braking force F _FR of the front left wheel braking force F _FL It is determined whether to increase the value. In the former case, the flow proceeds to the flow after step S9502, and in the latter case, the flow proceeds to the flow after step S9503. Here, the clockwise target moment M
^* Is required, the front right wheel braking force F _{FR is changed} to the front left wheel braking force F _FL
Since it should be larger, the flow after step S9503 will be considered. This step S9503
In the following flow, such as by a brake pedal is depressed increases, the absolute value of the front wheel braking force difference | [Delta] F _F
^* | The front wheel braking force difference proceeds to step S9509 if (substantially just to modify the code wheel braking force difference [Delta] F _F ^* same) is the front left wheel base braking force F _BFL more ΔF _F ^* | | absolute value of the front wheel braking force reduction amount ΔF F _(-)
, Which is directly subtracted from the front left wheel basic braking force F _BFL in the next step S9510 to become the front left wheel target braking force F _FL ^* . In this case, since the front wheel braking force increase amount ΔF _{F (+)} is “0”, the front right wheel basic braking force F _BFR
Becomes the front right wheel target braking force F _FR ^* as it is.

On the other hand, when the brake pedal is not depressed or is depressed only slightly, the absolute value | ΔF _F ^* | of the front wheel braking force difference becomes equal to the front left wheel basic braking force F.
If it is less than _BFL , the flow shifts to step S9508, where the front left wheel basic braking force F _BFL is reduced by the front wheel braking force reduction amount ΔF _{F (−)}
Is set to, it is of the front-left wheel target braking force F _FL ^* Since subtracted from the front left wheel base braking force F _BFL as such in the next step S9510 results in effectively a "0". On the other hand, the absolute value | ΔF _F of the front wheel braking force difference
^{* The} value obtained by subtracting the front left wheel basic braking force _FBFL from | is set as the front wheel braking force increase amount ΔFF ₍₊₎ , which is the next step S9.
At 510, it is added to the front right wheel basic braking force F _BFR to become the front right wheel target braking force F _FR ^* . That is, when the front left and right wheel target braking forces F _FL ^* and F _FR ^{* are} achieved from the state where the front left and right wheel basic braking forces F _BFL and F _BFR are equal immediately before the control, the front left wheel braking force F _FL becomes “ 0 ", but the front right wheel braking force _FFR is substantially the same as the absolute value | ΔF _F ^* | of the front wheel braking force difference, and a necessary braking force difference between the front left and right wheels is obtained. .

The same setting of the target braking force F _i ^* (including the rear wheel) is performed by, for example, the flow after the step S9502 (the front wheel side), the flow after the step S9511, and the flow after the step S9512 (the rear wheel side). ). FIG. 14 shows the state of the braking force. That is, as shown in the drawing, in order of priority of the braking force control between the left and right wheels in the oversteer state (OS in the figure), control to decrease the braking force of the turning inner wheel is given priority first, and then control of the turning inner wheel is given. When the power becomes zero, the control for increasing the braking force of the turning outer wheel is performed. Further, when the braking force control between the front and rear wheels in the oversteer state (OS in the figure) is performed, priority is given to the reduction control of the braking force of the rear wheel, and when the braking force of the rear wheel becomes zero next time. Control for increasing the braking force of the front wheels is performed. Therefore, for example, regarding the front turning outer wheel that generates the largest cornering force during turning, since the braking force does not become so large, even on a low μ road surface, the grip force and the cornering force of the front turning outer wheel are not so large. Not drop,
For example, it is possible to suppress or prevent the traveling line from shifting outward. However, since the braking force as a whole also decreases, it is disadvantageous in terms of actively reducing the vehicle speed or securing a braking distance.

Next, step S of the above-described calculation processing of FIG.
If the medium pressure increase / decrease mode is selected in 93, step S9
Then, the process proceeds from S4 to step S96, where the calculation processing of FIG. 11 is performed. Here, too, a case is considered in which a clockwise target moment M ^* is required to correct the oversteer state when turning left. In processing of FIG. 11, similarly to the processing of FIG. 10, step S9601 in front left wheel braking force F _FL and front right wheel braking force F _FR before the greater than either or front right wheel braking force F _FR It is determined whether the braking force is greater than the left wheel braking force F _FL , and in the case of the former, step S960
Proceed to the flow after 2 and in the latter case, step S96
Go to the flow after 03. Since we need ^* clockwise target moment M, the front right wheel braking force F _FR from should be larger than the front left wheel braking force F _FL, step S96
Consider the flow after 03. This step S9
In 603 after the flow, such as by a brake pedal is depressed increases, the absolute value of the half value of the front wheel braking force difference | ΔF _F ^* / 2 | (front wheel system is substantially just to modify the code If the half value of the power difference (the same as ΔF _F ^* / 2) is equal to or greater than the front left wheel basic braking force F _BFL , the flow shifts to step S9609 to return to the absolute value | ΔF _F ^* of the half value of the front wheel braking force difference ^. / 2 | front wheel braking force reduction amount [Delta] F F _(-) is also set to the front wheel braking force increment ΔF F ₍₊₎ with the following steps left wheel base braking force before the S9610 F _BFL front wheel braking force reduction amount from [Delta] F _{F (-)} Is reduced and the front left wheel target braking force F _FL
^* Next, a front right wheel base braking force F _BFR to the front wheel braking force increment ΔF F ₍₊₎ previous is added right wheel target braking force F _FR ^*.

On the other hand, because the brake pedal is not depressed or is depressed only slightly, the front right wheel basic braking force _FBFL is originally small, and as a result, the absolute value of half the difference between the front wheel braking force difference is obtained. | ΔF _F ^* / 2 | when it is determined before and is less than the left wheel base braking force F _BFL, like the arithmetic processing of FIG. 10, the left wheel base braking force F _BFL before the process proceeds to step S9608 Front wheel braking force decrease ΔF
_{F (-)} is set to, it is of the front-left wheel target braking force F _FL ^* Since subtracted from the front left wheel base braking force F _BFL as such in the next step S9610 results in effectively a "0". On the other hand, the absolute value | ΔF of the front wheel braking force difference
A value obtained by subtracting the front left wheel basic braking force _FBFL from _F ^* | is set as the front wheel braking force increase amount ΔF _{F (+)} , which is the next step S
At 9610, it is added to the front right wheel basic braking force _FBFR to become the front right wheel target braking force _FFR ^* . That is, when the front left and right wheel target braking forces F _FL ^* and F _FR ^{* are} achieved from the state where the front left and right wheel basic braking forces F _BFL and F _BFR are equal immediately before the control, the front left wheel braking force F _FL becomes “ 0 ", but the front right wheel braking force _FFR is substantially the same as the absolute value | ΔF _F ^* | of the front wheel braking force difference, and a necessary braking force difference between the front left and right wheels is obtained. .

The same setting of the target braking force F _i ^* (including the rear wheel) is performed by, for example, the flow after step S9602 (front wheel side), the flow after step S9611, and the flow after step S9612 (rear wheel side). ). Among them, the former, that is, for example, the absolute value | ΔF _F ^* / 2 | of the half value of the front wheel braking force difference is the front wheel braking force reduction amount ΔF _{F ( −).}
FIG. 15 shows the state of the braking force when the front wheel braking force increase amount ΔF _{F (+)} is also set. That is, the braking force of the turning outer wheel is increased and the braking force of the inner turning wheel is decreased by the same amount, as indicated by the braking force control between the left and right wheels in the oversteer state (OS in the figure) in the figure. . When the braking force between the front and rear wheels is controlled in the oversteer state (OS in the figure), the braking force of the front wheels is increased and the braking force of the rear wheels is decreased by the same amount. Therefore, for example, during a turn, the braking force is slightly increased on the front turning outer wheel that generates the largest cornering force. Therefore, on a medium μ road surface (hereinafter also referred to as a medium μ road surface), Grip force and cornering force do not decrease so much, for example, it is possible to prevent that the running line is shifted to the outside, and also the braking force of the entire vehicle does not change, so that the vehicle speed can be appropriately reduced, It is also possible to secure a braking distance. Incidentally, the front left wheel base braking force F _BFL front wheel braking force reduction amount [Delta] F F _(-) set and the absolute value of the front wheel braking force difference | [Delta] F _F ^* | value obtained by subtracting the front left wheel base braking force F _BFL from the front wheel Braking force increase ΔF
_{When F (+)} is set, as described above, the line pressure is originally small, so that a more reliable braking force difference is obtained to secure the response of the vehicle behavior control. It is.

Next, step S of the above-described calculation processing of FIG.
If the pressure increase priority mode is selected in 93, step S94
Then, the flow shifts to step S97, where the calculation processing in FIG. 12 is performed. Here, too, a case is considered in which a clockwise target moment M ^* is required to correct the oversteer state when turning left. In processing of FIG. 12, similarly to the processing of FIG. 10, step S9701 in front left wheel braking force F _FL and front right wheel braking force F _FR before the greater than either or front right wheel braking force F _FR It is determined whether the braking force is greater than the left wheel braking force F _FL , and in the case of the former, step S9702
The process proceeds to step S9703 in the latter case. Since we need ^* clockwise target moment M, the front from the right wheel braking force F _FR should be larger than the front left wheel braking force F _FL, consider the step S9703. In this step S9703, the absolute value | ΔF of the front wheel braking force difference
_F ^* | (substantially the same as the front wheel braking force difference ΔF _F ^* only by correcting the sign) is directly added to the front right wheel basic braking force F _BFR to become the front right wheel target braking force F _FR ^* . , The front left wheel basic braking force F _BFL becomes the front left wheel target braking force F _FL ^* as it is.

The same setting of the target braking force F _i ^* (including the rear wheels) is set, for example, in steps S9702 (front wheel side), steps S9705 and S9706 (rear wheel side). The state of the braking force at this time is shown in FIG.
Shown in That is, the oversteer state (O.D. in the figure) is shown in the figure.
As described in the braking force control between the left and right wheels in S), only the braking force of the turning outer wheel is increased. When the braking force control between the front and rear wheels in the oversteer state (OS in the figure) is performed, only the braking force of the front wheels is increased. Therefore, the braking force of the vehicle as a whole is increased, which is advantageous for actively reducing the vehicle speed and securing the braking distance. On the other hand, for example, during turning, since the braking force is increased at the front turning outer wheel that generates the largest cornering force, the grip force and the cornering force of the front turning outer wheel are reduced unless the road surface is high μ, for example, when traveling There is also the disadvantage that the lines may shift outward.

As can be seen from these descriptions, the pressure-decrease priority mode, the pressure-increase / decrease medium mode, and the pressure-increase priority mode are the same as those described above, except that it is determined whether the braking force to be reduced becomes zero. Front and rear wheel braking force difference ΔF _F ^* , ΔF _R
The weight for distributing ^* to the braking force decreasing side and the braking force increasing side is changed.

In the present embodiment, for example, in the region where the road surface μ or the lateral acceleration or the longitudinal acceleration is relatively small or less than a predetermined value, that is, on the low μ road surface, the pressure reduction is performed by the arithmetic processing executed in step S93 of FIG. Since the priority (braking force reduction priority) mode is selected, it is possible to avoid shifting the traveling line. Further, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is equal to or larger than a predetermined value, that is, a high μ road surface, the pressure increase priority (braking force increase priority) mode is selected, so that the braking distance can be secured. . Also,
A region where the road surface μ or the lateral acceleration or the longitudinal acceleration is less than a relatively large predetermined value and more than a relatively small predetermined value, that is, medium μ
On the road surface, the mode of increasing / decreasing pressure (simultaneous increase / decrease of braking force) mode is selected, so that it is possible to secure the braking distance and not to shift the traveling line. If the amount of change in the lateral acceleration per unit time is larger than a preset value, that is, if there is a high possibility that the driver is operating the steering wheel largely, priority is given to pressure reduction (braking force reduction priority). Since the mode is selected, it is possible to prevent the traveling line from shifting according to the driver's will. If the amount of change in the longitudinal acceleration per unit time is larger than a preset value, that is, if there is a high possibility that the driver is actively stepping on the brake pedal, priority is given to pressure reduction (braking force). Since the mode of decreasing priority is prohibited, or the mode of increasing or decreasing pressure (simultaneous increase / decrease of braking force) or the mode of increasing pressure (prioritizing increase of braking force) is selected, the vehicle speed is reduced according to the driver's will. A braking distance can be secured.

In addition, step S9 of the arithmetic processing of FIG.
When the arithmetic processing of FIG. 7 is executed in 3, when the vehicle is in the oversteer state, the pressure reduction priority (braking force reduction priority) mode is selected. In the understeer state, the medium pressure increase / decrease mode (simultaneous increase / decrease in braking force) mode or the pressure increase priority (braking force increase priority) mode is selected, so that the braking force is increased. By controlling in the direction, the vehicle speed can be reduced or the braking distance can be secured.

In addition, step S9 of the arithmetic processing of FIG.
When the calculation processing of FIG. 8 is executed in 3, if the brake pedal is being depressed further, priority is given to pressure reduction (priority to decrease braking force).
The mode is prohibited, or the medium pressure increase / decrease mode (simultaneous increase / decrease in braking force) mode or the pressure increase priority (braking force increase priority) mode is selected, so that the vehicle speed is reduced or the braking distance is reduced according to the driver's intention. Can be shorter.

In addition, step S9 of the arithmetic processing of FIG.
When the arithmetic processing of FIG. 9 is executed in 3, if the steering wheel is being turned further, the pressure reduction priority (braking force reduction priority) mode is selected, so that the traveling line is shifted according to the driver's intention. Can not be.

As described above, the step S95 of the arithmetic processing of FIG. 5 and the entire arithmetic processing of FIG. 10 constitute the braking force reduction priority control means of the present invention. Similarly, the steps S97 and S97 of the arithmetic processing of FIG. 12 constitutes the braking force increase priority control means, the step S96 of the arithmetic processing of FIG. 5 and the entire arithmetic processing of FIG. 11 constitute the braking force simultaneous increase / decrease control means, and the arithmetic processing of FIG. Step S9
Steps S9301 and S9311 of the calculation processing of FIG. 3 and FIG. 7 and step S9311 of the calculation processing of FIG. 8 constitute the vehicle traveling state detecting means, and steps S93 and S6 of the calculation processing of FIG. 8 and the steps S9302 and S9303 of the calculation processing of FIG. 7 and the step S9312 of the calculation processing of FIG.
9 and the step S9322 of the calculation processing of FIG. 9 constitute the braking force increase / decrease rate control means, and the acceleration sensor 15 and FIG.
7 constitute road surface friction coefficient state detecting means, lateral acceleration detecting means and longitudinal acceleration detecting means, and the yaw rate sensor 13 and step S930 of the calculation processing of FIG.
1 constitutes a steering state detecting means, and the brake pedal stroke sensor 19 or the line pressure sensor 16 and FIG.
Step S9311 of the calculation processing of (1) constitutes the brake pedal depression increase detecting means, and the steering angle sensor 14 and step S9321 of the calculation processing of FIG.

Hereinafter, a second embodiment of the vehicle behavior control device according to the present invention will be described. The outline of the brake fluid pressure control device of the present embodiment is the same as the brake fluid pressure / electric system diagram shown in FIG. 1 of the first embodiment. The configuration of the control unit that controls various sensors and controls provided in the vehicle is also the same as that of the first embodiment. The general flow of the braking force control executed by the control unit is also the same as that of the first embodiment shown in FIG.
Is the same as that shown in FIG.

In the present embodiment, the minor program for calculating the target braking force F _i ^*, which is executed in step S9 of the arithmetic processing of FIG. 2, is different from the arithmetic processing of FIG. Has been changed to However, they are relatively similar and have similar steps. Therefore, the same steps are denoted by the same reference numerals and description thereof will be omitted.
That is, in the calculation processing of FIG. 17, steps S93 to S97 of the calculation processing of FIG.
0 and step S110.

In step S100, the pressure increase / decrease weight coefficient (1) is determined by a control map search shown in FIG.
-X), x is calculated and set. In addition, in step S110, the target braking force F
Calculate _i ^* .

Next, step S of the arithmetic processing shown in FIG.
The control map of FIG. 18 searched at 100 will be described. Prior to this, also in the present embodiment, when controlling the braking force as in the first embodiment, the wheel cylinder pressure of the wheel cylinder pressure that preferentially increases the braking force is set. It should be noted that the pressure increase priority control and the pressure reduction priority control that preferentially reduces the braking force are performed. That is, in the control map of FIG. 18, the priority of the pressure reduction priority control corresponding to the pressure reduction priority mode of the first embodiment is set as the weight coefficient x. Therefore, the priority of the pressure increase priority control corresponding to the pressure increase priority mode of the first embodiment is represented by the weight coefficient (1-x). And in this control map,
As in the control map of FIG. 6 of the first embodiment, the lateral acceleration and the longitudinal acceleration generated in the vehicle are used as evaluation indices obtained by turning and acceleration / deceleration and equivalent to the road surface μ at that time.

In a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is relatively small or smaller than a predetermined value, the road μ is regarded as a low μ road surface (snow in the figure) such as a frozen road surface, and the traveling line The weighting factor x of the pressure reduction priority control is set to "1" so that the pressure reduction priority (braking force reduction priority) mode is set so as not to shift (the weighting factor (1-x) of the pressure increase priority control is "0"). ). On the other hand, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is a relatively large predetermined value or more, it is regarded as a high μ road surface (dry in the figure) such as a dry concrete road surface, and the braking distance is secured as described above. The pressure coefficient x of the pressure reduction priority control is set to "0" (the weight coefficient (1-x) of the pressure increase priority control is "1") so as to be in the pressure increase priority (braking force increase priority) mode. Further, in an intermediate area between the two areas, that is, an area where the road surface μ or the lateral acceleration or the longitudinal acceleration is equal to or less than the relatively large predetermined value and equal to or more than the relatively small predetermined value (wet in the figure), the braking distance is secured. The weighting factor x of the pressure-decreasing priority control is set to "0.5" so that the pressure-decreasing medium mode (braking force simultaneous increase / decrease) mode without shifting the running line is set (weighting factor (1- x) is also “0.5”).

However, in this embodiment, the mode is between the mode of increasing / decreasing pressure (simultaneous increase / decrease of braking force) mode and the mode of decreasing / decreasing priority (priority of decreasing braking force), or the mode of increasing / decreasing (simultaneous increase / decrease of braking force)
The weighting factor x of the pressure reduction priority control and the weighting factor (1-x) of the pressure increase priority control are analogized so that the control is smoothly connected between the mode and the pressure increase priority (braking force increase priority) mode. To change. More specifically, between the pressure reduction priority (braking force reduction priority) mode and the pressure increase / decrease medium (braking force simultaneous increase / decrease) mode, the weight of the pressure reduction priority control is increased in accordance with an increase in the road surface μ or the lateral acceleration or the longitudinal acceleration. The coefficient x decreases linearly, and the weight coefficient (1-x) of the pressure increase priority control increases linearly. Also, between the pressure increasing / decreasing medium mode (simultaneously increasing / decreasing braking force) mode and the pressure increasing priority (braking force increasing priority) mode, the weight coefficient x of the pressure decreasing priority control increases linearly with the increase of the road surface μ or the lateral acceleration or the longitudinal acceleration. And the weight coefficient (1-x) of the pressure increase priority control is linearly increased. The mode selection element as shown in the first embodiment, that is, the change amount of the lateral acceleration per unit time, the change amount of the longitudinal acceleration per unit time, the steer state such as the oversteer state and the understeer state, and the brake pedal The number of steps of the steering wheel or the number of steering wheels may be increased.

Next, step S of the arithmetic processing shown in FIG.
The arithmetic processing of FIG. 19 executed in 110 will be described. In this calculation process, first, in step S1101, it is determined whether the calculated front wheel braking force difference ΔF _F ^* is a positive value. If the front wheel braking force difference ΔF _F ^* is a positive value, the process proceeds to step S1101. The process moves to S1102; otherwise, the process moves to step S1103.

In the step S1102, it is determined whether or not the calculated front right wheel basic braking force _FBFR is less than the front wheel braking force difference (x · ΔF _F ^* ) multiplied by the pressure reduction priority control weighting coefficient. If the front right wheel basic braking force F _BFR is smaller than the front wheel braking force difference (x · ΔF _F ^* ) multiplied by the pressure reduction priority control weighting factor, the flow shifts to step S1104; otherwise, the flow advances to step S1105. Transition.

In step S1104, a value obtained by subtracting the front right wheel basic braking force _FBFR from the front wheel braking force difference ΔF _F ^{* is} set as the front wheel braking force increase amount ΔF _{F (+).} After the braking force _{FBFR is set} to the front wheel braking force reduction amount ΔFF _(-) , the flow shifts to step S1106.

In the step S1105, the front wheel braking force difference ((1-x)
· ΔF _F ^*) with a set to the front wheel braking force increment ΔF F _(+), the reduced pressure priority control weighting factor multiplied by the front wheel braking force difference (x · ΔF _F ^*) to the front wheel braking force reduction amount [Delta] F F _{( After} setting to- ₎ , the flow shifts to the step S1106.

In step S1106, the front wheel braking force reduction amount _{ΔBFR is calculated} from the front right wheel basic braking force _FBFR.
The value obtained by subtracting _{FF (-)} is set to the front right wheel target braking force _FFR ^* , and the value obtained by adding the front wheel braking force increase amount ΔFF ₍₊₎ to the front left wheel basic braking force _FBFL is used for the front left wheel. After setting the target braking force F _FL ^* , the flow shifts to step S1107.

On the other hand, in step S1103, the absolute value (x · | ΔF _F ) of the front wheel braking force difference obtained by multiplying the calculated front left wheel basic braking force _FBFL by the pressure reduction priority control weighting coefficient is used.
^* |) It is determined whether the below, the absolute value of the front left wheel base braking force F _BFL is vacuum priority control weighting factor multiplied by the front wheel braking force difference ^{_{(x · | ΔF F * |}} ) less than in the case of In step S1108, the process proceeds to step S1109. Otherwise, the process proceeds to step S1109.

In step S1108, the absolute value of the front wheel braking force difference | ΔF _F ^* |
_The value obtained by subtracting the _BFL is set to the front wheel braking force increase amount ΔFF _(+), and the front left wheel basic braking force _{FBFL is set} to the front wheel braking force decrease amount ΔFF ₍₋₎ , and then the process proceeds to step S1110. .

In the step S1109, the front wheel braking force difference ((1-x)
. | ΔF _F ^* |) is set as the front wheel braking force increase amount ΔF _{F (+)} , and the front wheel braking force difference (x · | ΔF _F ^* |) multiplied by the pressure reduction priority control weight coefficient is reduced. Amount ΔF _{F (-)}
Then, the flow shifts to the step S1110.

In step S1110, the front wheel braking force increase amount ΔF is added to the front right wheel basic braking force F _BFR.
The sum of _{F (+)} is set as the front right wheel target braking force F _FR ^*, and the value obtained by subtracting the front wheel braking force reduction amount ΔF _{F (−)} from the front left wheel basic braking force _FBFL is used as the front left wheel target braking force. After setting the braking force F _FL ^* , the flow shifts to step S1107.

In step S1107, it is determined whether or not the calculated rear wheel braking force difference ΔF _R ^* is a positive value. If the rear wheel braking force difference ΔF _R ^* is a positive value, the process proceeds to step S1107. The process moves to S1111; otherwise, the process moves to step S1112.

In step S1111, it is determined whether or not the calculated rear right wheel basic braking force _FBRR is smaller than the rear wheel braking force difference (x · ΔF _R ^* ) multiplied by the pressure reduction priority control weight coefficient. If the rear right wheel basic braking force F _BRR is smaller than the rear wheel braking force difference (x · ΔF _R ^* ) multiplied by the pressure reduction priority control weighting factor, the flow shifts to step S1113; The process moves to S1114.

In step S1113, a value obtained by subtracting the rear right wheel basic braking force _FBRR from the rear wheel braking force difference ΔF _R ^{* is} set as the rear wheel braking force increase amount ΔF _{R (+)} , and the rear right braking force difference ΔF _{R (+)} is set. After the wheel basic braking force F _{BRR is set} to the rear wheel braking force reduction amount ΔF _{R (−)} , the flow shifts to step S1115.

In step S1114, the rear wheel braking force difference ((1-x)) is multiplied by the pressure increase priority weighting coefficient.
ΔF _R ^* ) is set as the rear wheel braking force increase amount ΔF _{R (+)} , and the rear wheel braking force difference (x · ΔF _R ^* ) multiplied by the pressure reduction priority control weight coefficient is calculated as the rear wheel braking force reduction amount. After setting to ΔF _{R (−)} , the flow shifts to the step S1115.

In step S1115, the rear wheel braking force reduction amount _{ΔB is calculated} from the rear right wheel basic braking force F _BRR.
The value obtained by subtracting F _{R (-)} is set as the rear right wheel target braking force F _RR ^* , and the value obtained by adding the rear wheel braking force increase ΔF _{R (+)} to the rear left wheel basic braking force F _BRL is used as the rear braking force. After the target braking force F _RL ^* is set for the left wheel, the flow shifts to step S98 in the calculation processing in FIG.

On the other hand, in the step S1112, the absolute value (x · | ΔF _R ) of the rear wheel braking force difference obtained by multiplying the calculated rear left wheel basic braking force _FBRL by the pressure reduction priority control weighting coefficient is used.
^* |) Is determined, and the rear left wheel basic braking force _FBRL is less than the absolute value (x · | ΔF _R ^* |) of the rear wheel braking force difference multiplied by the pressure reduction priority control weighting factor. In this case, the process shifts to step S1116; otherwise, the process shifts to step S1117.

In step S1116, the rear left wheel basic braking force F is calculated from the absolute value | ΔF _R ^* | of the rear wheel braking force difference.
And sets the rear wheel braking force increment ΔF R ₍₊₎ a value obtained by subtracting the _BRL, the rear left wheel base braking force F _BRL rear wheel braking force reduction amount [Delta] F R _(-) from the set to the step S1118 Transition.

In step S1117, the rear wheel braking force difference ((1-x)) is multiplied by the pressure increase priority control weighting coefficient.
. | ΔF _R ^* |) is set to the rear wheel braking force increase amount ΔF _{R (+)} , and the rear wheel braking force difference (x · | ΔF _R ^* |) multiplied by the pressure reduction priority control weighting coefficient is set to the rear wheel. Braking force decrease ΔF _{R (-)}
Then, the flow shifts to the step S1118.

In step S1110, the rear wheel braking force increment ΔF is added to the rear right wheel basic braking force F _BRR.
The sum of _{R (+)} is set as the rear right wheel target braking force F _RR ^*, and the value obtained by subtracting the rear wheel braking force reduction amount ΔF _{R (−)} from the rear left wheel basic braking force _FBRL is the value of the rear left wheel. After the target braking force F _RL ^* is set, the flow shifts to step S98 in the calculation processing in FIG.

Next, the operation of the present embodiment will be described. As described above, it is determined which of the wheels should have a larger or smaller braking force, and the front and rear wheel braking force differences ΔF _F ^* and ΔF _R ^* are determined on the braking force decreasing side and the braking force increasing side. The front and rear wheel braking force increase / decrease ΔF _{j (+)} , ΔF _{j (−)} (j
If ForR) is set, pressure reduction priority (braking force reduction priority) mode, increasing / decreasing medium (braking force simultaneous increase / decrease) even with the same formula
A mode and a pressure increase priority (braking force increase priority) mode can be selected. More specifically, the pressure reduction priority control weight coefficient x
Is set to “1” and the pressure increase priority control weight coefficient (1-x) is set to “0”, the pressure reduction priority mode, the pressure reduction priority control weight coefficient x, and the pressure increase priority control weight coefficient (1-x) are set to “0. If 5 ", the pressure increase / decrease medium mode, and if the pressure reduction priority control weight coefficient x is" 0 "and the pressure increase priority control weight coefficient (1-x) is" 1 ", the pressure increase priority mode is set. The operation of the vehicle behavior in each of these modes is the same as that described in the first embodiment.

In the present embodiment, the pressure reduction priority control weight coefficient x and the pressure increase priority control weight coefficient (1−1) are calculated by the arithmetic processing executed in step S10 in FIG.
Since x) is set, for example, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is relatively small or less than a predetermined value, that is, on a low μ road surface, the pressure reduction priority (braking force reduction priority) mode is selected. Lines can be kept from shifting. Further, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is equal to or larger than a predetermined value, that is, a high μ road surface, the pressure increase priority (braking force increase priority) mode is selected, so that the braking distance can be secured. . Further, in a region where the road surface μ or the lateral acceleration or the longitudinal acceleration is a relatively large predetermined value or less and a relatively small predetermined value or more, that is, a medium μ road surface, the moderate pressure increase / decrease mode (simultaneous increase / decrease in braking force) mode is selected. It is possible to secure the braking distance and not to shift the traveling line.

In the present embodiment, the pressure reduction priority control weight coefficient x and the pressure increase priority control weight coefficient (1-x) are analogized between the control modes according to the road surface μ, the lateral acceleration, or the longitudinal acceleration. The advantage is that the change in the vehicle behavior that occurs when each control mode changes is smooth and does not give an uncomfortable feeling to the occupant.

As described above, step S110 of the arithmetic processing of FIG. 17 and the entire arithmetic processing of FIG. 19 constitute the braking force decrease priority control means, the braking force increase priority control means and the braking force simultaneous increase / decrease control means of the present invention. Similarly, FIG.
Step S100 of the calculation processing constitutes the vehicle traveling state detecting means, step S100 of the calculation processing of FIG. 17 and the control map of FIG. 18 constitute the braking force increase / decrease rate control means, and the acceleration sensor 15 and FIG. The control map constitutes road surface friction coefficient state detecting means, lateral acceleration detecting means, and longitudinal acceleration detecting means.

In the above-described embodiment, a case has been described in which a microcomputer is applied as the control unit. Alternatively, an electronic circuit such as a counter and a comparator may be combined.

In the above embodiment, the yaw rate is used as the control vehicle behavior, but other vehicle behaviors may be controlled simultaneously.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of a calculation process executed in the control unit of FIG. 1;

FIG. 3 is an explanatory diagram of a target moment for correcting a vehicle behavior set in the calculation processing of FIG. 2;

FIG. 4 is an explanatory diagram of a pressure increasing / decreasing characteristic used in the calculation processing of FIG. 2;

FIG. 5 is a flowchart showing a first embodiment of a minor program performed in the calculation processing of FIG. 2;

6 is an explanatory diagram of a control map used in the calculation processing of FIG.

FIG. 7 is a flowchart illustrating an example of a minor program executed in the calculation processing of FIG. 5;

FIG. 8 is a flowchart illustrating an example of a minor program executed in the calculation processing of FIG. 5;

FIG. 9 is a flowchart illustrating an example of a minor program performed in the calculation processing of FIG. 5;

FIG. 10 is a flowchart illustrating an example of a minor program executed in the calculation processing of FIG. 5;

FIG. 11 is a flowchart illustrating an example of a minor program executed in the calculation processing of FIG. 5;

FIG. 12 is a flowchart illustrating an example of a minor program performed in the calculation processing of FIG. 5;

FIG. 13 is a flowchart illustrating an example of a minor program performed in the calculation processing of FIG. 5;

FIG. 14 is an explanatory diagram of the operation of the arithmetic processing in FIG. 10;

FIG. 15 is an explanatory diagram of the operation of the calculation processing in FIG. 11;

FIG. 16 is an explanatory diagram of the operation of the calculation processing in FIG. 12;

FIG. 17 is a flowchart illustrating a second embodiment of the minor program performed in the calculation processing of FIG. 2;

18 is an explanatory diagram of a control map used in the calculation processing of FIG.

FIG. 19 is a flowchart illustrating an example of a minor program performed in the calculation processing of FIG. 17;

[Explanation of symbols]

 1FL to 1RR are wheels 2FL to 2RR are wheel cylinders 3 are pressure boosting pumps 4 are brake pedals 5 are master cylinders 6A and 6B are master cylinder interrupting valves 7A and 7B are pressure increasing pump interrupting valves 8FL to 8RR are pressure increasing control valves 9FL. 9RR is a check valve 10FL-19RR is a pressure reduction control valve 11A, 11B is a pressure reduction pump 12FL-12RR is a wheel speed sensor 13 is a yaw rate sensor 14 is a steering angle sensor 15 is an acceleration sensor 17 is a control unit 18A, 18B is a reservoir 19 Is a brake pedal stroke sensor 20RL, 20RR is a proportional valve

Claims (12)

[Claims] 1. A vehicle behavior control device for detecting a behavior of a vehicle and controlling a braking force of each wheel to generate a vehicle behavior correction moment, wherein a control between the wheels required to generate the vehicle behavior correction moment is provided. To get the power difference,
A vehicle behavior control device comprising a braking force reduction priority control means for giving priority to a reduction in braking force. 2. The braking force reduction priority control means increases the braking force of another wheel when the braking force of the wheel which has been reduced preferentially becomes zero.
The vehicle behavior control device according to claim 1. 3. A braking force increase priority control means for prioritizing an increase in braking force to obtain a braking force difference between wheels required to generate the vehicle behavior correcting moment, and a vehicle driving condition. And a braking force by the braking force decrease priority control means and a braking force by the braking force increase priority control means according to the traveling state of the vehicle detected by the vehicle traveling state detection means. 3. The vehicle behavior control device according to claim 1, further comprising: a braking force increase / decrease rate control unit that controls a rate of increase in the braking force. 4. A braking force for simultaneously increasing and decreasing the braking force so that the sum of the braking forces does not change, in order to obtain a braking force difference between the wheels required to generate the vehicle behavior correcting moment. A simultaneous increase / decrease control unit, wherein the braking force increase / decrease rate control unit is configured to reduce the braking force and increase the braking force by the braking force reduction priority control unit in accordance with the traveling state of the vehicle detected by the vehicle traveling state detection unit. 4. The vehicle behavior control device according to claim 3, wherein priorities of increasing the braking force by the priority control means and simultaneously increasing and decreasing the braking force by the simultaneous braking force increase / decrease control means are set. 5. A road surface friction coefficient state detecting means for detecting a friction coefficient state of a road surface as the vehicle traveling state detecting means, and the braking force increase / decrease rate control means includes a road surface detected by the road surface friction coefficient state detecting means. When the friction coefficient state is low, priority is given to the reduction of the braking force by the braking force reduction priority control means, and when the friction coefficient state of the road surface is high, the braking force is increased or the braking force is simultaneously increased / decreased by the braking force increase priority control means. The vehicle behavior control device according to claim 4, wherein priority is given to simultaneous increase and decrease of the braking force by the control means. 6. A vehicle according to claim 1, further comprising a lateral acceleration detecting means for detecting a lateral acceleration generated in the vehicle, wherein said braking force increase / decrease rate controlling means has a small lateral acceleration detected by said lateral acceleration detecting means. When the reduction of the braking force by the braking force reduction priority control means is prioritized, and when the lateral acceleration is large, the braking force increase by the braking force increase priority control means or the simultaneous increase / decrease of the braking force by the braking force simultaneous increase / decrease control means is performed. The vehicle behavior control device according to claim 4, wherein priority is given to the vehicle behavior control device. 7. The braking force increasing / decreasing ratio control means gives priority to a reduction in braking force by the braking force reduction priority control means when a change in lateral acceleration detected by the lateral acceleration detecting means is large. The vehicle behavior control device according to claim 6, wherein 8. The vehicle running condition detecting means includes longitudinal acceleration detecting means for detecting longitudinal acceleration generated in the vehicle, and the braking force increase / decrease rate controlling means has a small longitudinal acceleration detected by the longitudinal acceleration detecting means. When priority is given to the reduction of the braking force by the braking force reduction priority control means, and when the longitudinal acceleration is large, the braking force increase by the braking force increase priority control means or the simultaneous increase / decrease of the braking force by the braking force simultaneous increase / decrease control means is performed. The vehicle behavior control device according to any one of claims 4 to 7, wherein priority is given to the vehicle behavior control device. 9. The braking force increasing / decreasing ratio controlling means includes means for increasing the braking force or controlling simultaneous braking force increasing / decreasing control by the braking force increase priority controlling means when the amount of change in longitudinal acceleration detected by the longitudinal acceleration detecting means is large. 9. The vehicle behavior control device according to claim 8, wherein priority is given to simultaneous increase and decrease of the braking force by the means. 10. The vehicle driving condition detecting device according to claim 1, further comprising a steer state detecting unit that detects whether an actual vehicle behavior is an oversteer state or an understeer state with respect to a target value of the vehicle behavior. Means for prioritizing a reduction in braking force by the braking force reduction priority control means when the vehicle behavior detected by the steering state detection means is in an oversteer state, and by the braking force increase priority control means when in an understeer state. 10. The vehicle behavior control device according to claim 4, wherein priority is given to simultaneous increase / decrease of the braking force by the braking force increase / decrease control means. 11. The vehicle driving condition detecting means includes a brake pedal increase detecting means for detecting a brake pedal increasing operation, and the braking force increase / decrease rate controlling means includes:
When the additional brake pedal operation is detected by the additional brake pedal detection means, the reduction of the braking force by the braking force reduction priority control means is inhibited or the braking force is increased or the braking force is reduced by the braking force increase priority control means. The vehicle behavior control device according to any one of claims 4 to 10, wherein priority is given to simultaneous increase and decrease of the braking force by the simultaneous increase and decrease control means. 12. The vehicle driving condition detecting device according to claim 1, further comprising: a steering wheel turning-up detecting unit that detects a steering wheel turning-up operation, wherein the braking force increase / decrease rate controlling unit detects the steering wheel turning-up operation by the steering wheel turning-up detecting unit. When the turning operation is detected, priority is given to the reduction of the braking force by the braking force reduction priority control means, or the braking force is increased by the braking force increase priority control means or the braking force is simultaneously increased and decreased by the braking force simultaneous increase / decrease control means. The vehicle behavior control device according to any one of claims 4 to 11, wherein the control of the vehicle behavior is prohibited.