JP5274601B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance stability of an attitude of a vehicle that is about to be overturned. <P>SOLUTION: A brake fluid pressure control apparatus for the vehicle, which is constituted to be can individually braking coaxially-mounted right and left wheels, performs overturn suppression control by braking the wheels when an overturn tendency is detected during turning. When the overturn tendency is detected, an overturn suppression control part 120 starts to brake the coaxial turning inner wheel with a second braking force smaller than a first braking force, while braking the turning outer wheel with the first braking force. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a vehicular brake hydraulic pressure control device, and more particularly, to a vehicular brake hydraulic pressure control device that controls a brake and suppresses vehicle rollover.

  When the vehicle is about to roll over due to a sudden turn, the braking force is applied only to the turning outer wheel to reduce the lateral frictional force acting between the road surface and the tire and to roll over. There is a known method for suppressing the above (Patent Document 1).

  In addition, when the vehicle turns in one direction and then turns back in the opposite direction, it is particularly easy to roll over due to the reaction of the roll. There is known a technique for providing (Patent Document 2).

JP 10-081215 A Special table 2007-513002 gazette

  However, the method described in Patent Document 1 or Patent Document 2 has a problem that the braking force of the outer wheel after turning (inner wheel before turning) cannot be quickly raised during the turning operation after turning. In the technique of Patent Document 2, it is considered better than the method of Patent Document 1 because the spare brake is applied after the turning operation. However, since the spare brake of the turning inner wheel is given after the turning operation, the outer wheel after the turning operation is performed. The increase in the braking force is not always sufficient, and since the time for the preliminary braking is short, there is a problem that the contribution to the deceleration of the vehicle, which is one of the factors for suppressing the rollover, is small.

  Therefore, an object of the present invention is to provide a vehicle brake hydraulic pressure control device that can further improve the stability of the posture when the vehicle is likely to roll over.

The present invention that solves the above-described problem is configured such that left and right wheels provided on the same axis can be individually braked, and when a rollover tendency is detected during a turn, the wheels are braked to perform rollover suppression control. A brake fluid pressure control device for a vehicle, wherein an outer wheel target braking force setting means for setting a target outer wheel target braking force for braking a turning outer wheel with a first braking force, and a turning with a second braking force An inner ring target braking force setting unit that sets a target inner ring target braking force for braking the inner ring at a value smaller than the outer wheel target braking force, and the inner ring target braking force setting unit is set in advance. When the predetermined value is smaller than the value obtained by multiplying the outer wheel target braking force by a coefficient less than 1, the predetermined value is set as the inner wheel target braking force, and the predetermined value is a coefficient less than 1 for the outer wheel target braking force. If the value is greater than the value multiplied by the outer ring target braking Wherein a value obtained by multiplying less than one coefficient set to the inner ring target braking force, when the rollover tendency is detected, at the same time the braking in the first braking force to the turning outer wheel, the inner wheel on the same axis in The braking is started with the second braking force.

According to such a configuration, when a rollover tendency is detected, the turning inner wheel on the same axis (hereinafter simply referred to as the “inner ring”) is “simultaneously” when the outer turning wheel is braked with the first braking force. In this case, braking is started with a second braking force that is smaller than the first braking force, so that a larger braking force is applied to the turning outer wheel (hereinafter sometimes referred to simply as the “outer wheel”) than to the turning inner wheel. In this way, it is possible to suppress the tendency to roll over regardless of whether or not there is subsequent turnback steering, and if there is subsequent turnback steering, a certain amount of braking force has already been applied to the turning inner wheel (turning outer wheel after turning back). Is provided, the brake pressure of the outer ring can be quickly increased after turning over, and rollover can be effectively suppressed.
Further, according to such a configuration, the inner wheel target braking force is basically set to a predetermined value, so that a delay in the increase of the braking force of the outer wheel after turning over is prevented and the deceleration of the vehicle body is exerted while the outer wheel is being decelerated. When the braking force applied to the inner ring is small, the braking force of the inner ring can be made smaller than that of the outer ring, and in this case as well, the effect of suppressing rollover can be exhibited.

  Further, before the turn-back steering, by applying braking force not only to the outer wheel but also to the inner wheel, the vehicle body speed can be effectively reduced, and this can also suppress rollover. That is, the roll angle that directly indicates the rollover tendency depends on the vehicle body speed, and tends to increase as the vehicle body speed increases. Therefore, the rollover can be suppressed by reducing the vehicle body speed. Further, according to this configuration, since the vehicle body speed is low by using the braking force of the inner wheel before the turning-back steering, the rollover after the turning-back steering can be effectively suppressed.

  The rollover suppression control according to the present invention is executed when a rollover detection parameter indicating a rollover tendency exceeds at least a predetermined threshold, and the outer wheel target braking force setting unit is configured to set the rollover detection parameter to the predetermined threshold. The outer wheel target braking force can be set from the deviation.

  The larger the deviation between the rollover detection parameter indicating rollover tendency and the predetermined threshold value for determining whether or not to perform rollover suppression control, the higher the possibility of rollover. By setting this, it becomes possible to perform control according to the possibility of rollover.

  The inner wheel target braking force setting means sets the predetermined value to a first predetermined value for a predetermined time after the rollover suppression control is started, and sets the predetermined value to the first predetermined value after the predetermined time has elapsed. It is good also as a 2nd predetermined value smaller than this.

  According to such a configuration, the rising of the braking force can be improved by setting the inner wheel target braking force large at the beginning of the rollover suppression control, and the vehicle can be stabilized.

  In the vehicle brake hydraulic pressure control device described above, the rollover suppression control is executed on both the front and rear wheels, and the outer wheel target braking force setting means sets the outer wheel target braking force of the rear wheel to a third predetermined value. It is desirable to set the upper limit.

  With this configuration, a braking force is applied to both the front and rear wheels, and the vehicle body speed can be quickly reduced to improve the rollover suppression effect, and an upper limit value is set for the braking force of the rear wheels that easily slip. It is possible to prevent the braking force from being generated more than necessary.

  According to the present invention, during the rollover suppression control, the braking force is applied to the turning inner wheel simultaneously with the braking force applied to the turning outer wheel. Thus, it is possible to prevent a delay in the increase in the braking force of the turning outer wheel after turning over, and to further improve the stability of the posture when the vehicle is likely to roll over.

It is a lineblock diagram of vehicles provided with a brake fluid pressure control device for vehicles concerning an embodiment of the present invention. It is a block diagram of the hydraulic unit of the brake hydraulic pressure control apparatus for vehicles. It is a block diagram which shows the structure of a control part. (A) The block diagram which shows the structure of a parameter calculation means, (b) The block diagram which shows the structure of a ROM control braking force setting means. It is a graph which shows the relationship between the roll rate for threshold value calculation, and a roll angle threshold value. It is a flowchart which shows the whole process of rollover suppression control. It is a flowchart which shows the calculation process of a synthetic | combination roll angle | corner. It is a flowchart which shows the calculation process of a 1st distribution coefficient. It is a flowchart which shows the calculation process of a 2nd distribution coefficient. It is a flowchart which shows the setting process of a roll angle threshold value. It is a flowchart which shows the calculation process of an outer wheel target braking force. It is a flowchart which shows the calculation process of an inner ring | wheel target braking force. It is a graph which shows a time-dependent change of each parameter for explaining processing which computes the 1st synthetic roll angle. It is a graph which shows a time-dependent change of each parameter for explaining processing which computes the 2nd synthetic roll angle. It is a graph which shows the time-dependent change of each parameter for demonstrating the process which calculates a synthetic | combination roll rate. It is a graph explaining until it calculates a roll angle threshold value from a synthetic roll rate. It is a graph explaining calculation of deviation (DELTA) Ra. (A) The graph explaining calculation of PI output value from deviation (DELTA) Ra, (b) The graph which shows the time-dependent change of an outer-wheel target braking force. It is a graph which shows a time-dependent change of an inner wheel target braking force. It is a graph which shows the time-dependent change of the target braking force about each of (a) front right wheel, (b) front left wheel, (c) rear right wheel, and (d) rear left wheel. It is a graph which shows the time-dependent change of the distribution coefficient, the rollover detection parameter, the caliper pressure, and the wheel lift amount when the rollover suppression control is performed by the apparatus of the present embodiment.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, the vehicle brake hydraulic pressure control device A is for appropriately controlling a braking force (brake hydraulic pressure) applied to each wheel W of the vehicle CR, and an oil path (hydraulic pressure path). And a hydraulic unit 10 provided with various components, and a control unit 100 for appropriately controlling various components in the hydraulic unit 10.

  The control unit 100 includes a wheel speed sensor 91 that detects the wheel speed of the wheel W, a steering angle sensor 92 that detects the steering angle of the steering ST, and a lateral force that detects an acceleration (lateral acceleration) acting in the lateral direction of the vehicle CR. An acceleration sensor 93 and a yaw rate sensor 94 that detects the turning angular velocity (actual yaw rate) of the vehicle CR are connected. The detection results of the sensors 91 to 94 are output to the control unit 100.

  The control unit 100 includes, for example, a CPU, a RAM, a ROM, and an input / output circuit, and inputs from the wheel speed sensor 91, the steering angle sensor 92, the lateral acceleration sensor 93, and the yaw rate sensor 94, and a program stored in the ROM. Control is performed by performing each arithmetic processing based on the data.

  The wheel cylinder H is a hydraulic device that converts the brake hydraulic pressure generated by the master cylinder MC and the vehicle brake hydraulic pressure control device A into the operating force of the wheel brakes FR, FL, RR, RL provided on each wheel W. These are connected to the hydraulic pressure unit 10 of the vehicle brake hydraulic pressure control device A via respective pipes.

  As shown in FIG. 2, the hydraulic unit 10 includes a master cylinder MC that is a hydraulic pressure source that generates a brake hydraulic pressure corresponding to a pedaling force applied by the driver to the brake pedal BP, and wheel brakes FR, FL, RR, RL. It is arranged between. The hydraulic unit 10 includes a pump body 10a that is a base body having an oil passage through which brake fluid flows, a plurality of inlet valves 1 and outlet valves 2 arranged on the oil passage.

  The two output ports M1, M2 of the master cylinder MC are connected to the inlet port 12A of the pump body 10a, and the outlet port 12B of the pump body 10a is connected to each wheel brake FL, RR, RL, FR. In normal times, the oil passage is communicated from the inlet port 12A to the outlet port 12B in the pump body 10a, so that the depression force of the brake pedal BP is transmitted to the wheel brakes FL, RR, RL, FR. It is like that.

  The oil path starting from the output port M1 leads to the wheel brake FL on the left side of the front wheel and the wheel brake RR on the right side of the rear wheel, and the oil path starting from the output port M2 is the wheel brake FR on the right side of the front wheel and the wheel brake on the left side of the rear wheel. It leads to RL. Hereinafter, the oil passage starting from the output port M1 is referred to as “first system”, and the oil passage starting from the output port M2 is referred to as “second system”.

  The hydraulic unit 10 is provided with two control valve means V corresponding to each wheel brake FL, RR in the first system, and similarly corresponding to each wheel brake RL, FR in the second system. Two control valve means V are provided. Further, the hydraulic unit 10 is provided with a reservoir 3, a pump 4, an orifice 5a, a pressure regulating valve (regulator) R, and a suction valve 7 in each of the first system and the second system. Further, the hydraulic unit 10 is provided with a common motor 9 for driving the first system pump 4 and the second system pump 4. The motor 9 is a motor capable of controlling the rotation speed. In the present embodiment, the pressure sensor 8 is provided only in the second system.

  In the following, the oil passages from the output ports M1 and M2 of the master cylinder MC to the respective pressure regulating valves R are referred to as “output hydraulic pressure passages A1”, and the oil from the first system pressure regulating valve R to the wheel brakes FL and RR. The oil passages from the road and the second system pressure regulating valve R to the wheel brakes RL and FR are respectively referred to as “wheel hydraulic pressure passage B”. In addition, an oil path from the output hydraulic pressure path A1 to the pump 4 is referred to as “suction hydraulic pressure path C”, an oil path from the pump 4 to the wheel hydraulic pressure path B is referred to as “discharge hydraulic pressure path D”, and The oil passage from the wheel fluid pressure passage B to the suction fluid pressure passage C is referred to as “open passage E”.

  The control valve means V is a valve that controls the flow of hydraulic pressure from the master cylinder MC or the pump 4 side to the wheel brakes FL, RR, RL, FR side (specifically, the wheel cylinder H side). The pressure can be increased, held or decreased. Therefore, the control valve means V includes an inlet valve 1, an outlet valve 2, and a check valve 1a.

  The inlet valve 1 is a normally open electromagnetic valve provided between each wheel brake FL, RR, RL, FR and the master cylinder MC, that is, in the wheel hydraulic pressure path B. The inlet valve 1 is normally opened to allow the brake hydraulic pressure to be transmitted from the master cylinder MC to the wheel brakes FL, FR, RL, RR. Further, the inlet valve 1 is blocked by the control unit 100 when the wheel W is about to be locked, so that the brake hydraulic pressure transmitted from the brake pedal BP to each wheel brake FL, FR, RL, RR is cut off. .

  The outlet valve 2 is a normally closed electromagnetic valve interposed between each wheel brake FL, RR, RL, FR and each reservoir 3, that is, between the wheel hydraulic pressure path B and the release path E. Although the outlet valve 2 is normally closed, the brake fluid pressure acting on each wheel brake FL, FR, RL, RR is reduced by being opened by the control unit 100 when the wheel W is about to be locked. Relief to each reservoir 3

  The check valve 1a is connected to each inlet valve 1 in parallel. This check valve 1a is a one-way valve that only allows the brake fluid to flow from the wheel brakes FL, FR, RL, RR to the master cylinder MC, and when the input from the brake pedal BP is released. Even when the inlet valve 1 is closed, the brake fluid is allowed to flow from the wheel brakes FL, FR, RL, RR to the master cylinder MC.

  The reservoir 3 is provided in the release path E and has a function of absorbing brake fluid pressure that is released when each outlet valve 2 is opened. Further, between the reservoir 3 and the pump 4, a check valve 3a that allows only the flow of brake fluid from the reservoir 3 side to the pump 4 side is interposed.

The pump 4 is interposed between the suction hydraulic pressure path C leading to the output hydraulic pressure path A1 and the discharge hydraulic pressure path D leading to the wheel hydraulic pressure path B, and sucks the brake fluid stored in the reservoir 3 And has a function of discharging to the discharge hydraulic pressure path D. As a result, the brake fluid absorbed by the reservoir 3 can be returned to the master cylinder MC, and even when the driver does not operate the brake pedal BP, brake fluid pressure is generated and applied to the wheel brakes FL, RR, RL, FR. A braking force can be generated.
The amount of brake fluid discharged from the pump 4 depends on the number of rotations of the motor 9. For example, when the number of rotations of the motor 9 increases, the amount of brake fluid discharged by the pump 4 also increases.

  The orifice 5a attenuates the pulsation of the pressure of the brake fluid discharged from the pump 4 and the pulsation generated when the pressure regulating valve R described later operates.

  The pressure regulating valve R is normally open, and allows the brake fluid to flow from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B. Further, when the pressure on the wheel cylinder H side is increased by the brake fluid pressure generated by the pump 4, the pressure regulating valve R cuts off the flow of the brake fluid and discharges the fluid pressure passage D, the wheel fluid pressure passage B, and the wheel cylinder. It has a function of adjusting the pressure on the H side below the set value. Therefore, the pressure regulating valve R includes the switching valve 6 and the check valve 6a.

  The switching valve 6 is a normally open type linear solenoid valve interposed between the output hydraulic pressure path A1 leading to the master cylinder MC and the wheel hydraulic pressure path B leading to each wheel brake FL, FR, RL, RR. . Although not shown in detail, the valve body of the switching valve 6 is urged toward the wheel hydraulic pressure path B and the wheel cylinder H by the electromagnetic force corresponding to the applied current, and the pressure of the wheel hydraulic pressure path B is output. When the pressure in the hydraulic pressure path A1 is higher than a predetermined value (this predetermined value depends on the applied current), the brake fluid escapes from the wheel hydraulic pressure path B to the output hydraulic pressure path A1, The pressure on the wheel hydraulic pressure passage B side is adjusted to a predetermined pressure.

  The check valve 6a is connected to each switching valve 6 in parallel. The check valve 6a is a one-way valve that allows the flow of brake fluid from the output hydraulic pressure path A1 to the wheel hydraulic pressure path B.

  The suction valve 7 is a normally closed electromagnetic valve provided in the suction fluid pressure path C, and switches the suction fluid pressure path C to a state in which it is opened or shut off. When the switching valve 6 is closed, that is, when the driver does not operate the brake pedal BP, the intake valve 7 is opened by the control unit 100 when the brake fluid pressure is applied to each wheel brake FL, FR, RL, RR ( Opened).

  The pressure sensor 8 detects the brake hydraulic pressure of the output hydraulic pressure path A1 of the second system, and the detection result is input to the control unit 100.

  Next, details of the control unit 100 will be described. As shown in FIG. 3, the control unit 100 opens and closes the control valve means V, the switching valve 6 (pressure regulating valve R), and the suction valve 7 in the hydraulic unit 10 based on signals input from the sensors 91 to 94. The operation of the wheel brakes FL, RR, RL, FR is controlled by controlling the operation and the operation of the motor 9. The control unit 100 includes a skid control unit 110, a rollover suppression control unit 120, a target braking force setting unit 130, a valve drive unit 140, a motor drive unit 150, and a storage unit 180. The storage unit 180 appropriately stores preset constants, values detected by the sensors, and values calculated by the respective function units.

  The skid control unit 110 is a known control means for stabilizing the behavior by suppressing the skid of the vehicle CR. The skid control unit 110 controls the braking force applied to some of the four wheels W based on signals detected by the wheel speed sensor 91, the steering angle sensor 92, the lateral acceleration sensor 93, and the yaw rate sensor 94. Execute. The braking force applied to each wheel W calculated by the skid control unit 110 is output to the target braking force setting unit 130.

  The rollover suppression control unit 120 controls the rollover suppression by individually applying braking force to the left and right wheels W provided on the same axis when the rollover tendency of the vehicle CR is detected by the rollover detection parameter while the vehicle CR is turning. It has a function to execute. Specifically, when a rollover tendency is detected, the outer turning wheel is braked with the first braking force, and at the same time, the inner turning wheel on the same axis is applied with the second braking force that is smaller than the first braking force. It has a function to start braking. For this reason, the rollover suppression control unit 120 includes a roll angle calculation unit 121, a roll rate calculation unit 122, a corrected lateral acceleration calculation unit 123, a turning speed calculation unit 124, a steering determination unit 125, and a turnover determination unit 126. And an unstable level calculation means 127, a parameter calculation means 128, and a ROM (rollover suppression) control braking force setting means 129.

The roll angle calculation means 121 includes a lateral G base roll angle Ra1 as an example of the first roll angle, a yaw rate base roll angle Ra2 as an example of the second roll angle, and a steering angle base roll angle Ra3 as an example of the third roll angle. Is a means for calculating. These roll angle calculation methods are known and can be calculated by the following calculation formula.
Ra1 = (Hg × W × Yg) / (Gf + Gr)
Ra2 = (Hg × W × ω × Vx) / (Gf + Gr)
Ra3 = (Hg × W × ω θ × Vx) / (Gf + Gr)
Hg: vertical distance between roll axis and center of gravity W: sprung weight Gf, Gr: roll stiffness Yg: lateral acceleration ω: yaw rate ω _θ : standard yaw rate (standard yaw rate is calculated based on steering angle and vehicle body speed Vx )
Vx: Body speed

  The roll rate calculating means 122 calculates the lateral G base roll rate Ra1 ′ from the lateral G base roll angle Ra1, and calculates the yaw rate base roll rate Ra2 ′ from the yaw rate base roll angle Ra2. These roll rates are obtained by calculating the temporal change rate of the roll angle.

  The corrected lateral acceleration calculating unit 123 has a function of calculating a corrected lateral acceleration Ygm, which is a value obtained by performing a filtering process so that the absolute value of the lateral acceleration Yg is difficult to decrease as a value for evaluating the lateral acceleration Yg. Specifically, the absolute value of the lateral acceleration Yg is taken, and when this absolute value increases, the corrected lateral acceleration Ygm is made the same as the absolute value, and when the absolute value decreases, the corrected lateral acceleration Ygm decreases. The correction lateral acceleration Ygm is changed to be smaller than the previous value within a predetermined change rate range (see the corrected lateral acceleration graph in FIG. 13).

  The turning speed calculating means 124 is a means for calculating the rate of change of the steering angle δ and filtering this to calculate the turning speed δ ′.

  The steering determination means 125 is a means for determining whether or not sudden steering has been performed. Specifically, the steering determination unit 125 performs the rapid steering when the absolute value of the turning speed δ ′ is equal to or greater than a predetermined value δ′th and the absolute value of the corrected lateral acceleration Ygm is equal to or greater than the predetermined value Ygth. Judge that it was made.

The switching determination unit 126 is a unit that determines whether or not there is a sudden switching. Specifically, the return determination unit 126 determines that there is a sudden return when all of the following five conditions are satisfied.
(1) The sign indicating the left and right of the steering angle δ is different from the sign indicating the left and right of the lateral acceleration Yg, that is, the sign of the value of the steering angle when the steering is steered to the left, and the vehicle stably turns left. The sign of the lateral acceleration and roll angle values acting when the vehicle is turning and the sign of the roll rate value when the vehicle turns left and the roll angle becomes large are defined as a first sign (for example, left), and steering The sign of the steering angle value when the vehicle is steered to the right, the sign of the lateral acceleration and roll angle values that act when the vehicle is turning to the right stably, and the roll angle increases when the vehicle turns right When the sign of the roll rate value is defined as the second sign (for example, right), one of the steering angle δ and the lateral acceleration Yg is the first sign and the other is the second sign. about.
(2) One of the lateral G base roll angle Ra1 and the lateral G base roll rate Ra1 'is the first code and the other is the second code.
(3) One of the yaw rate base roll angle Ra2 and the yaw rate base roll rate Ra2 'is the first code and the other is the second code.
(4) The absolute value of the lateral G base roll rate Ra1 'is not less than a predetermined value Ra1'th.
(5) The absolute value of the yaw rate base roll rate Ra2 'is not less than a predetermined value Ra2'th.

  The instability level calculating means 127 is based on the actual yaw rate Ys obtained by performing a known filter process on the actual yaw rate detected by the yaw rate sensor 94, and the reference yaw rate Yc obtained by a known method from the steering angle δ and the vehicle body speed Vx. In addition, it has a function of calculating an unstable level of the traveling state of the vehicle CR by a conventionally known method. Specifically, the unstable level calculation means 127 performs a filtering process on the difference between the actual yaw rate Ys and the reference yaw rate Yc (deviation between the actual yaw rate Ys and the reference yaw rate Yc) to obtain the unstable level. The instability level is a large value when the instability in the traveling state of the vehicle CR is large.

  The parameter calculation means 128 calculates a value (parameter) indicating a rollover tendency based on the values calculated by the respective means described above, calculates a threshold calculation roll rate that is a change rate of the roll angle of the vehicle CR, and This is means for setting the roll angle threshold value Rath as the parameter threshold value so that the larger the threshold calculation roll rate, the smaller the value.

  The parameter calculation unit 128 uses a first roll angle (lateral G base roll angle Ra1) corresponding to the actual roll angle and a second roll angle (using a parameter that changes at a phase earlier than the first roll angle) ( The first combined roll angle Ra12 is calculated by combining the yaw rate base roll angle Ra2) with a predetermined distribution, and when it is determined by the steering determination means 125 that the rapid steering is performed, it is determined that the rapid steering is not performed. The first combined roll angle Ra12 is calculated by increasing the distribution of the second roll angle with respect to the first roll angle as compared with the above.

  Then, the parameter calculation means 128 calculates the third roll angle (steering angle base roll angle Ra3) obtained from the parameter changing at a phase earlier than the first roll angle and the second roll angle and the first combined roll angle Ra12. The second combined roll angle Ra as a rollover detection parameter is calculated by combining with a predetermined distribution, and when it is determined that there is a sudden turnover by the turnover judging means 126 than when it is judged that there is no sudden turnover. Also, the distribution of the third roll angle relative to the first synthetic roll angle Ra12 is increased to calculate the second synthetic roll angle Ra.

  In the present embodiment, as the predetermined distribution for calculating the first combined roll angle Ra12, the first distribution coefficient K1 that changes according to the turning speed is used, and the predetermined distribution for calculating the second combined roll angle Ra is calculated. As the distribution, a second distribution coefficient K2 that changes according to a sudden turn-back is used. Therefore, as shown in FIG. 4A, the parameter calculation unit 128 includes a first counter 128A, a second counter 128B, a first distribution coefficient setting unit 128C, and a second distribution coefficient setting unit 128D.

  The first counter 128A adds the first count value C1 within the range of the upper limit value C1max when it is determined by the steering determination means 125 that the sudden steering has been performed, and when it is determined that the sudden steering is not being performed. 1 count value C1 is subtracted. At this time, the addition amount and the subtraction amount may be the same value or different values. In this embodiment, when the sudden steering is performed, the subtraction amount is set smaller than the addition amount in order to keep the effect of the sudden steering relatively long. The first counter 128A performs addition even after the first distribution coefficient K1 reaches a predetermined upper limit value described later. Thus, even if the first count value C1 starts to be subtracted after the first distribution coefficient K1 reaches the predetermined upper limit value, the first distribution coefficient is maintained until the first count value C1 reaches a value corresponding to the predetermined upper limit value. Since K1 is maintained at the predetermined upper limit value, the rollover suppressing effect can be improved even after the sudden steering is finished.

  The second counter 128B adds the second count value C2 within the range of the upper limit C2max when it is determined by the switching determination means 126 that there is a sudden switching, and the second counter 128B is the second when it is determined that there is no sudden switching. The count value C2 is subtracted. At this time, the addition amount and the subtraction amount may be the same value or different values. In the present embodiment, when the turnback steering is performed, the subtraction amount is set smaller than the addition amount in order to leave the influence of the turnback steering relatively long. The second counter 128B performs addition even after the second distribution coefficient K2 reaches a predetermined upper limit value to be described later. Thus, even if the second count value C2 starts to be subtracted after the second distribution coefficient K2 reaches the predetermined upper limit value, the second distribution coefficient is maintained until the second count value C2 reaches a value corresponding to the predetermined upper limit value. Since K2 is maintained at a predetermined upper limit value, it is possible to improve the rollover suppressing effect particularly after turning over.

  The first distribution coefficient setting means 128C sets the first distribution coefficient K1 corresponding to the distribution of the yaw rate base roll angle Ra2 with respect to the lateral G base roll angle Ra1 within a range equal to or less than a predetermined upper limit value according to the first count value C1. . The first distribution coefficient K1 set here is also used as a distribution coefficient of the yaw rate base roll rate Ra2 'with respect to the lateral G base roll rate Ra1'. In the present embodiment, the first distribution coefficient K1 is a value obtained by multiplying the first count value C1 by a constant coefficient α1, and the predetermined upper limit value is 1.

  The second distribution coefficient setting means 128D sets a second distribution coefficient K2 corresponding to the distribution of the steering angle base roll angle Ra3 with respect to the first combined roll angle Ra12 in a range equal to or less than a predetermined upper limit value according to the second count value C2. To do. In the present embodiment, the second distribution coefficient K2 is a value obtained by multiplying the second count value C2 by a constant coefficient α2, and the predetermined upper limit value is K2max, which is a value smaller than 1.

Using the first distribution coefficient K1 and the second distribution coefficient K2 calculated by each of the above means 128A to 128D, the parameter calculation means 128 calculates the first combined roll angle Ra12 and the second combined roll angle Ra by the following equations. To do.
Ra12 = K1 * Ra2 + (1-K1) * Ra1
Ra = K2 * Ra3 + (1-K2) * Ra12

  Further, the parameter calculation means 128 includes a threshold calculation roll rate calculation means 128E as shown in FIG. 4 for setting the roll angle threshold value Rath. Here, the roll angle used for calculating the roll rate for threshold calculation may be a roll angle corresponding to the actual roll angle, such as a roll angle obtained by a roll angle sensor or a lateral G base roll angle, or the like. The estimated roll angle calculated from these parameters may be used. The roll angle may be the same as the rollover detection parameter or may be obtained separately. Furthermore, as long as the meaning of the roll angle as a physical quantity remains, the roll angle may be filtered or may be a value obtained by performing calculation processing such as synthesis with other values. In the present embodiment, the lateral G base roll angle Ra1 and the yaw rate base roll angle Ra2 calculated by the roll angle calculation unit 121 are used for calculating the threshold calculation roll rate.

  The roll rate calculation means 128E for threshold value calculation has a lateral G base roll rate Ra1 ′ that is a rate of change of the first roll angle (lateral G base roll angle Ra1) corresponding to the actual roll angle, and a phase earlier than the first roll angle. And a yaw rate base roll rate Ra2 ′, which is a rate of change of the second roll angle (yaw rate base roll angle Ra2) obtained using the parameter that changes at a predetermined distribution, and is used as a roll rate for threshold calculation The rate Ra12 'is calculated. The roll rate calculation means 128E for threshold calculation calculates the second roll rate for the first roll rate when it is determined that the steering is determined by the steering determination means 125, rather than when it is determined that the rapid steering is not performed. Is increased to calculate the combined roll rate Ra12 ′.

Specifically, the roll rate calculation means 128E for threshold value calculation uses the first distribution coefficient K1 calculated by the first distribution coefficient setting means 128C, and calculates the combined roll rate Ra12 ′ by the following equation.
Ra12 '= K1 * Ra2' + (1-K1) * Ra1 '

  Furthermore, the threshold calculation roll rate calculation means 128E sets the threshold calculation roll rate to 0 when the unstable level is less than the predetermined value Lv.

The parameter calculation unit 128 uses the threshold calculation roll rate value set by the threshold calculation roll rate calculation unit 128E, and a conversion table between the threshold calculation roll rate and the roll angle threshold Rath stored in the storage unit 180. The roll angle threshold value Rath is set with reference to FIG. In this conversion table, as shown in FIG. 5, the roll angle threshold value Rath decreases as the threshold calculation roll rate increases. More specifically, when the roll rate for threshold calculation is γ1, the roll angle threshold Rath is a constant value ε, and when the roll rate for threshold calculation is from γ1 to γ2, the roll angle threshold Rath is 0 with a constant gradient. When the roll rate for threshold value calculation is larger than γ2, the roll angle threshold value is set to zero.
By taking a constant value ε until the threshold calculation roll rate is up to γ1, it is possible to prevent the rollover suppression control from intervening more than necessary in turning by slow steering such as J-turn turning, and the threshold calculation roll rate is more than γ2. If it is larger, the roll angle threshold is 0, so that the rollover suppression control is reliably executed in a situation where the vehicle easily rolls over.

  As shown in FIG. 4B, the ROM control braking force setting unit 129 includes an outer wheel target braking force setting unit 129A and an inner wheel target braking force setting unit 129B.

  The outer wheel target braking force setting means 129A is a means for setting a target outer wheel target braking force for braking the turning outer wheel with the first braking force, and the second combined roll angle Ra and roll as a rollover detection parameter. The outer wheel target braking force is set from the deviation ΔRa from the angle threshold value Rath. The rollover detection parameter is an index indicating that the rollover possibility is higher as the rollover detection parameter is larger, and the roll angle threshold value Rath is a reference value for determining the possibility of rollover. Therefore, the greater the deviation ΔRa between the rollover detection parameter and the predetermined threshold (here, the roll angle threshold Rath), the higher the possibility of rollover. Therefore, the braking force applied to the turning outer wheel is set to a value corresponding to this deviation ΔRa. Thus, it is possible to suppress the rollover by applying an appropriate braking force to the outer ring.

Specifically, the deviation ΔRa can be obtained as follows. First, the deviation ΔRa (left) when turning left and the deviation ΔRa (right) when turning right are calculated according to the following equations. Note that the roll angle threshold value Rath is 0 or a positive value.
ΔRa (left) = MAX {(Ra−Rath), 0}
ΔRa (right) = MAX {((−Rath) −Ra), 0}
The larger one of ΔRa (left) and ΔRa (right) is defined as ΔRa.

  In this embodiment, in order to set a more appropriate braking force by PI control, the outer wheel target braking force setting means 129A obtains a PI output value from the deviation ΔRa, and the outer wheel target braking force Fout has a large value. In order to adjust the depth, a value obtained by multiplying the PI output value by the correction coefficient is input.

  Further, the outer wheel target braking force setting means 129A sets the rear wheel target braking force Fout1 so that the predetermined value Foutmax (third predetermined value) is an upper limit value. Since the rear wheels are more likely to slip during braking than the front wheels, by providing an upper limit on the target value of the braking force, it is possible to suppress instability of the posture of the vehicle CR due to slip of the rear wheels.

  The deviation ΔRa is a value from which the outer wheel target braking force is calculated. Therefore, if the rollover tendency is not determined after the rollover tendency is determined, 0 is substituted by the outer wheel target braking force setting unit 129A. The

  The inner wheel target braking force setting means 129B is a means for setting the target inner wheel target braking force for braking the turning inner wheel with the second braking force with a value smaller than the outer wheel target braking force. In the present embodiment, a predetermined value set in advance is set as the inner ring target braking force. Specifically, this predetermined value is the first predetermined value B1 for a predetermined time Tm1 after the start of the rollover suppression control, and is greater than the first predetermined value B1 after the predetermined time Tm1 has elapsed. A small second predetermined value B2 is assumed. As a result, the braking force rises better, so that braking by the inner wheel can be effectively applied from the beginning of the rollover suppression control to reduce the vehicle body speed, and the vehicle can be stabilized by reducing the rollover tendency.

  Further, when the tendency to roll over is small, the outer wheel target braking force is set to be small, so that the inner wheel target braking force setting means 129B is set so that the inner wheel target braking force is smaller than the outer wheel target braking force at this time as well. If the predetermined value (the first predetermined value B1 or the second predetermined value B2) is smaller than the value obtained by multiplying the outer wheel target braking force by a coefficient β less than 1, the predetermined value is set to the inner ring target control. If the predetermined predetermined value is equal to or greater than a value obtained by multiplying the outer wheel target braking force by a coefficient β less than 1, a value obtained by multiplying the outer wheel target braking force by a coefficient β less than 1 is set. Set to. Thereby, the inner wheel target braking force is always smaller than the value obtained by multiplying the outer wheel target braking force by a coefficient β of less than 1. That is, it is possible to suppress rollover by increasing the braking force of the outer ring more than the braking force of the inner ring. A specific processing method for setting the inner ring target braking force will be described later with reference to a flowchart.

  Then, the ROM control braking force setting unit 129 determines whether the vehicle CR is in a right turn or a left turn from the value of the second combined roll angle Ra, and sets a target braking force for each wheel. Specifically, the front wheel target braking force Fout calculated by the outer wheel target braking force setting unit 129A, the rear wheel outer wheel target braking force Fout1, and the inner wheel target braking force setting unit 129B calculated by the front wheel inner wheel. The target braking force is set for each wheel on the basis of the target braking force Fin of the rear wheel and the target braking force Fin1 for the inner wheel of the rear wheel.

The rollover suppression control unit 120 constantly monitors the second synthetic roll angle Ra, and the deviation ΔRa between the second synthetic roll angle Ra and the positive roll angle threshold Rath exceeds a predetermined value ΔRath (ΔRath is 0 or positive). In this case, a braking force is applied to at least one of the wheel brakes FL, RR, RL, FR to execute the rollover suppression control. Here, the predetermined value ΔRath may be an arbitrary value, and may be 0, for example. However, by setting the predetermined value ΔRath to an appropriate value, it is possible to suppress the rollover suppression control from being more sensitive than necessary. Can do. The braking force applied to each wheel at this time is simultaneously applied to the left and right coaxial wheels W, and is always applied to both the left and right coaxial wheels W during the rollover suppression control. That is, the start of applying the braking force is simultaneously on the left and right. In the present embodiment, since braking force is applied to both the front and rear wheels during the rollover suppression control, the braking force is always applied to all four wheels during the rollover suppression control. In this embodiment, in order to avoid a sudden change in the braking force of the outer ring even after the rollover suppression control flag is changed from ON to OFF, the braking force is not reduced immediately to 0 but gradually reduced to 0. I will make it.
The target braking force of each wheel W for rollover suppression control set in this way is output to the target braking force setting unit 130.

  The target braking force setting unit 130 compares the braking force to be applied to each wheel W output from the skid control unit 110 and the braking force to be applied to each wheel W output from the rollover suppression control unit 120 to determine the larger one. It has a function of setting a braking force as a target braking force for each wheel W. Then, the operation of each valve of the hydraulic unit 10 and the operation of the motor 9 are output to the valve drive unit 140 and the motor drive unit 150, respectively, according to the target braking force.

  The valve drive unit 140 actually drives the control valve means V, the pressure regulating valve R, and the suction valve 7 in accordance with instructions from the target braking force setting unit 130.

  The motor driving unit 150 has a function of driving the motor 9 to rotate in accordance with an instruction from the target braking force setting unit 130.

  The process in the case of performing rollover suppression control in the control unit 100 as described above will be described. As shown in FIG. 7, the control unit 100 first reads detection signals from various sensors such as a wheel speed sensor 91, a steering angle sensor 92, a lateral acceleration sensor 93, and a yaw rate sensor 94 (S1). Then, the composite roll angle is calculated (S100).

  As shown in FIG. 7, the roll angle calculation unit 121 first calculates the combined roll angle based on the detection values of the sensors 91 to 94 and the constants stored in the storage unit 180. Ra1, yaw rate base roll angle Ra2, and steering angle base roll angle Ra3 are calculated (S102 to S104).

  Next, the roll rate calculating means 122 calculates the rate of change of the lateral G base roll angle Ra1, calculates the lateral G base roll rate Ra1 ', calculates the rate of change of the yaw rate base roll angle Ra2, and calculates the yaw rate base roll rate. Ra2 'is calculated (S105). Then, the corrected lateral acceleration calculating unit 123 calculates the corrected lateral acceleration Ygm from the lateral acceleration Yg. Further, the turning speed calculation means 124 calculates the rate of change of the steering angle δ, and filters this to calculate the turning speed δ ′ (S106).

Next, the first distribution coefficient setting unit 128C of the rollover suppression control unit 120 calculates the first distribution coefficient K1 (S200). The first distribution coefficient K1 is calculated by the process shown in FIG.
Specifically, first, the steering determination unit 125 determines whether the absolute value of the turning speed δ ′ is equal to or greater than a predetermined value δ′th and whether the absolute value of the corrected lateral acceleration Ygm is equal to or greater than the predetermined value Ygth. (S201). If FIG. 13 is referred, it is the range of the time t11-t13 that satisfy | fills this. When this is satisfied, it can be said that rollover is relatively likely to occur because sudden steering is performed in which the turning speed δ ′ is large and the lateral acceleration Yg is large to some extent. Therefore, when the condition of step S201 is satisfied (S201, Yes), the first counter 128A adds the first count value C1 (S202). Then, if the first count value C1 is greater than the upper limit value C1max (S203, Yes), the first counter 128A sets the first count value C1 to the upper limit value C1max (S204), and the first count value C1 is the upper limit value. If the value is less than or equal to the value C1max (S203, No), the added value is directly used as the first count value C1.

  On the other hand, when the condition is not satisfied in step S201 (S201, No), that is, when the rapid steering is not performed, the first counter 128A subtracts the first count value C1 (S208, time t13 in FIG. 13). see t15). When the first count value C1 is less than 0 (S209, Yes), the first count value C1 is set to 0 (S210). When the first count value C1 is 0 or more (S209, No), the value as it is is set as the first count value C1.

  When the first count value C1 is determined by the above steps, the first distribution coefficient K1 is obtained by multiplying the first count value C1 by the coefficient α1 (S205). When the first distribution coefficient K1 is larger than 1 (S206, Yes), the first distribution coefficient K1 is set to the upper limit value 1 (S207), and when the first distribution coefficient K1 is 1 or less (S206, No), the value as it is is defined as the first distribution coefficient K1.

Next, the second distribution coefficient setting unit 128D of the rollover suppression control unit 120 calculates a second distribution coefficient K2 (S300). The second distribution coefficient K2 is calculated by the process shown in FIG.
Specifically, first, the turning-back determination unit 126 determines whether or not δ × Yg is negative, that is, whether or not the signs indicating the left and right of the steering angle δ and the lateral acceleration Yg are different (whether they are counter steered). In FIG. 14, it corresponds to the times t21 to t26) (S301). When δ × Yg is negative (S301, Yes), the cut-off determination means 126 indicates whether Ra1 × Ra1 ′ is negative, that is, the left and right of the lateral G base roll angle Ra1 and the lateral G base roll rate Ra1 ′. It is determined whether the signs are different and whether or not the absolute value of the lateral G base roll rate Ra1 'is equal to or greater than a predetermined value Ra1'th (whether or not the turnover is sudden) (S302). When the condition of step S302 is satisfied (S302, Yes), the cut-off determination unit 126 further indicates whether Ra2 × Ra2 ′ is negative, that is, a sign indicating the left and right of the yaw rate base roll angle Ra2 and the yaw rate base roll rate Ra2 ′. And whether the absolute value of the yaw rate base roll rate Ra2 'is equal to or greater than a predetermined value Ra2'th (whether or not the turning-back is sudden) is determined (S303). When the condition of step S303 is satisfied, the turn-back determination unit 126 determines that there has been a sudden turn-back steering. Referring to FIG. 14, steps S301 to S303 are satisfied in the range from time t22 to t24. When this is satisfied, it can be said that rollover is likely to occur because there is a sudden turn. Therefore, the second counter 128B adds the second count value C2 (S304). Then, if the second count value C2 is greater than the upper limit value C2max (S305, Yes), the second counter 128B sets the second count value C2 to the upper limit value C2max (S306), and the second count value C2 is the upper limit value. If the value is less than or equal to the value C2max (S305, No), the added value is directly used as the second count value C2.

  On the other hand, in any of steps S301 to S303, when the condition is not satisfied (No in S301 to S303), that is, when sudden turning-back is not performed, the second counter 128B subtracts the second count value C2. (S311, see times t24 to t26 in FIG. 14). When the second count value C2 is less than 0 (S312, Yes), the second count value C2 is set to 0 (S313), thereby setting the second count value C2 to a value of 0 or more. When the second count value C2 is 0 or more (S312, No), the value as it is is set as the second count value C2.

  When the second count value C2 is determined by the above steps, the second distribution coefficient K2 is obtained by multiplying the second count value C2 by the coefficient α2 (S307). When the second distribution coefficient K2 is larger than K2max, which is a value smaller than 1 (S308, Yes), the second distribution coefficient K2 is set to the upper limit value K2max (S309), and the second distribution coefficient K2 is equal to or less than K2max. In this case (S308, No), the value as it is is set as the second distribution coefficient K2.

Returning to FIG. 7, when the first distribution coefficient K1 and the second distribution coefficient K2 are obtained, the parameter calculation means 128
Ra12 = K1 * Ra2 + (1-K1) * Ra1
Thus, the lateral G base roll angle Ra1 and the yaw rate base roll angle Ra2 are combined with the first distribution coefficient K1 to calculate the first combined roll angle Ra12 (S107). As shown in FIG. 13, the first combined roll angle Ra12 is based on the lateral G base roll angle Ra1, and when the first distribution coefficient K1 is larger than 0 (time t11 to t15), the lateral G base roll angle Ra1. The yaw rate base roll angle Ra2 that changes at an earlier phase is synthesized, and from time t12 to t14, the value perfectly follows the yaw rate base roll angle Ra2.

And the parameter calculation means 128 is
Ra = K2 * Ra3 + (1-K2) * Ra12
Thus, the second combined roll angle Ra is calculated by combining the first combined roll angle Ra12 and the steering angle base roll angle Ra3 with the second distribution coefficient K2 (S108). As shown in FIG. 14, the second combined roll angle Ra is based on the first combined roll angle Ra12, and when the second distribution coefficient K2 is larger than 0 (time t22 to t26), the lateral G base roll angle Ra1. Further, the steering angle base roll angle Ra3 that changes at a phase earlier than the yaw rate base roll angle Ra2 is combined with the first combined roll angle Ra12, and takes a value that is quite close to the steering angle base roll angle Ra3 from time t23 to t25. .

Returning to FIG. 6, the parameter calculation means 128 sets the roll angle threshold value Rath in step S400. Specifically, as shown in FIG. 10, the roll rate calculating means 128E for threshold value calculation
Ra12 '= K1 * Ra2' + (1-K1) * Ra1 '
Thus, the combined roll rate Ra12 'is calculated by combining the lateral G base roll rate Ra1' and the yaw rate base roll rate Ra2 'with the first distribution coefficient K1 (S401). As shown in FIG. 15, the combined roll rate Ra12 ′ is based on the lateral G base roll rate Ra1 ′, and when the first distribution coefficient K1 is greater than 0 (time t11 to t15), the lateral G base roll angle Ra1. The yaw rate base roll rate Ra2 ′ based on the yaw rate base roll angle Ra2 that changes at an earlier phase is synthesized, and from time t12 to t14, the value perfectly follows the yaw rate base roll rate Ra2 ′.

  Then, the threshold calculation roll rate calculation means 128E calculates the threshold calculation roll rate by performing absolute value processing on the combined roll rate Ra12 ′ as shown in FIG. 16 and filtering processing so as not to decrease (S402). ).

  Furthermore, the threshold calculation roll rate calculation means 128E determines whether or not the unstable level calculated by the unstable level calculation means 127 is equal to or greater than a predetermined value Lv (S403, No), and if it is less than Lv (No in S403). The rate is set to 0 (zero) (S404), and if it is equal to or higher than Lv (S403, Yes), the roll rate for threshold calculation is not changed.

  Next, the parameter calculation means 128 sets the roll angle threshold value Rath from the threshold calculation roll rate with reference to the threshold value calculation roll rate and roll angle threshold value Rath conversion table of FIG. 5 (S405). As a result, as shown in FIG. 16, when the threshold calculation roll rate suddenly increases at time t31 or t32 to t33, the roll angle threshold value Rath decreases rapidly, and the threshold calculation roll rate is γ2 or more. At (time t33 to t34), the roll angle threshold value Rath becomes zero.

  When the second composite roll angle Ra and the roll angle threshold value Rath as the rollover detection parameters are obtained in this way, as shown in FIG. 6, the rollover suppression control unit 120 performs the second composite roll angle Ra and the roll angle threshold value Rath. Deviation ΔRa is calculated (S4). Then, the deviation ΔRa is compared with the predetermined value ΔRath, and if the deviation ΔRa is larger than the predetermined value ΔRath (S5, Yes, times t1 to t7 in FIG. 17), the rollover suppression control flag is turned ON (S6). On the other hand, when the deviation ΔRa is not larger than the predetermined value ΔRath (S5, No, refer to before t1 and after t7 in FIG. 17), the rollover suppression control flag is turned OFF. Further, the deviation ΔRa is set to 0 in order to prevent the deviation ΔRa from affecting the following setting of the outer wheel target braking force (S7). Note that the condition for whether or not to enter the rollover suppression control may include that the vehicle body speed Vx is greater than or equal to a predetermined value and that the corrected lateral acceleration Ygm is greater than or equal to a predetermined value.

Next, the outer wheel target braking force setting unit 129A sets the outer wheel target braking force for the rollover suppression control (S500). Specifically, as shown in FIGS. 11 and 18 (a), a P (proportional) component and an I (integral) component are calculated from the deviation ΔRa, and a sum of these is obtained to obtain a PI output value ( S501). The I component has an upper limit value Imax as shown in FIG. Then, the outer wheel target braking force setting unit 129A calculates Fout by multiplying the PI output value by a predetermined correction coefficient (S502). Here, as can be seen by comparing FIGS. 18A and 18B, a correction coefficient smaller than 1 is used.
Further, the outer wheel target braking force setting unit 129A calculates Fout1 subjected to limit processing with Foutmax as the braking force for the rear wheel (S503).

  Next, the inner wheel target braking force setting means 129B sets the inner wheel target braking force for the rollover suppression control (S600). Specifically, as shown in FIG. 12, first, it is determined whether or not the rollover suppression control is started and the wheel cylinder pressure is equal to or lower than a predetermined value (S601). Whether the rollover suppression control is started is determined by looking at the previous value and current value of the rollover suppression control flag. If the previous value is OFF and the current value is ON, the rollover suppression control starts. It can be determined that it is a time. The determination as to whether or not the wheel cylinder pressure is less than or equal to a predetermined value is arbitrary, but if the wheel cylinder pressure is greater than or equal to the predetermined value, there is no need to consider the rise of the braking force of the inner ring. In addition to the conditions of S601. When the condition of step S601 is satisfied (S601, Yes), Tm1 is substituted into the timer Tm and the timer is started (S602). When the condition of step S601 is not satisfied (S601, No), it is determined whether the rollover suppression control is completed or the turning direction is determined (S603). If the condition of step S603 is satisfied (S603, Yes), because the rollover suppression control has been completed or the inner wheel has been switched left and right due to the turning of the steering wheel, the timer Tm is substituted by 0 and reset (S604). When the condition of step S603 is not satisfied (S603, No), the timer Tm is counted down (S605). Then, after steps S602, S604, and S605, in order to avoid the value of the timer Tm becoming negative, the larger value of Tm and 0 is substituted into Tm (S606).

Next, the inner wheel target braking force setting means 129B sets the inner wheel target braking force according to the value of the timer Tm (hereinafter, refer also to FIG. 19 for setting of the inner wheel target braking force).
First, it is determined whether or not the rollover suppression control flag is ON (S607). If it is not ON (S607, No), the inner wheel target braking force is 0 for both the front wheels (Fin) and the rear wheels (Fin1). (S608). If the rollover suppression control flag is ON (S607, Yes), it is determined whether the timer Tm is greater than 0 (S609). If it is greater than 0 (S609, Yes), the rollover suppression control is in the initial stage. The inner wheel target braking force is set to the first predetermined value B1 for both the front wheel (Fin) and the rear wheel (Fin1) (S610). On the other hand, if the timer Tm is not larger than 0 (No in S609), the rollover suppression control is not in the initial stage, so the inner wheel target braking force is set to the second predetermined value B2 for both the front wheel (Fin) and the rear wheel (Fin1). (S611).

Further, the inner wheel target braking force setting means 129B compares the value obtained by multiplying the outer wheel target braking force Fout for the front wheel by the coefficient β with the already determined inner wheel target braking force Fin for the front wheel, and determines the smaller one as the new inner wheel target braking force Fin. The braking force Fin is set (S612). Thus, when the inner wheel target braking force Fin (first predetermined value B1 or second predetermined value B2) is smaller than the value obtained by multiplying the outer wheel target braking force by the coefficient β, the first predetermined value B1 or the second predetermined value When the predetermined value B2 is set as the inner wheel target braking force Fin as it is and the inner wheel target braking force Fin (the first predetermined value B1 or the second predetermined value B2) is equal to or larger than the value obtained by multiplying the outer wheel target braking force by the coefficient β. The value obtained by multiplying the outer wheel target braking force by the coefficient β is set as the inner wheel target braking force Fin.
Similarly, the rear wheel inner wheel target braking force Fin1 is set to a smaller inner wheel target braking force Fin1 compared to a value obtained by multiplying the rear wheel outer wheel target braking force Fout1 by a coefficient β ( S612).

  When the target braking force Fout for the outer wheel of the front wheel, the target braking force Fout1 for the outer wheel of the rear wheel, the target braking force Fin for the inner wheel of the front wheel, and the target braking force Fin1 for the inner wheel of the rear wheel are obtained as described above. In step S14 and subsequent steps in FIG. 6, a target braking force is set for each wheel based on whether the vehicle CR is turning left or right.

Specifically, the ROM control braking force setting means 129 determines whether or not the second combined roll angle Ra is larger than 0 (S14), and if it is larger than 0, the left turn (S14, Yes), the right The target braking force F _FR of the front wheel (outer wheel) is set to Fout, the target braking force F _RR of the right rear wheel is set to Fout 1, the target braking force F _FL of the left front wheel (inner wheel) is set to Fin, and the left rear setting a target braking force _{F RL} of the wheel to Fin1 (S15). Conversely, because if the second combined roll angle Ra not greater than 0 is the right turn (S14, No), the target braking force _{F FR} of the right front wheel (inner ring) is set to Fin, of the right rear wheel The target braking force F _RR is set to Fin1, the target braking force F _FL of the left front wheel (outer wheel) is set to Fout, and the target braking force F _RL of the left rear wheel is set to Fout1 (S16).

  The target braking force for rollover suppression control for each wheel set as described above is as shown in FIGS.

  When the target braking force for each wheel is set by the above processes, the rollover suppression control unit 120 outputs the target braking force for each wheel to the target braking force setting unit 130. Then, the target braking force setting unit 130 sets the larger one of the target braking force output from the skid control unit 110 and the target braking force output from the rollover suppression control unit 120 as the target braking force. Thus, an instruction is output to the valve drive unit 140 and the motor drive unit 150 so that the braking force is applied to each wheel. Thereby, a braking force is simultaneously applied to all four wheels W (S17).

  As described above, according to the vehicle brake hydraulic pressure control device A of the present embodiment, when the rollover tendency is determined, the braking force of all four wheels is simultaneously controlled so that the inner wheel has a smaller braking force than the outer wheel. Granting begins. Regardless of whether or not there is a return steering, the braking force is always applied to all four wheels simultaneously. In other words, the application of braking force for rollover suppression control is started simultaneously on the left and right wheels on the same axis, so that the vehicle body speed can be effectively reduced by using the braking force of the inner ring, and thereby the tendency to rollover is reduced. Can be suppressed. And when there is a turning-back steering, preliminary braking is applied from the beginning of the rollover suppression control to the inner wheel before turning, so that a large braking force is quickly applied to the outer wheel (inner wheel before turning) after turning. be able to. Therefore, when turn-back steering is performed, the brake pressure of the outer wheel can be quickly increased, and rollover can be effectively suppressed.

  According to the vehicle brake fluid pressure control apparatus A, the outer wheel target braking force is set based on the roll angle indicating the rollover tendency (second synthetic roll angle Ra) and the deviation ΔRa between the roll angle threshold Rath. Control according to the strength of the can.

  Further, by applying braking force to both the front and rear wheels W, the vehicle CR can be effectively decelerated, the tendency of rollover is suppressed, and the outer wheel target braking force of the rear wheel is limited to a predetermined value Foutmax. Therefore, instability of the vehicle CR due to rear wheel slip can be suppressed.

  According to the vehicle brake fluid pressure control device A, the vehicle wheel speed is rapidly reduced by setting the inner wheel target braking force to be large at the beginning of the rollover suppression control, so that the vehicle CR can be stabilized. it can.

  Further, according to the vehicle brake hydraulic pressure control device A of the present embodiment, when the steering is suddenly performed, the yaw rate base roll angle Ra2 that changes at a phase earlier than the lateral G base roll angle Ra1 corresponding to the actual roll angle is set. In consideration of this, the second composite roll angle Ra (first composite roll angle Ra12) is calculated and used as a rollover detection parameter. Suppression control can be started. In addition, when a sudden turning is performed, the second combined roll angle Ra is calculated by taking into account the steering angle base roll angle Ra3 that changes at a phase earlier than the lateral G base roll angle Ra1 and the yaw rate base roll angle Ra2. Since this is used as a rollover detection parameter, when the possibility of rollover is higher, this can be predicted more quickly, and rollover suppression control can be started promptly to improve the rollover suppression effect.

  This will be described with reference to FIG. 21. When the first distribution coefficient K1 and the second distribution coefficient K2 are not 0 (time t41 to t44, particularly time t42 to t43), the second combined roll angle is determined by the rollover detection parameter. As shown in the graph, the change occurs at a phase earlier than the lateral G base roll angle and the first composite roll angle, and as a result, the rollover suppression control is executed earlier, so that the caliper pressure of the wheel brake FL is quickly increased. (A solid line indicates this embodiment, and a broken line indicates a comparative example). For this reason, as shown in the graph of the wheel lift amount, the solid line embodiment can suppress the wheel lift more than the broken line comparative example.

  Then, according to the vehicle brake hydraulic pressure control apparatus A of the present embodiment, the parameter calculation means 128 sets the roll angle threshold value Rath so that the roll angle threshold value Rath decreases as the threshold calculation roll rate increases. Therefore, when the roll rate for threshold calculation is large, the roll angle threshold Rath becomes small. As a result, the lateral G base roll angle Ra1 as a rollover detection parameter easily exceeds the roll angle threshold Rath, and the roll angle suddenly increases. When the vehicle is likely to roll over as in the case where the vehicle rolls over, it is possible to quickly start the rollover suppression control and to improve the stability of the vehicle.

  When the instability level is less than the predetermined value Lv, the vehicle brake hydraulic pressure control device A sets the roll rate for threshold calculation to 0, so that the roll angle threshold Rath increases and rollover suppression control is started unnecessarily. There is nothing to do.

  Further, the vehicle brake fluid pressure control device A is configured to provide a yaw rate base that is a rate of change of the yaw rate base roll angle Ra2 that changes at a phase earlier than the lateral G base roll angle Ra1 corresponding to the actual roll angle when sudden steering is performed. The roll rate Ra2 ′ is taken into account to calculate the synthetic roll rate Ra12 ′, and the roll rate for calculating the threshold and the roll angle threshold value Rath are calculated based on the synthetic roll rate Ra12 ′. Therefore, when the possibility of rollover is high, This can be predicted early and the rollover suppression control can be started quickly.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  For example, in the embodiment, the lateral G base roll angle Ra1 is exemplified as the first roll angle, and the yaw rate base roll angle Ra2 is exemplified as the second roll angle, but the lateral G base roll angle Ra1 and the second roll angle are exemplified as the first roll angle. As the steering angle base roll angle Ra3, these may be combined with the first distribution coefficient K1 as the rollover detection parameter.

  Further, in the above-described embodiment, the cut-back determining unit 126 determines the right and left of the roll angle and the roll rate for both the lateral G base roll angle Ra1 and the yaw rate base roll angle Ra2 in order to accurately determine the turnover. Although it has been determined that the absolute value of the roll rate is equal to or greater than the predetermined value, it is possible to determine only one of the first roll angle and the second roll angle to determine a sudden turn-back. That is, when at least one of the first roll angle and the second roll angle has a different sign indicating the left and right of the roll angle and the roll rate, and the absolute value of the roll rate at which the sign is different is equal to or greater than a predetermined value It may be determined that there is a sudden turn-back.

  In the embodiment, the second composite roll angle Ra is used as a rollover detection parameter in order to enable the rollover suppression control to be executed earlier, but it is obtained from the first composite roll angle Ra12 and the lateral acceleration. A roll angle or a roll angle detected from a roll angle sensor may be used as a rollover detection parameter.

  In the embodiment described above, the first distribution coefficient K1 when the steering is not performed is 0, but may be a value larger than 0. Further, although the upper limit value of the first distribution coefficient K1 is 1, it may be a value smaller than 1. Further, the first distribution coefficient K1 when the sudden turn-off is not performed is 0, but may be a value larger than 0.

  In the embodiment, the first distribution coefficient setting unit 128C and the second distribution coefficient setting unit 128D multiply each count value by a coefficient to determine each distribution coefficient. However, the relationship between each count value and each distribution coefficient May be stored in advance in a table, and each distribution coefficient may be determined from each count value based on this table.

  In the above-described embodiment, the steering determination unit 125 suddenly detects when the absolute value of the turning speed is equal to or greater than a predetermined value and the value subjected to the filtering process so that the absolute value of the lateral acceleration is difficult to decrease is equal to or greater than the predetermined value. Although it has been determined that steering has been performed, it may be determined that sudden steering has been performed when the absolute value of the steering speed is equal to or greater than a predetermined value and the absolute value of the lateral acceleration is equal to or greater than a predetermined value.

  In the embodiment, the parameter calculation unit 128 calculates a threshold calculation roll rate that is the rate of change of the roll angle of the vehicle CR, and the smaller the value that is filtered so that the threshold calculation roll rate is less likely to decrease, the smaller the value. Although the roll angle threshold (parameter threshold) is set so as to be a value, the parameter threshold may be set using a threshold calculation roll rate that is not filtered.

  In the embodiment, the lateral G base roll rate Ra1 ′ is exemplified as the first roll rate, and the yaw rate base roll rate Ra2 ′ is exemplified as the second roll rate, but the lateral G base roll rate Ra1 ′, the second roll is exemplified as the first roll rate. The steering angle base roll rate calculated based on the steering angle may be used as the rate, and these may be combined with the first distribution coefficient K1 to serve as a rollover detection parameter.

  In the above embodiment, the roll angle threshold value has a value that increases the roll angle threshold value so that the rollover suppression control is difficult to start because the rollover possibility is low when the roll rate is small. However, in the present invention, the roll angle threshold may be a constant value.

  In the above embodiment, the outer wheel target braking force is set by PI control, but the detailed method for setting the outer wheel target braking force is not limited to this.

  In the above embodiment, the braking force is applied to both the front wheel and the rear wheel during the rollover suppression control. However, the braking force may be applied to only one of the front wheel and the rear wheel.

91 Wheel speed sensor 92 Steering angle sensor 93 Lateral acceleration sensor 94 Yaw rate sensor 100 Control unit 110 Side slip control unit 120 Roll-over suppression control unit 121 Roll angle calculation unit 122 Roll rate calculation unit 123 Corrected lateral acceleration calculation unit 125 Steering determination unit 126 Reversal determination Means 128 Parameter calculation means 128A First counter 128B Second counter 128C First distribution coefficient setting means 128D Second distribution coefficient setting means 128E Roll rate calculation means for threshold calculation 129 ROM control braking force setting means 129A Outer wheel target braking force setting means 129B Inner ring target braking force setting means A A vehicle brake hydraulic pressure control device

Claims (4)

This is a vehicular brake hydraulic pressure control device that is configured to be able to individually brake left and right wheels provided on the same shaft, and that brakes the wheels and performs rollover suppression control when a rollover tendency is detected during a turn. And
Outer wheel target braking force setting means for setting a target outer wheel target braking force for braking the turning outer wheel with the first braking force;
An inner ring target braking force setting means for setting a target inner wheel target braking force for braking the turning inner wheel with the second braking force at a value smaller than the outer wheel target braking force;
The inner ring target braking force setting means sets the predetermined value as the inner ring target braking force when the predetermined value is smaller than the outer wheel target braking force multiplied by a coefficient less than 1. If the predetermined value is greater than or equal to the value obtained by multiplying the outer wheel target braking force by a coefficient less than 1, a value obtained by multiplying the outer wheel target braking force by a coefficient less than 1 is set as the inner wheel target braking force;
If the rollover tendency is detected, at the same time the braking in the first braking force to the turning outer wheel, a vehicle, characterized in that to start the braking by the second braking force to the turning inner wheel on the same axis Brake fluid pressure control device. The rollover suppression control is executed when a rollover detection parameter indicating a rollover tendency exceeds at least a predetermined threshold,
2. The vehicle brake hydraulic pressure control apparatus according to claim 1 , wherein the outer wheel target braking force setting means sets an outer wheel target braking force from a deviation between the rollover detection parameter and the predetermined threshold. The inner wheel target braking force setting means sets the predetermined value to a first predetermined value for a predetermined time after the rollover suppression control is started, and sets the predetermined value to the first predetermined value after the predetermined time has elapsed. The vehicular brake hydraulic pressure control device according to claim 1 or 2, wherein the second predetermined value is smaller than the predetermined value. The rollover suppression control is executed on both the front and rear wheels,
The outer ring target braking force setting means, the outer ring target braking force of the rear wheel, the third first term a predetermined value from claim 1, characterized in that set to the upper limit to claim 3 The brake fluid pressure control apparatus for vehicles as described.

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