JPH09109854A - Vehicle behavior control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent that the braking force of rear wheels is deteriorated attributable to the spin suppression control when a braking system of front wheels is failed, and only smaller deceleration than that expected by a driver is obtained. SOLUTION: In a behavior control device, the spin condition is detected, the drift-out condition is detected, the braking force of each wheel is controlled according to the degree of the spin condition and the drift-out condition, and the behavior is controlled by reducing the braking force of the rear wheels especially in the spin condition (Steps 150-190). A judgment is made whether the braking system of the front wheels is failed or not (Step 120), and when it is failed, the behavior control is prohibited, and the braking force of the rear wheels is prevented from being reduced (Step 135).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a behavior control device for suppressing and reducing undesirable behavior such as spin and drift out when a vehicle such as an automobile turns.

[0002]

2. Description of the Related Art As one of behavior control devices for controlling the behavior of a vehicle such as an automobile at the time of turning, for example, Japanese Patent Laid-Open No.
As described in Japanese Patent No. 24304, there is conventionally known a yaw rate feedback type behavior control device for controlling a braking force so that an actual yaw rate of a vehicle becomes a target yaw rate calculated based on a running state of the vehicle.

According to such a behavior control device, since the braking force is controlled so that the actual yaw rate becomes the target yaw rate, the unstable behavior can be reduced even if spin or drift out occurs during turning. It is possible to stabilize the turning behavior of the vehicle as compared with the case where the braking force control is not performed.

[0004]

Generally, in order to suppress the spin state of a vehicle, it is effective to increase the cornering force of the front wheels and decrease the cornering force of the rear wheels. Therefore, when a spin state is detected, the braking force of the front wheels is increased so that the cornering force of the front wheels is increased, and the braking force of the rear wheels is reduced so that the cornering force of the rear wheels is decreased, thereby suppressing the spin state. It is possible.

However, when the braking device for increasing / decreasing the braking force is a braking device composed of two systems, a front wheel system and a rear wheel system, respectively, for increasing / decreasing the braking force of the front wheels and the rear wheels, the front wheel system is for some reason. If the spin suppression control is executed in a situation where the vehicle fails and cannot normally generate the braking force of the front wheels, the following problems occur.

That is, when the driver of the vehicle performs a braking operation in a situation in which the front wheel system has failed, the front wheel system has failed and no braking force is applied to the front wheels. Occurs. Thus, in a situation where braking force is generated only on the rear wheels, the vehicle is likely to be in a spin state due to a decrease in the lateral force of the rear wheels. Since the braking force is reduced, a situation in which only a deceleration smaller than the driver's expected deceleration is obtained.

The present invention has been made in view of the above-mentioned problems in the conventional behavior control device, and the main object of the present invention is to suppress spin control when a failure state of the front wheel system is detected. By preventing the braking force of the rear wheels from being reduced by the above, the braking force of the rear wheels is reduced due to the execution of spin suppression control when the front wheel system fails, and the deceleration expected by the driver is reduced. Is to prevent a smaller deceleration from being obtained.

[0008]

According to the present invention, the main problem as described above has a structure of claim 1, that is, a braking system in which the brake system is composed of two systems, a front wheel system and a rear wheel system. However, in the vehicle behavior control device that reduces the braking force of the rear wheels and executes the spin suppression control when the vehicle is in the spin state, the detection means for detecting the failure state of the front wheel system, and the front wheel system And a means for prohibiting execution of the spin suppression control when a failure state is detected, which is achieved by a vehicle behavior control device.

According to this structure, when the failure state of the front wheel system is detected, the execution of the spin suppression control is prohibited,
This prevents the braking force of the rear wheels from decreasing, so it is possible to avoid a large lack of braking force of the rear wheels when the braking force of the front wheels does not occur. It is prevented that a deceleration smaller than the speed is obtained.

Generally, as the brake pedal force increases, the braking force of the front wheels also increases, so the deceleration of the vehicle also increases. However, if the front wheel system is in a failed state, the braking force of the front wheels will increase even if the brake pedal force increases. Since the vehicle deceleration does not increase normally, the deceleration of the vehicle does not normally increase. Therefore, it is possible to determine whether the front wheel system is in a failed state or not depending on whether the vehicle deceleration with respect to the brake pedal force is small.

Therefore, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the structure of claim 1, the detecting means has a deceleration of the vehicle with respect to a brake pedal force smaller than a predetermined value. It is sometimes configured to determine that the front wheel system is in a failed state (configuration of claim 2).

In addition, since the ground load of the front wheel on the inside of the turn is small when the spin suppression control is executed, when the vehicle has an ABS device, a relatively strong braking operation is performed by the driver in such a situation. Then, the ABS device operates and the front wheels (especially the front wheels on the inside of the turn) are ABS controlled. However, when the front wheel system is in a failed state, the master cylinder pressure becomes a high value due to relatively strong braking operation. However, the ABS control for the front wheels is not performed.

Therefore, according to the present invention, in order to effectively achieve the above-mentioned main problem, in the structure of claim 1, the vehicle has an ABS device, and the detecting means executes the spin suppression control. In the meantime, when the master cylinder pressure of the braking device is equal to or higher than a predetermined value and the front wheels are not under ABS control, it is configured to determine that the front wheel system is in a failed state (configuration of claim 3). According to this configuration, the failure state of the front wheel system can be accurately determined.

[0014]

When the friction coefficient of the road surface is low, the deceleration of the vehicle does not normally increase even if the brake pedal force increases. Therefore, depending on whether or not the vehicle deceleration with respect to the brake pedal force is small. Cannot always accurately determine whether or not the front wheel system is in a failed state.
However, in the case of a vehicle having an ABS device, if the friction coefficient of the road surface is low and the slip ratio of the wheel during braking becomes high, the ABS
Since the device operates, it is possible to more accurately determine whether or not the front wheel system is in a failure state by determining whether or not the deceleration of the vehicle with respect to the brake pedal force is small in the situation where the ABS control is not performed. Can be determined.

Therefore, according to a preferred embodiment of the means for solving the problems of the present invention, in the structure of claim 2, the vehicle is AB.
The detecting device is configured to have a front wheel system failure state when the deceleration of the vehicle with respect to the brake pedal force is smaller than a predetermined value when the ABS control is not being performed.

According to another preferred mode of the means for solving the problems of the present invention, in the configuration of the preferred mode described above, the detecting means is not under ABS control and behavior control is not executed, and the vehicle speed is a predetermined value. In the above case, when the deceleration of the vehicle with respect to the brake pedal force is smaller than a predetermined value, it is determined that the front wheel system is in a failed state.

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention;

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of one embodiment of a behavior control device according to the present invention.

In FIG. 1, a braking device 10 includes a master cylinder 14 for pumping brake oil from first and second ports in response to a driver's depression of a brake pedal 12, and an oil pressure in the master cylinder. And a hydro booster 16 for increasing the brake oil to a pressure (regulator pressure) corresponding to the above. Master cylinder 1
The first port 4 is a brake hydraulic control conduit 18 for the front wheels.
The brake hydraulic control devices 20 and 22 for the left and right front wheels
The second port is connected to a three-port two-position switching type electromagnetic control valve 28 for the right and left rear wheels by a rear wheel brake hydraulic control conduit 26 having a proportional valve 24 on the way. The control valve 28 is connected by a conduit 30 to a brake hydraulic control device 32 for the left rear wheel and a brake hydraulic control device 34 for the right rear wheel.

The braking device 10 also has an oil pump 40 that pumps the brake oil stored in the reservoir 36 and supplies it as high-pressure oil to the high-pressure conduit 38. The high-pressure conduit 38 is connected to the hydrobooster 16 and the switching valve 44, and an accumulator 46 for accumulating high-pressure oil discharged from the oil pump 40 as accumulator pressure is connected to the middle of the high-pressure conduit 38. There is. As shown in the drawing, the switching valve 44 is also a 3-port 2-position switching type electromagnetic switching valve, and is connected to the hydrobooster 16 by a regulator pressure supply conduit 47 for four wheels.

The brake hydraulic control devices 20 and 22 for the left and right front wheels are wheel cylinders 48FL and 48FR for controlling the braking force to the corresponding wheels, three-port two-position switching type electromagnetic control valves 50FL and 50FR, and a reservoir. Low pressure conduit 5 as return passage connected to 36
2 and the switching valve 44. The normally open electromagnetic on-off valves 54FL and 54FR and the normally closed electromagnetic on-off valve 56FL provided in the middle of the regulator pressure supply conduit 53 for the left and right front wheels. And 56 FR. Open / close valve 5
The regulator pressure supply conduits 53 for the left and right front wheels between the 4FL, 54FR and the on-off valves 56FL, 56FR are connected conduits 58FL, 5FL.
It is connected to the control valves 50FL and 50FR by 8FR.

A brake hydraulic pressure control device 32 for the left and right rear wheels,
Reference numeral 34 denotes a normally-open electromagnetic on-off valve 60RL, 60 provided between the control valve 28 and the low-pressure conduit 52 in the middle of the conduit 30.
RR and normally closed solenoid-operated on-off valves 62RL, 62RR, and wheel cylinders 64RL, 64RR for controlling braking force on the corresponding wheels, respectively.
RL and 64RR are connected to the conduit 30 between the on-off valves 60RL and 60RR and the on-off valves 62RL and 62RR by connection conduits 66RL and 66RR, respectively.

The control valves 50FL and 50FR are respectively the brake hydraulic control conduit 18 for the front wheels and the wheel cylinder 48FL.
And 48FR and wheel cylinder 48FL
, 48FR and the connection conduits 58FL and 58FR, the first position shown in the figure, the brake hydraulic control conduit 18 and the wheel cylinders 48FL and 48FR are disconnected, and the wheel cylinders 48FL and 48FR are connected to the connection conduit 58FL.
, And 58FR.

A regulator pressure supply conduit 68 for the left and right rear wheels is connected between the switching valve 44 and the left and right rear wheel control valve 28. The control valve 28 is connected to the brake hydraulic pressure control conduit 26 for the rear wheels. The on-off valves 60RL and 60RR are connected in communication with each other, and the on-off valves 60RL and 60RR and the regulator pressure supply conduit 68 are connected.
The first position shown in the figure for shutting off the communication with the brake hydraulic pressure control conduit 26, shutting off the communication between the brake hydraulic pressure control conduit 26 and the on-off valves 60RL, 60RR, and the on-off valves 60RL, 60RR and the regulator pressure supply conduit 6.
It is adapted to switch to a second position where 8 is connected for communication.

The control valves 50FL, 50FR, 28 function as master cylinder pressure shutoff valves, and when these control valves are in the first position shown, the wheel cylinders 48FL, 48FL.
FR, 64RL, 64RR are connected in communication with conduits 18, 26,
By supplying the master cylinder pressure to each wheel cylinder, the braking force of each wheel is controlled according to the amount of depression of the brake pedal 12 by the driver, and the control valves 50FL, 50FL
When 0FR, 28 is in the second position, each wheel cylinder is shut off from the master cylinder pressure.

The switching valve 44 is a wheel cylinder 48F.
The control valves 50FL, 50FR, 28 are switched to the second position and the opening / closing valves 54FL, 54FR serve to switch the hydraulic pressure supplied to the L, 48FR, 64RL, 64RR between the accumulator pressure and the regulator pressure. , 60RL, 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR in the positions shown, when the switching valve 44 is maintained in the first position shown, the wheel cylinders 48FL, 48FR, 64R.
By supplying the regulator pressure to L and 64RR, the pressure in each wheel cylinder is controlled by the regulator pressure, so that the braking pressure of that wheel becomes the depression amount of the brake pedal 12 regardless of the braking pressure of the other wheels. It is controlled in the pressure increasing mode by the corresponding regulator pressure.

Even if each valve is set to the pressure increasing mode by the regulator pressure, when the pressure in the wheel cylinder is higher than the regulator pressure, the oil in the wheel cylinder flows backward and the control mode is the pressure increasing mode. Nevertheless, the actual braking pressure drops.

Also, the control valves 50FL, 50FR, 28 are switched to the second position and the opening / closing valves 54FL, 54FR, 60RL,
When the switching valve 44 is switched to the second position with the 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR in the positions shown, the wheel cylinders 48FL, 48FR, 64R.
By supplying the accumulator pressure to L and 64RR, the pressure in each wheel cylinder is controlled by the accumulator pressure higher than the regulator pressure, and thereby, regardless of the depression amount of the brake pedal 12 and the braking pressure of other wheels. The braking pressure of the wheels is controlled in the pressure increasing mode by the accumulator pressure.

Further, with the control valves 50FL, 50FR, 28 switched to the second position, the on-off valves 54FL, 54FR, 6
0RL and 60RR are switched to the second position, and the on-off valve 56F
When L, 56FR, 62RL, 62RR are controlled to the illustrated state, the pressure in each wheel cylinder is maintained regardless of the position of the switching valve 44, and the control valves 50FL, 50FR, 28 are switched to the second position. Open / close valves 54FL, 54FR, 6
0RL, 60RR and open / close valves 56FL, 56FR, 62RL, 62
When RR is switched to the second position, the pressure in each wheel cylinder is reduced irrespective of the position of the switching valve 44, so that the wheel of that wheel is irrespective of the depression amount of the brake pedal 12 and the braking pressure of other wheels. The braking pressure is controlled in the pressure reduction mode.

Thus, the braking device 10 has a front wheel braking system including a front wheel brake hydraulic pressure control conduit 18 for increasing / decreasing the left and right front wheel braking force, a left and right front wheel braking hydraulic pressure control device 20 and 22, and a left and right rear wheel braking force. The brake hydraulic pressure control conduit 26 for the rear wheels, the control valve 28, the brake hydraulic pressure control devices 32 and 34, etc., for the rear wheels that increase and decrease

Switching valve 44, control valves 50FL, 50FR, 2
8, the on-off valves 54FL, 54FR, 60RL, 60RR and the on-off valves 56FL, 56FR, 62RL, 62RR are controlled by the electric control device 70 as described in detail later. The electric control device 70 includes a microcomputer 72 and a drive circuit 74.
Although the microcomputer 72 is not shown in detail in FIG.
PU), read only memory (ROM), random access memory (RAM), and input / output port device, which are connected to each other by a bidirectional common bus. Good.

In the input / output port device of the microcomputer 72, a signal indicating the vehicle speed V from the vehicle speed sensor 76, a signal indicating the lateral acceleration Gy of the vehicle body from a lateral acceleration sensor 78 provided substantially at the center of gravity of the vehicle body, and a yaw rate sensor 80. A signal indicating the yaw rate γ of the vehicle body, a signal indicating the steering angle θ from the steering angle sensor 82, a signal indicating the longitudinal acceleration Gx of the vehicle body from the longitudinal acceleration sensor 84 provided substantially at the center of gravity of the vehicle body, a wheel speed sensor 86FL- From 86RR, wheel speeds (circumferential speeds) Vwfl, Vwfr, Vwr of the left and right front wheels and the left and right rear wheels respectively.
A signal indicating l and Vwrr and a signal indicating the pressure Pm in the master cylinder 14 are input from the pressure sensor 88.

The lateral acceleration sensor 78, the yaw rate sensor 80 and the like detect the lateral acceleration and the like with the left turning direction of the vehicle being positive, and the longitudinal acceleration sensor 84 detects the longitudinal acceleration with the accelerating direction of the vehicle being positive. There is. The pressure sensor 88 is provided in the brake hydraulic pressure control conduit 26 between the master cylinder 14 and the proportional valve 24 so as to detect the hydraulic pressure in the hydraulic chamber on the rear wheel side of the master cylinder 14.

Although not shown in FIG. 1, the vehicle of the illustrated embodiment is provided with an ABS device.
The BS device increases, holds, or reduces the braking pressure of each wheel when the wheel speed of each wheel becomes lower than the reference wheel speed based on the estimated vehicle speed when the driver performs a braking operation. The ABS control is performed, and a signal indicating whether or not the ABS control is executed is input to the input / output port device of the microcomputer 72.

The ROM of the microcomputer 72 stores the control flow of FIGS. 2 to 7 and the maps of FIGS. 8 to 10 as will be described later, and the CPU will be described later on the basis of the parameters detected by the various sensors described above. The spin state quantity S for determining the turning behavior of the vehicle by performing various calculations as described above.
S and the drift-out state quantity DS are obtained, the turning behavior of the vehicle is estimated based on these state quantities, and the turning behavior is controlled by controlling the braking force of each wheel based on the estimation result.

Next, the turning behavior control routine of the vehicle will be described with reference to the flow charts shown in FIGS. The control according to the flowcharts shown in FIGS. 2 and 3 is started by closing an ignition switch (not shown) and is repeatedly executed at predetermined time intervals.

First, in step 10, the vehicle speed sensor 7
A signal or the like indicating the vehicle speed V detected in 6 is read, and in step 20, the lateral acceleration Gy is deviated from the product V * γ of the vehicle speed V and the yaw rate γ as a deviation Gy-V * γ. That is, the side slip acceleration Vyd of the vehicle is calculated, and in step 30, the side slip velocity Vy of the vehicle body is calculated by integrating the side slip acceleration Vyd.
The slip angle β of the vehicle body is calculated as the ratio Vy / Vx of the vehicle side slip velocity Vy to the vehicle longitudinal velocity Vx (= vehicle speed V).

In step 40, the spin amount SV is calculated as the linear sum K1 * β + K2 * Vyd of the vehicle body slip angle β and the lateral slip acceleration Vyd, where K1 and K2 are positive constants, respectively, and in step 50, the yaw rate is calculated. The turning direction of the vehicle is determined based on the sign of γ, and the spin state quantity SS is calculated as SV when the vehicle is turning left and as -SV when the vehicle is turning right, and the spin state is calculated when the calculation result is a negative value. The quantity is zero. The spin amount SV may be calculated as a linear sum of the vehicle body slip angle β and its differential value βd.

In step 60, the target yaw rate γ is calculated according to the following equation 1 using Kh as a stability factor.
In addition to calculating c, the reference yaw rate γt is calculated according to the following equation 2 using T as a time constant and s as a Laplace operator. Incidentally, the target yaw rate γc may be calculated in consideration of the lateral acceleration Gy of the vehicle in consideration of a dynamic yaw rate.

[0040]

## EQU1 ## γ c = V * θ / (1 + Kh * V ² ) * H

## EQU2 ## γt = γc / (1 + T * s)

In step 70, the drift-out amount DV is calculated according to the following equation (3). The drift-out amount DV may be calculated according to the following equation 4 with H as the wheel base.

[0042]

## EQU3 ## DV = (γt−γ)

## EQU4 ## DV = H * (γt−γ) / V

In step 80, the turning direction of the vehicle is determined based on the sign of the yaw rate γ, and the drift-out state amount DS is calculated as DV when the vehicle is turning left and is calculated as -DV when the vehicle is turning right. When the calculation result is a negative value, the drift-out state quantity is 0.

At step 90, the spin state quantity SS
The slip ratio target value Rssfo of the front wheel on the outside of the turning is calculated from the map corresponding to the graph shown in FIG. 8 based on the above, and in step 100, it corresponds to the graph shown in FIG. 9 based on the drift-out state quantity DS. From the map, the slip ratio target value Rsall of the entire vehicle is calculated.

In step 110, the target slip ratios Rsfo, Rsfi, and Rsro of the front wheel on the outer side of the turn, the front wheel on the inner side of the turn, the rear wheel on the outer side of the turn, and the rear wheel on the inner side of the turn Rsfo, Rsfi, and Rsro are set as Ksri as the distribution ratio of the rear wheel on the inside of the turn. , Rsri are calculated.

## EQU00005 ## Rsfo = Rssfo Rsfi = 0 Rsro = (Rsall-Rssfo) * (100-Ksri) / 100 Rsri = (Rsall-Rssfo) * Ksri / 100

In step 120, the flags F1 and F are set.
2, it is determined whether at least one of F3 is 1, that is, whether the brake system of the front wheels is in a failed state. If a positive determination is made, the routine proceeds to step 130, and a negative determination is made. When the determination is made, in step 120, the target slip ratios Rsfo, Rsfi, Rsro, and Rsr of each wheel are determined.
It is determined whether or not all i are 0. When a positive determination is made in step 120, step 1
After the flag F is reset to 0 in step 30, the process returns to step 10, and if a negative determination is made, step 14
At 0 the flag F is set to 1.

In step 150, the turning direction of the vehicle is determined on the basis of the sign of the yaw rate γ, whereby the inner and outer turning wheels are specified, and the final target slip ratio Rsi (i = fr, fl, rr, rl) are calculated. That is, when the final target slip ratio Rsi is a left turn and a right turn of the vehicle, the following equations 6 and 7 are given respectively.
Is required in accordance with

[0048]

Rsfr = Rsfo Rsfl = Rsfi Rsrr = Rsro Rsrl = Rsri

Rsfr = Rsfi Rsfl = Rsfo Rsrr = Rsri Rsrl = Rsro

In step 160, the target wheel speed Vwti of each wheel is calculated according to the following equation 8 using Vb as the reference wheel speed (for example, the wheel speed of the front wheel on the inside of the turn).

Vwti = Vb * (100-Rsi) / 100

In step 170, Vwid is the wheel acceleration of each wheel (differential value of Vwi), Ks is a constant constant coefficient, and the target slip amount SP of each wheel is calculated according to the following equation (9).
i is calculated, and in step 180, the duty ratio D of each wheel is calculated from the map corresponding to the graph shown in FIG.
ri is calculated.

## EQU9 ## SPi = Vwi-Vwti + Ks * (Vwid-Gx)

Further, at step 190, the switching valve 44
Is switched to the second position to introduce the accumulator pressure, and the control signal is output to the control valves 28, 50FR to 50RL of the wheels corresponding to the wheels whose final target slip Rsi is not 0. The control valve is switched and set to the second position. Further, the control signal corresponding to the duty ratio Dri is output to the opening / closing valve of each wheel to control the supply / discharge of the accumulator pressure to / from the wheel cylinders 48FR to 48RL, thereby controlling the braking pressure of each wheel.

In this case, when the duty ratio Dri is a value between the negative reference value and the positive reference value, the upstream side opening / closing valve is switched to the second position and the downstream side opening / closing valve is set to the first position. By being held in the position, the pressure in the corresponding wheel cylinder is held, and when the duty ratio is equal to or greater than the positive reference value, the upstream and downstream on-off valves are controlled to the positions shown in FIG. The pressure in the wheel cylinder is increased by supplying the accumulator pressure to the corresponding wheel cylinder, and when the duty ratio is equal to or less than the negative reference value, the upstream and downstream opening / closing valves are in the second position. When the brake oil in the corresponding wheel cylinder is changed to the low pressure conduit 52,
To reduce the pressure in the wheel cylinder.

When the pressure in the wheel cylinder is increased, the open / close valve on the upstream side is opened / closed according to the duty ratio, and when the pressure in the wheel cylinder is reduced, the open / close valve on the downstream side is opened / closed according to the duty ratio. It is opened and closed. As a result, the increasing / decreasing gradient of the pressure in the wheel cylinder becomes larger as the duty ratio becomes larger.

Next, the routine for setting the flags Fa and Fb will be described with reference to the flow chart shown in FIG.
The control according to the flowchart shown in FIG. 4 is executed by interruption every predetermined time (this will be described later with reference to FIG.
The same applies to the control by the flowchart shown in FIG. 7).

First, in step 210, a signal indicating the master cylinder pressure Pm is read, and step 2
At 20, it is determined whether or not the master cylinder pressure Pm exceeds the reference value S1 (a positive constant). If a positive determination is made, the process proceeds to step 240, and if a negative determination is made, the step is performed. At 230, the count values C1 and C2 of the counter are reset to 0 and the flags Fa and Fb are reset to 0.

At step 240, it is judged if at least one of the front wheels is under ABS control. If a negative judgment is made, it is judged at step 250 whether the flag F is 1 or not. It is determined whether or not the behavior control by the braking force control is being performed. If the determination is negative, it is determined in step 260 whether the vehicle speed V is equal to or higher than the reference value V1 (a positive constant). Is determined. When an affirmative determination is made in step 260, the process proceeds to step 270, and an affirmative determination is made in step 240 or step 250 or step 260.
If a negative determination is made at step 230, the routine proceeds to step 230.

In step 270, it is judged whether or not the master cylinder pressure Pm is less than or equal to the reference value S2 (a positive constant). If a positive judgment is made, step 29 is executed.
0, and when a negative determination is made, step 280
In this case, the longitudinal acceleration Gx of the vehicle is N, where N is a positive constant.
It is determined whether or not N is exceeded, and if a positive determination is made, the process proceeds to step 300, and if a negative determination is made, the process proceeds to step 310.

In step 290, the longitudinal acceleration Gx
Is-(Pm-N1) * N, where N1 and N2 are positive constants.
It is determined whether or not 2 is exceeded, and when a positive determination is made, the count value C1 is incremented by 1 in step 300, and when a negative determination is made, the count value C2 is set by 1 in step 310. Incremented.

At step 320, the count value C1
Is determined to exceed a reference value H1 (a positive constant integer), and if a negative determination is made, step 3
If the determination is affirmative, the process proceeds to step 33.
At 0, flag Fa is set to 1 and flag Fb is reset to 0.

At step 340, the count value C2
Is determined to exceed a reference value H2 (a positive fixed integer), and if a positive determination is made, step 3
At 50, the flag Fa is reset to 0 and at the same time the flag Fb is set to 1. When a negative determination is made, at step 360 the flags Fa and Fb are reset to 0.

Next, the flag F1 setting routine will be described with reference to the flow chart shown in FIG.

In step 410, the flag Fa is 1
If a negative determination is made, the process proceeds to step 430, and if an affirmative determination is made, the count value Cf of the counter is incremented by 1 in step 420 and then the process proceeds to step 470. .

In step 430, the flag Fb is 1
If a negative determination is made, the routine proceeds to step 470. If an affirmative determination is made, the count value Cf is decremented by 1 at step 440 and then the routine proceeds to step 450. In step 450, it is determined whether or not the count value Cf is negative. If a negative determination is made, the process proceeds to step 470. If an affirmative determination is made, the count value Cf is determined in step 460. It is reset to 0.

At step 470, the count value Cf
Is determined to exceed a reference value H3 (a positive constant integer), and if a positive determination is made, step 4
The flag F1 is set to 1 at 80, and when a negative determination is made, the flag F1 is reset to 0 at step 490.

Therefore, in this routine, the count value Cf of the counter satisfies the condition that "both left and right front wheels are not under ABS control, behavior control is not executed, and the vehicle speed is equal to or higher than the reference value V1". (1) "Gx>-(Pm -N1) * N2 and S1 <Pm ≤ S2" or "Gx> -N and Pm>"
It is incremented when "S2" continues for a time corresponding to H1, and (2) "Gx≤- (Pm-N1) * N2 and S1 <Pm≤S2" or "Gx≤-N and Pm> S2. Is decremented when it continues for a time corresponding to H2, and the flag F1 becomes 1 when the count value Cf exceeds H3.

In other words, during normal braking in which neither ABS control nor behavior control is executed, the relationship between the master cylinder pressure Pm and the longitudinal acceleration Gx of the vehicle is such that only a deceleration corresponding to the failure of the front wheel brake system occurs. Moreover, when this state continues for a predetermined time, the flag F1 is set to 1 and it is determined that the front wheel system has failed.

Next, the flag F2 setting routine will be described with reference to the flow chart shown in FIG.

Steps 510, 520 of this routine,
540 is step 2 of the routine shown in FIG.
Similar to 10, 220, 240, step 52
When a negative determination is made at 0, step 530
At this time, the count value C3 of the counter is reset to 0, and when a positive determination is made at step 540, the flag F2 is reset to 0 at step 550.

In step 560, it is determined whether or not the rear wheels are ABS controlled. If a negative determination is made, the process proceeds to step 530, and if an affirmative determination is made, the vehicle speed is set in step 570. V is the reference value V2
It is determined whether or not (positive constant) or more, and if a negative determination is made, the process proceeds to step 530, and if an affirmative determination is made, the process proceeds to step 580.

Steps 580 to 600 are executed in the same manner as steps 270 to 290 of the routine shown in FIG. 4, and when a negative determination is made in step 590 or 600, the process proceeds to step 530, and these steps are executed. If a positive determination is made in step 61
At 0, the count value C3 is incremented by 1.
At step 620, the count value C3 is the reference value H3.
It is determined whether or not (positive constant integer) is exceeded. If a negative determination is made, the process returns to step 510, and if an affirmative determination is made, the flag F2 is set to 1 in step 630. It

Therefore, in this routine, "the left and right front wheels are not under ABS control, the rear wheels are under ABS control, the behavior control is not executed, and the vehicle speed is equal to or higher than the reference value V2". When the condition is satisfied, "Gx>-(Pm-N1) * N2 and S1 <
Pm .ltoreq.S2 "or"Gx> -N and Pm> S2 "
Flag F1 becomes 1 when continues for a time corresponding to H3.

In other words, during the ABS control of the rear wheels, the relationship between the master cylinder pressure Pm and the longitudinal acceleration Gx of the vehicle is such that only the deceleration corresponding to the failure of the brake system of the front wheels occurs and the left and right front wheels are If the ABS control is not performed and this state continues for a predetermined time, the flag F2 is set to 1 and it is determined that the front wheel system has failed.

Next, the flag F3 setting routine will be described with reference to the flowchart shown in FIG.

Steps 710 and 720 are shown in FIG.
The routine is executed in the same manner as steps 210 and 240 of the routine shown in FIG. 7, and the flag F3 is reset to 0 in step 730 when an affirmative determination is made in step 720. In step 740, it is judged whether or not the master cylinder pressure Pm exceeds the reference value S3 (a positive constant), and if a positive judgment is made, is the flag F 1 in step 750? Whether or not, that is, whether or not the behavior control by the braking force control is being performed is determined.

When a positive determination is made in step 750, the count value C4 is 1 in step 760.
When it is incremented and a negative determination is made in step 740 or 750, the count value C4 is reset to 0 in step 770. Step 780
In this case, it is determined whether or not the count value C4 exceeds the reference value H4 (a positive constant integer). If a negative determination is made, the process returns to step 710, and if a positive determination is made, the step is performed. At 790, flag F3 is set to one.

Therefore, in this routine, the flag F3 is set to "1" when the condition that "both left and right front wheels are not under ABS control, behavior control is being executed, and Pm>S3" is satisfied.

In other words, the flag F3 is set when the front wheel (especially the turning inner wheel) is not ABS-controlled although the master cylinder pressure Pm is equal to or higher than the predetermined value due to the braking operation performed by the driver during the behavior control. It is determined to be 1 and the front wheel system is defective.

Thus, in the illustrated embodiment, the vehicle side slip acceleration Vyd is calculated in step 20, the vehicle body slip angle β is calculated in step 30, and the linear sum of these is calculated in step 40. The spin amount SV is calculated as, and the spin amount SV is calculated in step 50.
Is calculated as an absolute value of the spin state quantity SS.

Further, in step 60, the reference yaw rate γt is calculated, in step 70 the drift-out amount DV is calculated, and in step 80, the drift-out state amount DS is obtained as an absolute value. Is calculated, and the target value Rssfo of the slip ratio of the front wheel on the outside of the turning is calculated in step 90, and step 100 is executed.
At this time, the target slip ratio Rsall of the entire vehicle is calculated,
In step 110, the target slip ratio Rsfo of each wheel,
Rsfi, Rsro, and Rsri are calculated.

Further, in step 120, the flag F1,
It is determined whether at least one of F2 and F3 is 1, that is, whether or not the brake system of the front wheels is in a failed state, and in step 130, the target slip ratios of all the wheels are determined. It is determined whether it is 0, that is, whether behavior control is unnecessary.

When the turning behavior of the vehicle is stable, an affirmative decision is made in step 130, the flag F is reset to 0 in step 135, and the process returns to step 10. Therefore, in this case Does not execute the behavior control in steps 150 to 190, so that the braking pressure of each wheel is adjusted by the driver to the brake pedal 12.
It is controlled according to the amount of depression.

When the turning behavior of the vehicle is unstable, a negative determination is made in step 130,
The flag F is set to 1 in step 140, and the final target slip ratio Rsi of each wheel is set in step 150.
(I = fr, fl, rr, rl) is calculated, the target wheel speed Vwti of each wheel is calculated in step 160, and the wheel speed of each wheel becomes the target wheel speed Vwti in steps 170-190. These braking forces are controlled so that the turning behavior of the vehicle is stabilized.

In other words, the braking force of each wheel is controlled based on both the spin state amount and the drift-out state amount, thereby reducing the unstable behavior of the wheel in both the spin state and the drift-out state. To be done. In particular, the target slip ratio of the rear wheels, which is calculated based on the amount of spin state, becomes a negative value.Therefore, when the vehicle is in a spin state, the braking force of the rear wheels is reduced and the cornering force of the rear wheels is increased. Therefore, spin is suppressed.

When the front wheel braking system is in a failed state, an affirmative decision is made in step 110, whereby the flag F is reset to 0 in step 130, and steps 140 to 190, that is, the behavior. The control is not executed, and therefore, the braking force of the rear wheels is not reduced by the behavior control, so that it is possible to prevent the expected deceleration from being obtained even when the driver depresses the brake pedal.

Further, according to the illustrated embodiment, the determination as to whether or not the front wheel braking system is defective is made in three modes according to the routines shown in FIGS. 5 to 7, and in step 120. Therefore, if the failure of the front wheel system is determined by any one of these three modes, the execution of the behavior control is prohibited, so compared to the case of only one of the three modes. The failure of the front wheel system is accurately determined.

Although the present invention has been described in detail above with respect to a specific embodiment, the present invention is not limited to the above-described embodiment, and various other embodiments are possible within the scope of the present invention. It will be apparent to those skilled in the art that

For example, in the above embodiment, the braking force of each wheel is controlled by the wheel speed feedback, but the braking force of each wheel is controlled by the pressure feedback of the pressure in the wheel cylinder. May be done.

Further, the behavior control device of the present invention may be applied to a vehicle in which an ABS device is not mounted, in which case the steps relating to the ABS control of each routine in the illustrated embodiment are omitted.

[0089]

As is apparent from the above description, according to the structure of claim 1 of the present invention, the execution of the spin suppression control is prohibited when the failure state of the front wheel system is detected, whereby the rear wheel is executed. It is possible to prevent the braking force of the front wheels from decreasing, so avoiding a large lack of the braking force of the rear wheels in the situation where the braking force of the front wheels does not occur. It can be prevented that only deceleration is obtained.

According to the second aspect of the present invention, the detecting means determines that the front wheel system is in a failed state when the deceleration of the vehicle with respect to the brake pedal force is smaller than a predetermined value. In this case, the failure state can be detected with certainty.

According to the third aspect of the present invention, when the detection means is executing the spin suppression control, the master cylinder pressure of the braking device is equal to or higher than a predetermined value, and the front wheels are not in the ABS control, the front wheel system fails. Since the state is determined to be the state, even in this case, when the front wheel system is in a failed state, the failed state can be reliably detected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a hydraulic circuit and an electric control device of an embodiment of a behavior control device according to the present invention.

FIG. 2 is a flowchart showing a first half of a behavior control routine in the embodiment.

FIG. 3 is a flowchart showing the latter half of a behavior control routine in the embodiment.

FIG. 4 is a flowchart showing a routine for setting flags Fa and Fb in the embodiment.

FIG. 5 is a flowchart showing a flag F1 setting routine in the embodiment.

FIG. 6 is a flowchart showing a flag F2 setting routine in the embodiment.

FIG. 7 is a flowchart showing a flag F3 setting routine in the embodiment.

FIG. 8 is a graph showing a relationship between a spin state amount SS and a slip ratio target value Rssfo of a front wheel on the outside of a turn.

FIG. 9 is a graph showing a relationship between a drift-out state amount DS and a slip ratio target value Rsall of the entire vehicle.

FIG. 10 is a graph showing the relationship between the target slip amount SPi and the duty ratio Dri of each wheel.

[Explanation of symbols]

 10 ... Braking device 14 ... Master cylinder 16 ... Hydro booster 20, 22, 32, 34 ... Brake hydraulic pressure control device 28, 50FL, 50FR ... Control valve 44 ... Switching valve 44FL, 44FR, 64RL, 64RR ... Wheel cylinder 70 ... Electric type Control device 76 ... Vehicle speed sensor 78 ... Lateral acceleration sensor 80 ... Yaw rate sensor 82 ... Steering angle sensor 84 ... Longitudinal acceleration sensor 86FL to 86RR ... Wheel speed sensor 88 ... Pressure sensor

Claims (3)

[Claims] 1. A brake system comprising a front wheel system and a rear wheel system.
A vehicle behavior control device that has a braking device configured in a system and reduces the braking force of the rear wheels to perform spin suppression control when the vehicle is in a spin state detects the failure state of the front wheel system. And a means for prohibiting execution of the spin suppression control when a failure state of the front wheel system is detected. 2. The vehicle behavior control device according to claim 1, wherein the detection means determines that the front wheel system is in a failed state when the deceleration of the vehicle with respect to the brake pedal force is smaller than a predetermined value. A vehicle behavior control device characterized by being provided. 3. The vehicle behavior control device according to claim 1, wherein the vehicle has an ABS device, the detecting means is executing the spin suppression control, and the master cylinder pressure of the braking device is a predetermined value. The vehicle behavior control device is configured to determine that the front wheel system is in a failed state when the front wheels are not under ABS control.