JPH06278589A - Anti-skid braking device for vehicle - Google Patents

Abstract

PURPOSE:To improve running ability and driving stability on a trodden snow road or the like by restraining increase in the rough road index immediately after start of braking or start of ABS control. CONSTITUTION:At the processing for setting a rough road judging threshold value in a rough road index calculation processing, a timer T1 is started at start of braking (S70, S71), a timer T2 is started at start of ABS control (S72, S73) and in case where T1<=300ms or T2>=300ms (S74: YES), a rough road judging threshold value A0 is set at a prescribed value A1, while in the other cases, the rough road judging threshold value A0 is set at a prescribed value A2 (wherein, A1>A2) at S75. Thus, the rough road judging criteria immediately after the start of braking or immediately after start of ABS control is relaxed to correct brake oil pressure downward.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiskid brake device for suppressing an excessive braking force when a vehicle is being braked, and more particularly to an antiskid brake device in which the rough road judgment standard is relaxed at the beginning of the start of antiskid control.

[0002]

2. Description of the Related Art As a vehicle braking system, an anti-skid brake device has been put into practical use, which prevents a wheel from being locked or a skid state from occurring during braking. This type of anti-skid brake device controls a wheel speed sensor that detects the wheel speed of four wheels, an electromagnetic control valve that adjusts the brake hydraulic pressure, and an electromagnetic control valve based on the wheel speed detected by the wheel speed sensor. And a control device. This control device, for example, determines the acceleration / deceleration of the wheel based on the detected wheel speed, and when the wheel deceleration becomes equal to or less than a predetermined value, the electromagnetic control valve is pressure-reduced to reduce the braking pressure, and the braking pressure is reduced. When the wheel speed increases and the wheel acceleration reaches a predetermined value, the braking pressure is increased by increasing the pressure of the control valve.

Such a series of braking pressure control (hereinafter referred to as AB
(S control) is continued until the vehicle stops, for example, to prevent the wheels from being locked or skided during sudden braking, so that the vehicle can be stopped at a short braking distance while ensuring directional stability. Becomes by the way,
In the normal ABS control, the wheels are more likely to slip than when running on a bad road such as a gravel road or a snow-covered road. Therefore, the bad road condition of the road is determined by using the wheel speed and the bad road is determined. Various control amounts of the ABS control are changed according to the state so that the brake hydraulic pressure is controlled to increase in a bad road. For example, in Japanese Unexamined Patent Publication No. 64-106762, a bad road index indicating a bad road condition is calculated based on the output value of the wheel speed detecting means, and the smaller the bad road index, the closer to the original shape of the control variable. A wheel behavior detecting device is described in which filter means for outputting a waveform is provided and the brake hydraulic pressure is controlled by an output signal of the filter means.

[0004]

In the conventional anti-skid brake control, a bad road is always judged based on the same bad road judgment standard. By the way, immediately after the start of braking or immediately after the start of ABS control, the wheel speed is likely to fluctuate, so that the rough road index indicating the degree of the rough road tends to be large, and the brake hydraulic pressure is based on the large rough road index. Will be set higher. And, especially when the vehicle is traveling on a snow-covered road, immediately after the start of braking or AB
If the rough road index becomes large immediately after the start of the S control and the brake oil pressure is controlled to be high, there is a problem that the slip amount increases and the running stability and the running performance deteriorate. The technique disclosed in the above publication has a problem in that, as the road becomes rougher, the output of the filter means is smoothed away from the original shape of the control variable, which makes it difficult to perform ABS control according to the rough road index. An object of the present invention is to provide an anti-skid brake device for a vehicle that can suppress an increase in the rough road index immediately after the start of braking or immediately after the start of ABS control.

[0005]

According to another aspect of the present invention, there is provided an anti-skid brake device for a vehicle, which comprises a wheel speed detecting means for detecting a wheel rotation speed, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure, and a wheel speed detecting means. In a vehicle anti-skid brake device equipped with an anti-skid control means for operating the hydraulic pressure adjusting means based on the wheel speed, based on the wheel speed detected by the wheel speed detection means and a predetermined rough road determination standard, A rough road determination means for determining the degree of a rough road for use in setting the control threshold value in the anti-skid control means,
It is provided with a judgment reference relaxing means for relaxing the rough road judgment standard in the rough road judging means for a predetermined time from the braking start time and for a predetermined time from the control start time by the anti-skid control means.

According to a second aspect of the present invention, there is provided an anti-skid brake system for a vehicle according to the first aspect, wherein the bad road determination means determines a bad road by a rate of change in wheel speed obtained from wheel speeds in a predetermined sampling period. It is configured to determine the degree of a bad road by using the number of times equal to or more than the value. The anti-skid brake device for a vehicle according to claim 3,
The apparatus according to claim 2, wherein the determination criterion relaxing means is configured to relax the rough road determination criterion by increasing the rough road determination threshold value.

According to a fourth aspect of the present invention, there is provided an anti-skid brake device for a vehicle according to the second aspect, wherein the determination reference relaxing means is configured to relax the rough road determination reference by lengthening the predetermined sampling period. It is a thing.
According to a fifth aspect of the present invention, in the anti-skid brake device for a vehicle according to the second aspect, the determination reference easing means is configured to reduce the rough road determination reference by changing the counting method of the number of times. .

According to a sixth aspect of the present invention, there is provided an antiskid brake device for a vehicle, comprising wheel speed detecting means for detecting a rotational speed of a wheel.
An antiskid brake device for a vehicle, comprising: an oil pressure adjusting means for adjusting a brake oil pressure; and an antiskid control means for activating the oil pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In the rough road determination means for determining the degree of rough road based on the wheel speed and the predetermined rough road determination standard, and the determination result of the rough road determination means, for a predetermined time from the braking start time, And a correction means for instructing the antiskid control means to correct the brake hydraulic pressure in a decreasing direction for a predetermined time from the start of control by the antiskid control means.

[0009]

According to the anti-skid brake device for a vehicle of the present invention, in the anti-skid brake device including the wheel speed detecting means, the hydraulic pressure adjusting means, and the anti-skid control means, there is provided a rough road judging means. A judgment criterion easing means is provided, and based on the detected wheel speed and a predetermined rough road judgment criterion, the degree of the rough road to be used for setting the control threshold value in the anti-skid control means is judged, and from the braking start time. Since the rough road judgment standard is relaxed for a predetermined time and for a predetermined time from the control start time by the anti-skid control means, the degree of the rough road is judged to be gentle during the above both predetermined times. As a result, the control threshold value is set as in the case where the degree of the bad road is low, so that the running performance and the running stability on the snowy road and the like are improved. Moreover, after both the predetermined times have elapsed, the rough road is judged according to the normal rough road judgment standard, so that it is possible to accurately judge the extent of the bad road and perform anti-skid control according to the extent of the bad road. .

According to another aspect of the vehicle anti-skid brake device of the present invention, wheel speed detecting means, hydraulic pressure adjusting means,
In an anti-skid brake device equipped with an anti-skid control means, a bad road determination means and a correction means are provided, and the degree of a bad road is determined based on the detected wheel speed and a predetermined bad road determination standard, and the determination result Is used to instruct the antiskid control means to correct the brake hydraulic pressure in the decreasing direction for a predetermined time from the braking start time and for a predetermined time from the control start time by the antiskid control means. Since the brake oil pressure is corrected in the decreasing direction during the predetermined time, the running performance and running stability on a snowy road or the like are improved. Moreover, after both the predetermined times have elapsed, the rough road is judged according to the normal rough road judgment standard, so that it is possible to accurately judge the extent of the bad road and perform anti-skid control according to the extent of the bad road. .

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in the vehicle according to this embodiment, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and 4 are driving wheels, and the output torque of the engine 5 from the automatic transmission 6 is changed. Propeller shaft 7, differential 8 and left and right drive shafts 9,10
It is configured to be transmitted to the left and right rear wheels 3 and 4 via. Each of the wheels 1 to 4 includes a disc 11a to 14a that rotates integrally with the wheel, and a braking device 11b that includes a caliper 11b to 14b that receives the supply of a braking pressure to brake the rotation of the disc 11a to 14a. 14 are provided respectively, and a brake control system that operates these braking devices 11 to 14
15 are provided.

The brake control system 15 includes a booster device 17 for increasing the stepping force on the brake pedal 16 by the driver.
And a master shilling 18 for generating a braking pressure according to the stepping force increased by the booster 17. Front wheel braking pressure supply line 19 from this master shilling 18
Is branched into two routes, and the front wheel branch braking pressure line 19
a, 19b are connected to the calipers 11a, 12a of the brake devices 11, 12 of the left and right front wheels 1, 2 respectively, and the brake device 11 of the left front wheel 1 is connected.
One branch brake pressure line 19a for the front wheel, which is connected to, is provided with a first valve unit 20, which includes an electromagnetic on-off valve 20a and an electromagnetic relief valve 20b, which leads to the braking device 12 for the right front wheel 2. Branch braking pressure line 19 for the other front wheel
Similarly to the first valve unit 20, a second valve unit 21 including an electromagnetic on-off valve 21a and an electromagnetic relief valve 21b is also provided at b.

On the other hand, the rear wheel braking pressure supply line 22 from the master cylinder 18 is connected to the first and second valve units 20, 2.
As in the case of 1, a third valve unit 23 including an electromagnetic on-off valve 23a and an electromagnetic relief valve 23b is provided. The rear wheel braking pressure supply line 22 is branched into two paths on the downstream side of the third valve unit 23, and the rear wheel branch braking pressure lines 22a and 22b are connected to the brake devices 13 of the left and right rear wheels 3 and 4. , 14 calipers 13b, 14b are connected respectively. The brake control system 15 includes a first channel that variably controls the braking pressure of the braking device 11 for the left front wheel 1 via the first valve unit 20, and a braking device 12 for the right front wheel 2 via the second valve unit 21. Via the second channel that variably controls the braking pressure and the third valve unit 23, the left and right rear wheels
A third channel for variably controlling the braking pressure of both the braking devices 3, 14 is provided, and the first to third channels are controlled independently of each other.

The brake control system 15 includes the first to
A control unit 24 for controlling the third channel is provided. The control unit 24 includes a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16 and a steering angle sensor 26 for detecting a steering angle of the steering wheel. Receiving the steering angle signal and the wheel speed signals from the wheel speed sensors 27 to 30 respectively detecting the rotational speeds of the respective wheels, the braking pressure control signals corresponding to these signals are sent to the first to third valve units.
By outputting to 20,21,23 respectively, braking control for slips of the left and right front wheels 1,2 and rear wheels 3,4, that is, AB
The S control is performed in parallel for each of the first to third channels.

The control unit 24 determines the first to the first based on the wheel speed indicated by the wheel speed signal from each wheel speed sensor 27-30.
Open / close valves 20a, 21a, 23 in the third valve units 20, 21, 23
By controlling the opening and closing of a and the relief valves 20b, 21b, and 23b by duty control, the braking force is applied to the front wheels 1, 2 and the rear wheels 3, 4 with the braking pressure according to the slip condition. There is. In addition, the first to third valve units
The brake oil discharged from the relief valves 20b, 21b, 23b of 20, 21, 23 is returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

In the ABS non-controlled state, no braking pressure control signal is output from the control unit 24, and the relief valves 20b, 21b and 23b in the first to third valve units 20, 21 and 23 are respectively, as shown in the figure. Since the valves are held closed and the on-off valves 20a, 21a, 23a of the units 20, 21, 23 are kept open, respectively, the braking pressure generated in the master cylinder 18 in response to the stepping force of the brake pedal 16 is applied to the front wheel braking. The left and right front wheels 1 and 2 via the pressure supply line 19 and the rear wheel braking pressure supply line 22.
Also, the braking force is supplied to the braking devices 11 to 14 of the rear wheels 3 and 4, and the braking force corresponding to these braking pressures is directly applied to the front wheels 1 and 2 and the rear wheels 3 and 4.

Next, an outline of the brake control performed by the control unit 24 will be described. Control unit 24
Indicates the wheel speed Vw1 to which the signals from the wheel speed sensors 27 to 30 indicate.
Based on Vw4, decelerations DVw1 to DVw4 and accelerations AVw1 to AVw4 for each wheel are calculated, respectively. Explaining the method of calculating the acceleration or deceleration, the control unit 24 divides the difference between the previous value of the wheel speed and the current value by the sampling cycle Δt (for example, 7 ms), and then converts the result into the gravitational acceleration. Is updated as the current acceleration or deceleration.

Further, the control unit 24 executes a predetermined rough road judgment processing to judge whether or not the traveling road surface is a bad road. Explaining the outline of the rough road determination processing, as shown in FIG. 7, the wheel acceleration or the wheel deceleration is not less than the rough road determination threshold A0 for a predetermined period T0 for each wheel corresponding to each channel. When the number of times is 0 to 3, the bad road flag Fak is set to 0, when the number of times is 4 to 7, the bad road flag Fak is set to 1, and the number of times is When it is 8 or more, the rough road flag Fak is set to 2. However, the brake switch is OFF
During the predetermined period after the change from ON to ON and the predetermined period after the ABS control is started, the value of the rough road determination threshold value A0 is set larger than that in the normal case in order to relax the rough road determination standard. . The rough road determination processing (bad road index setting processing) will be described later with reference to FIGS. 5 and 6.

Further, the control unit 24 includes a rear wheel 3, which represents wheel speed and acceleration / deceleration for the third channel.
Select 4. In this embodiment, the rear wheels when slipping
Taking into account the detection error of the wheel speed sensors 29, 30 of 3 and 4, the smaller wheel speed of both wheel speeds is selected as the rear wheel speed, and the acceleration and deceleration obtained from that wheel speed are calculated as the rear wheel speed. It will be selected as the wheel acceleration and the rear wheel deceleration.

Further, the control unit 24 estimates the road surface friction coefficient for each channel and, in parallel with it, calculates the pseudo vehicle speed. The control unit 24 controls the wheel speeds of the rear wheels obtained from the signals from the wheel speed sensors 29 and 30 and the wheel speeds of the left and right front wheels 1 and 2 indicated by the signals from the wheel speed sensors 27 and 28 and the pseudo vehicle body speed. From the above, the slip ratios for the first to third channels are calculated respectively. In that case, the slip ratio is calculated by the following relational expression. Slip rate = (wheel speed / pseudo vehicle speed) × 100 Therefore, as the deviation of the wheel speed from the pseudo vehicle speed increases, the slip rate decreases, and the slip tendency of the wheel increases.

Next, the control unit 24 includes
Various control threshold values used for controlling the third channel are set, and the lock determination processing for each channel is performed using these control threshold values, and the first to third valve units 2
The phase determination process for defining the control amount for 0, 21, 23 and the cascade determination process are performed.

The lock determination process will now be described. For example, in the lock determination process for the first channel for the left front wheel, the control unit 24
First, the current value of the continuation flag Fcn1 for the first channel is set as the previous value, and then the pseudo vehicle body speed Vr and the wheel speed Vw1 are set to predetermined conditions (for example, Vr <5 Km / H, Vw1 <
7.5 Km / H) is satisfied, and when these conditions are satisfied, continuation flag Fcn1 and lock flag F
Each lok1 is reset to 0, and if not satisfied, it is determined whether the lock flag Flok1 is set to 1 or not. If the lock flag Flok1 is not set to 1, the lock flag Flok1 is set to 1 under a predetermined condition (for example, when the pseudo vehicle body speed Vr is higher than the wheel speed Vw1).

On the other hand, when the control unit 24 determines that the lock flag Flok1 is set to 1, for example, the phase value P1 of the first channel is set to 5 indicating the phase V and the slip ratio S1 is 90%. If it is larger, the continuation flag Fcn1 is set to 1.
The lock determination process is similarly performed for the second and third channels.

Explaining the outline of the phase determination processing, the control unit 24 compares the control threshold values set according to the running state of the vehicle with the wheel acceleration / deceleration and the slip ratio to determine the ABS non-controlled state. Showing phase 0, showing a pressure increasing state during ABS control, phase I showing a holding state after pressure increasing, phase II showing a depressurized state, phase IV showing a sudden depressurized state and holding state after depressurizing. The phase V is selected. In the cascade determination process, particularly on a low friction road surface such as ice burn, even if a small braking pressure is applied to the wheels, the wheels are easily locked. Therefore, the cascade locked state in which the wheels are continuously locked in a short time is determined. The cascade flag Fcs is set to 1 when a predetermined condition in which cascade lock is likely to occur is satisfied.

In this way, the control unit 24 sets a control amount according to the phase value P1 set for each channel, and then sends a braking pressure control signal according to the control amount to the first to third valve units 20. , 21 and 23 are output respectively. As a result, the first to third valve units 20, 21,
The braking pressure of the front wheel branch braking pressure lines 19a, 19b and the rear wheel branch braking pressure lines 22a, 22b on the downstream side of 23 is increased or decreased, or is maintained at the pressure level after the increase or decrease. .

The process of estimating the road surface friction coefficient is performed, for example, by
The first channel is performed as follows based on the flowchart of FIG. In the figure, the reference numeral Si (i = 1,
2, 3, ...) Show each step. The control unit 24 reads various data (S
1) Next, it is determined whether or not the ABS flag Fabs is set to 1 (that is, whether or not ABS control is in progress) (S2). This ABS flag Fabs is, for example,
Lock flags Flok1, Flok2, Flok3 of the third channel
Is set to 1 when any one of them is set to 1, and is reset to 0 when the brake switch 25 is switched from the ON state to the OFF state. When it is determined that the ABS flag Fabs is not set to 1, the friction coefficient value Mu1 is set to 3 indicating a high friction road surface in S3.

When the control unit 24 determines in S2 that the ABS flag Fabs is set to 1, that is, when the ABS control is being performed,
In S4, the wheel deceleration DVw1 in the previous cycle is -20
If it is Yes as a result of the determination, it is also determined in S5 whether the wheel acceleration AVw1 in the previous cycle is greater than 10 G. If the result of the determination is No, in S6. The friction coefficient value Mu1 is set to 1 indicating a low friction road surface. On the other hand, the control unit 24 determines that the wheel deceleration DVw1 is -2 in S4.
When it is determined that it is not less than 0 G, S5 is skipped and the process proceeds to S7, it is determined whether the wheel acceleration AVw1 is greater than 20 G, and if the result of the determination is Yes, 3 is set as the friction coefficient value Mu1. On the other hand, when the determination is No, the friction coefficient value Mu1 is set to 2 indicating a medium friction road surface in S9. The road friction coefficient is similarly estimated for the second and third channels.

Next, the calculation process of the pseudo vehicle body speed Vr will be described with reference to the flowchart of FIG. First, the control unit 24 reads various data (S2
0), and then the wheel speed Vw1 ~ indicated by the signals from the sensors 27 ~ 30
The maximum wheel speed Vwm is calculated from Vw4 (S21), and the maximum wheel speed change amount ΔVwm per sampling cycle Δt of the maximum wheel speed Vwm is calculated (S22). Next, the control unit 24 reads the vehicle speed correction value CVr corresponding to the representative friction coefficient value Mu (minimum value of the first to third channels) from the map shown in FIG. 4 in S23, and S24
The maximum wheel speed change amount ΔVwm at the vehicle speed correction value CVr
It is determined whether or not the following.

As a result of the determination, when it is determined that the wheel speed change amount ΔVwm is less than or equal to the vehicle body speed correction value CVr, S2
5, the vehicle speed correction value C from the previous value of the pseudo vehicle speed Vr
The value obtained by subtracting Vr is replaced with the current value. Therefore, the pseudo vehicle body speed Vr decreases at a predetermined gradient according to the vehicle body speed correction value CVr. On the other hand, the control unit 24
In S24, the wheel speed change amount ΔVwm is set to the vehicle speed correction value CV.
When it is determined that the maximum wheel speed Vwm is greater than r, that is, when the maximum wheel speed Vwm shows an excessive change, it is determined in S26 whether the value obtained by subtracting the maximum wheel speed Vwm from the pseudo vehicle body speed Vr is a predetermined value V0 or more. That is, it is determined whether or not there is a large difference between the maximum wheel speed Vwm and the pseudo vehicle body speed Vr. Then, when there is no large difference, the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the pseudo vehicle body speed Vr is replaced with the current value in S27.

Further, when there is a large difference between the maximum wheel speed Vwm and the pseudo vehicle body speed Vr, the control unit 24 replaces the maximum wheel speed Vwm with the pseudo vehicle body speed Vr in S27. In this way, the pseudo vehicle body speed Vr of the vehicle is updated every sampling period Δt according to the wheel speeds Vw1 to Vw4.

Next, the rough road index calculation processing executed by the control unit 24 will be described with reference to the flowcharts of FIGS. The rough road index calculation process is a process individually executed for each of the first to third channels, but in this embodiment, the process for the first channel will be described as an example. The rough road index is an index showing the degree of a bad road on a running road and corresponds to the bad road flag Fak. In the control threshold setting process of FIG. The control threshold value is corrected according to the value of the rough road flag Fak. After starting this process, various data are read (S50), and then
A rough road determination threshold value setting process is executed (S51).

Here, the rough road determination threshold value setting process will be described with reference to the flowchart of FIG. First, it is determined whether or not the brake switch has changed from OFF to ON (that is, whether or not the brake pedal has been depressed) (S70). If the determination result is Yes, the timer T
1 is reset and then started (S71), and then the process proceeds to S74. On the other hand, if the determination result in S70 is No, AB
It is determined whether or not the S control is started (S72).
When the BS control is started, the lock flag Flok1 is switched from 0 to 1, so that the determination is made based on the lock flag Flok1. If the result of the determination in S72 is Yes, the timer T2 is reset and then started (S73), and then the process proceeds to S74. If the result of the determination is No, the process directly proceeds to S74.

Next, the count time T1 of the timer T1 is 3
Whether or not it is 00 ms or less, or the count time T of the timer T2
2 is less than or equal to 300 ms (S74). If the determination result is Yes, the bad road determination threshold value A0 is set to the predetermined value A1, and if the determination result in S74 is No, it is The road determination threshold value A0 is set to a predetermined value A2 smaller than the predetermined value A1. However, the brake switch is OF
For a predetermined time (300 ms in this embodiment) from the time of changing from F to ON, and a predetermined time (300 ms in this embodiment) from the time when the ABS control is started, the rough road judgment criterion is set. The predetermined value A1 is set to a value larger than the predetermined value A2 in order to alleviate and correct the brake oil pressure to the increase side.

As described above, the rough road judgment threshold value A0
5 is set, it is determined in S52 of FIG. 5 whether or not the flag Fa is 0. Since the flag Fa is initially set to 0, the first determination result is Yes and S53.
Move to. In S53, the counter I is cleared, the timer T is reset and then started, and then S
At 54, the flag Fa is set to 1, and then S5.
Go to 5. When the determination result of S52 is No, S53
Then, S54 is skipped and the process proceeds to S55. In S55, the wheel acceleration A of the left front wheel 1 corresponding to the first channel
Vw1 (however, including wheel deceleration) is calculated by differentiating the wheel speed Vw1 with respect to time.

Next, in S56, the wheel acceleration AVw1
It is determined whether the absolute value of is greater than or equal to the rough road determination threshold value A0, and if the determination result is Yes, the counter I is incremented (S57) and the process proceeds to S58, and when the determination result is No. Skips S57 and moves to S58 (see FIG. 7). In S58, it is determined whether or not the count time T of the timer T is equal to or longer than the predetermined time T0, and the predetermined time T0 is reached.
Until the time elapses, the process returns from S58 repeatedly, and the counter I counts the number of times that the absolute value of the wheel acceleration AVw1 becomes equal to or greater than the rough road determination threshold A0 during the predetermined time T0.

When the predetermined time T0 has elapsed, the process proceeds from S58 to S59, the flag Fa is reset to 0 for the next predetermined time and counting, and then S60 to S60.
At 64, based on the count value I of the counter I, I
The bad road flag Fak (bad road index) is set to 0 when ≦ 3, the bad road flag Fak is set to 1 when 3 <I ≦ 7, and the bad road is set when 7 <I. The flag Fak is set to 2. Thus, the rough road flag F is set every predetermined time T0.
The rough road index calculation processing in which ak is set to any one of 0, 1, and 2 is executed. However, the second channel, the third
Similarly, the rough road index calculation processing is executed for the channels. Then, in the rough road determination threshold value setting process of FIG. 6, for a predetermined time (300 ms in this embodiment) from the time when the brake switch changes from OFF to ON,
Further, during a predetermined time (300 ms in this embodiment) from the time when the ABS control is started, the rough road determination threshold value A0 is set to be larger than the predetermined value A2 applied at a time other than these periods. Since the predetermined value A1 is set, the rough road determination standard is relaxed during this period.

Next, the process of setting various control threshold values will be described with reference to the flowchart of FIG. The control threshold setting process is executed independently for each channel. Here, the control threshold setting process for the first channel for the left front wheel will be described. The control unit 24 reads various data in S31,
Next, in S32, as shown in FIG. 9, a representative friction coefficient value Mu obtained from the wheel speeds Vw1 to Vw4 is determined from a table in which the vehicle speed range and the road surface friction coefficient are preset.
And a running condition parameter corresponding to the pseudo vehicle speed Vr. Here, the minimum value of the friction coefficient values Mu1 to Mu3 of the first to third channels is used as the representative friction coefficient value Mu. For example, when the representative friction coefficient value Mu is 1 indicating the low friction road surface and the pseudo vehicle body speed Vr belongs to the medium speed range, the LM for the medium speed low friction road surface is set as the traveling state parameter.
2 will be selected.

Further, the bad road flag Fak indicates a bad road condition 1
When it is set to, as shown in FIG. 9, the traveling state parameter corresponding to the pseudo vehicle body speed Vr is selected. In this case, for example, when the pseudo vehicle body speed Vr belongs to the medium speed range, H for medium speed and low friction road surface is set as the traveling state parameter.
M2 is forced to be selected. This is because the road surface friction coefficient tends to be estimated to be small because the wheel speed fluctuates greatly when the vehicle runs on a rough road.

After selecting the running condition parameters, the control unit 24 reads out various control threshold values corresponding to the running condition parameters from the control threshold value setting table shown in FIG. 10 in S32. Here, as various control threshold values, as shown in FIG. 10, 1-2 intermediate deceleration threshold value B12 for switching determination from phase I to phase II, switching determination from phase II to phase III 2-3 intermediate slip ratio threshold value Bsg, 3-5 intermediate deceleration threshold value B35 for switching determination from phase III to phase V, 5-5 for switching determination from phase V to phase I.
The 1-slip-rate threshold value Bsz and the like are set for each running state parameter.

In this case, the deceleration threshold value that greatly influences the braking force is set so that the braking performance when the road surface friction coefficient is large and the control response when the road surface friction coefficient is small are compatible with each other at a high level. , As the level of the representative friction coefficient value Mu decreases, that is, as the road surface friction coefficient decreases, 0
It is set to approach G. Here, when the control unit 24 selects LM2 for the medium speed / low friction road surface as the traveling state parameter, as shown in the column of LM2 in the control threshold setting table of FIG. Speed threshold B12, 2-3 intermediate slip ratio threshold Bsg, 3-5 intermediate deceleration threshold B35, 5
As the -1 slip ratio threshold value Bsz, -0.5G, 90
The respective values of%, 0G and 90% are read out respectively.

Next, the control unit 24 sets S33.
At, it is determined whether or not the representative friction coefficient value Mu is set to 3, which indicates a high friction road surface. When it is determined as Yes, it is determined at S34 whether the rough road flag Fak is set to 0 or not. As a result of the determination, the rough road flag Fak
If is set to 0, the process proceeds to S35, it is determined whether the absolute value of the steering angle θ indicated by the steering angle signal is smaller than 90 °, and when the absolute value of the steering angle θ is not smaller than 90 °, ,
In S36, control threshold correction processing is performed according to the steering angle θ. This control threshold value correction processing is performed based on the control threshold value correction table illustrated in FIG.

That is, in the control threshold value correction table of FIG. 11, in order to ensure the steerability when the steering wheel operation amount is large when the road is not a bad road with low friction and medium friction,
The value obtained by adding 5% to each of the 3 intermediate slip ratio threshold value Bsg and the 5-1 intermediate slip ratio threshold value Bsz is the final 1
-2 slip ratio threshold value Bsg and final 5-1 slip ratio threshold value Bsz are set, and other intermediate threshold values are set as they are as final threshold values.

On a bad road with high friction (the bad road flag Fak is 1
Or 2), in order to ensure the running performance when the steering wheel operation amount is small, 5% or 8% are respectively set from the 2-3 intermediate slip ratio threshold value Bsg and the 5-1 intermediate slip ratio threshold value Bsz. The subtracted values are set as the final 1-2 slip ratio threshold Bsg and the final 5-1 slip ratio threshold Bsz. Also, the high-friction rough road flag Fak is 2
In order to secure the steerability when the steering wheel operation amount is large, 2-3 intermediate slip ratio threshold values Bsg and 5-
The values obtained by subtracting 5% from the one intermediate slip ratio threshold Bsz are set as the final 1-2 slip ratio threshold Bsg and the final 5-1 slip ratio threshold Bsz. Next, when the determination result in S35 is No, each of the intermediate threshold values is directly set as the final threshold value.

On the other hand, the control unit 24 uses S34
When it is determined that the rough road flag Fak is set to 1 or 2, in S37, the relation between the rough road flag Fak and the steering angle θ is determined based on the control threshold correction table of FIG. The values obtained by correcting the 2-3 intermediate slip ratio threshold Bsg and the 5-1 slip ratio threshold Bsz, respectively, are used as the final 2-3 intermediate slip ratio threshold Bsg and the final 5-1 slip ratio threshold. A correction process for setting as Bsz is executed, and then, in S38, based on the control threshold correction table of FIG. 11, 1-2 intermediate deceleration threshold B12 to 1.0G (when Fak = 1) or 1.2. G (Fa
A correction process is performed in which a value obtained by subtracting (when k = 2) is set as the final 1-2 deceleration threshold value B12.

This is because the wheel speed sensors 27 to 30 are likely to make erroneous detections at the time of determining a bad road, so that the response of the control is delayed and a good braking force is secured. Incidentally, other intermediate threshold values are set as they are as final threshold values. Further, when the control unit 24 determines in S33 that the representative friction coefficient value Mu is not 3, the control unit 24 proceeds to S35. The control thresholds are set for the second and third channels as in the case of the first channel.

Next, regarding the operation of the ABS control described above, the ABS control for the first channel will be taken as an example.
This will be described with reference to the time chart of FIG. In the ABS non-controlled state during deceleration, the braking pressure generated in the master cylinder 18 is gradually increased by the depression operation of the brake pedal 16, so that the wheel speed Vw1 of the left front wheel 1 changes as shown in FIG. 12 (c). When the rate (deceleration DVW1) reaches -3G, the lock flag Flok1 of the first channel is set to 1 as shown in FIG.
Shift to BS control.

In the first cycle immediately after the start of this control, the friction coefficient value Mu1 is set to 3 indicating a high friction road surface (see S2 and S3 in FIG. 2), so the bad road flag Fak
Is 0 and the pseudo vehicle body speed Vr calculated from the wheel speed Vw1 belongs to, for example, the medium speed range, the HM2 for medium speed and high friction road surface is selected as the traveling state parameter, and various controls are performed based on this traveling state parameter. The threshold is set. That is, various control threshold values preset in the HM2 column in the control threshold setting table of FIG. 10 are read.

Next, the slip ratio S obtained from the wheel speed Vw1
1, the wheel deceleration DVw1, the wheel acceleration AVw1 and various control threshold values are compared. In this case, as shown in FIG. 7D, the phase value P1 is changed from 0 to 2, so the braking pressure is changed. Is maintained at the level immediately after the pressure increase, as shown in FIG. Then, the slip ratio S1 is 2
-3 When the slip value falls below the intermediate slip ratio threshold value Bsg (90%), the phase value P1 is changed from 2 to 3.
At this time, the relief valve 20b of the first valve unit 20 is turned on / off in accordance with a predetermined duty ratio, and the braking pressure decreases with a predetermined gradient from the time tb as shown in FIG. As a result, the braking force gradually decreases, and the rotational force of the front wheels 1 begins to recover. When the wheel deceleration DVw1 further decreases to the 3-5 intermediate deceleration threshold value B35 (0G) as the braking pressure continues to decrease, the phase value P1 is changed from 3 to 5, as shown in FIG. Then, from that time tc, the braking pressure is maintained at the level after the pressure reduction.

When the state of this phase V continues and the slip ratio S1 exceeds the 5-1 slip ratio threshold Bsz (90%), the continuation flag Fcn is set as shown in FIG.
l is set to 1. As a result, the ABS control on the first channel shifts from the time td to the second cycle. At this time, the phase value P1 is forcibly changed to 1. Immediately after the transition to the phase I, the opening / closing valve 20a of the first valve unit 20 has a duty ratio of 100% according to the initial rapid pressure increase time Tpz set based on the duration of the phase V in the first cycle. The braking pressure is steeply increased as shown in (e) of the figure. After the initial rapid pressure increase time Tpz, the on-off valve 20a is turned on / off according to a predetermined duty ratio. The braking pressure gradually increases with a gentler gradient. Thus, immediately after the shift to the second cycle, the braking pressure is reliably increased, and a good braking pressure is secured.

On the other hand, after the second cycle, as shown in FIG.
As shown in the flow chart of FIG. 5, an appropriate friction coefficient value Mu1 is determined in accordance with the wheel deceleration DVw1 and the wheel acceleration AVw1 in the previous cycle, and it corresponds to the running state parameter corresponding to these friction coefficient value and the vehicle body speed Vr. Since various control threshold values to be set are selected from the control threshold value setting table of FIG. 8, precise control of the braking pressure according to the running state is performed. Then, in the state of phase V in the second cycle, for example, the slip ratio S1 is 5-
When it is determined that the value is larger than the 1-slip ratio threshold value Bsz, the phase value P1 is set to 1 and the process proceeds to the third cycle. Further, as described with reference to FIG. 8, the control threshold value is corrected in accordance with the rough road index and the magnitude of the steering angle θ when the rough road is determined, and the control threshold is representative even in the non-bad road state or the rough road determination. When the friction coefficient value Mu is not 3 indicating a high friction road surface, the control threshold value is similarly corrected when the steering angle θ shows a relatively large value, so that the braking pressure becomes more precise according to the running state. Will be controlled.

Here, as described with reference to FIGS. 5 and 6, a predetermined time (300 ms in this embodiment) after the start of braking.
During this period and during a predetermined time (300 ms in this embodiment) after the start of the ABS control, the rough road determination threshold value A0 is set higher than the other times, that is, the rough road determination standard is relaxed. It has become. Further, in the control threshold correction table of FIG. 11, the larger the bad road flag Fak (bad road index), the smaller the thresholds B12, Bsg, Bsz are corrected, and the correction is performed in the increasing direction of the brake hydraulic pressure. That is, as the rough road index becomes smaller, the correction is performed in the direction of decreasing the brake oil pressure. Therefore, for a predetermined time after the start of braking, and A
During a predetermined time after the start of the BS braking, the bad road index is calculated to be small and the brake hydraulic pressure is corrected in a decreasing direction, so that the running performance and running stability on a snowy road or the like are improved. Moreover, at times other than the above predetermined time, the degree of bad road is judged by the normal rough road judgment standard, and various control thresholds are set in consideration of the bad road index. According to this, ABS control can be performed.

Next, it is possible to change a part of the processing of FIGS. 5 and 6 in the above embodiment as follows. 1]
In S75 and S76 of FIG. 6, the rough road determination threshold value A0
Instead of setting, the predetermined time T0 in S58 is set to the first predetermined time t1 in S75, and the predetermined time T0 in S58 is set to the second predetermined time t2 (however, t2) in S76.
1> t2). That is, during the predetermined time after the start of braking and during the predetermined time after the start of ABS braking, the sampling period T0 counted by the counter I is set longer than the normal time to relax the rough road determination standard. And

2] Instead of setting the rough road judgment threshold value A0 in S75 and S76 of FIG. 6, the judgment in S74 is made.
When Yes, the increment of the counter I in S57 is stopped. That is, during the predetermined time after the start of braking and during the predetermined time after the start of ABS braking, the counting by the counter I is stopped to relax the rough road determination standard. Alternatively, during a predetermined time after the start of braking and during a predetermined time after the start of ABS braking, each time the judgment result of S56 is Yes, it is incremented by 1/2 in S57 and the value below the decimal point is rounded down. It is also possible to apply the value of I to S60 and S62. That is, by changing the counting method by the counter I, the rough road determination standard is alleviated.

The predetermined time of 300 ms in S74 is an example, and a predetermined time of 300 ms or less or a predetermined time of 300 ms or more may be used. Also,
The numerical value 3 in S60 and the numerical value 7 in S62 are merely examples, and other numerical values may be applied.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an anti-skid brake device for a vehicle according to an embodiment.

FIG. 2 is a flowchart of road surface friction coefficient estimation processing.

FIG. 3 is a flowchart of a pseudo vehicle speed calculation process.

FIG. 4 is a diagram of a map of vehicle body speed correction values.

FIG. 5 is a flowchart of rough road index calculation processing.

6 is a flowchart of a rough road determination threshold value setting process in S51 of FIG.

FIG. 7 is a time chart of wheel acceleration.

FIG. 8 is a flowchart of a control threshold value setting process.

FIG. 9 is a chart of a table in which running state parameters are set.

FIG. 10 is a chart of a table in which various control threshold values are set.

FIG. 11 is a chart of a table in which correction values of various control threshold values are set.

FIG. 12 is an operation time chart of the anti-skid brake device.

[Explanation of symbols]

 1, 2 front wheels 3, 4 rear wheels 11-14 brake device 15 brake control system 27-30 wheel speed sensor 20, 21, 23 1st-3rd valve unit 20a, 21a, 23a open / close valve 20b, 21b, 23b relief valve 24 control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kensuke Hayabuchi, 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) 3-1-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Narudec Within the corporation

Claims (6)

[Claims] 1. A wheel speed detecting means for detecting a rotation speed of a wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure, and an anti-skid control for operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In a vehicle anti-skid brake device having means, based on the wheel speed detected by the wheel speed detection means and a predetermined rough road determination standard, for use in setting a control threshold value in the anti-skid control means A rough road determination means for determining the degree of a rough road, and a rough road determination standard in the rough road determination means for a predetermined time from the braking start time and for a predetermined time from the control start time by the anti-skid control means An anti-skid brake device for a vehicle, comprising: a criterion reducing means. 2. The rough road judging means judges the degree of a bad road by using the number of times that the wheel speed change rate obtained from the wheel speed becomes equal to or more than a bad road judgment threshold value in a predetermined sampling period. An anti-skid brake device for a vehicle characterized by being configured. 3. The vehicle anti-vehicle according to claim 2, wherein the determination reference easing means is configured to relax the rough road determination reference by increasing the rough road determination threshold value. Skid brake device. 4. The anti-skid brake device for a vehicle according to claim 2, wherein the determination criterion relaxing means is configured to relax the rough road determination criterion by lengthening the predetermined sampling period. . 5. The anti-skid brake device for a vehicle according to claim 2, wherein the determination criterion relaxing means is configured to relax the rough road determination criterion by changing a counting method of the number of times. . 6. A wheel speed detecting means for detecting a rotation speed of a wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure, and an anti-skid control for operating the hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In a vehicle anti-skid brake device including means, a bad road determination unit that determines a degree of a bad road based on a wheel speed detected by the wheel speed detection unit and a predetermined bad road determination reference; Using the determination result of the determination means, the antiskid control means is instructed to correct the brake hydraulic pressure in a decreasing direction for a predetermined time from the braking start time and for a predetermined time from the control start time by the antiskid control means. An anti-skid brake device for a vehicle, comprising: