JP3199198B2 - Anti-skid brake system for vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid brake device for suppressing an excessive braking force when braking a vehicle, and more particularly to an anti-skid brake device having an improved technique for setting a pseudo vehicle speed.

[0002]

2. Description of the Related Art As a vehicle brake system, an anti-skid brake device has been put to practical use in which the locking or skid state of wheels during braking is prevented. This type of anti-skid brake device controls a wheel speed sensor that detects wheel speeds of four wheels, an electromagnetic control valve that adjusts brake oil pressure, and an electromagnetic control valve based on the wheel speed detected by the wheel speed sensor. A control device. This control device obtains the acceleration / deceleration of the wheel based on, for example, the detected wheel speed, and when the wheel deceleration becomes equal to or less than a predetermined value, reduces the braking pressure by controlling the pressure of the electromagnetic control valve to decrease the braking pressure. When the wheel speed increases and the wheel acceleration reaches a predetermined value, the braking pressure is increased by controlling the pressure of the control valve.

[0003] 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 skid during sudden braking, and to stop the vehicle at a short braking distance while ensuring the directional stability of the vehicle. Becomes The ABS
In the control, the pseudo vehicle speed is an important parameter because the slip ratio is obtained based on the wheel speed of each wheel and the pseudo vehicle body. In the conventional ABS control, however, the wheel speed of the four wheels is usually used. In many cases, the highest wheel speed is set as the pseudo vehicle speed.

By the way, when the brake oil pressure of the non-drive wheel is reduced on a high friction road surface, the wheel speed of the non-drive wheel recovers rapidly, and the non-drive wheel is turned off the road surface and spins up. Japanese Patent Publication No. 3-56224 discloses that the higher of the non-driven wheel speed and the pseudo vehicle speed calculated from the wheel speed is used as the pseudo vehicle speed for controlling the driving wheels. In response to a spin-up of a wheel, when a wheel acceleration of a drive wheel becomes equal to or more than a predetermined value, a wheel speed of a non-drive wheel is excluded from a pseudo vehicle speed calculation for a predetermined time after the detection. Is described.

[0005]

In the technique of setting the maximum wheel speed among the four wheel speeds as the pseudo vehicle speed as in the prior art, the braking force acting on the front wheel brake device is large. Since the amount of elastic deformation of the tire is also large, when the brake oil pressure of the front wheel is reduced by the ABS control, the PAVE phenomenon in which the wheel speed of the front wheel rapidly recovers immediately after the pressure reduction, and the wheel speed increases instantaneously. Therefore, the maximum wheel speed is selected from the front wheel speeds, and the pseudo vehicle speed is set to be higher than the actual value. As a result, the accuracy of the pseudo vehicle speed decreases, and the accuracy and reliability of the ABS control are reduced. There is a problem that the performance is reduced.

[0006] The above-mentioned publication discloses an ABS for setting a pseudo vehicle speed from the wheel speeds of two non-driven wheels.
This is a countermeasure against spin-up of non-driven wheels at the end of pressure reduction by control, and the technique disclosed in this publication cannot solve the above problem. An object of the present invention is to provide an anti-skid brake device for a vehicle that can set a pseudo vehicle body speed from wheel speeds of four wheels with high accuracy.

[0007]

According to a first aspect of the present invention, there is provided an anti-skid brake device for a vehicle, comprising: wheel speed detecting means for detecting rotation speeds of front wheels and rear wheels; hydraulic pressure adjusting means for adjusting brake oil pressure; An anti-skid control device for operating a hydraulic pressure adjusting device based on the wheel speed detected by the device, the anti-skid brake device comprising: First determination means for determining whether or not a predetermined time has elapsed; second determination means for determining whether or not a predetermined time has elapsed since the end of the pressure reduction of the right front wheel brake hydraulic pressure by the anti-skid control means; and detection by the wheel speed detection means. Wheel speed signals of the four wheels
Based on the determination result of the determination means, when a predetermined time has elapsed from the end of the pressure reduction for the brake hydraulic pressure of the left and right front wheels, the highest wheel speed of the four wheel speeds is set as the pseudo vehicle speed, Pseudo vehicle speed setting means for setting the maximum wheel speed among the wheel speeds of the wheels excluding the left and / or right front wheels that have not passed the predetermined time as the pseudo vehicle speed when the predetermined time has not elapsed. It is.

[0008]

According to the first aspect of the present invention, there is provided an anti-skid brake device having a wheel speed detecting means, a hydraulic pressure adjusting means, and an anti-skid control means. A determination means and a pseudo vehicle speed setting means are provided, and when a predetermined time has elapsed from the end of the pressure reduction of the brake hydraulic pressure of the left and right front wheels, the maximum wheel speed of the four wheel speeds is set as the pseudo vehicle speed. Also, when the predetermined time has not elapsed, since the maximum wheel speed among the wheel speeds of the wheels excluding the left and / or right front wheels that have not elapsed the predetermined time has been set as the pseudo vehicle speed, When the brake hydraulic pressure of the left and right front wheels is reduced by the ABS control, the pseudo vehicle speed is set from the abnormally high front wheel speed generated by the PAVE phenomenon. It is possible to really prevent. As a result, the accuracy of the pseudo vehicle speed can be enhanced, the accuracy and reliability of the ABS control can be enhanced, and the braking performance can be enhanced.

[0009]

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, left and right front wheels 1 and 2 are driven wheels, left and right rear wheels 3 and 4 are driving wheels, and the output torque of an engine 5 is Propeller shaft 7, differential device 8, and left and right drive shafts 9,10
And transmitted to the left and right rear wheels 3 and 4 via the. Each of the wheels 1 to 4 is provided with a disc 11a to 14a which rotates integrally with the wheel, and a brake device 11 to which calipers 11b to 14b which brake the rotation of the discs 11a to 14a when braking pressure is supplied. A brake control system for operating these brake devices 11 to 14 is provided respectively.
15 are provided.

The brake control system 15 includes a booster 17 for increasing the depression force of the brake pedal 16 by the driver.
And a master shilling 18 for generating a braking pressure corresponding 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 paths, and these front wheel branch braking pressure lines 19
a and 19b are respectively connected to calipers 11a and 12a of brake devices 11 and 12 of left and right front wheels 1 and 2, respectively.
A first valve unit 20 comprising an electromagnetic on-off valve 20a and an electromagnetic relief valve 20b is provided on one of the front-branch branch braking pressure lines 19a leading to the brake 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, b also has a second valve unit 21 including an electromagnetic on-off valve 21a and an electromagnetic relief valve 21b.

On the other hand, the first and second valve units 20 and 2 are connected to the brake pressure supply line 22 for the rear wheels from the master cylinder 18.
Similarly to 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 these rear wheel branch braking pressure lines 22a, 22b are connected to the brake devices 13 for the left and right rear wheels 3, 4. , 14 are connected to calipers 13b, 14b, respectively. The brake control system 15 includes a first channel for variably controlling the braking pressure of the brake device 11 of the left front wheel 1 via the first valve unit 20, and a brake channel 12 for the right front wheel 2 via the second valve unit 21. A left and right rear wheel via a second channel for variably controlling the braking pressure and a third valve unit 23;
There is provided a third channel for variably controlling the braking pressure of both the brake devices 13 and 14, and the first to third channels are controlled independently of each other.

The brake control system 15 has first to first
A control unit 24 for controlling the third channel is provided. The control unit 24 receives a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16 and a brake signal from a steering angle sensor 26 for detecting the 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 rotation speeds of the respective wheels, a braking pressure control signal corresponding to these signals is transmitted to the first to third valve units.
20, 21 and 23, respectively, to control the braking of the left and right front wheels 1 and 2 and the rear wheels 3 and 4 against slip, that is, AB
The S control is performed in parallel for each of the first to third channels.

The control unit 24 controls the first to first wheels based on the wheel speeds indicated by the wheel speed signals from the respective wheel speed sensors 27 to 30.
On-off valves 20a, 21a, 23 in the third valve units 20, 21, 23
a and the relief valves 20b, 21b, 23b are controlled by duty control to apply braking force to the front wheels 1, 2 and the rear wheels 3, 4 with a braking pressure according to the slip state. I have. In addition, the first to third valve units
The brake oil discharged from each of the relief valves 20b, 21b, 23b at 20, 21, and 23 is returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

In the ABS non-control state, the control pressure signal is not output from the control unit 24, and the relief valves 20b, 21b, 23b in the first to third valve units 20, 21, 23, respectively, as shown in FIG. Since the open / close valves 20a, 21a, 23a of the units 20, 21, 23 are held open, respectively, the braking pressure generated in the master cylinder 18 in accordance with the depressing force of the brake pedal 16 increases the braking pressure for the front wheels. Left and right front wheels 1 and 2 via a pressure supply line 19 and a rear wheel braking pressure supply line 22.
The braking force is supplied to the braking devices 11 to 14 of the rear wheels 3 and 4, and the braking force according 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
Are the wheel speeds Vw1 to Vw1 indicated by the signals from the wheel speed sensors 27 to 30.
Based on Vw4, decelerations DVw1 to DVw4 and accelerations AVw1 to AVw4 are calculated for each wheel. The calculation method of the acceleration or the deceleration will be described. The control unit 24 divides the difference between the current value of the wheel speed and the previous value of the wheel speed by the sampling period Δt (for example, 7 ms), and converts the result into a gravitational acceleration. Is updated as the current acceleration or deceleration.

The control unit 24 executes a predetermined rough road determination process to determine whether or not the traveling road surface is a rough road. This rough road determination processing is executed as follows. For example, if the number of times that the deceleration or acceleration of the rear wheels 3, 4 exceeds a predetermined upper limit or lower limit within a predetermined time is within a set value, the bad road flag Fak is maintained at 0 to indicate the acceleration and deceleration. If the number of times that the value exceeds the upper limit value and the lower limit value within a certain period of time is equal to or greater than a set value, it is determined that the traveling road surface is a bad road, and the bad road flag Fak is set to 1. Further, the control unit 24 selects the rear wheels 3, 4 representing the wheel speed and acceleration / deceleration for the third channel. In the present embodiment, the smaller one of the two wheel speeds is selected as the rear wheel speed in consideration of the detection error of the two wheel speed sensors 29, 30 of the rear wheels 3, 4 at the time of slip. The acceleration and the deceleration obtained from the speed are selected as the rear wheel acceleration and the rear wheel deceleration.

Further, the control unit 24 estimates a road surface friction coefficient for each channel, and calculates a pseudo vehicle speed in parallel with the estimation. The control unit 24 controls the rear wheel speeds obtained from the signals from the wheel speed sensors 29 and 30, 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 speed. Then, the slip rates for the first to third channels are calculated respectively. In this case, the slip rates are calculated by the following relational expression. Slip ratio = (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 tendency of the wheels to slip increases.

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

Here, the lock determination processing will be described. For example, in the lock determination processing 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 speed Vr and the wheel speed Vw1 are set under predetermined conditions (for example, Vr <5Km / H, Vw1 <
7.5Km / H) is determined, and when these conditions are satisfied, the continuation flag Fcn1 and the lock flag F
lok1 is reset to 0, respectively, and if not satisfied, it is determined whether or not the lock flag Flok1 is set to 1. 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 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%. When it is larger than 1, the continuation flag Fcn1 is set to 1.
Note that the lock determination process is similarly performed on the second and third channels.

The control unit 24 compares the control thresholds set according to the running state of the vehicle with the wheel acceleration / deceleration and the slip ratio to determine the ABS non-control state. Phase 0 indicating a pressure increasing state during ABS control, Phase II indicating a holding state after pressure increasing, Phase III indicating a depressurizing state, Phase IV indicating a rapid depressurizing state, and holding state after depressurizing Phase V is selected.

In the cascade determination process, especially on a low friction road surface such as an ice burn, the wheel is easily locked even with a small braking pressure. Therefore, the cascade lock state in which the wheel lock state occurs continuously 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 applies a braking pressure control signal according to the control amount to the first to third valve units 20. , 21, and 23 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 downstream of 23 is increased or reduced, or maintained at the increased or reduced pressure level. .

The process of estimating the road surface friction coefficient is, for example, as follows.
The first channel is performed as follows based on the flowchart of FIG. Note that the reference symbol Si (i = 1,
(2, 3,...) Indicate 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 the ABS control is being performed) (S2). The ABS flag Fabs is, for example,
Lock flag Flok1, Flok2, Flok3 of the third channel
Is set to 1 when any one of them is set to 1, and reset to 0 when the brake switch 25 switches from ON to OFF. When it is determined that the ABS flag Fabs is not set to 1, in S3, 3 indicating a high friction road surface is set as the friction coefficient value Mu1.

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

Next, the calculation process of the pseudo vehicle speed Vr will be described with reference to the flowcharts of FIGS. First, the control unit 24 reads various data (S20), and then determines whether it is the first channel decompression ending timing (S21). This judgment is based on the relief valve 20
The determination is made from the end of the output of the braking control signal to b. If the result of this determination is that it is time to end pressure reduction, S2
In step 2, the timer T1 is reset and started.
Move to 25.

If the result of determination in S21 is that it is not the pressure reduction end timing, it is next determined whether or not it is the pressure reduction end timing of the second channel (S23).
It is determined from the end of the output of the braking control signal to the relief valve 21b. As a result of the determination, if it is the decompression end timing, the timer T2 is reset and started in S24, and then the process proceeds to S25. If not, the process directly proceeds to S25.

In S25, it is determined whether or not the count time T1 of the timer T1 is 32 ms or less, that is, whether or not only a time of 32 ms or less has elapsed from the timing of the end of decompression of the first channel. , S26, it is determined whether or not the count time T2 of the timer T2 is 32 ms or less, that is, whether or not only the time of 32 ms or less has elapsed from the timing of the end of the decompression of the second channel.

If the determination result in S26 is Yes, the first,
Only the time of 32 ms or less has elapsed since the end of the depressurization of the second channel. During this period, the maximum wheel speed of the front wheels 1 and 2 may be excessively detected. It is not preferable to determine the maximum wheel speed from Vw1 and Vw2. Therefore, in S27, the maximum wheel speed Vwm is obtained from the wheel speeds Vw3 and Vw4 of the rear wheels 3 and 4, and
Move to 32.

If the determination result in S26 is No, only 32 ms or less has elapsed since the end of the decompression of the first channel, and it is not preferable to obtain the maximum wheel speed from the wheel speed Vw1 of the left front wheel 1. Therefore, in S28, the maximum wheel speed Vwm is obtained from the wheel speeds Vw2, Vw3, Vw4 of the right front wheel 2 and the rear wheels 3, 4, and the process proceeds to S32. Next, if the determination result in S25 is No, it is determined in S29 whether the count time T2 of the timer T2 is 32 ms or less, and if the determination result is Yes, 32 ms or less from the timing of the end of the decompression of the second channel. During this period, and during this period, the wheel speed V of the right front wheel 2
It is not preferable to find the maximum wheel speed from w2. Therefore, in S30, the maximum wheel speed Vwm is obtained from the wheel speeds Vw1, Vw3, Vw4 of the left front wheel 1 and the rear wheels 3, 4, and S32
Move to.

Next, when the determination result in S29 is No, 32 m from the timing of the end of the pressure reduction of the first and second channels.
s or more has elapsed, and the wheel speed Vw of the front wheels 1 and 2
Since there is no problem even if the maximum wheel speed Vwm is determined from Vw2, the maximum wheel speed Vwm is determined from the wheel speeds Vw1 to Vw4 of the left and right front wheels 1, 2 and the rear wheels 3, 4 in S31.
Move to 2. Next, the maximum wheel speed change amount ΔVwm per sampling period Δt of the maximum wheel speed Vwm is calculated (S3).
2). Next, the control unit 24 determines in S33 the representative friction coefficient value Mu (first to third values) from the map shown in FIG.
The vehicle speed correction value CVr corresponding to (the minimum value of the channel) is read, and it is determined in S34 whether the maximum wheel speed change amount ΔVwm is equal to or less than the vehicle speed correction value CVr.

If it is determined that the wheel speed change amount .DELTA.Vwm is equal to or less than the vehicle speed correction value CVr, the program proceeds to S3.
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 speed Vr decreases at a predetermined gradient corresponding to the vehicle speed correction value CVr. On the other hand, the control unit 24
In S34, the wheel speed change amount ΔVwm is equal to the vehicle speed correction value CV.
When it is determined that it is greater than r, that is, when the maximum wheel speed Vwm shows an excessive change, it is determined in S36 whether or not a value obtained by subtracting the maximum wheel speed Vwm from the pseudo vehicle speed Vr is equal to or more than a predetermined value V0. That is, it is determined whether or not there is a large difference between the maximum wheel speed Vwm and the pseudo vehicle speed Vr. If there is no large difference, the value obtained by subtracting the vehicle speed correction value CVr from the previous value of the pseudo vehicle speed Vr is replaced with the current value in S37.

Further, when a large gap occurs between the maximum wheel speed Vwm and the pseudo vehicle speed Vr, the control unit 24 replaces the maximum wheel speed Vwm with the pseudo vehicle speed Vr in S37. In this way, the pseudo vehicle body speed Vr of the vehicle is updated for each sampling cycle Δt according to each wheel speed Vw1 to Vw4.

Next, the process of setting various control thresholds 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 left front wheel first channel will be described. The control unit 24 reads various data in S31,
Next, in S32, as shown in FIG. 6, a representative friction coefficient value Mu obtained from the wheel speeds Vw1 to Vw4 from a table in which the vehicle speed range and the road surface friction coefficient are set as parameters.
And a running state parameter corresponding to the pseudo vehicle speed Vr. Here, as the representative friction coefficient value Mu, the minimum value among the friction coefficient values Mu1 to Mu3 of the first to third channels is used. For example, when the representative friction coefficient value Mu is 1 indicating a low friction road surface and the pseudo vehicle body speed Vr belongs to the medium speed region, the LM for the medium speed low friction road surface is used as the traveling state parameter.
2 will be selected.

Further, the rough road flag Fak indicates 1 which indicates a rough road state.
When the vehicle speed is set to, as shown in FIG. 7, a traveling state parameter corresponding to the pseudo vehicle speed Vr is selected. In this case, for example, when the pseudo vehicle speed Vr belongs to the medium speed range, the running state parameter H for the medium speed low friction road surface is used.
M2 is forcibly selected. This is because the road surface friction coefficient tends to be estimated to be small during running on a rough road due to large fluctuations in wheel speed.

After selecting the driving state parameters, the control unit 24 reads various control thresholds corresponding to the driving state parameters from the control threshold setting table shown in FIG. 8 in S33. Here, as shown in FIG. 8, the various control thresholds include a 1-2 intermediate deceleration threshold B for determining switching from phase I to phase II.
12, 2- for judging switching from phase II to phase III
3 Intermediate slip ratio threshold value Bsg, 3-5 intermediate deceleration threshold value B3 for determining switching from phase III to phase V
5. 5-1 for determining switching from phase V to phase I
A slip ratio threshold value Bsz and the like are set for each traveling state parameter.

In this case, the deceleration threshold value which has a large effect on the braking force is set so that the braking performance when the road surface friction coefficient is large and the control responsiveness when the road surface friction coefficient is small are both compatible at a high level. , As the level of the representative friction coefficient value Mu decreases, that is, as the road surface friction coefficient decreases.
It is set to approach G. Here, when LM2 for a medium-speed low-friction road surface is selected as the traveling state parameter, as shown in the column of LM2 in the control threshold value setting table in FIG.
1-2 intermediate deceleration threshold value B12, 2-3 intermediate slip rate threshold value Bsg, 3-5 intermediate deceleration threshold value B35, 5-
As one slip ratio threshold value Bsz, -0.5G, 90
%, 0G, and 90% are read out.

Next, the control unit 24 executes S33
In, it is determined whether or not the representative friction coefficient value Mu is set to 3 indicating a high friction road surface. If it is determined to be Yes, it is determined in S34 whether or not the rough road flag Fak is set to 1. As a result of the determination, the rough road flag F
If ak is not set to 1, the process proceeds to S35, where it is determined whether the absolute value of the steering angle θ indicated by the steering angle signal is smaller than 90 °, and the absolute value of the steering angle θ is not smaller than 90 °. At this time, in S36, a correction process of the control threshold value according to the steering angle θ is performed. This control threshold value correction process is performed as shown in FIG.
This is performed based on the control threshold value correction table illustrated in FIG.

That is, in the control threshold value correction table shown in FIG. 9, the 2-3 intermediate slip ratio threshold value Bsg and the 5-1 intermediate slip ratio are set in order to secure the steering performance when the steering wheel operation amount is large. The values obtained by adding 5% to the threshold values Bsz are set as the final 1-2 slip ratio threshold Bsg and the final 5-1 slip ratio threshold Bsz, and the other intermediate thresholds are left as they are. Set as the final threshold. When the result of the determination in S35 is Yes, each of the intermediate thresholds is set as the final threshold as it is.

On the other hand, the control unit 24 executes S34
When it is determined that the rough road flag Fak is set to 1, the process proceeds to S37, and the steering angle θ is set in the same manner as in S35.
It is determined whether or not the absolute value of the intermediate slip ratio is smaller than 90 °. When the determination is Yes, in S38, based on the control threshold correction table of FIG. -5 from the slip ratio threshold value Bsz
% Is set as the final 2-3 intermediate slip ratio threshold value Bsg and the final 5-1 slip ratio threshold value Bsz. A correction process of setting a value obtained by subtracting 1.0 G from the intermediate deceleration threshold value B12 as the final 1-2 deceleration threshold value B12 is performed.

This is because, when a bad road is determined, the wheel speed sensors 27 to 30 are liable to make an erroneous detection, so that the response of the control is delayed to secure a good braking force. The other intermediate thresholds are set as final thresholds. When the control unit 24 determines in S37 that the absolute value of the steering angle θ is not smaller than 90 °, the control unit 24 proceeds to S39 and performs a correction process of the control threshold value according to only the rough road. Further, the control unit 24
When it is determined that the representative friction coefficient value Mu is not 3 in S33, the process proceeds to S35. It should be noted that control threshold values are set for the second and third channels in the same manner as in the case of the first channel.

Next, the operation of the above-described ABS control will be described by taking the ABS control for the first channel as an example.
This will be described with reference to the time chart of FIG. In the ABS non-control state at the time of deceleration, the brake pressure generated in the master cylinder 18 is gradually increased by the depression operation of the brake pedal 16, and as shown in FIG. 10 (c), the wheel speed Vw1 of the left front wheel 1 changes. When the amount (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, since the friction coefficient value Mu1 is set to 3 indicating a high friction road surface (see S2 and S3 in FIG. 2), the rough road flag Fak
Is zero and the pseudo vehicle speed Vr calculated from the wheel speed Vw1 belongs to, for example, a middle speed range, HM2 for a middle speed and high friction road surface is selected as a running condition parameter, and various controls are performed based on the running condition parameter. A threshold is set. That is, various control threshold values preset in the column of HM2 in the control threshold value setting table of FIG. 8 are read.

Next, the slip ratio S obtained from the wheel speed Vw1
1. The wheel deceleration DVw1 and the wheel acceleration AVw1 are compared with various control thresholds. In this case, the phase value P1 is changed from 0 to 2 as shown in FIG. Is maintained at the level immediately after the pressure increase, as shown in FIG. And the slip ratio S1 is 2
When the value falls below the −3 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 according to a predetermined duty ratio, and the braking pressure decreases at a predetermined gradient from time tb as shown in FIG. As a result, the braking force gradually decreases, and the rotational force of the front wheels 1 starts to recover. When the brake pressure is further reduced and the wheel deceleration DVw1 drops to the 3-5 intermediate deceleration threshold B35 (0G), the phase value P1 is changed from 3 to 5, as shown in FIG. Then, the braking pressure is maintained at the reduced level from time tc.

When the slip ratio S1 continues to exceed the 5-1 slip ratio threshold value Bsz (90%) in the state of this phase V, as shown in FIG.
l is set to 1. As a result, the ABS control in the first channel shifts to the second cycle from time td. At this time, the phase value P1 is forcibly changed to 1. Immediately after the transition to the phase I, the on-off valve 20a of the first valve unit 20 is set to the 100% duty ratio in accordance with the initial rapid pressure increase time Tpz set based on the duration of the phase V in the first cycle. As shown in FIG. 3E, the braking pressure is increased at a steep gradient. After the initial rapid increase time Tpz has elapsed, 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 transition 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, FIG.
As shown in the flowchart, 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 corresponds to a traveling state parameter corresponding to these friction coefficient values and the vehicle speed Vr. Since the control threshold value to be performed is selected from the control threshold value setting table of FIG. 8, a precise control of the braking pressure according to the traveling state is performed. Thereafter, in the state of the phase V in the second cycle, for example, when it is determined that the slip ratio S1 is larger than the 5-1 slip ratio threshold value Bsz,
The phase value P1 is set to 1, and the process shifts to the third cycle. Further, as described with reference to FIG. 6, the control threshold value is corrected in accordance with the magnitude of the steering angle θ at the time of determining a rough road, and the representative friction coefficient value Mu is also determined at the time of determining a non-rough road state or a rough road. Is not 3, which indicates 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 can be controlled more precisely according to the running state. become.

Here, in the setting of the pseudo vehicle speed Vr unique to the present invention, during the period within 32 ms after the brake hydraulic pressure of the first channel and / or the second channel is reduced,
Among the wheel speeds excluding the wheel speeds Vw1 and / or Vw2 corresponding to the channel, the maximum wheel speed is set to the pseudo vehicle speed Vr.
, The abnormally high wheel speed Vw1 generated within 32 ms after the brake oil pressure of the front wheels 1 and 2 is reduced.
And / or Vw2 is not set as the pseudo vehicle speed Vr. As a result, the accuracy of the pseudo vehicle speed Vr is increased, and A
The accuracy and reliability of BS control can be improved. The time of 32 ms is an example, and the time of 32 ms
A predetermined time of s or less or a predetermined time of 32 ms or more may be employed.

[Brief description of the 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 a road surface friction coefficient estimation process.

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

FIG. 4 is the remaining part of the flowchart of the pseudo vehicle speed calculation process.

FIG. 5 is a diagram of a map of a vehicle speed correction value.

FIG. 6 is a flowchart of a control threshold value setting process.

FIG. 7 is a table of a table in which traveling state parameters are set.

FIG. 8 is a table of a table in which various control thresholds are set.

FIG. 9 is a chart of a table in which correction values of various control thresholds are set.

FIG. 10 is an operation time chart of the anti-skid brake device.

[Explanation of symbols]

 1, 2 front wheel 3, 4 rear wheel 11-14 brake device 15 brake control system 27-30 wheel speed sensor 20, 21, 23 first to third valve unit 20a, 21a, 23a on-off valve 20b, 21b, 23b relief valve 24 control unit

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Reihiro Watanabe 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (72) Keizumi Masu 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Naru JP-A-1-244955 (JP, A) JP-A-61-36053 (JP, A) JP-A-62-146758 (JP, A) JP-A-2-169362 (JP) , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T ^7/ 12-8/96

Claims (1)

(57) [Claims] 1. A wheel speed detecting means for detecting a rotational speed of a front wheel and a rear wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure,
An anti-skid brake device for a vehicle, comprising: anti-skid control means for operating a hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detection means. First determining means for determining whether or not a predetermined time has elapsed from the second control means; second determining means for determining whether or not a predetermined time has elapsed from the end of the pressure reduction of the brake hydraulic pressure of the right front wheel by the anti-skid control means; Wheel speed signals of the four wheels detected at
Based on the determination results of the first and second determination means, when a predetermined time has elapsed from the end of the pressure reduction for the left and right front wheel brake hydraulic pressures, the highest wheel among the four wheel speeds is set as the pseudo vehicle speed. When the predetermined time has not elapsed, the left side where the predetermined time has not elapsed and / or
An anti-skid brake device for a vehicle, comprising: a pseudo-vehicle speed setting unit that sets a maximum wheel speed among wheel speeds of wheels except for a right front wheel as a pseudo-vehicle speed.