JPH06344890A - Antiskid brake device for vehicle - Google Patents

Abstract

PURPOSE:To reconcile the prevention of cascade lock and the shortening of braking distance by providing a pseudo car body speed correcting means for correcting a pseudo car body speed to be close to a wheel speed when the wheel speed is not returned to the pseudo car body speed in spite of the regulation by a pressure intensification regulating means. CONSTITUTION:All four wheels are locked, and a pseudo car body speed VR is calculated by subtracting a deceleration according to a frictional coefficient value from the latest value. When the wheel speed W1 of a left front wheel does not exceed the pseudo car body speed VR, a control unit (pressure boosting regulating means) sets a cascade flag. Therefore, at a point of time when a phase value is changed, the braking pressure is never boosting, and is kept as the braking pressure after pressure reduction. Thus, the wheel speed W1 exceeds the pseudo car body speed VR, the pseudo car body speed is renewed to an upper value and conformed to the actual car body speed, and the generation of cascade lock of a wheel resulted from the unconformity between the pseudo car body speed and the actual car body speed is suppressed.

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 estimating a pseudo vehicle body speed in the control thereof.

[0002]

2. Description of the Related Art In recent years, an anti-skid brake device (ABS) has been sometimes equipped as a vehicle brake device for the purpose of preventing the occurrence of a wheel lock or skid state during braking. This type of anti-skid brake device is usually a wheel speed sensor that detects the rotational speed of the wheel, that is, the wheel speed, a control valve that adjusts the brake pressure, and the vehicle speed based on the wheel speed detected by the wheel speed sensor. And a pseudo vehicle body speed calculating means for calculating a pseudo vehicle body speed imitating a vehicle body speed (also simply referred to as a vehicle speed), and the control valve when the wheel speed falls to a predetermined slip relationship with respect to the pseudo wheel speed during braking. By reducing the brake pressure to reduce the brake pressure, the wheel speed is restored, and when the wheel speed is restored to a predetermined relationship, the control valve is pressure-increased to increase the brake pressure. There is. Then, by continuously performing such a series of control of the brake pressure (hereinafter referred to as ABS control) until, for example, the vehicle stops, the vehicle body speed of the vehicle decreases according to a predetermined gradient.
This prevents the wheels from being locked or skided at the time of sudden braking, and the braking distance can be shortened as much as possible without losing the directional stability of the vehicle.

Incidentally, the pseudo vehicle body speed calculated by the pseudo vehicle body speed calculating means is usually set so as to decrease at a predetermined speed change rate (deceleration) based on the wheel speed detected by the wheel speed sensor. Further, when the wheel speed exceeds the pseudo vehicle body speed due to the reduction of the brake pressure, the value is updated to an upper value corresponding to the wheel speed.

However, on a road surface (low μ road) having a low road surface friction coefficient such as ice burn, the wheels are locked before the wheel speed returns to the pseudo vehicle speed, and the wheel speed is reduced due to the lock. The pseudo vehicle body speed may be updated to a value lower than the actual vehicle body speed (actual vehicle body speed). This update is an erroneous determination of the pseudo vehicle body speed, and if this erroneous determination is continuously performed, the error between the pseudo vehicle body speed and the actual vehicle body speed increases with time. At this time, a so-called cascade lock phenomenon occurs in which wheel lock continuously occurs in a short time.

Therefore, in order to prevent such an erroneous determination of the pseudo vehicle body speed or the occurrence of a cascade lock, for example, as disclosed in Japanese Patent Laid-Open No. 4-197864, a wheel speed detected by a wheel speed sensor is used. A road surface friction coefficient estimating means for estimating the road surface friction coefficient based on the road surface friction coefficient is provided, and when the road surface friction coefficient estimated by the estimating means is low, when the holding phase after depressurization in ABS control shifts to the pressure increasing phase or from the depressurizing phase. By performing processing (so-called cascade processing) such as prohibiting pressure increase when shifting to the pressure increase phase, the pseudo vehicle body speed is reliably updated to an upper value even on low μ roads such as ice burn, and the actual vehicle speed It is known to have been made to match.

[0006]

However, in the case where such cascade processing is continuously performed, the braking force tends to be insufficient because the increase of the brake pressure is suppressed.
It has the drawback of increasing the braking distance. Further, if the wheel speed does not exceed the pseudo vehicle body speed even after performing the cascade processing once, it is often due to the fact that the pseudo vehicle body speed is set to a high value.

The present invention has been made in view of the above points, and an object of the present invention is to prevent cascade lock and shorten braking distance by appropriately performing cascade processing and setting of pseudo vehicle speed. It is intended to provide an anti-skid brake device for a vehicle that can effectively achieve compatibility with both.

[0008]

In order to achieve the above object, in the invention according to claim 1, the wheel speed has a predetermined relationship with the pseudo vehicle speed calculated by simulating the actual vehicle speed during braking. At this time, in an anti-skid brake device for a vehicle configured such that the brake pressure of the wheel increases / decreases in accordance with a cycle including a pressure increase phase and a pressure decrease phase, the wheel speed returns to the pseudo vehicle speed during the increase / decrease control of the brake pressure. If not, a pressure increase regulation means for regulating the pressure increase in the next pressure increase phase, and if the wheel speed does not return to the pseudo vehicle speed despite the regulation by the pressure increase regulation means, the pseudo vehicle speed approaches the wheel speed. And a pseudo vehicle body speed correction means for making the above correction.

The invention according to claim 2 is dependent on the invention according to claim 1, and shows a more specific content of the correction by the pseudo vehicle body speed correcting means, which is one of the components. That is, the pseudo vehicle body speed correction means performs the correction in accordance with the peak of the wheel speed when correcting the pseudo vehicle body speed.

[0010]

With the above construction, in the invention according to claim 1,
When the wheel speed does not return to the pseudo vehicle body speed during the brake pressure increase / decrease control, that is, during the ABS control, first, the pressure increase regulation means regulates the pressure increase in the next pressure increase phase. If the wheel speed does not return to the pseudo vehicle speed despite the restriction, the pseudo vehicle speed correction means corrects the pseudo vehicle speed to approach the wheel speed.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a vehicle braking system equipped with an anti-skid brake device according to an embodiment of the present invention. In this vehicle, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and 4 are drive wheels, and the output torque of the engine 5 is from the automatic transmission 6 to the propeller shaft 7, the differential device 8 and the left and right drive wheels. It is adapted to be transmitted to the left and right rear wheels 3 and 4 via the shafts 9 and 10.

Each of the wheels 1 to 4 has one of these wheels 1 to 4.
4 are provided with brake devices 11-14 each of which is configured to integrally rotate with 4 and calipers 11b-14b that receive the supply of the braking pressure and brake the rotation of these disks 11a-14a. In addition, the vehicle is equipped with a brake control device 15 that controls the operation of these brake devices 11-14.

The brake control device 15 is a booster device 1 for increasing the stepping force on the brake pedal 16 by the driver.
7 and a master cylinder 18 that generates a braking pressure according to the stepping force increased by the booster 17. The front wheel braking pressure supply line 19 guided from the pressure chamber 18a of the master cylinder 18 is branched into a left front wheel braking pressure supply line 19a and a right front wheel braking pressure supply line 19b. 19a is the left front wheel 1
The braking pressure supply line 19b for the right front wheel is connected to the caliper 11b of the braking device 11 in FIG.
The left front wheel braking pressure supply line 19a includes a first solenoid valve 20a and a first solenoid relief valve 20b.
Similarly to the first valve unit 20, the electromagnetic opening / closing valve 21a and the electromagnetic relief valve 21 are provided in the right front wheel braking pressure supply line 19b.
A second valve unit 21 consisting of b and b is provided.

In the rear wheel braking pressure supply line 22 led from the pressure chamber 18a of the master cylinder 18,
Similar to the first and second valve units 20 and 21, the electromagnetic on-off valve 23a and the electromagnetic relief valve 23b are provided.
And a third valve unit 23 consisting of The rear wheel braking pressure supply line 22 is branched downstream of the third valve unit 23 into a left rear wheel braking pressure supply line 22a and a right rear wheel braking pressure supply line 22b. The wheel braking pressure supply line 22a is provided on the left rear wheel 3.
The brake pressure supply line 22b for the right rear wheel is connected to the caliper 13b of the brake device 13 in FIG.
That is, the brake control device 15 in the present embodiment is
By operating the first valve unit 20, the left front wheel 1
For variably controlling the braking pressure of the brake device 11 in
A channel, a second channel that variably controls the braking pressure of the braking device 12 on the right front wheel 2 by operating the second valve unit 21, and both brakes on the left and right rear wheels 3, 4 by operating the third valve unit 23. A third channel for variably controlling the braking pressure of the devices 13, 14 is provided, and these first to third channels are controlled independently of each other.

Further, 30 is an ON state of the brake pedal 16.
Brake switch for detecting ON / OFF, 32, 33, 3
Reference numerals 4 and 35 denote four wheel speed sensors that detect the rotational speeds of the wheels 1 to 4, that is, the wheel speeds, respectively, and the detection signals of these sensors and switches are all the above first to third
It is input to the control unit 41 that controls the channel.

The control unit 41 outputs a braking pressure control signal corresponding to the detection signal to the first to third valve units 20, 21, 23, respectively, so that the left and right front wheels 1, 2 and the rear wheel 3 are provided. , 4 for slip control, that is, ABS control is performed in parallel for each of the first to third channels. That is, the control unit 41 includes the wheel speed sensors 32 to 32.
Based on the wheel speed indicated by the wheel speed signal from 35, the first
-Opening / closing valves 20a, 21a, 23a and relief valves 20b, 21b in the third valve units 20, 21, 23,
By controlling the opening and closing of each of 23b and 23b by the duty control, the braking force is applied to the front wheels 1 and 2 and the rear wheels 3 and 4 with the braking pressure according to the slip state. The first to third valve units 20, 21, 2
The brake oil discharged from the relief valves 20b, 21b, 23b in No. 3 is stored in the reservoir tank 18 of the master cylinder 18 via a drain line (not shown).
Returned to b.

In the ABS non-controlled state, no braking pressure control signal is output from the control unit 41. Therefore, as shown in the drawing, the relief valves 20b, 20b, 20c in the first to third valve units 20, 21, 23 are shown.
21b and 23b are respectively closed and held, and the on-off valves 20a and 21 of the valve units 20, 21 and 23 are closed.
a and 23a are held open. This allows the master cylinder 18 to respond to the depression force of the brake pedal 16.
The braking pressure generated in 1) is applied to the left and right front wheels 1 and 2 via the front wheel braking pressure supply line 19 and the rear wheel braking pressure supply line 22.
And the braking devices 11 to 14 on the rear wheels 3 and 4, and a braking force corresponding to the braking pressure of these is applied to the front wheels 1 and 1.
2 and the rear wheels 3 and 4 are directly applied.

Next, an outline of the ABS control performed by the control unit 41 will be described.

That is, the control unit 41 is
The acceleration and deceleration of each wheel are calculated based on the wheel speeds indicated by the signals from the wheel speed sensors 32 to 35. Here, the calculation method of the acceleration or the deceleration will be described. The control unit 41 calculates the difference between the previous value of the wheel speed and the current value as the sampling cycle Δt (for example, 7 m).
After dividing by s), the result converted into gravitational acceleration is updated as the current acceleration or deceleration.

Further, the control unit 41 executes a predetermined rough road judgment processing to judge whether or not the traveling road surface is a bad road. This rough road determination processing is executed as follows, for example. That is, the control unit 41 maintains the rough road flag FAKURO at 0 if the number of times the deceleration or acceleration of the rear wheels 3, 4 exceeds a predetermined upper limit value or lower limit value within a fixed time is within a set value. , If the value indicating the acceleration and deceleration exceeds the upper limit value and the lower limit value within a certain period of time or more, it is determined that the traveling road surface is a bad road and the bad road flag FAKURO is set to 1. .

Then, the control unit 41 selects the rear wheels 3 and 4 representing the wheel speed and acceleration / deceleration for the third channel. In the present embodiment, the smaller wheel speed of the two wheel speeds is selected as the rear wheel speed in consideration of the detection error of the both wheel speed sensors 34, 35 of the rear wheels 3, 4 during slip. The acceleration and deceleration obtained from the wheel speed are selected as the rear wheel acceleration and the rear wheel deceleration.

Further, the control unit 41 estimates the road surface friction coefficient μ for each of the above channels and, in parallel with it, calculates the pseudo vehicle body speed of the vehicle.

The control unit 41 controls the rear wheel speeds obtained from the signals from the wheel speed sensors 34 and 35 and the wheel speeds of the left and right front wheels 1 and 2 indicated by the signals from the wheel speed sensors 32 and 33 and the pseudo vehicle body. The slip ratios for the first to third channels are calculated from the speed. The slip ratio is calculated by the following relational expression, slip ratio = wheel speed / pseudo vehicle speed × 100 (%). That is, as the deviation of the wheel speed with respect to the pseudo vehicle speed increases, the slip ratio decreases, and the slip tendency of the wheel increases.

Subsequently, the control unit 41 sets various control threshold values used for controlling the first to third channels.

Here, the outline of the control threshold setting processing will be described. The control threshold setting process is performed as follows, for example. That is, the control unit 41 selects a control threshold value corresponding to the friction coefficient value and the pseudo vehicle body speed from various control threshold values set in advance according to the vehicle speed range and the road surface friction coefficient, and The control threshold value is corrected according to the determination result of the rough road determination process. Here, as the control threshold value, for example, the 0-2 deceleration threshold value B02 for judging the transition from the phase 0 indicating the ABS non-control state to the phase II indicating the holding state after the pressure increase, and the pressure increase state. The 1-2 deceleration threshold value B12 for judging the shift from the phase I to the phase II shown above, and the 2-3 deceleration threshold value B23 for judging the shift from the phase II to the phase III showing the deceleration state. 3-5 deceleration threshold value B35 for judging transition from phase III to phase V indicating the holding state after deceleration, and 5-1 slip ratio threshold value for judging pressure increase from this phase V to phase I B
The initial slip ratio threshold value BS for SZ and the first cycle are set in accordance with the vehicle speed range and the road surface friction coefficient. In this case, the deceleration threshold value that greatly affects the braking force is the braking performance when the road surface friction coefficient is high,
In order to achieve a high level of control responsiveness when the road friction coefficient is low, the smaller the friction coefficient value level,
That is, the lower the road friction coefficient is, the closer it is to 0G.

Then, the control unit 41 uses the control threshold values to perform a lock determination process for each channel and the first to third valve units 20, 2 described above.
Phase determination processing for defining control amounts for 1 and 23 is performed.

The lock determination process will be described below. For example, in the lock determination process for the first channel for the left front wheel, the control unit 41 first sets the current value of the continuation flag FCON1 for the first channel as the previous value, then the pseudo vehicle speed VR and the left front wheel. One wheel speed W1 is a predetermined condition (for example, VR <5 Km / h, W1 <7.5 Km / h)
Is satisfied. If these conditions are satisfied, the continuation flag FCON1 and the lock flag FLOCK1 are reset to 0, respectively. If they are not satisfied, the lock flag FLOCK1 is set to 1 or not. To judge. If the lock flag FLOCK1 is not set to 1, the lock flag FLOCK1 is set to 1 under a predetermined condition (for example, when the pseudo vehicle speed VR is higher than the wheel speed W1).

On the other hand, when the control unit 41 determines that the lock flag FLOCK1 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 9
When it is larger than 0%, the continuation flag FCON1 is set to 1.

Incidentally, for the second and third channels,
The lock determination process is performed as in the case of the first channel.

Further, to explain the outline of the phase determination processing, the control unit 41 compares the control threshold values set according to the driving state of the vehicle with the wheel acceleration / deceleration and the slip ratio to determine whether or not the ABS has been determined. Phase 0 showing the control state, Phase I showing the pressure increasing state during ABS control, Phase II showing the holding state after pressure increasing, Phase III showing the pressure reducing state, Phase IV showing the sudden pressure reducing state.
Also, the phase V indicating the holding state after depressurization is selected.

Then, the control unit 41 sets a control amount according to the phase value set for each channel, and then outputs a braking pressure control signal according to the control amount to the first to third valve units 20. , 21, 23, respectively. As a result, the braking pressure of the front wheel braking pressure supply lines 19a, 19b and the rear wheel braking pressure supply lines 22a, 22b on the downstream side of the first to third valve units 20, 21, 23 is increased or decreased. Or
The pressure level may be maintained after the pressure increase or pressure reduction.

The process of estimating the road surface friction coefficient μ is performed as follows according to the flowchart of FIG. 2 for the first channel, for example.

That is, after reading various data in step S1, it is determined in step S2 whether the ABS flag FABS is set to 1 or not. That is, it is determined whether or not ABS control is in progress. This ABS flag F
ABS is set to 1 when any of the lock flags FLOCK1, FLOCK2, and FLOCK3 of the above-mentioned first to third channels is set to 1, and when the brake switch 25 is switched from ON to OFF. Is reset to 0. When it is determined that the ABS flag FABS has not been set to 1, the routine proceeds to step S8, where the friction coefficient value MU1 is set to a high μ value having a high road friction coefficient.
Set 3 to indicate the path.

If it is determined in step S2 that the ABS flag FABS is set to 1, that is, if it is determined that ABS control is in progress, step S3
Then, it is determined whether the wheel deceleration DW1 in the previous cycle is smaller than -20G. If the determination is YES, the process proceeds to step S4 to see if the wheel acceleration AW1 in the previous cycle is also greater than 10G. judge. When this determination is NO, at step S6, 1 indicating a low μ road is set as the friction coefficient value MU1.

On the other hand, when it is determined in step S3 that the wheel deceleration DW1 is not smaller than -20 G, step S4 is skipped and step S5 follows.
It is determined whether the wheel acceleration AW1 is greater than 20G,
When the determination is YES, 3 is set as the friction coefficient value MU1 in step S8, while when the determination is NO, 2 is set as the friction coefficient value MU1 in step S7, which indicates the medium μ road of the road surface friction coefficient.

Incidentally, regarding the second and third channels,
Similarly, the road surface friction coefficient is estimated.

On the other hand, the process for calculating the pseudo vehicle body speed is specifically performed as follows according to the flowchart of FIG.

That is, after reading various data in step S11, the maximum wheel speed W is selected from the wheel speeds W1 to W4 indicated by the signals from the wheel speed sensors 32 to 35 in step S12.
MX is determined, and at step S13, a wheel speed change amount ΔWMX per sampling period Δt of the wheel speed WMX is calculated.

Subsequently, in step S14, the vehicle speed correction value CVR corresponding to the representative friction coefficient value MU (minimum value of the first to third channels) is read from the map shown in FIG. It is determined whether the wheel speed change amount ΔMMX is smaller than the correction value CVR. When it is determined that the wheel speed change amount ΔWMX is smaller than the vehicle body speed correction value CVR, 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 step S16. 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, when it is determined in step S15 that the wheel speed change amount ΔWMX is larger than the vehicle speed correction value CVR, that is, when the maximum wheel speed WMX shows an excessive change, in step S17 the pseudo vehicle speed VR is changed. It is determined whether the value obtained by subtracting the maximum wheel speed WMX is larger than the predetermined value V0. That is, it is determined whether or not there is a large difference between the maximum wheel speed WMX and the pseudo vehicle speed VR.
When there is a large gap, the above step S16
Is executed and 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. On the other hand, when there is no large opening, the maximum wheel speed WMX is set in step S18.
Is replaced with the pseudo vehicle speed VR.

In this way, the pseudo vehicle speed VR of the vehicle
Is calculated based on the wheel speeds W1 to W4 of the wheels 1 to 4 and is updated at every sampling period Δt.

The characteristic feature of the present invention is that the pseudo vehicle body speed VR calculated in this way, particularly the friction coefficient value MU when it is judged that the wheels 1 to 4 are in the locked or skid state.
The pseudo vehicle body speed VR (step S16 in FIG. 3) calculated using the deceleration (vehicle body speed correction value CVR) according to the above is corrected based on the wheel speeds W1 to W4 of the respective wheels 1 to 4. The correction processing of the pseudo vehicle body speed is performed according to the flowchart of FIG. 5 for the first channel, for example.

That is, first, after reading various data in step S21, the ABS flag FABS is read in step S22.
Is 1 or not, that is, whether or not ABS control is in progress. When the determination is NO, the routine directly returns, while when the determination is YES, it is determined in step S23 whether the non-return flag FNR is 1 or not.

When the determination in step S23 is NO, it is determined in step S24 whether the wheel speed W1 of the left front wheel 1 is smaller than the pseudo vehicle speed VR and does not exceed the pseudo vehicle speed VR. Sometimes, in step S25, the non-return flag FNR is set to 1, and then the process returns.
When the determination in step S24 is NO, that is, when the wheel speed W1 of the left front wheel 1 is higher than the pseudo vehicle speed VR, the routine directly returns.

On the other hand, when the determination in step S23 is YES, that is, when the wheel speed W1 of the left front wheel 1 does not exceed the pseudo vehicle speed VR, the wheel speed W is determined in step S26.
Wait for pressure increase in pressure increase phrase I until 1 becomes a deceleration state (deceleration 0 G), and maintain the held state after pressure reduction. This operation is performed by setting the cascade flag FCAS to 1 and restricting the pressure increasing phase I.
By the control flow of steps S22, S23, S26, ABS
Pressure increasing regulation means 42 is configured to regulate the pressure increase in the next pressure increasing phase when the wheel speed W1 does not return to the pseudo vehicle speed VR during the control.

Subsequently, in step S27, it is determined whether the wheel speed W1 is smaller than or larger than the pseudo vehicle body speed VR, and if the result of the determination is YES, the pseudo vehicle body speed VR is set to the wheel speed W1 in step S28. Is corrected so as to match the peak of the above condition, the non-return flag FNR is cleared to 0 in step S29, and then the process returns. When the determination in step S27 is NO, step S28 is skipped, the process proceeds to step S29, and the non-return flag FNR is cleared to 0. Step S
By 27 and S28, the pseudo vehicle body speed correction means for correcting the pseudo vehicle body speed VR according to the apex of the wheel speed W1 when the wheel speed W1 does not return to the pseudo vehicle body speed VR despite the regulation by the pressure increase regulating means 42. 43 is configured.

Next, the operation of the above embodiment, particularly the ABS control by the control unit 41, will be described by taking the ABS control for the first channel as an example.

That is, in the ABS non-controlled state at the time of deceleration, the braking pressure generated in the master cylinder 18 is gradually increased by the depression operation of the brake pedal 16, and FIG.
As shown in (c), the amount of change in the wheel speed W1 of the left front wheel 1,
That is, when the wheel deceleration DW1 reaches -3G,
As shown in FIG. 9A, the lock flag FLOCK1 for the first channel is set to 1, and the ABS control is started from the time ta. In the first cycle immediately after the start of the control, as described above, the friction coefficient value M
Since U1 is set to 3 indicating the high μ road (see steps S2 and S8 in FIG. 2), the control unit 41 sets various control threshold values corresponding to the high μ road.

Then, the control unit 41 compares the slip ratio S1, the wheel deceleration DW1, and the wheel acceleration AW1 calculated from the wheel speed W1 with the various control threshold values. In this case, assuming that the initial slip ratio threshold Bs is set to 90%, for example, when the slip ratio S1 indicates 96%, the control unit 4
1, the phase value P1 is changed from 0 to 2 as shown in FIG. As a result, the braking pressure (brake hydraulic pressure)
Is maintained at the level immediately after the pressure increase, as shown in FIG. Then, for example, the slip ratio S1
Becomes lower than the 2-3 slip ratio threshold value BSG (for example, 90%), the control unit 41 changes the phase value P1 from 2 to 3. As a result, the relief valve 20b of the first valve unit 20 is turned on / off in accordance with a predetermined duty ratio, and as shown in FIG. 6 (f), the braking pressure is reduced with a predetermined gradient from the time tb and the braking force is reduced. Gradually decreases, and the rotational force of the rear wheels 3, 4 begins to recover accordingly.

The braking pressure continues to decrease, and the wheel deceleration D continues.
When W1 has decreased to the 3-5 deceleration threshold value B35 (0G), the control unit 41 determines the phase value P1.
Is changed from 3 to 5. As a result, the braking pressure is maintained at the reduced pressure level from the time tc as shown in FIG.

Then, the state of phase V continues, and the slip ratio S1 becomes 5-1 slip ratio threshold value B51 (for example, 9).
0%), the control unit 41
Sets the continuation flag Fcon1 to 1, as shown in FIG. This allows AB on the third channel
The S control shifts from the time td to the second cycle.

In this case, since the control unit 41 forcibly changes the phase value P1 to 1, the opening / closing valve 20a of the first valve unit 20 is normally opened / closed at a predetermined duty ratio, and the braking pressure is set to a predetermined value. Increase pressure on the gradient. However, the four wheels 1 to 4 are all locked, the pseudo vehicle body speed VR is calculated by subtracting the deceleration corresponding to the friction coefficient value MU from the previous value, and the wheel speed W1 of the left front wheel 1 is calculated as the pseudo vehicle body speed VR. When it does not exceed the limit, the control unit 41 (pressure increase regulating means 42) sets the cascade flag FCAS to 1, as shown in FIG. For this reason,
At the time point td when the phase value P1 is changed to 1, the braking pressure is not increased and is maintained at the reduced braking pressure. As a result, the wheel speed W1 exceeds the pseudo vehicle body speed VR, and the pseudo vehicle body speed is updated to an upper value to match the actual vehicle body speed, which is caused by the disagreement between the pseudo vehicle body speed and the actual vehicle body speed. It is possible to suppress the occurrence of cascade lock on the wheels. When the wheel speed W1 of the left front wheel 1 is in the decelerating state, the control unit 41 clears the cascade flag FCAS to 0, whereby the brake pressure is increased as shown in FIG.

Despite the cascade processing in the second cycle, when the wheel speed W1 of the left wheel 1 does not exceed the pseudo vehicle speed VR again when shifting from the second cycle to the third cycle, Control unit 4
1 (pseudo vehicle speed correcting means 43) corrects the pseudo vehicle speed VR by decreasing it in accordance with the apex of the wheel speed W1 in the third cycle, as shown in FIG. This correction is based on the fact that if the wheel speed W1 does not exceed the pseudo vehicle body speed VR even if the cascade processing is performed once, the pseudo vehicle body speed VR is often set high. By this correction, it is possible to prevent the malfunction of the ABS control based on the incorrect setting of the pseudo vehicle body speed VR.

[0055]

As described above, according to the vehicle anti-skid brake device of the present invention, when the wheel speed does not return to the pseudo vehicle speed during the ABS control, first, the pressure increase in the next pressure increase phase is performed. If the vehicle speed is regulated and the wheel speed does not return to the pseudo vehicle speed regardless of this regulation, the pseudo vehicle body speed is corrected so as to approach the wheel speed. Therefore, it is possible to effectively set both prevention of wheel lock and reduction of braking distance.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a braking system of a vehicle including an anti-skid brake device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a road surface friction coefficient estimation process.

FIG. 3 is a flowchart showing a process of calculating a pseudo vehicle body speed.

FIG. 4 is a diagram showing a map used in the calculation processing.

FIG. 5 is a flowchart showing a correction process of a pseudo vehicle body speed.

FIG. 6 is a time chart diagram for explaining the operation of ABS control.

[Explanation of symbols]

 1, 2 front wheels 3, 4 rear wheels 32 to 35 wheel speed sensor 41 control unit 42 pressure increase regulation means 43 pseudo vehicle speed correction means

Claims (2)

[Claims] 1. When the wheel speed has a predetermined relationship with the pseudo vehicle speed calculated by simulating the actual vehicle speed during braking, the brake pressure of the wheel increases or decreases in accordance with a cycle including a pressure increasing phase and a pressure decreasing phase. In the anti-skid brake device for a vehicle configured as described above, when the wheel speed does not return to the pseudo vehicle body speed during the increase / decrease control of the brake pressure, the pressure increase regulating means for regulating the pressure increase in the next pressure increase phase is provided. A vehicle including a pseudo vehicle body speed correction means for correcting the pseudo vehicle body speed to approach the wheel speed when the wheel speed does not return to the pseudo vehicle body speed despite the regulation by the pressure increase regulation means. Anti-skid brake equipment. 2. The anti-skid brake device for a vehicle according to claim 1, wherein the pseudo vehicle body speed correction means corrects the pseudo vehicle body speed in accordance with a peak of a wheel speed when the pseudo vehicle body speed is corrected.