JP3378870B2 - 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 which suppresses an excessive braking force when a vehicle is being braked, and more particularly, to an increase / decrease control for increasing / decreasing the brake pressure in accordance with a cycle including a pressure increasing phase and a pressure decreasing phase. It is related to the setting of the pressure increase rate of the pressure phase.

[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.

In this case, the pressure increasing phase of ABS control is
Normally, for example, as disclosed in Japanese Patent Publication No. 57-4544, pressure is first increased at a relatively large pressure rate and then at a relatively small pressure rate. In particular, in the above-mentioned publication, the duration of the pressure increasing phase of the large pressure rate in the control cycle is made to depend on the pressure increasing amount in the preceding one cycle or several cycles, and as the pressure increasing amount increases, It is disclosed that the duration of the pressure boosting phase is lengthened.

[0004]

By the way, in the case of such ABS control, it is desirable that the duration of the pressure boosting phase is substantially constant. That is, if the duration is longer than the standard time, the braking distance becomes longer, and conversely, if the duration is shorter than the standard time, the pressure control becomes rough and the wheels are easily locked.

However, although the base pressure of the brake device varies depending on the depression amount of the brake pedal, the ABS control is performed regardless of the depression amount of the brake pedal. ABS
In reality, the duration of the pressure increasing phase in the control cannot be made constant due to the difference in the base pressure of the brake device. This also applies to the publications exemplified above.

The present invention has been made in view of the above points, and an object of the present invention is to detect the duration of the pressure boosting phase in the ABS control so as to make the duration substantially constant. By controlling the change of
It is intended to provide an anti-skid brake device for a vehicle, which can achieve appropriate BS control.

[0007]

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 a vehicle anti-skid brake device configured to increase / decrease the brake pressure of the wheel according to a cycle including a pressure increase phase and a pressure decrease phase, a measuring means for measuring the duration of the pressure increase phase in the preceding cycle; The longer the duration and the higher the friction coefficient of the road surface, the longer
It is configured to include a comparison unit that compares a standard time set in advance with the above, and an adjustment unit that adjusts the pressure increase rate of the pressure increase phase in the subsequent cycles in accordance with the comparison result by the comparison unit. .

The invention according to claim 2 is dependent on the invention according to claim 1, and shows a specific example of the adjustment of the pressure increase rate by the adjusting means which is one of the components. That is, the adjusting means increases the pressure increase rate of the pressure increase phase in the subsequent cycle from the pressure increase rate of the pressure increase phase in the preceding cycle when the duration time is longer than the standard time, and advances when the duration time is shorter than the standard time. The pressure increasing rate of the pressure increasing phase in the subsequent cycle is set lower than the pressure increasing rate of the pressure increasing phase in the cycle .

[0009]

With the above construction, in the invention according to claim 1,
The duration of the pressure boosting phase in the preceding cycle is measured by the measuring means, and the duration and the friction coefficient of the road surface are high.
The comparison means compares the standard time that is set so that the time becomes longer . Then, according to the comparison result, the adjusting means adjusts the pressure increasing rate in the pressure increasing phase in the subsequent cycles. For example, when the duration is longer than the standard time, for example, when the duration is longer than the standard time, the pressure increasing rate of the pressure increasing phase of the subsequent cycle is increased from the pressure increasing rate of the pressure increasing phase of the preceding cycle. When it is short, the pressure increase rate of the pressure increase phase in the preceding cycle is made lower than the pressure increase rate of the pressure increase phase in the preceding cycle. By adjusting the pressure increasing rate in this manner, the duration of the pressure increasing phase in the subsequent cycles becomes substantially equal to the standard time.

The tendency of the wheels to lock depends on the coefficient of friction of the road surface on which the vehicle travels, and the lower the coefficient of friction, the stronger the tendency.
Therefore, as in the present invention, the higher the friction coefficient of the road surface is, the longer the standard time is set. Therefore, the duration of the pressure-increasing phase is adjusted to increase or decrease according to the strength of the wheel lock tendency. Therefore, both prevention of wheel lock and reduction of braking distance can be achieved at the same time.

[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 brake pressure supply line 19b for the right front wheel is connected to the caliper 11a of the brake 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.
The valve unit 20 is provided, and the braking pressure supply line 19b for the right front wheel is also provided with an electromagnetic opening / closing valve 21a and an electromagnetic relief valve 21 in the same manner as the first valve unit 20.
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 brake 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 the control amounts for 1 and 23 and adjustment processing of the pressure increase rate in phase I indicating the pressure increase state (that is, pressure increase phase) I are 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, and then sets the pseudo vehicle speed VR and the wheel speed. It is determined whether W1 satisfies a predetermined condition (for example, VR <5 Km / h, W1 <7.5 Km / h), and when these conditions are satisfied, the continuation flag FCON1 and the lock flag FLOCK1 are respectively set. While reset to 0, if not satisfied, lock flag F
Determine if LOCK1 is set to 1. 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 no large opening, 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, if a large opening occurs, the maximum wheel speed W is reached in step S18.
Replace MX with pseudo body 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 pressure increase rate adjusting process, which is a characteristic part of the present invention, is performed according to the flowchart of FIG.

That is, in FIG. 5, first, various data are read in step S21, and then in step S22, AB is read.
It is determined whether the S control flag FABS is set to 1, that is, whether the ABS control is being performed. This judgment is NO
On the other hand, when the ABS control is YES in the case of YES, it is determined in step S23 whether or not the pressure increase phase flag FINC is set to 1. That is, it is determined whether or not it is the pressure increasing phase I indicating the pressure increasing state during the ABS control.

If it is not in the pressure-increasing phase, the ABS control is changed to the pressure-increasing phase I in step S24, and the pressure-increasing is started. A timer (not shown) is activated in S26, and then the process returns. On the other hand, if it is in the pressure increasing phase, step S27
After the ABS control changes from boosting phase I to another phase (for example, holding phase II after boosting) and waits for boosting to end, the timer is stopped at step S28 to start boosting The time to the end, that is, the duration TINC of the pressure boosting phase I is read, and the pressure boosting phase flag FINC is reset to 0 in step S29. The timer and the control flow of steps S21 to S29 constitute a measuring means 42 for measuring the duration TINC of the pressure increasing phase I in the preceding cycle.

Then, in step S30, the above continuation time TIN
It is determined whether C is longer than the standard time To. As shown in FIG. 6, the standard time To is the friction coefficient μ of the road surface.
Is set to be longer (larger) as a linear function as becomes higher. The step S30 constitutes the comparing means 43 for comparing the duration TINC and the standard time To.

When the determination in step S30 is YES,
That is, when the duration time TINC is longer than the standard time To, the pressure increase rate of the pressure increase phase in the subsequent cycles is set to the continuation time TINC and the standard time T in step S31.
Raise according to the difference from o, and then return.
On the other hand, when the determination in step S30 is NO, that is, when the duration TINC is shorter than the standard time To, step S30 is performed.
At 32, the pressure increasing rate in the pressure increasing phase in the subsequent cycles is decreased in accordance with the difference between the above-mentioned continuation time TINC and the standard time To, and then the process returns. Step S30
The control flow from S32 to S32 constitutes the adjusting means 44 for adjusting the pressure increasing rate of the pressure increasing phase in the subsequent cycles according to the comparison result of the comparing means 43.

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 during deceleration, the braking pressure generated in the master cylinder 18 is gradually increased by the depression operation of the brake pedal 16,
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 23b of the third valve unit 23 is turned on / off in accordance with a predetermined duty ratio, and as shown in FIG. 7 (e), 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, the control unit 41 forcibly changes the phase value P1 to 1. Immediately after the transition to the phase I, the opening / closing valve 23a of the third valve unit 23 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 opening / closing is performed at a high rate, and the braking pressure is increased steeply as shown in FIG. After the initial rapid pressure increase time TPZ ends, the on-off valve 2
0a is turned on / off according to a predetermined duty ratio,
The braking pressure gradually rises according to a gentler gradient than the above gradient.

On the other hand, after the second cycle, as shown in FIG.
As shown in the flow chart of FIG. 2, an appropriate friction coefficient value MU1 is determined according to the deceleration DW1 and the acceleration AW1 in the previous cycle, and the friction coefficient value MU1 is determined.
The control threshold value according to the control threshold value is selected, and thus the control unit 41, which controls the precise control pressure according to the running state, is For example, when it is determined that the slip ratio S1 is larger than the 5-1 slip ratio threshold BSZ, the phase value P1 is set to 1 and the process proceeds to the third cycle.

In the case of the present embodiment, the duration TINC of the pressure-intensifying phase I in the second cycle is measured by the measuring means 42, and the duration 43.
C is compared with a preset standard time To. Then, when the duration TINC is longer than the standard time To, the adjusting means 44 adjusts the pressure increasing rate (pressure increasing gradient) of the pressure increasing phase I (more specifically, the pressure increasing phase other than the initial sudden pressure increase) in the third cycle and the subsequent cycles. ) Is increased by a predetermined amount (the amount corresponding to the difference between the continuation time TINC and the standard time To) according to the duty ratio of the on-off valve 20a, and when the continuation time TINC is shorter than the standard time To, in the third cycle and the subsequent cycles. The pressure increase rate of the pressure increase phase I is decreased by a predetermined amount. As a result, the duration of the pressure intensifying phase I in the third cycle and the subsequent cycles is always substantially constant, so that prevention of wheel lock and shortening of the braking distance can be effectively achieved, and the ABS control Can be optimized.

Here, the tendency of the wheels to lock differs depending on the friction coefficient μ of the road surface on which the vehicle travels, and becomes stronger as the friction coefficient μ decreases. Therefore, in the present embodiment, the standard time To is set to be longer as the friction coefficient μ is higher. Therefore, the duration time T of the pressure increasing phase is set according to the strength of the wheel lock tendency.
INC can be increased / decreased to prevent wheel lock and reduce braking distance.

[0056]

As described above, according to the vehicle anti-skid brake device of the present invention, the duration time of the pressure intensification phase in the preceding cycle is measured and compared with the standard time, and the following steps are performed according to the comparison result. By adjusting the pressure increase rate of the pressure increase phase in the cycle, the duration of the pressure increase phase in the subsequent cycles can be made to substantially match the standard time, so that wheel locking can be prevented and the braking distance can be shortened. It is possible to achieve both effectively and A
BS control can be optimized.

Further , since the standard time is set longer as the friction coefficient of the traveling road surface is higher, the duration of the pressure-increasing phase is adjusted according to the strength of the wheel lock tendency. It is possible to achieve both prevention and reduction of the 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 pressure increase rate adjustment process.

FIG. 6 is a diagram showing a map used in the adjustment processing.

FIG. 7 is a time chart diagram for explaining the operation of ABS control.

[Explanation of symbols]

1, 2 front wheels 3,4 rear wheels 41 Control unit 42 Measuring means 43 Comparison means 44 Adjustment means

Claims (2)

(57) [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, the measuring means for measuring the duration of the pressure boosting phase in the preceding cycle, and the longer the duration and the friction coefficient of the road surface, the longer
The comparison means for comparing the preset standard time as described above and the adjustment means for adjusting the pressure increase rate of the pressure increase phase in the subsequent cycle according to the comparison result by the comparison means are provided. Anti-skid brake system for vehicles. 2. The adjusting means increases the pressure increase rate of the pressure increase phase in the subsequent cycle from the pressure increase rate of the pressure increase phase in the preceding cycle when the duration is longer than the standard time, and the duration is longer than the standard time. 2. The antiskid brake device for a vehicle according to claim 1, wherein when the pressure is short, the pressure increase rate of the pressure increase phase in the preceding cycle is made lower than the pressure increase rate of the pressure increase phase in the subsequent cycle .