JPH08104218A - Antiskid brake device for vehicle - Google Patents

Abstract

PURPOSE: To advance rise up of braking force, to lengthen a synchronized period, so as to improve brakability, by controlling a brake fluid pressure so that a pressure increasing speed in the former period of slow pressure increasing phase continued to a quick pressure increasing phase is generated larger than a pressure increasing speed in the latter period of the slow pressure increasing phase. CONSTITUTION: A pressure increasing phase comprises a quick pressure increasing phase and a slow pressure increasing phase following to this quick pressure increasing phase, and in the initial quick pressure increasing phase, a pressure increasing valve 20a is driven by prescribed duty ratio, to close a pressure reducing valve 20b. Next in a transfer to the slow pressure increasing phase, when obtained 300ms after a quick pressure increasing time, duty ratio Du of the pressure increasing valve 20a is calculated, and a value of subtracting 1% from the preceding time duty ratio Du of the pressure increasing valve 20a is set as the this time duty ratio Du to output a brake control signal. That is, the pressure increasing valve 20a is controlled so as to decrease its duty ratio Du 1% by 1% at each arithmetic period 8ms. In this way, a period, where a wheel speed V1 is placed near a car body speed Vr, is increased as long as possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle anti-skid brake device, and more particularly to an anti-skid brake device having improved pressure increasing characteristics in a slow pressure increasing phase of a pressure increasing phase.

[0002]

2. Description of the Related Art Conventionally, various anti-skid brake devices for controlling a brake fluid pressure based on a vehicle speed and a wheel speed have been put into practical use in order to suppress the locking of the wheel during braking of the vehicle and ensure the braking performance. Has been done. In this anti-skid brake system, the brake fluid pressure for the front wheels is divided into two systems, left and right, and the brake fluid pressure for the rear wheels is integrated left and right.
A control valve for controlling hydraulic pressure (pressure increasing valve and pressure reducing valve) is provided in the brake hydraulic system that is controlled by two independent systems, right and left, so that the slip ratio of the wheels reaches the target value via the control valve. The brake fluid pressure is adjusted to a certain level, but a predetermined fluid pressure control cycle consisting of a pressure increase phase, a pressure increase holding phase, a pressure reduction phase, and a pressure reduction holding phase can be repeated for a plurality of cycles, or a pressure increase phase and a pressure reduction phase can be used. It is general to repeat a predetermined hydraulic pressure control cycle a plurality of cycles.

Here, the pressure increasing phase is usually a rapid pressure increasing phase for recovering the decompressed amount of the brake fluid pressure at an early stage, and a slow pressure increasing phase following the normal pressure increasing phase for locking to obtain a braking force. It consists of a gradual pressure increase phase in which the brake fluid pressure is gradually increased while being suppressed. During the anti-skid control, when the wheel speed is close to the vehicle speed (synchronized state), if the brake fluid pressure is appropriate, the braking force is substantially generated while maintaining an appropriate slip. From the standpoint of (1), it is desirable that the period in the synchronized state be maintained as long as possible and the brake fluid pressure during this synchronized period be set appropriately.

In the conventional apparatus, the pressure increasing speed in the slow pressure increasing phase is generally set to a predetermined speed. However, in Japanese Patent Laid-Open No. 193659/1992, the lock tendency is released to the next lock. An antilock control device for a vehicle is described, which counts the synchronization period until the tendency occurs, and when the synchronization period is equal to or more than a predetermined value, corrects the pressure increase rate in the next pressure increase in the direction of increasing the pressure increase. ing. Japanese Patent Laid-Open No. 5-238375 discloses an anti-lock brake device configured to set a rapid pressure increase period for the next rapid pressure increase based on a synchronizing period.

[0005]

When the pressure increasing speed in the slow pressure increasing phase of the pressure increasing phases is set to a predetermined speed as in the conventional anti-skid brake device, the initial pressure in the slow pressure increasing phase is increased. Since the increasing speed of the brake fluid pressure is lower than the desired speed, the braking force rises slowly, and the braking force cannot be generated early. Moreover, since the increasing speed of the brake fluid pressure in the latter half of the slow pressure increasing phase is not sufficiently low, a locking tendency is likely to occur early, it is difficult to maintain the synchronizing period for a long time, and the braking performance cannot be sufficiently improved. There is a problem. An object of the present invention is to provide an anti-skid brake device for a vehicle that can accelerate the rising of the braking force in the slow pressure increasing phase of the pressure increasing phase, lengthen the synchronizing period, and improve the braking performance. .

[0006]

According to a first aspect of the present invention, a wheel speed detecting means for detecting a rotational speed of a wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure of front wheels and a rear wheel, and a wheel speed detecting means. Based on the wheel speed detected in, the vehicle equipped with an anti-skid control means for controlling the fluid pressure adjusting means so that the brake fluid pressure changes in a fluid pressure control cycle including at least a pressure increasing phase and a pressure reducing phase. In the anti-skid brake device, the pressure-increasing phase consists of a rapid pressure-increasing phase and a slow pressure-increasing phase that follows, and the anti-skid control means has a pressure-increasing speed in the first half of the slow pressure-increasing phase.
The brake fluid pressure is controlled so as to be higher than the pressure increase rate in the latter half of the slow pressure increase phase.

According to a second aspect of the present invention, wheel speed detecting means for detecting the rotational speed of the wheel, hydraulic pressure adjusting means for adjusting the brake hydraulic pressure of the front and rear wheels, and wheel speed detected by the wheel speed detecting means. On the basis of, in an anti-skid brake device of a vehicle comprising an anti-skid control means for controlling the hydraulic pressure adjusting means so that the brake hydraulic pressure changes in a hydraulic control cycle including at least a pressure increasing phase and a pressure reducing phase, The pressure-increasing phase includes a rapid pressure-increasing phase and a slow pressure-increasing phase that follows, and the anti-skid control means has a pressure-increasing speed that increases as the wheel speed approaches the vehicle speed in a predetermined period after the start of the slow pressure-increasing phase. The brake fluid pressure is controlled so as to increase.

According to a third aspect of the invention, in the second aspect of the invention, the anti-skid control means controls the brake fluid pressure so that the pressure increasing speed gradually decreases after a predetermined period has elapsed after the start of the slow pressure increasing phase. It is configured to do.

[0009]

According to the present invention, the wheel speed detecting means detects the rotational speed of the wheel, the hydraulic pressure adjusting means adjusts the brake hydraulic pressure of the front wheels and the rear wheels, and the antiskid control means operates. Based on the detected wheel speed, the fluid pressure adjusting means is controlled so that the brake fluid pressure changes in a fluid pressure control cycle including at least a pressure increasing phase and a pressure reducing phase. The pressure-increasing phase includes a rapid pressure-increasing phase and a slow pressure-increasing phase that follows, and the anti-skid control means determines that the pressure-increasing speed in the first period of the slow pressure-increasing phase is higher than that in the latter period of the slow pressure-increasing phase. Control the brake fluid pressure to increase. Therefore, the brake fluid pressure rises earlier in the first half of the slow pressure-increasing phase, so that the braking force rises earlier and the braking performance is improved. Moreover, since the increase in brake fluid pressure in the second half of the slow pressure increase phase is slower than in the first half, the locking tendency is less likely to occur, and the duration of the synchronized state in which the wheel speed approaches the vehicle speed becomes longer, which results in braking. You can improve your sex.

According to the second aspect of the present invention, the wheel speed detecting means detects the rotational speed of the wheel, the hydraulic pressure adjusting means adjusts the brake hydraulic pressure of the front wheels and the rear wheels, and the antiskid control means detects it. Based on the wheel speed, the hydraulic pressure adjusting means is controlled so that the brake hydraulic pressure changes in a hydraulic pressure control cycle including at least a pressure increasing phase and a pressure decreasing phase. The pressure-increasing phase includes a rapid pressure-increasing phase and a slow pressure-increasing phase that follows, and the anti-skid control means has a pressure-increasing speed that increases as the wheel speed approaches the vehicle speed in a predetermined period after the start of the slow pressure-increasing phase. Control the brake fluid pressure to increase. Normally, at the beginning of the slow pressure-increasing phase, the wheel speed approaches the vehicle body speed, but in the predetermined period after the start of the slow pressure-increasing phase, the pressure increases as the wheel speed approaches the vehicle body speed. Since the brake fluid pressure is controlled so as to increase the speed, the brake fluid pressure rises earlier and the braking force rises earlier, so that the braking performance is improved.

According to the third aspect of the invention, the same action and effect as the second aspect are achieved, but the antiskid control means gradually reduces the pressure increasing speed after a predetermined period has elapsed after the start of the slow pressure increasing phase. Since the brake fluid pressure is controlled as described above, the tendency to lock is less likely to occur, and the duration of the synchronized state in which the wheel speed approaches the vehicle body speed becomes longer, so that the braking performance can be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, the brake system of this vehicle will be described. As shown in FIG. 1, in the vehicle according to this embodiment, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and 4 are drive wheels, and the output torque of the engine 5 is the automatic transmission 6.
Is transmitted to the left and right rear wheels 3 and 4 via the propeller shaft 7, the differential device 8 and the left and right drive shafts 9 and 10. Each of the wheels 1 to 4 is a brake device 11 including discs 11a to 14a that rotate integrally with the wheels and calipers 11b to 14b that receive the supply of braking pressure and brake the rotation of the discs 11a to 14a.
14 are provided respectively, and these brake devices 11 to 14 are provided.
There is provided a brake control system 15 for operating the.

The brake control system 15 includes a booster 17 for increasing the depression force of a brake pedal 16 by a driver and a master silling 18 for generating a braking pressure according to the depression force increased by the booster 17. Have and. The front wheel braking pressure supply line 19 from the master shilling 18 is branched into two paths, and the front wheel branching braking pressure lines 19a and 19b are respectively connected to the calipers 11a and 12a of the brake devices 11 and 12 of the left and right front wheels 1 and 2. The braking pressure line 19a connected to the brake device 11 for the left front wheel 1 is provided with a first valve unit 20 including an electromagnetic pressure increasing valve 20a and an electromagnetic pressure reducing valve 20b. The braking pressure line 19b leading to the braking device 12 is also provided with a second valve unit 21 including an electromagnetic pressure increasing valve 21a and an electromagnetic pressure reducing valve 21b.

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

The brake control system 15 includes a first
An ABS control unit 24 for controlling the third channel is provided. The ABS control unit 24 includes a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16 and a steering angle sensor for detecting a steering angle of the steering wheel. In response to the steering angle signals from the wheel speed sensors 26 and the wheel speed signals from the wheel speed sensors 27 to 30 that detect the rotational speeds of the four wheels 1 to 4, respectively, braking pressure control signals corresponding to these signals Anti-skid brake control (hereinafter referred to as ABS control) for suppressing locking and skid of the left and right front wheels 1 and 2 and rear wheels 3 and 4 by outputting to the third valve units 20, 21 and 23, respectively, for each channel. First to third
All channels are set to run in parallel.

The ABS control unit 24 includes pressure increasing valves 20a, 21a, 23a, which are duty solenoid valves in the first to third valve units 20, 21, 23, based on the wheel speeds detected by the wheel speed sensors 27-30. Pressure reducing valves 20b, 21b, 23 composed of duty solenoid valves
By controlling b and duty control, the front wheels 1 and 2 and the rear wheels 3 and 3 are controlled by the braking pressure according to the slip state.
The braking force is applied to No. 4. Each pressure reducing valve 2 in the first to third valve units 20, 21, 23
The brake oil discharged from 0b, 21b, 23b is supplied to the master cylinder 1 via a drain line (not shown).
8 is returned to the reservoir tank 18a.

In the ABS non-controlled state, no braking pressure control signal is output from the ABS control unit 24, the pressure reducing valves 20b, 21b and 23b are kept closed as shown, and the pressure increasing valves 20a, 21a and 23a are held. Are held open, the braking pressure generated in the master cylinder 18 in accordance with the depression force of the brake pedal 16 is applied to the brake device 11
To 14 and the braking forces corresponding to these braking pressures are directly applied to the front wheels 1 and 2 and the rear wheels 3 and 4.

The ABS control unit 24 is supplied with the detection signals of the wheel speed sensors 27 to 30, the steering angle sensor 26, the brake switch 25, etc., and the ABS control unit 24 is supplied with sensors and switches. Waveform shaping circuit that shapes the detection signals of the detection signals as required, an A / D converter that performs AD conversion of various detection signals as required, an input / output interface, a microcomputer, a drive for a pressure increasing valve and a pressure reducing valve. It consists of a circuit, multiple timers, etc.
The ROM of the microcomputer stores in advance control programs for antiskid brake control and various controls associated therewith, tables, maps and the like, and the RAM is provided with various work memories.

Next, an outline of the ABS control will be described. The wheel speeds V1 to V1 detected by the wheel speed sensors 27 to 30 are described.
Decelerations DV1 to DV4 and acceleration for each wheel based on V4
AV1 to AV4 are calculated respectively. In this case, the difference between the previous value of the wheel speed and the current value is divided by the sampling period Δt (for example, 8 ms), and the result is converted into gravity acceleration to be updated as the current acceleration or deceleration.

Further, it is determined whether or not the traveling road surface is a bad road by a predetermined bad road determination process. In this case, the number of times that the wheel acceleration or the wheel deceleration of the driven wheels 1 and 2 exceeds a predetermined rough road determination threshold value during a predetermined period is counted, and when the number of times is a predetermined value or less, the rough road flag is counted. Set Fak to 0,
When the number of times is larger than a predetermined value, the bad road flag Fak
Is set to 1. Although the ABS control is executed for each channel, the wheel speed of each wheel and the road surface friction state value Mu for each channel are calculated, and the pseudo vehicle speed Vr common to the three channels is calculated using these data. It In the present embodiment, the slip ratio of each wheel is calculated by slip ratio = (wheel speed / pseudo vehicle speed Vr) × 100, so the vehicle speed Vr
The larger the deviation of the wheel speed from, the smaller the slip ratio, and the greater the tendency of the wheel to slip.

Next, the main routine of the anti-skid brake control for each channel will be described with reference to the flowchart of FIG. 2 by taking the control for the first channel as an example.
2, 3, ...) Show each step. It should be noted that this main routine is a process executed every predetermined minute time (for example, 8 ms). First, various signals (brake SW signal,
The wheel speed V1) is read (S1), then it is determined whether the brake switch 25 is ON (S2), and the determination is No.
When, the brake is returned and the brake switch 25 is turned on.
In this case, the road surface friction state value Mu is calculated (S3), the pseudo vehicle body speed Vr is then calculated (S4), the control threshold value is set (S5), and the control signal output process is then executed. (S6), and then returns.

Calculation processing of road surface friction state value Mu ... FIG.
Reference First, various signals (flag Fabs, wheel speed V1) are read (S10), and then it is determined whether the flag Fabs is 1 (S11). This flag Fabs is set when any of the lock flags Flok1 to Flok3 of the first to third channels is 1.
When the determination in S11 is No, the road surface friction state value Mu indicates a high friction state Mu = 3.
Is set to (S12), and then the process returns. Flag F
When abs is 1, it is determined whether the deceleration DV of the left front wheel 1 is smaller than -20G (S13), and when the determination is Yes, it is determined whether the acceleration AV of the left front wheel 1 is larger than 10G ( S14), if the acceleration is AV ≦ 10 G as a result of the determination, the road surface friction state value Mu is Mu = 1 indicating a low friction state.
Is set (S15), and then the process returns.

When the deceleration DV <-20G or the acceleration AV> 10G, it is determined whether or not the acceleration AV> 20G (S16). When the determination is Yes, the road surface friction state value Mu indicates the high friction state. Is set to Mu = 3 (S
17) and then return. When the determination in S16 is No, the road surface friction state value Mu indicates the medium friction state Mu.
= 2 is set (S18), and then the process returns. As described above, the road surface frictional state value Mu for the first channel is estimated at small time intervals based on the acceleration / deceleration of the wheel speed V1 and stored in the memory while being updated.
The road surface frictional states are similarly estimated for the second and third channels, but the road surface frictional state values for the first to third channels will be referred to as Mu (1), Mu (2), and Mu (3) below. Enter.

Calculation Processing of Pseudo Body Speed Vr--See FIGS. 4 and 5. Next, the calculation processing of the pseudo vehicle body speed Vr of the first channel will be described. First, various signals (wheel speeds V1 to V
4. Friction state values Mu (1), Mu (2), Mu (3) and the previous vehicle speed Vr) are read (S20), and then the wheel speed V1
~ The maximum wheel speed Vwm is calculated from V4 (S21),
Next, the maximum wheel speed change amount ΔVwm per sampling cycle Δt of the maximum wheel speed Vwm is calculated (S22). Next, from the map shown in FIG. 5, the frictional state values Mu (Mu (1), Mu
(2), the vehicle speed correction value Cvr corresponding to Mu (3) is read (S23), and it is then determined whether the maximum wheel speed change amount ΔVwm is equal to or less than the vehicle speed correction value Cvr. (S2
4).

As a result of the determination, when it is determined that the wheel speed change amount ΔVwm is equal to or less than the vehicle body speed correction value Cvr, the vehicle body speed Vr.
The value obtained by subtracting the vehicle speed correction value Cvr from the previous value of is replaced with the current value (S25). Therefore, the vehicle body speed Vr decreases at a predetermined gradient according to the vehicle body speed correction value Cvr.
On the other hand, when the wheel speed change amount ΔVwm is larger than the vehicle body speed correction value Cvr (when the maximum wheel speed Vwm shows an excessive change), the value obtained by subtracting the maximum wheel speed Vwm from the pseudo vehicle body speed Vr is the predetermined value V0. It is determined whether or not the above (S26).

That is, it is judged whether or not there is a large difference between the maximum wheel speed Vwm and the vehicle body speed Vr. If there is a large difference, the process proceeds to S25, and the maximum wheel speed Vwm and the vehicle body speed Vr are also compared. When there is no large gap between them, the maximum wheel speed Vwm is replaced with the vehicle body speed Vr (S27). In this way, the pseudo vehicle body speed Vr of the vehicle is updated every moment according to the wheel speeds V1 to V4. The calculation of the pseudo vehicle body speed Vr is a common calculation process for the first to third channels.

Control threshold value setting process--see FIGS. 6 to 9 Next, the control threshold value setting process will be described with reference to FIGS. First, various signals (vehicle speed Vr, frictional state values Mu (1), Mu (2), Mu (3), flag Fak, steering angle θ) are read (S30), and then in S31, as shown in FIG. As shown in FIG. 5, a traveling state parameter corresponding to the friction state value Mu and the vehicle body speed Vr is selected from the table TB1 having the vehicle speed range, the road surface friction state value Mu and the rough road flag Fak as parameters, and the selected traveling state is selected. Various control thresholds corresponding to the parameters are set based on the table TB2 in FIG. 8 and stored in the work memory.

However, as the friction state value Mu applied to the table TB1 of FIG. 7, the minimum value of the friction state values Mu (1) to Mu (4) is applied. For example, when the friction state value Mu is 1. In addition, when the vehicle body speed Vr is in the medium speed range, the traveling state parameter LM2 is selected. On the other hand, when the bad road flag Fak = 1 and the road is in a bad road condition, as shown in FIG. 7, a running condition parameter corresponding to the vehicle speed Vr is selected. That is, when traveling on a rough road, the wheel speed fluctuates greatly and the road surface friction coefficient tends to be estimated to be small.

Here, as shown in table TB2, as various control threshold values, a 1-2 intermediate deceleration threshold value B12 for switching from phase I to phase II in FIG. 14 and a phase II to phase III. 2 for switching to
-3 Intermediate slip rate threshold value Bsg, 3-5 Intermediate deceleration threshold value B for determination of switching from phase III to phase V
35, 5-1 for judging switching from phase V to phase I
The slip ratio threshold Bsz and the like are set for each running state parameter.

The deceleration threshold value, which greatly affects the braking force, becomes 0 G as the friction state value Mu decreases in order to achieve both the braking performance in the high friction state and the responsiveness in the low friction state. It is set to approach. Table T
In the example of B2, when the traveling state parameter is LM2, 1
-2 intermediate deceleration threshold B12, 2-3 intermediate slip ratio threshold Bsg, 3-5 intermediate deceleration threshold B35, 5-1 slip ratio threshold Bsz, -0.5G, 90% , 0
G and 90% are read out respectively.

Next, the frictional state value Mu (here, Mu =
It is determined whether Mu (1)) is 3 (S32), the process proceeds to S34 if No, and the bad road flag Fak is 0 if Yes.
It is determined whether or not (S33). When the rough road flag Fak = 0, the absolute value of the steering angle θ detected by the steering angle sensor 93 is 90.
It is determined whether or not it is less than ° (S34), and the absolute value of the steering angle θ ≧ 9
When the angle is 0 °, the control threshold value correction process according to the steering angle θ is performed (S35). This control threshold correction processing is performed by the control threshold correction table (table TB shown in FIG. 9).
It is executed based on 3) and then returns.

In the table TB3 of FIG. 9, the 2-3 intermediate slip ratio threshold is provided in order to secure the steering performance when the steering wheel operation amount is large when the road is not a bad road with low friction, medium friction and high friction. The value obtained by adding 5% to the value Bsg and the 5-1 slip ratio threshold value Bsz is set as the final threshold value, and the other threshold values are set as they are as the final threshold value. Bad road with high friction (Flag F
When ak = 1), 5% is subtracted from 2-3 intermediate slip ratio threshold value Bsg and 5-1 slip ratio threshold value Bsz in order to secure the running performance when the steering wheel operation amount is small. Is set as the final threshold. Then S
When the determination at 34 is Yes, each control threshold value is set as it is as a control threshold value, and the process returns.

On the other hand, when it is determined in S33 that the rough road flag Fak = 1, the table TB of FIG. 9 is determined in S36.
3, the steering angle θ is calculated based on the rough road flag Fak and the steering angle θ.
Only when <90 °, 2-3 intermediate slip ratio threshold B
A value obtained by subtracting 5% from each of sg and the 5-1 slip ratio threshold value Bsz is set as a control threshold value, and the correction processing is executed. Next, in S37, based on the table TB3, 1-2 intermediate values are set. A correction process is performed in which a value obtained by subtracting 1.0 G from the deceleration threshold value B12 is set as a control threshold value, and S
Return from 37. The correction in S37 is for delaying the control responsiveness and ensuring a good braking force because the wheel speed sensors 27 to 30 are likely to make erroneous detections on a bad road.

Control signal output process: See FIGS. 10 to 11. Next, a phase is set by various control threshold values, and a control signal output process for outputting a braking control signal of each phase to the pressure increasing valve or the pressure reducing valve. The first channel will be described as an example with reference to the flowcharts of FIGS. First, various signals required for the following arithmetic processing are read (S50), and then the brake switch 25 is turned on.
It is judged whether or not it is N (S51), and if the judgment is No, S
When the vehicle returns from 52 and the brake switch 25 is ON, the vehicle speed Vr is a predetermined value C1 (for example, 5.0 Km / H).
Below, and the wheel speed V1 is a predetermined value (eg 7.5 Km / H)
It is determined whether or not the following (S53). If the determination in S53 is Yes, the vehicle is sufficiently decelerated, and there is no need for ABS control, so the process returns via S52, but the determination in S53 is
If No, the process proceeds to S54.

At S52, the phase flag P1, the lock flag Flok1, and the continuation flag Fcn1 are reset to 0, respectively, and then the process returns. Next, in S54, it is determined whether or not the lock flag Flok1 is 0, and if the flag Flok1 is 0 before the ABS control is started, the process proceeds to S55 to determine the wheel speed V1.
Deceleration DV1 (provided that DV1 ≦ 0) is a predetermined value D0
(Eg, -3G) or less is determined, and the determination is Yes
If so, the process proceeds to S56. On the other hand, the determination in S54 is No.
If so, the process proceeds to S59.

Next, if the determination in S55 is Yes, the lock flag Flok1 is set to 1 (S66), then the flag P1 is set to 2, and the phase II (holding phase after pressure increase) is entered ( (S57), then a braking control signal preset for phase II is output to the pressure increasing valve 20a and the pressure reducing valve 20b (S58), and then the process returns. In this case, the pressure increasing valve 20a and the pressure reducing valve 20b are kept closed (duty ratio = 0).

After the ABS control is started, since the flag Flok1 = 1, the process proceeds from S54 to S59, and the flag P1 is 2
It is determined whether or not (S59), and when the flag P1 = 2, S6.
If the flag P1 = 2 is not satisfied, the process proceeds to S63. In S60, it is determined whether or not the slip ratio S1 is equal to or less than the 2-3 intermediate slip ratio threshold Bsg.
However, if the slip ratio S1 ≦ threshold value Bsg is reached by repeating the above steps, the flag P1 is set to 3 in S61 subsequent to S60 and the phase III (pressure reduction phase) is executed. ).

Next, in S62, a braking control signal preset for phase III is output to the pressure increasing valve 20a and the pressure reducing valve 20b, and then the process returns. Phase II
At I, the booster valve 20 is closed (duty ratio =
0) and the pressure reducing valve 20b is driven at a predetermined duty ratio. If the flag P1 is not 2 in the determination of S59, it is determined in S63 following S59 whether the flag P1 is 3 or not, and if the flag P1 = 3, S6.
4. If the determination in S63 is No, the process proceeds to S67.

Next, in S64, it is determined whether or not the deceleration DV1 is equal to the 3-5 intermediate deceleration threshold value B35, and it is determined as No at the beginning, so the process proceeds from S64 to S62. When the deceleration DV1 = the threshold value B35 is repeated, the flag P1 is set to 5 in S65, and the phase V (post-reduction pressure holding phase) is entered. Next, in S66, a braking control signal preset for phase V is output to the pressure increasing valve 20a and the pressure reducing valve 20b, and then the process returns. In this case, booster valve 2
0a and the pressure reducing valve 20b are kept closed.
Next, if the determination in S63 is No, it is determined in S67 whether or not the flag P1 = 5, and if the flag P1 = 5, S is determined.
68, and if the flag P1 = 5 is not satisfied, S7
Move to 4. When the flag P1 = 5, it is determined whether the slip ratio S1 is 5-1 slip ratio threshold value Bsz or more (S68).

At the beginning, it is determined as No, so S6
The process from 8 to S66 is repeated. In phase V, the slip ratio S1 increases and the determination in S68 is Yes.
When s is reached, in S69, the flag P1 is set to 1 and the phase I (pressure increase phase) is entered, and the continuation flag Fcn1 is set to 1. The pressure increasing phase of the phase I includes a rapid pressure increasing phase and a slow pressure increasing phase subsequent to the rapid pressure increasing phase. Next, S70
In step S71, the timer T1 that counts the elapsed time after the start of phase I is reset and then started. Next, in step S71, it is determined whether or not the count time T1 of the timer T1 is less than or equal to a preset rapid pressure increase time Tpz. When the rapid pressure increase time Tpz or less, the process proceeds from S71 to S72 and S
In 72, the braking control signal preset for the initial rapid pressure increase of the phase I is the pressure increasing valve 20a and the pressure reducing valve 2
It is output to 0b and then returns. In this case, the pressure increasing valve 20a is driven at a predetermined duty ratio, and the pressure reducing valve 20b is kept closed.

Next, after the shift to phase I, the determination in S67 is No, so the flow shifts from S67 to S77, and
At 77, it is determined whether the flag P1 = 1, and the flag P1
= 1, the deceleration DV1 is 1-2 in S78.
It is determined whether or not the intermediate deceleration threshold value B12 or less. At the beginning, the determination is No. Therefore, the process proceeds from S78 to S71, and before the rapid pressure increase time Tpz elapses, the process proceeds from S71 to S72. repeat. While repeating this, when the rapid pressure increase time Tpz elapses after shifting to the phase I, S71
Since the determination of No is No, the process proceeds to S73 and proceeds to the slow pressure increasing phase.

At S73, the value (T1-Tpz) obtained by subtracting the sudden pressure increase time Tpz from the time T1 measured by the timer T1 is 300.
Whether ms or less, that is, 300 after the rapid pressure increase time Tpz has elapsed
It is determined whether or not it is within ms. If the determination is Yes, S7
4, the slip ratio S is shown in the table TB4 of FIG.
(Here, the slip ratio S1) is applied to increase the pressure increasing valve 20.
The duty ratio Du of a is calculated, and then, in S76, a braking control signal for gradually increasing the pressure of phase I is output to the pressure increasing valve 20a and the pressure reducing valve 20b, and then the process returns. In this case, the pressure increasing valve 20a is driven at the duty ratio Du set in S74, and the pressure reducing valve 20b is driven.
Is kept closed.

Within the range of (T1−Tpz) ≦ 300 ms, the pressure increasing valve 20 is selected from the table TB4 at every calculation cycle of 8 ms.
The duty ratio Du of a is set. After that, (T1-
When Tpz)> 300 ms, the determination in S73 is No. Therefore, the process proceeds from S73 to S75, and in S75,
A value obtained by subtracting 1% from the previous value of the duty ratio Du of the booster valve 20a is set as the current duty ratio Du, and S
At 76, a braking control signal for setting the duty ratio Du of the pressure increasing valve 20a set at S75 is output. That is, the duty ratio Du of the pressure increasing valve 20a is controlled to decrease by 1% every 8 ms in the calculation cycle.

FIG. 13 shows the contents of the table TB4 in an easy-to-understand manner. In order to maintain the synchronized state in which the wheel speed V1 approaches the vehicle speed Vr, the vehicle speed Vr and the next pressure reduction are performed. The threshold value (which corresponds to 2-3 intermediate slip ratio threshold value Bsg × Vr) is 3/4 and 1 /
4, the 1/4 section is further divided into 3/4 and 1/4, and the 1/4 section is further divided into 3/4 and 1/4, and the wheel speed V1 becomes the vehicle body speed Vr. The closer it is, the booster valve 20
The duty ratio of a is set to be large. As described above, the slip ratio S is defined as S = wheel speed V / vehicle body speed Vr.

Next, if the determination in S78 is Yes, S7
In step 9, the flag P1 is set to 2, and then S58.
Move to. Thus, after the start of ABS control, the phase
II, Phase III, Phase V, Phase I, Phase
II, phase III, ... Are executed in this order over a plurality of cycles, and when the determination in S53 is Yes or the brake switch 25 is OFF, a series of ABS control ends (see FIG. 14). . The ABS control described above has been described by taking the ABS control of the brake device 11 for the left front wheel 1 as an example, but the ABS control is also executed in parallel for the other brake devices 12 to 14.

Next, the operation of the ABS control described above will be described with reference to FIG. 14 by taking the brake device 11 for the left front wheel 1 as an example.
Will be described with reference to. In the ABS control non-execution state during deceleration, when the brake fluid pressure generated by the depression operation of the brake pedal 25 is gradually increased and the rate of change of the wheel speed V1 (deceleration DV1) reaches -3G, the lock flag is set. Flok1 is set to 1, and the ABS control is substantially started from the time ta. In the first cycle immediately after the start of the control, the frictional state value Mu is set to 3 (high frictional state), and various control threshold values are set according to the traveling state parameter.

Next, the slip ratio S1 of the front wheels 1 and the wheel deceleration DV1 are compared with various control thresholds, and the phase is changed from phase 0 to phase II. Held in. When the slip ratio S1 falls below the 2-3 intermediate slip ratio threshold Bsg, the phase II
To phase III (pressure reduction phase), the brake fluid pressure is reduced at a predetermined gradient from time tb, and the rotational force of the front wheels 1 begins to recover. When the wheel deceleration DV1 further decreases to the threshold value B35 (0G) after depressurization, the phase shifts from phase III to phase V (holding phase after depressurization), and from that time tc, the brake fluid pressure becomes the level after depressurization. Retained.

When the slip ratio S1 becomes equal to or higher than the 5-1 slip ratio threshold Bsz in this phase V, the continuation flag Fcnl is set to 1, and the ABS control shifts from the time td to the second cycle. At this time, the brake fluid pressure is forcibly shifted to phase I (pressure increase phase), and immediately after the shift to phase I, the brake fluid pressure is increased steeply for a preset rapid pressure increase time Tpz. After the pressure is applied, the brake fluid pressure gradually increases with a gentler gradient. Thus
Immediately after the shift to the second cycle, the brake fluid pressure is reliably increased and a good braking pressure is secured.

On the other hand, after the second cycle, the appropriate frictional state value Mu is determined, and various control threshold values corresponding to the traveling state parameters determined by the frictional state value Mu and the vehicle body speed Vr are stored in tables TB2 and TB3. Since it is set based on, the precise control of the brake fluid pressure is performed according to the running state. After that, in the phase V in the second cycle, when the slip ratio S1 is larger than the threshold value Bsz, the phase I of the third cycle is entered.

Here, in the ABS control of the present application, as shown in S71, S73 to S76 of FIG. 11, and FIG. 12 and FIG. In this case, the wheel speed V1 becomes a value approaching the vehicle body speed Vr, but 300 in the first half of the slow pressure increasing phase.
During ms, based on the table TB4, the closer the wheel speed V1 is to the vehicle body speed Vr, the larger the duty ratio Du of the pressure increasing valve 20a is set, and in the latter half of the slow pressure increasing phase (after 300 ms has elapsed), The duty ratio Du of the pressure increasing valve 20a is configured to gradually decrease.

In this way, the duty ratio of the pressure increasing valve 20a in the first half of the slow pressure increasing phase is set to a large value, and the pressure increasing speed is increased in the state where the wheel speed V1 is close to the vehicle body speed Vr. By slowly increasing the pressure in the latter period of the slow pressure increasing phase, the period (synchronization period) in which the wheel speed V1 is close to the vehicle body speed Vr is made as long as possible, and the braking performance can be improved. By controlling the pressure increasing speed in the slow pressure increasing phase in this way, as shown in FIG. 15, the period of the synchronized state in which the wheel speed V1 approaches the vehicle body speed Vr is lengthened to enhance the braking performance. You can

It should be noted that the road surface friction estimation processing, the pseudo vehicle speed calculation processing, and the like in the above embodiment are merely examples, and various other methods may be used for the calculation. The brake fluid pressure may be independently controlled on the right and left sides, or the period Tpz of the rapid pressure increase phase may be set to be variable by learning control or the like. "300 ms" is an example, and may be set to an appropriate time of 300 ms or less, or an appropriate time of 300 ms or more, or may be variably controlled by learning control or the like, depending on the characteristics of the brake device. . The duty ratio Du of the table TB4 is also an example and is not limited to this. It is needless to say that the present invention can be implemented in a mode in which various modifications are added without departing from the spirit of the present invention.

[Brief description of drawings]

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

FIG. 2 is a flowchart of a main routine of anti-skid brake control.

FIG. 3 is a flowchart of a subroutine for calculating a road friction state value.

FIG. 4 is a flowchart of a subroutine of a pseudo vehicle body speed calculation process.

FIG. 5 is a diagram of a map of vehicle body speed correction values.

FIG. 6 is a flowchart of a subroutine of control threshold value setting processing.

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

FIG. 8 is a chart of a table in which various control threshold values are set.

FIG. 9 is a chart of a control threshold correction table.

FIG. 10 is a part of a flowchart of a control signal output processing subroutine.

FIG. 11 is the remaining part of the flowchart of the control signal output processing subroutine.

FIG. 12 is a chart of a table in which the duty ratio of the pressure increasing valve is set.

FIG. 13 is an explanatory diagram for explaining the contents of the table of FIG.

FIG. 14 is an operation time chart of anti-skid brake control.

FIG. 15 is a time chart corresponding to a main part of the operation time chart.

[Explanation of symbols]

 1, 2 front wheels (driven wheels) 3, 4 rear wheels (driving wheels) 11-14 braking device 15 braking system 24 ABS control unit 27-30 wheel speed sensor

Claims (3)

[Claims] 1. A wheel speed detecting means for detecting a rotation speed of a wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure of front wheels and a rear wheel, and a wheel speed detected by the wheel speed detecting means.
An anti-skid brake device for a vehicle, comprising: an anti-skid control means for controlling a hydraulic pressure adjusting means so that a brake hydraulic pressure changes in a hydraulic pressure control cycle including at least a pressure increasing phase and a pressure reducing phase. Consists of a rapid pressure increase phase and a slow pressure increase phase that follows, and the anti-skid control means is configured so that the pressure increase speed in the first half of the slow pressure increase phase is higher than the pressure increase in the latter half of the slow pressure increase phase. An anti-skid brake device for a vehicle, characterized in that it is configured to control the brake fluid pressure. 2. A wheel speed detecting means for detecting a rotational speed of a wheel, a hydraulic pressure adjusting means for adjusting a brake hydraulic pressure of front wheels and a rear wheel, and a wheel speed detected by the wheel speed detecting means,
An anti-skid brake device for a vehicle, comprising: an anti-skid control means for controlling a hydraulic pressure adjusting means so that a brake hydraulic pressure changes in a hydraulic pressure control cycle including at least a pressure increasing phase and a pressure reducing phase. Consists of a rapid pressure increase phase and a slow pressure increase phase that follows, and the antiskid control means is such that the pressure increase speed increases as the wheel speed approaches the vehicle speed for a predetermined period after the start of the slow pressure increase phase. An anti-skid brake device for a vehicle, characterized in that it is configured to control the brake fluid pressure. 3. The anti-skid control means is configured to control the brake fluid pressure such that the pressure increasing speed gradually decreases after a predetermined period has elapsed after the start of the slow pressure increasing phase. Item 3. The vehicle anti-skid brake device according to Item 2.