JPH0840242A - Antiskid brake device for vehicle - Google Patents

Abstract

PURPOSE:To prevent the deceleration speed shortage, preventing a driver from being given with the erroneous operation feeling, on the restart of the ABS control, by changing the control starting threshold value to the side where the control starting threshold value is easily started, up to the time when the prescribed conoition is established, after the completion of the ABS control. CONSTITUTION:A control unit 24 receives each detection signal supplied from a brake switch 25, steering angle sensor 26, and the wheel spend sensors 27-30, and outputs the brake hydraulic signal into each valve unit 20, 21, 23 of a brake control system 15, and carries out the ABS control for each wheel 1-4 in parallel. Accordingly, when the calculation value of the wheel speed exceeds the prescribed control starting threshold value, ABS control is carried out. In this case, up to the time when the prescribed condition is established after the completion of the ABS control, the control unit 24 varies the control starting threshold value to the side where the ABS control can be easily started. Accordingly, on the restart of the ABS control, preventing the driver from being applied with the erroneous operation feeling, the deceleration speed shortage is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle antiskid brake device.

[0002]

2. Description of the Related Art A vehicle anti-skid brake system is
Basically, the braking pressure (brake oil pressure) applied to the wheels is controlled to increase or decrease so that the wheels decelerate at the target deceleration or at the target slip ratio or slip amount. Accordingly, this is referred to as ABS control) to prevent the wheels from being locked or skid during braking, and to stop the vehicle for a short braking distance without losing directional stability. In this case, the ABS control is performed when the wheel deceleration exceeds a predetermined threshold value and increases, or when the wheel slip rate or slip amount exceeds a predetermined threshold value and increases. It is usually started.

Here, the wheel deceleration is generally calculated by differentiating the wheel speed, and the control start threshold value for this wheel deceleration is set to, for example, about -3 G (value converted into gravitational acceleration). .

The slip ratio is calculated from the vehicle speed and the wheel speed by the following equation. As the vehicle speed, the maximum value of the rotational speeds of the four wheels of the vehicle is generally used as the pseudo vehicle speed.

Slip rate = {(vehicle body speed-wheel speed) /
Vehicle speed} × 100% Then, the control start threshold value for this slip ratio is
For example, it is set to about 15%. Further, the slip amount is a deviation obtained by subtracting the wheel speed from the vehicle body speed, and the control start threshold value for this slip amount is, for example, 5 km.
It is set to about / h.

As disclosed in, for example, Japanese Unexamined Patent Publication No. Hei 5-162630, when the deceleration of the wheels exceeds a predetermined control start threshold value at the start of the ABS control, the braking pressure is reduced to the ABS. The control is started to prevent the wheels from being locked, and when the slip amount of the wheels exceeds a predetermined control start threshold value, the ABS control is started from the holding of the braking pressure to shorten the braking distance. .
Further, as disclosed in, for example, Japanese Patent Laid-Open No. 6-24313, there is a case in which the ABS control is terminated when the ABS pressure increasing state continues for a predetermined time.

[0007]

By the way, the above ABS
When the control start threshold value of the control is set with respect to the slip amount of the wheel, for example, when the control start threshold value is set relatively shallow (low), the ABS control is performed even when the ABS control is not required. There is a concern that control will start. That is, there are cases where the driver slowly depresses the brake pedal while grasping the condition of the road surface. In that case, the driver's own brake operation often prevents the wheels from being locked or skid. If the ABS control is started in such a case, the driver's intention is not reflected in the wheel braking pressure control, and the driver may feel a malfunction.

On the other hand, if the control start threshold value is set to be relatively deep (high), the braking pressure decompression start time is delayed, and the braking pressure at the decompression start time becomes considerably high before the decompression starts. Therefore, there is a drawback in that the amount of pressure reduction increases with the start of pressure reduction, giving the driver a feeling of insufficient braking force called “G missing”.

The present invention can solve the above two problems under a predetermined condition despite the above two problems. That is, an object of the present invention is to provide an anti-skid brake control device for a vehicle, which avoids giving a driver a feeling of malfunction and prevents the occurrence of an insufficient vehicle deceleration state.

[0010]

According to a first aspect of the present invention, there is provided wheel speed detecting means for detecting the rotational speed of a wheel, braking pressure adjusting means for adjusting the braking pressure of the wheel, and ABS control means for actuating the braking pressure adjusting means to start ABS control when a calculated value calculated based on the wheel speed detected by the wheel speed detecting means exceeds a predetermined control start threshold value. The anti-skid brake device for a vehicle provided with threshold value changing means for changing the control start threshold value to a side where ABS control can be easily performed until a predetermined condition is satisfied when the ABS control ends. It is characterized by

The calculated value calculated on the basis of the wheel speed comprises a wheel deceleration and / or a wheel slip amount.

Further, when the threshold value changing means changes the control start threshold value to a side in which the ABS control can be easily performed, for example, the control start threshold value is set to the side as described in claim 3. It consists of lowering.

According to one aspect of the present invention, as described in claim 4, the predetermined condition is that the depression of the brake pedal is released.

According to another aspect of the present invention, as described in claim 5, the predetermined condition is that a predetermined time has elapsed since the control start threshold value was changed. The threshold value changing means operates to gradually return the control start threshold value to the original value after the lapse of the predetermined time.

[0015]

In the vehicle anti-skid brake device according to the present invention, it has been found that the driver does not feel any malfunction even if the ABS control is started immediately after the ABS control is finished. That is, when the ABS control is finished, the threshold value changing means for changing the control start threshold value to the side in which the ABS control can be easily performed is provided, so that the control start threshold value is normally set relatively low. Set it deeply to eliminate the feeling of malfunction when the brake pedal is stepped on slowly, and immediately after this ABS control is completed and this is finished, the driver will restart ABS as long as the brake pedal is pressed. Since the control start threshold value is changed relatively shallowly,
Even if the S control is started early, there is little concern that it will give the driver a malfunctioning feeling, and at that time, the control start threshold value is changed to a shallower level, so there is no risk of giving a feeling of insufficient braking force. It is a thing.

Then, while the driver is stepping on the brake pedal, the control start threshold value changed relatively shallowly is set.
Alternatively, by holding the brake pedal for a predetermined time only, it is possible to eliminate a malfunction feeling when the brake pedal is depressed next time.

[0017]

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

As shown in FIG. 1, in the vehicle according to this embodiment, the left and right front wheels 1 and 2 are driven wheels and the left and right rear wheels 3 and 4 are drive wheels, and the output torque of the engine 5 is an 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 includes a disc 11a to 14a that rotates integrally with the wheel, and a brake including a caliber 11b to 14b that receives the brake hydraulic pressure and brakes the rotation of the disc 11a to 14a. Device 11-
14 are provided respectively, and these brake devices 11 to 11 are provided.
A brake control system 15 for actuating 14 is provided.

The brake control system 15 includes a booster 17 for increasing the stepping force of a brake pedal 16 by a driver, and a master cylinder 1 for generating a brake hydraulic pressure according to the stepping force increased by the booster 17.
8 and. The front wheel brake hydraulic pressure supply line 19 from the master cylinder 18 is branched into two paths, and the front wheel branch brake hydraulic pressure lines 19a and 19b are connected to the calibers 11 of the brake devices 11 and 12 for the left and right front wheels 1 and 2.
a, 12a, one branch brake hydraulic line 1 for the front wheel, which is connected to the brake device 11 for the left front wheel 1
9a is provided with a first valve unit 20 including an electromagnetic on-off valve 20a and an electromagnetic relief valve 20b, and is connected to the other front wheel branch brake hydraulic line 19b leading to the brake device 12 for the right front wheel 2. Similarly to the first valve unit 20, the second valve unit 21 including an electromagnetic on-off valve 21a and an electromagnetic relief valve 21b is also provided.
Is provided.

Relief valve 20 of the first valve unit 20
The brake oil discharged from b and the brake oil discharged from the relief valve 21b of the second valve unit 21 are stored in the common reservoir 31 and are pumped up from the reservoir 31 by the pump 32 operated during the ABS control. Are supplied to the front wheel brake hydraulic pressure supply line 19. The brake oil in the reservoir 31 passes through a drain line (not shown) to the reservoir tank 18a of the master cylinder 18.
Is returned to.

On the other hand, the brake hydraulic pressure supply line 22 for the rear wheels from the master cylinder 18 is provided with an electromagnetic opening / closing valve 23a and an electromagnetic relief valve 23b, like the first and second valve units 20 and 21. The third valve unit 23 is provided.

This rear wheel brake hydraulic pressure supply line 22
Is branched into two paths on the downstream side of the third valve unit 23, and these rear wheel branch brake hydraulic lines 22a, 2
2b are connected to the calibers 13b and 14b of the brake devices 13 and 14 for the left and right rear wheels 3 and 4, respectively.

Relief valve 23 of the third valve unit 23
The brake oil discharged from b is stored in the reservoir 33, and the brake oil pumped up from the reservoir 33 by the pump 34 operated during the ABS control is supplied to the rear wheel brake hydraulic pressure supply line 22. . The brake oil in the reservoir 33 is also returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

The brake control system 15 includes a brake device 11 for the left front wheel 1 via a first valve unit 20.
The first channel for variably controlling the brake hydraulic pressure of the
Brake device 1 for right front wheel 2 via valve unit 21
A second channel for variably controlling the brake hydraulic pressure of No. 2 and a third channel for variably controlling the brake hydraulic pressure of both brake devices 13, 14 for the left and right rear wheels 3, 4 via the third valve unit 23 are provided. The first to third channels are configured to be controlled independently of each other.

The brake control system 15 includes a first
~ Control unit 24 for controlling the third channel
The control unit 24 is provided with a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16, a steering angle signal from a steering angle sensor 26 for detecting a steering angle of the steering wheel, and rotation of each wheel. By receiving the wheel speed signals from the wheel speed sensors 27 to 30 respectively detecting the speeds and outputting the brake hydraulic pressure control signals corresponding to these signals to the first to third valve units 20, 21, 23, respectively, Braking control for slipping of the left and right front wheels 1, 2 and rear wheels 3, 4, that is, ABS
The control is performed in parallel for each of the first to third channels.

The control unit 24 makes a first determination based on the wheel speed detected by each wheel speed sensor 27-30.
-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 the front and rear wheels 23b and 23b respectively, the front wheels 1 and 2 and the rear wheels 3 and 4 are controlled by the brake hydraulic pressure according to the locked state.
It is designed to apply braking force to.

In the ABS non-controlled state, a brake hydraulic pressure control signal is output from the control unit 24, and the first to third valve units 20, 2 as shown in the figure.
Relief valves 20b, 21b, 23b in Nos. 1 and 23 are held closed, respectively, and each valve unit 20, 2
Since the on-off valves 20a, 21a and 23a of the valves 1 and 23 are held open, the brake hydraulic pressure generated in the master cylinder 18 in response to the stepping force of the brake pedal 16 is applied to the front wheel brake hydraulic pressure supply line 19 and the rear wheel brake. It is supplied to the brake devices 11 to 14 of the left and right front wheels 1, 2 and the rear wheels 3, 4 via the hydraulic pressure supply line 22, and the control force corresponding to these brake hydraulic pressure is applied to the front wheels 1, 2 and the rear wheels 3, 4. It will be given directly.

Next, an outline of the brake control performed by the control unit 24 will be described.

The control unit 24 controls the wheel speeds Vw1 to Vw indicated by the signals from the wheel speed sensors 27 to 30.
Based on 4, the accelerations AVw1 to AVw4 and the decelerations DVw1 to DVw4 for the respective wheels are calculated. Here, the calculation method of the acceleration or deceleration will be described. The control unit 24 divides the difference between the previous value of the wheel speed and the current value by the sampling cycle Δt (for example, 7 ms), and then calculates the result as the gravitational acceleration. The converted value is updated as the current acceleration and deceleration.

The control unit 24 has a third
The rear wheels 3 and 4 which represent the wheel speed for the channel and the acceleration / deceleration are selected, but both wheel speeds are taken into consideration in consideration of the detection error of the both wheel speed sensors 29 and 30 of the rear wheels 3 and 4 at the time of slip. The lower wheel speed of Vw3 and Vw4 is selected as the rear wheel speed Vwr, and the acceleration and deceleration obtained from the rear wheel speed Vwr are selected as the rear wheel acceleration and the rear wheel deceleration. .

Further, the control unit 24 estimates the pseudo vehicle body speed Vr and the road surface friction coefficient μ of the vehicle, and the pseudo vehicle body speed Vr is obtained as follows.

That is, the control unit 24 is
After determining the maximum wheel speed Vw _MAX from among the wheel speeds Vw1 to Vw4 indicated by the signals from the wheel speed sensors 27 to 30, the maximum wheel speed Vw _{MAX is set} to the pseudo vehicle body speed V.
adopted as r. In that case, the maximum wheel speed Vw _MAX
Wheel speeds Vw3 and Vw indicated by signals from wheel speed sensors 29 and 30 provided on the rear wheels 3 and 4, which are drive wheels.
4 is adopted, the wheel speeds Vw1, V indicated by signals from the wheel speed sensors 27, 28 provided on the front wheels 1, 2 which are driven wheels due to slipping of the rear wheels 3, 4 and the like.
When the wheel speeds Vw3 and Vw4 are larger than w2, the larger one of the wheel speeds Vw1 and Vw2 of the front wheels 1 and 2 is adopted as the pseudo vehicle body speed Vr.

On the other hand, when any of the front wheels 1 and 2 and the rear wheels 3 and 4 is locked, as shown in Table 1 below, a table preset corresponding to the road surface friction state value Mu is referred to Assuming a change amount (hereinafter, referred to as a vehicle body speed change amount) ΔVr of the pseudo vehicle body speed Vr per unit time, the pseudo vehicle body speed Vr is decreased according to the vehicle body speed change amount ΔVr.

[0035]

[Table 1]

That is, as will be described later, when the road surface friction state value Mu estimated on the basis of the pseudo vehicle body speed Vr is set to 1 which indicates a low μ road surface, the vehicle body speed change amount ΔVr has a small change of −0. When 3G (value converted into gravitational acceleration) is selected and the road surface friction state value Mu is set to 3 which indicates a high μ road surface, -1.2G, which has a large change in the vehicle body speed change amount ΔVr, is selected. It will be. Then, when the vehicle body speed change amount ΔVr is set to 2 which is an intermediate state between the high μ road surface and the low μ road surface, −0.8 G intermediate between the two is selected as the vehicle body speed change amount ΔVr.

In this way, the similar vehicle speed Vr is updated every sampling period Δt according to the wheel speeds Vw1 to Vw4.

On the other hand, the road surface friction coefficient is specifically determined as follows.

That is, the control unit 24 is
The vehicle body speed change amount ΔVr is calculated from the pseudo vehicle body speed Vr estimated as described above, and the vehicle body speed change is stored in the friction state value table set in advance according to the vehicle body speed change amount as shown in Table 2 below. The amount ΔVr is applied and set as the corresponding frictional state value Mu.

[0040]

[Table 2]

Here, the table of the frictional state value Mu is set in three stages according to the vehicle body speed change amount ΔVr. For example, the vehicle body speed change amount ΔV converted into gravitational acceleration.
When r is a value larger than −0.3 G, that is,
When the absolute value of ΔVr is smaller than 0.3 G and the change is small, 1 indicating a low μ road surface is selected as the friction state value Mu. On the other hand, when the vehicle body speed change amount ΔVr is a value larger than −1.2 G, that is, when the absolute value of ΔVr is larger than 1.2 G and there are many changes, the frictional state value Mu indicates a high μ road surface. Is selected. And
When the vehicle body speed change amount ΔVr indicates an intermediate value between the two values, 2 indicating the medium μ road surface is selected as the friction state value Mu.

Further, the control unit 24 obtains the wheel speeds Vw1 and Vw2 of the left and right front wheels 1 and 2 indicated by the signals from the wheel speed sensors 27 and 28 and the rear wheels obtained from the signals from the wheel speed sensors 29 and 30. Wheel speed Vwr
And the pseudo vehicle body speed Vr, the slip ratios for the first to third channels are calculated. The slip ratio is calculated by the following formula.

Slip rate = {(vehicle body speed-wheel speed) /
Vehicle body speed} × 100% That is, as the deviation of the wheel speed from the pseudo vehicle body speed Vr increases, the slip tendency of the wheel increases.

Next, the control unit 24
~ Various control threshold values used to control the third channel are set, and lock determination processing for each channel is performed using these control threshold values, and the first to third valve units 20,
Phase determination processing and the like for defining the control amounts for 21, 23 are performed.

Here, the outline of the phase determination processing will be described. The control unit 24 compares the respective threshold values set according to the running state of the vehicle with the wheel acceleration / deceleration and the slip ratio to determine whether or not the ABS is determined. Phase 0 showing the control state, Phase I showing the pressure increase state during ABS control, Phase I showing the holding state after pressure increase
I, phase III indicating a depressurized state, phase IV indicating a sudden depressurized state, and phase V indicating a holding state after depressurization are selected. And from phase 0 to phase
0-2 deceleration threshold value B ₀₂ for judging transition to II, that is, for judging ABS control start, phase I to phase
1-2 deceleration threshold value B ₁₂ for transition determination to II, 2-3 slip ratio threshold value Bsg for transition determination from phase II to phase III, transition determination from phase III to phase V A 3-5 deceleration threshold value B ₃₅ , a 5-1 slip ratio threshold value Bsz for determining the transition from phase V to phase I, and the like are set according to the vehicle speed range and the road surface μ. In this case, the deceleration threshold that greatly affects the control force is the braking performance when the road surface μ is large and the road surface μ
In order to achieve both a high level of control responsiveness and a low level of control responsiveness, the lower the frictional state value Mu, that is, the smaller the road surface μ, the closer to 0G.

The lock determination process will be described. For example, in the lock determination process for the first channel for the left front wheel, the control unit 24
First, the current value of the continuation flag Fcn1 for the first channel is set as the previous value, and then the vehicle body speed Vr and the wheel speed Vw1 are set to predetermined conditions (for example, Vr <5 km / h, V
w1 <7.5 km / h) is determined, and when these conditions are satisfied, the continuation flag Fcn1 and the lock flag Flok1 are reset to 0, respectively, and if not satisfied, the lock flag Flok1 is reset. Is set to 1 or not.

If the lock flag Flok1 is not set to 1, the lock flag Flok1 is set to 1 under a predetermined condition (for example, when the wheel deceleration becomes -3G).

On the other hand, in the control unit 24, when the lock flag Flok1 is set to 1, for example, the phase flag P1 of the first channel is set to 5 indicating the phase V, and the slip ratio S1 is 5 to be described later. When it is larger than the 1-slip ratio threshold Bsz, 1 is set to the continuation flag Fcn1. The lock determination process is similarly performed for the second and third channels.

Thus, the control unit 24 is
A brake pressure signal corresponding to the phase instructed by each phase flag P1 is output to each of the first to third valve units 20, 21 and 23 for each channel.
Accordingly, the first to third valve units 20, 21, 2
Branch brake pressure line 19 for front wheels on the downstream side of 3
a, 19b and the branch brake pressure line 22a for the rear wheels,
The brake pressure of 22b is increased or decreased, or is maintained at the pressure level after the increase or decrease.

Here, the 0-2 deceleration threshold value B ₀₂ 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, that is, the ABS control start threshold value. In the case of the present embodiment, two types are set, for example, the first control start threshold B ₀₂ 1 set to -3G and the second control start threshold set to -2G, for example. The values B ₀₂ 2 and are prepared (| B ₀₂ 1 |> | B ₀₂ 2 |). Then, normally, the first control start threshold value B ₀₂ 1 is set for each channel,
When the wheel speed Vw1 of each channel, Vw2, Vwr deceleration exceeds the first control start threshold B ₀₂ 1 above, the ABS control of the channel is adapted to be started, in the embodiment When the ABS control ends, the control start threshold value is changed from the first control start threshold value B ₀₂ 1 to the second control start threshold value B ₀₂ 2 so that the ABS control can be easily performed again. Is configured to. Then, when the depression of the brake pedal 16 is released and the brake signal from the brake switch 25 is turned off, the control start threshold value is changed from the second control start threshold value B ₀₂ 2 to the first control start value. The threshold value B ₀₂ 1 is set back.

Instead of or in addition to the 0-2 deceleration threshold value B ₀₂ , the ABS control start threshold value is set to a slip amount which is a value obtained by subtracting the wheel speed from the pseudo vehicle body speed Vr. You may set it. Again, 2
The ABS control start threshold value of the type is 0-2 slip amount threshold value BS for judging the transition from phase 0 to phase II.
₀₂ 1, BS ₀₂ 2 (BS ₀₂ 1> BS
₀₂ 2). Normally, the first control start threshold value BS ₀₂ 1 is adopted for each channel, and the deviation between the pseudo vehicle body speed Vr and the wheel speeds Vw1, Vw2, Vwr of each channel, that is, the slip amount, causes the first control start threshold. Value BS ₀₂
When it exceeds 1, the ABS control of the channel is started. However, like the above, when the ABS control is finished, the ABS start control is facilitated so that the ABS control can be easily entered again. Is changed from the first control start threshold value BS ₀₂ 1 to the second control start threshold value BS ₀₂ 2. Then, when the depression of the brake pedal 16 is released and the brake signal from the brake switch 25 is turned off, the control start threshold value is changed from the second control start threshold value BS ₀₂ 2 to the first control start value. It is adapted to be returned to the threshold BS ₀₂ 1. In that case, the first and second control start thresholds BS ₀₂ 1 and BS ₀₂ 2 are set to 5 km / h and 3 km / h, respectively.

Next, the ABS control in this embodiment will be described with reference to the time chart of FIG. 2 by taking the ABS control for the first channel as an example.

The above-mentioned 0-2 which is the ABS control start threshold value
As the deceleration threshold value B ₀₂ , the first control start threshold value B ₀₂ 1 is normally adopted, and the brake hydraulic pressure generated by the depression operation of the brake pedal 16 gradually increases in the ABS non-controlled state during deceleration. , The wheel speed Vw1 of the left front wheel 1
When the deceleration of the signal reaches -3G (first control start threshold value B ₀₂ 1), the lock flag Flok of the first channel is
1 is set to 1, ABS control is started from the time ta, the phase shifts from phase 0 to phase II, and the brake hydraulic pressure is maintained at the level immediately after the pressure increase.

In the first cycle after the start of the control, the frictional state value Mu is set to a value corresponding to the road surface frictional state, and various control threshold values are set according to the running state parameter.

When the slip ratio S1 increases above the 2-3 slip ratio threshold value Bsg, the phase II is shifted to the phase III, and the relief valve 20b is turned on according to a predetermined duty ratio.
N / OFF, the brake oil pressure is reduced at a predetermined gradient from the time tb, the braking force is gradually reduced, and the rotational force of the front wheels 1 starts to be recovered. When the wheel deceleration DVw1 continues to decrease to the threshold value B ₃₅ (0G), the phase shifts from phase III to V, and the brake oil pressure is maintained at the reduced pressure level from time tc. .

When the slip ratio S1 becomes equal to or less than the 5-1 slip ratio threshold value Bsz in this phase V, the continuation flag Fcn1 is set to 1 and the ABS control starts at time t.
The process shifts from d to the second cycle. At this time, forcibly shifts to phase I, and immediately after shifting to this phase I,
As described above, the opening / closing valve 20a is 100% closed when the relief valve 20b is closed during the rapid pressure increase time Tpz set by using the pressure increase time of the previous cycle as a parameter.
And the brake hydraulic pressure is steeply increased, and after the rapid pressure increase time Tpz elapses, the on-off valve 20 is opened.
a is turned on / off at a predetermined duty ratio, and the brake hydraulic pressure gradually increases with a gentler gradient. Thus, immediately after the shift to the second cycle, the brake hydraulic pressure is reliably increased and a good brake hydraulic pressure is secured.

On the other hand, even after the second cycle, appropriate friction state values Mu are determined, and these friction state values Mu are determined.
The various control thresholds corresponding to the running state parameters corresponding to the pseudo vehicle speed Vr and the pseudo vehicle body speed Vr provide precise control of the brake hydraulic pressure according to the running state.

After that, phase V in the second cycle
In, for example, when it is determined that the slip ratio S1 is larger than the threshold value Bsz, the phase I of the third cycle is performed. Next, a process of changing the ABS control start threshold value, that is, the 0-2 deceleration threshold value B ₀₂ , which is a characteristic part of the present embodiment, will be described with reference to the flowchart of FIG.

As described above, the first control start threshold value B ₀₂ 1 is usually set for each channel, and the deceleration of the wheel speeds Vw1, Vw2, Vwr of each channel is set to the first control start threshold value B 2. ₀₂ When the number exceeds 1, ABS control of the relevant channel is started.
When the S control ends, the control start threshold value is set to the first control start threshold value B so that the ABS control can be easily performed again.
It is configured to change from ₀₂ 1 to the second control start threshold value B ₀₂ 2. Then, when the depression of the brake pedal 16 is released and the brake signal from the brake switch 25 is turned off, the control start threshold value is changed from the second control start threshold value B ₀₂ 2 to the first control start value. The threshold value B ₀₂ 1 is set back.

First, in S1 of FIG. 3, whether or not the brake signal from the brake switch 25 is ON, that is,
It is determined whether or not the brake pedal 16 is depressed, and if the brake pedal 16 is depressed (S1: YES),
In the next S2, it is determined whether or not the channel is under ABS control. If ABS control is in progress (S2: YES),
In S3, it is determined whether the ABS control is finished, and when the ABS control is finished (S3: YES), the process proceeds to S4. S
In No. 4, the ABS control start threshold value of the channel is set to
The control start threshold value B ₀₂ 1 (-3G) is changed to the second control start threshold value B ₀₂ 2 (-2G) so that the ABS control can be easily performed again. Next, in S5, the brake switch 2
It is determined whether or not the brake signal from 5 is switched from ON to OFF, that is, whether or not the depression of the brake pedal 16 is released. While the brake signal is ON (S5: NO), the process returns to S4. , ABS control start threshold value is fixed to the second control start threshold value B ₀₂ 2. And
When the brake signal is switched from ON to OFF (S5: YES), the process proceeds to S6 and the ABS control start threshold value is changed from the second control start threshold value B ₀₂ 2 to the first control start threshold value B ₀₂ 1. Return and return.

As described above, in this embodiment, the ABS
When the control ends, the ABS control start threshold value is changed from the deeper first control start threshold value B ₀₂ 1 to the shallower second control start threshold value B ₀₂ 2, and the ABS control is started again. Since it is made easy, the relatively deep 1 control start threshold value B ₀₂ 1 eliminates the feeling of malfunction when the brake pedal is slowly depressed, and immediately after the ABS control is performed and this is finished. Means that the driver expects ABS to start again as long as the driver depresses the brake pedal.
_{Even if the} ABS control is started early by the control start threshold value changed to _02, there is little concern that it will give the driver a feeling of malfunction, and at that time, the control start threshold value is changed to a shallower value. As a result, there is no possibility of giving a feeling of insufficient braking force. Then, the control start threshold value changed relatively shallowly is held while the driver depresses the brake pedal or only for a predetermined time,
It is possible to prevent a feeling of malfunction when the brake pedal is depressed next time.

FIG. 4 is an ABS showing another embodiment of the present invention.
It is a flow chart of control start threshold change processing. The processing from S11 to S14 in FIG. 4 is the same as S1 in FIG.
This is the same as the processing from S4 to S4, and by this series of processing, the ABS control start threshold value is changed from the first control start threshold value B ₀₂ 1 to the second control start threshold value B ₀₂ 2. Next, in S15, it is determined whether or not a predetermined time has elapsed from the time when the ABS control start threshold value was changed due to the end of the ABS control, and until the predetermined time has elapsed (S15:
(NO), returning to S14, the ABS control start threshold value is fixed to the second control start threshold value _B022 . Then, when the predetermined time has elapsed (S15: YES), the process proceeds to S16, where the ABS control start threshold value is set to the second control start threshold value B.
It gradually returns from ₀₂ 2 to the first control start threshold value B ₀₂ 1 and returns.

It is apparent that this embodiment also has the same effect as the above-mentioned embodiments.

When the above-mentioned 0-2 slip amount threshold value BS ₀₂ is adopted as the ABS control start threshold value, when the ABS control ends, in S4 of FIG. 3 and S14 of FIG. The ABS control start threshold is set to the first
By changing the control start threshold BS ₀₂ 1 (5 km / h) to the second control start threshold BS ₀₂ 2 (3 km / h),
It is possible to easily enter the ABS control.

[Brief description of drawings]

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

[Fig. 2] Operation time chart of the anti-skid brake device

FIG. 3 is a flowchart of ABS control start threshold value changing processing.

FIG. 4 is a flowchart similar to FIG. 3 according to another embodiment.

[Explanation of symbols]

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

Claims (5)

[Claims] 1. A wheel speed detecting means for detecting a rotation speed of a wheel, a braking pressure adjusting means for adjusting a braking pressure of the wheel, and a calculated value calculated based on the wheel speed detected by the wheel speed detecting means. An anti-skid brake device for a vehicle, comprising: an anti-skid control means for activating the braking pressure adjusting means to start anti-skid control when a predetermined control start threshold value is exceeded. When the anti-skid control is completed, a threshold changing means for changing the control start threshold to a side where the anti-skid control is easily entered until a predetermined condition is satisfied is provided. Skid brake device. 2. The calculated value comprises a wheel deceleration and / or a wheel slip amount.
The anti-skid brake device for a vehicle according to. 3. The control start threshold value is changed by the threshold value changing means to a side where anti-skid control is likely to be performed, which is to lower the control start threshold value. The anti-skid brake device for a vehicle according to 1 or 2. 4. The anti-skid brake device for a vehicle according to claim 1, wherein the predetermined condition is that the depression of the brake pedal is released. 5. The predetermined condition is that a predetermined time has elapsed since the control start threshold value was changed, and the threshold value changing means sets the control start threshold value after the predetermined time period has elapsed. 4. The antiskid brake device for a vehicle according to claim 1, wherein the value is gradually returned to the original value.