JPH0848231A - Vehicle anti-skid brake system - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide an anti-skid brake device for a vehicle in which an erroneous determination is prevented by limiting the range of the erroneous determination of the ABS control due to a step on the road surface. A control channel for variably controlling the braking pressure of the wheels to perform anti-skid control is provided for each of the front wheels and the rear wheels, and each of the control channels operates a braking pressure adjusting means based on the wheel speed to perform the braking. In an anti-skid brake device for a vehicle, which is provided with anti-skid control means for periodically increasing / decreasing pressure and erroneous operation determining means for determining erroneous operation of the anti-skid control means, an erroneous control channel on the front wheel side is provided. When the operation determination is made, a means is provided for forcibly bringing the control channel on the rear wheel side into a state in which the error operation determination is made after a lapse of a predetermined time from the time when the operation determination is made. The predetermined time is changed according to the vehicle speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid brake device for surely detecting a skid state of a vehicle and performing proper braking control.

[0002]

2. Description of the Related Art As a vehicle braking system, an anti-skid brake device has been put into practical use, which prevents a wheel from being locked or a skid state from occurring during braking.

This type of anti-skid brake system is
It has a wheel speed sensor for detecting a wheel speed, an electromagnetic control valve for adjusting a brake hydraulic pressure, and a control unit for controlling the electromagnetic control valve based on the wheel speed detected by the wheel speed sensor. The control unit obtains the acceleration and deceleration of the wheel based on the detected wheel speed, and when the wheel deceleration exceeds a predetermined threshold value, the electromagnetic control valve is pressure-reduced to control the braking pressure (brake pressure). hydraulic)
And the wheel speed increases due to the decrease in the braking pressure, and when the wheel acceleration reaches a predetermined value, the braking pressure is increased by controlling the pressure increase of the electromagnetic control valve.

By continuing such a series of braking pressure control (hereinafter referred to as ABS control as necessary) until just before the vehicle stops, for example, during sudden braking or on a low μ road having a low friction coefficient μ on the road surface. It is possible to prevent the wheels from being locked or skided in the vehicle and to stop the vehicle for a short braking distance while ensuring the directional stability of the vehicle. Then, such ABS control is generally executed in a plurality of control cycles in which three phases of pressure increase, pressure decrease, and holding are one cycle.

By the way, in braking operation, when the brake hydraulic pressure is increased, the wheel speed is decreased and the vehicle speed is decreased. However, if the rotation of the wheels is excessively restricted by the sudden increase in the brake hydraulic pressure, the wheels slip and the vehicle speed does not decrease so much. In such a case, it is necessary to reduce the brake oil pressure to eliminate the slip state of the wheels and restore the grip force to the road surface. When the ABS control is started and the brake hydraulic pressure is reduced when the slip of the wheel becomes large due to the excessive pressure increase in this way, excessive pressure reduction occurs and braking performance is deteriorated. Therefore, it is necessary to start ABS control as accurately and promptly as possible.

From this point of view, the deceleration of the wheel or the slip amount of the wheel exceeds a predetermined threshold value regardless of whether or not a brake operation signal is input from the brake switch as a condition for starting the ABS control. At this time, an anti-skid brake device has been proposed which is configured so that ABS control is automatically started.

However, for example, when the wheel crosses a step on the road surface, deceleration that temporarily exceeds the threshold value may occur. Therefore, in a vehicle equipped with an anti-skid brake device configured to start ABS control when the wheel deceleration or the slip amount of the wheel exceeds a predetermined threshold value, when the wheel gets over a step, However, the ABS control is started against the driver's will, the brake hydraulic pressure is reduced, the braking distance becomes longer, and the driver may feel uncomfortable due to unnecessary start of the ABS control. .

Therefore, an anti-skid brake device has been proposed in which the start condition of ABS control is made blunt when a step on the traveling road surface is detected, and is disclosed in, for example, Japanese Unexamined Patent Publication No. 5-213178. As described above, when the wheel speed becomes equal to or higher than a predetermined speed within a predetermined time immediately after the ABS control is started, and the wheel acceleration reaches a predetermined negative value and a predetermined positive value within the predetermined time, the road surface There is also proposed an antilock brake device that determines that there is a step in the vehicle and terminates the ABS control.

[0009]

By the way, when the ABS control start condition is set so as to prevent the ABS control from malfunctioning due to a step or the like on the traveling road surface, a criterion for detecting the step on the traveling road surface is set. It is necessary to clearly distinguish between the ABS control and the reference as the starting condition of the ABS control. However, since it is difficult to accurately detect the step on the road surface on the basis of the acceleration and deceleration of the wheels as a criterion, an erroneous determination may occur in the ABS control malfunction, and as a result, the ABS Despite the fact that it is necessary to start the control, if the start of the ABS control is obstructed, or even if it is started, it is determined to be a malfunction and the ABS control ends early. Problem occurred.

In view of the above-mentioned circumstances, the present invention provides an anti-skid brake device for a vehicle in which the range of the malfunction determination of the ABS control due to a step on the traveling road surface or the like is limited to prevent the false determination. To aim.

[0011]

According to a first aspect of the present invention, control channels for variably controlling the braking pressure of the wheels to perform anti-skid control are provided for the front wheels and the rear wheels, and each control channel has a wheel. Wheel speed detecting means for detecting the rotation speed of the wheel, braking pressure adjusting means for adjusting the braking pressure of the wheel, and the braking pressure adjusting means for operating the braking pressure based on the wheel speed detected by the wheel speed detecting means. An anti-skid control means for periodically increasing or decreasing,
In an anti-skid brake device for a vehicle, which is provided with an erroneous operation determining means for determining an erroneous operation of the anti-skid control means, when the erroneous operation determination is made by the erroneous operation determining means in the control channel on the front wheel side, It is provided with means for forcibly bringing the control channel on the rear wheel side into a state where the malfunction determination is made by the malfunction determination means after a predetermined time has elapsed since the malfunction determination was made. Is.

The predetermined time is changed according to the vehicle speed (claim 2).

According to a third aspect of the present invention, the wheel speed detecting means for detecting the rotational speed of the wheel, the braking pressure adjusting means for adjusting the braking pressure of the wheel, and the wheel speed detected by the wheel speed detecting means are used. Anti-skid control means for operating the braking pressure adjusting means to periodically increase or decrease the braking pressure;
An antiskid brake device for a vehicle, which is provided with an erroneous operation determining means for determining an erroneous operation of the antiskid control means, is provided with a means for prohibiting the erroneous operation determination by the erroneous operation determining means in a high speed range. It is characterized by.

According to a fourth aspect of the present invention, the wheel speed detecting means for detecting the rotational speed of the wheel, the braking pressure adjusting means for adjusting the braking pressure of the wheel, and the wheel speed detected by the wheel speed detecting means are used. Anti-skid control means for operating the braking pressure adjusting means to periodically increase or decrease the braking pressure;
In an anti-skid brake device for a vehicle, which is provided with an erroneous operation determining means for determining an erroneous operation of the anti-skid control means, when the wheel slip amount is larger than a set value, the erroneous operation determination means It is characterized by having a means for prohibiting.

According to the present invention, there is provided a means for preventing the antiskid control from being started for a predetermined time when the malfunction determination is made by the malfunction determining means during the non-antiskid control. (Claim 5) Alternatively, a configuration is provided which prohibits the antiskid control from being started for a predetermined time when the malfunction determination is made by the malfunction determination unit during the non-antiskid control (Claim 6). ) Can be.

According to a seventh aspect of the present invention, the wheel speed detecting means for detecting the rotational speed of the wheel, the braking pressure adjusting means for adjusting the braking pressure of the wheel, and the wheel speed detected by the wheel speed detecting means are used. Anti-skid control means for operating the braking pressure adjusting means to periodically increase or decrease the braking pressure;
In an anti-skid brake device for a vehicle, which is provided with an erroneous operation determining means for determining an erroneous operation of the anti-skid control means, the erroneous operation determining means determines an erroneous operation when a skid time of a wheel is a predetermined time or less. In addition to the above, when the acceleration of returning the wheel speed after decompression is smaller than a predetermined value, a means for prohibiting the malfunction determination by the malfunction determination means is provided.

In this case, when the skid time of the wheel is a predetermined time or less and the return acceleration of the wheel speed after decompression is a predetermined value or more, the malfunction determining means may determine the malfunction (claim). Item 8).

According to a ninth aspect of the present invention, a plurality of control channels are provided for variably controlling the braking pressure of the wheels to perform anti-skid control, and the wheel speed detection for detecting the wheel rotation speed is provided in the plurality of control channels. Means, braking pressure adjusting means for adjusting the braking pressure of the wheels, and anti-skid control for periodically increasing or decreasing the braking pressure by operating the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. Means and an erroneous operation determining means for determining erroneous operation of the antiskid control means, wherein at least one control channel of the plurality of control channels is an antiskid control device. When it is in the middle, it is provided with means for prohibiting the malfunction determination by the malfunction determination means in the other control channel. And it is characterized in and.

According to one aspect of the invention of claim 9, 2
When one control channel shares a reservoir of brake fluid and a pump that pumps the brake fluid from the reservoir and supplies the brake fluid to the brake device of the wheel via the braking pressure adjusting means, one control channel is During the skid control, the malfunction determination by the malfunction determining means in another control channel is prohibited (claim 10).

According to the seventh aspect of the present invention, when the malfunction determination is made by the malfunction determining means after the antiskid control is started, the antiskid control is immediately stopped. (Claim 11).

According to a twelfth aspect of the present invention, the wheel speed detecting means for detecting the rotational speed of the wheel, the braking pressure adjusting means for adjusting the braking pressure of the wheel, and the wheel speed detected by the wheel speed detecting means are used. A plurality of control channels provided with an anti-skid control means for operating the braking pressure adjusting means to periodically increase and decrease the braking pressure are provided, and each of the control channels has an erroneous determination of an erroneous operation of the anti-skid control. In an anti-skid brake device for a vehicle provided with operation determining means, a brake sensor that outputs an ON signal when the brake pedal is depressed is provided, and when the signal from the brake sensor is OFF, Is also characterized by making the malfunction determination by the malfunction determination means sensitive.

According to one aspect of the invention of claim 12,
During the non-anti-skid control, when a positive change in the acceleration / deceleration of the wheel of a predetermined value or more is detected, it is determined that the malfunction is determined by the malfunction determining means, and the signal from the brake sensor is turned off. At this time, the predetermined value is set smaller than when it is on (claim 13). Then, when the malfunction determination is made by the malfunction determining means, the anti-skid control can be prevented from being started for a predetermined period of time.

[0023]

[Advantageous Effects of the Invention] When the vehicle is traveling forward, if the front wheels pass over bumps, bumps, etc. on the road surface, a predetermined time corresponding to the vehicle speed at that time (for example, about 250 ms at 40 km / h) Later, the rear wheel will get over the projections, steps, etc. on the road surface. Therefore, if an erroneous operation is determined in the control channel on the front wheel side due to the front wheel getting over the protrusion, step, etc., the control channel on the rear wheel side after the lapse of the predetermined time from the time when the erroneous operation determination is made. It can be predicted that a malfunction determination will be made in the case of
In a configuration in which the S control channel is provided for each of the front wheel and the rear wheel, when a malfunction determination is made in the control channel on the front wheel side, the control on the rear wheel side is performed after a predetermined time has elapsed from the time when the malfunction determination was made. By providing a means for forcibly bringing the channel into the state in which the malfunction determination is made by the malfunction determining means, unnecessary malfunction determination in the control channel on the rear wheel side is prohibited, and the control channel on the rear wheel side is prohibited. Therefore, it is possible to prevent an erroneous determination with respect to the erroneous operation determination, and it is possible to prevent the start and / or the continuation of the ABS control when the ABS control is truly required.

As in the second aspect of the invention, the predetermined time can be set according to the vehicle speed by shortening the predetermined time according to the vehicle speed as the vehicle speed increases.

In the high speed range, the running stability of the vehicle is impaired even by a slight slip of the wheels.
It is preferable that the BS control is started easily. However, in the invention of claim 3, since the means for prohibiting the malfunction determination in the high speed range is provided, it is necessary to truly start the ABS control in the high speed range. The control start in the scene is not obstructed, and the running stability of the vehicle in the high speed range is improved.

According to the fourth aspect of the present invention, when the slip amount of the wheel is larger than the set value, the means for prohibiting the malfunction determination by the malfunction determination means is provided. , ABS can be actuated, whereby a large slip can be quickly recovered, and running stability is improved.

According to the fifth and sixth aspects of the present invention, during non-antiskid control, when the malfunction determination is made by the malfunction determining means, the means for preventing the antiskid control from being started for a predetermined time or the antiskid control is provided. By providing a means to prohibit, A
It is possible to prevent the BS control from being started.

According to the invention of claim 7, when the skid time of the wheel is less than a predetermined time, the malfunction is determined, and when the return acceleration of the wheel speed after depressurization is smaller than a predetermined value, the malfunction determination means makes an error. By providing the means for prohibiting the operation determination, there is an advantage that the malfunction determination can be surely performed and the ABS control when the ABS control is truly required is not hindered. That is, in the normal ABS control, the skid time for one cycle from the start of pressure reduction due to a drop in the wheel speed to the return of the wheel speed to near the pseudo vehicle body speed is 50 ms or more. Therefore, if the skid time is shorter than 50 ms, it may be determined as a malfunction. Further, when the wheel gets over a step or the like, the acceleration when the wheel speed once dropped returns to +10 G or more. Therefore, when the return acceleration of the wheel speed after depressurization is smaller than +10 G, the normal A
It may be determined that it is BS control.

Further, when the skid time is near 50 ms, it is difficult to determine whether the wheel speed is restored by the ABS control or by overcoming a step or the like. When the skid time is less than the predetermined time and the return acceleration of the wheel speed after depressurization is more than the predetermined value, the malfunction is determined, so that the accurate malfunction can be determined.

By the way, since the ABS control device is equipped with a large number of electromagnetic control valves and an electric pump that pumps brake fluid from a reservoir and supplies it to the wheel brake device via the electromagnetic control valves, the ABS control is started. Then, the opening / closing sound of the electromagnetic control valve, the rotation sound of the motor for driving the pump, and the like are generated, and these sounds are noisy. Therefore, it is desirable to prevent unnecessary ABS control from being started due to malfunction.
There is not much difference in noise between the case where only one channel is under ABS control and the case where all channels are under ABS control.

Further, two control channels (for example, a control channel for the left front wheel and a control channel for the right front wheel) share a reservoir, and one control channel is under normal ABS control and the other control channel. Is non-ABS
In the control state, the other control channel that was in the non-ABS control state started ABS control, but assuming that the ABS control is stopped immediately after the start due to the malfunction judgment, Since the control channel is under ABS control, brake fluid is accumulated in the reservoir. At this time, since the brake pedal is stepped on, in the control channel where the ABS control is stopped, the reduced brake hydraulic pressure is increased to the hydraulic pressure of the master cylinder all at once, so if the wheels slip due to this increase in pressure, The ABS control is started again to perform a sudden pressure reduction, but the brake fluid due to the rapid pressure reduction cannot be stored in the reservoir, and the pumping of the brake fluid by the pump cannot catch up. Therefore, there is a possibility that a pressure reduction defect or a pressure increase defect may occur.

Therefore, according to the invention of claim 9, when at least one control channel of the plurality of control channels is under ABS control, a means for prohibiting malfunction determination in another control channel is provided. ,
It is possible to prevent the control channel in the non-ABS control state from stopping the ABS control immediately after the ABS control is started, and it is possible to avoid the occurrence of the pressure reduction defect and the pressure increase defect. Further, noise does not increase for the above reason.

According to the tenth aspect of the invention, the two control channels are provided with a brake fluid reservoir, and the brake fluid is pumped up from the reservoir to supply the brake fluid to the wheel brake device via the braking pressure adjusting means. When one control channel is in the anti-skid control when it is shared with the pump, the malfunction determination by the malfunction determining means in the other control channel is prohibited. There is no risk of defects.

According to the eleventh aspect of the invention, when the malfunction determination is made by the malfunction determining means after the antiskid control is started, the means for immediately stopping the antiskid control is provided. ABS
Unnecessary control operations can be limited as much as possible.

Further, since it is not necessary to enter the ABS control when the brake pedal is not stepped on, it is preferable that the ABS control is made difficult to start by making it easy to make a malfunction determination. In the invention of
A brake sensor that outputs an ON signal when the brake pedal is depressed is provided, and when the signal from the brake sensor is OFF, malfunction detection is made more sensitive than when it is ON, so that the brake pedal is not depressed. At times, there is an advantage that the ABS control is less likely to be started, and a malfunction is less likely to occur. In that case, when a positive change in the acceleration / deceleration of the wheel of a predetermined value or more is detected during the non-anti-skid control, the malfunction determination is made by the malfunction determination means. In addition, when the signal from the brake sensor is off, the predetermined value is made smaller than when the signal is on, so that it is possible to easily prevent malfunctions when the brake pedal is not depressed.

Also in this case, as in the invention of claim 14, when the malfunction determination is made by the malfunction determining means, the anti-skid control is difficult to be started for a predetermined time. It is possible to prevent the ABS control from being started when necessary.

[0037]

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 driving 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 is a brake including disks 11a to 14a which rotate integrally with the wheels and calibers 11b to 14b which brake the rotation of the disks 11a to 14a by receiving brake hydraulic pressure. 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 device 17 for increasing the stepping force on the brake pedal 16 by the driver, and a master cylinder 1 for generating a brake hydraulic pressure according to the stepping force increased by the booster device 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 wheel 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 has 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. It receives the wheel speed signals from the wheel speed sensors 27 to 30 respectively detecting the speeds, and outputs brake hydraulic pressure control signals corresponding to these signals to the first to third valve units 20, 21, 23.
To the front and rear wheels 1 and 2 and the rear wheels 3 and 4 on the left and right to control the braking, that is, AB
The S 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 and 2 are output 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.
4, the decelerations DVw1 to DVw4 and the accelerations AVw1 to AVw4 for each wheel are calculated.

Explaining the method of calculating the acceleration or deceleration, the control unit 24 calculates the difference between the previous value of the wheel speed and the current value and the sampling cycle Δ.
After dividing by t (for example, 7 ms), a value obtained by converting the result into gravitational acceleration is updated as the current acceleration and deceleration.

Further, the control unit 24 executes a predetermined rough road judgment processing to judge whether or not the traveling road surface is a bad road. Explaining the outline of this rough road determination, for each wheel corresponding to each channel, the number of times that the wheel acceleration or wheel deceleration is equal to or higher than a predetermined rough road determination threshold value during a predetermined period is counted. When the number of times is less than or equal to the predetermined value, the rough road flag Fak is set to 0, and when the number of times is larger than the predetermined value, the rough road flag Fak is set to 1.

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 one of the wheel speeds is selected as the rear wheel speed, and 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 24 calculates the road surface friction coefficient of each of the three channels and the pseudo vehicle body speed Vr of the vehicle in parallel with the road surface friction coefficient of each of the three channels.

The control unit 24 controls the rear wheel speeds obtained from the signals from the wheel speed sensors 29, 30 and the wheel speeds of the left and right front wheels 1, 2 detected by the wheel speed sensors 27, 28 and the pseudo vehicle body speed Vr. From 1st to 3rd
The slip amount for each channel is calculated, but in this embodiment, the non-slip ratio represented by the following equation is used.

Non-slip ratio = (wheel speed / pseudo vehicle body speed) × 100% Therefore, the pseudo vehicle body speed Vr (hereinafter simply referred to as the vehicle body speed Vr
The deviation of the wheel speed with respect to () will increase, and the non-slip rate decreases, and 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,
A phase determination process for defining the control amount for 21, 23 and a cascade determination process are performed.

The phase determining process will be briefly described below. The control unit 24 compares the respective threshold values set according to the traveling state of the vehicle with the wheel acceleration / deceleration and the non-slip ratio. Phase 0 indicating a non-controlled state, Phase I that is a pressure increasing state during ABS control, Phase that is a holding state after pressure increasing
II, phase III which is a depressurized state, phase IV which is a rapidly depressurized state, and phase V which is a holding state after depressurization are selected.

The lock determining process will be described. For example, in the lock determining 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, the phase flag P1 of the first channel is set to 5 indicating the phase V, and the non-slip ratio S1 is 5 which will be described later. -1 When the continuation flag Fcn1 is larger than the non-slip rate threshold value Bsz, 1 is set. The lock determination process is similarly performed for the second and third channels.

In the above-described cascade determination process, the wheels are easily locked even with a small brake pressure, especially on a low friction road surface such as an ice burn. This is a determination, and the cascade flag Fcs is set to 1 when a predetermined condition in which cascade lock is likely to occur is satisfied.

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.

Next, a method of calculating the road surface friction coefficient (road surface μ) will be described.

First, the road surface friction coefficient Mu of the first channel
When calculating 1, the road surface friction coefficient Mu1 is calculated on the basis of the wheel speed Vw1 of the front wheels 1 and its acceleration Vg. However, the acceleration Vg after acceleration is sufficient by using a timer of 500 ms and a timer of 100 ms. Not grow 50
The acceleration Vg is calculated by the following equation from the change of the wheel speed Vw1 every 100 ms until the lapse of 0 ms in 100 ms.

Vg = K1 × [Vw1 (i) −Vw1 (i-100)] After the lapse of 500 ms when the acceleration Vg becomes sufficiently large, the acceleration is calculated by the following equation from the change of the wheel speed every 500 ms for 500 ms. Vg is calculated.

Vg = K2 × [Vw1 (i) −Vw1 (i-500)] In the above equation, Vw1 (i) is the current wheel speed,
Vw1 (i-100) is the wheel speed 100 ms before, Vw
1 (i-500) is the wheel speed before 500 ms, K1, K
2 is a predetermined constant. The road surface friction coefficient Mu1
Is calculated by three-dimensional interpolation from the μ table shown in FIG. 2 using the wheel speed Vw1 obtained as described above and its acceleration Vg. However, the road surface μ = 1.0 to 2.5 corresponds to low friction, the road surface μ = 2.5 to 3.5 corresponds to medium friction, and the road surface μ = 35 to 5.0 corresponds to high friction. .

Next, the road surface friction coefficient Mu of the second channel
When calculating 2, the wheel speed Vw2 is used for the same calculation as described above, and the surface friction coefficient Mu3 of the third channel is set equal to the smaller one of the road surface friction coefficient Mu1 and the road surface friction coefficient Mu2. . However, the road surface μ detected by three dedicated road surface μ sensors corresponding to the first to third channels
May be applied.

Next, the calculation processing of the pseudo vehicle body speed Vr will be described with reference to the flowchart of FIG. The following vehicle speed Vr means a pseudo vehicle speed.

First, the control unit 24 reads various data (S20), then calculates the maximum wheel speed Vwm from the wheel speeds Vw1 to Vw4 indicated by the signals from the sensors 27 to 30 (S21), and then Maximum wheel speed V
The maximum wheel speed change amount Δwm per sampling period Δt of wm is calculated (S22).

Next, the control unit 24 sets S2.
3 in the friction state value Mu (first
~ Minimum road friction value of channel 3) The vehicle body speed correction value CVr is read out, and it is determined in S24 whether the maximum wheel speed change amount ΔVwm is equal to or less than the vehicle body speed correction value CVr.

As a result of the determination, the wheel speed change amount ΔVwm
When it is determined that is equal to or smaller than the vehicle body speed correction value CVr (S24: YES), the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the vehicle body speed Vr is replaced with the current value in S25. Therefore, the vehicle body speed Vr is the vehicle body speed correction value CV.
It will decrease with a predetermined gradient according to r.

On the other hand, the control unit 24 uses S2
4, the wheel speed change amount ΔVwm is the vehicle body speed correction value C.
When it is determined that it is larger than Vr (S24: NO), that is, when the maximum wheel speed Vwm shows an excessive change,
In S26, the pseudo vehicle body speed Vr to the maximum wheel speed Vw
It is determined whether the value obtained by subtracting m is greater than or equal to the predetermined value Vo.

That is, the maximum wheel speed Vwm and the vehicle body speed V
It is determined whether or not there is a large difference with r. When there is a large difference (S26: YES), the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the vehicle body speed Vr is replaced with the current value in S25.

Further, when there is no large difference between the maximum wheel speed Vwm and the vehicle body speed Vr (S26: NO), the control unit 24 replaces the maximum wheel speed Vwm with the vehicle body speed Vr in S27. Thus
The vehicle body speed Vr of the vehicle is updated every sampling period Δt according to the wheel speeds Vw1 to Vw4.

Next, the process of setting various control threshold values will be described with reference to the flowchart of FIG. 5 and FIGS. The control threshold value setting process is executed independently for each channel, but here, the control threshold value setting process for the first channel for the left front wheel will be described.

The control unit 24 reads various data in S30, and then, in S31, the frictional state value Mu and the vehicle body speed Vr are calculated from the table preset with the vehicle speed range and the road surface μ as parameters as shown in FIG. The driving condition parameter according to is selected. For example, when the friction state value Mu is 1, which is indicated by the low friction road surface, and the vehicle body speed Vr is in the medium speed range, the LM2 for the medium speed low friction road surface is selected as the traveling state parameter. The friction state value M
u is determined from the minimum one of the friction coefficients Mu1 to Mu3. In FIG. 6, Mu = 1 indicates a low friction state, M
u = 2 corresponds to a medium friction state, and Mu = 3 corresponds to a high friction state.

On the other hand, when the bad road flag Fak is set to 1 indicating the bad road condition, the running condition parameter corresponding to the vehicle body speed Vr is selected as shown in FIG. In this case, for example, when the vehicle body speed Vr belongs to the medium speed range, the HM for the medium speed and low friction road surface is used as the traveling state parameter.
2 is forced to be selected. That is, the road surface μ tends to be estimated to be small due to the large fluctuation of the wheel speed during traveling on a rough road.

After selecting the running condition parameter, the control unit 24 reads each control threshold value corresponding to the running condition parameter from the control threshold setting table shown in FIG. 7 in S32.

Here, as various control threshold values, 0-2 deceleration threshold value B ₀₂ for judging transition from phase 0 (ABS non-control state) to phase II (holding state after pressure increase), That is, in addition to the ABS control start threshold value,
As shown in FIG. 1, 1-2 intermediate deceleration threshold B ₁₂ for determining the transition from phase I to phase II, 2-3 intermediate non-slip ratio threshold Bsg for determining the transition from phase II to phase III. , 3-5 intermediate deceleration threshold value B ₃₅ for judging transition from phase III to phase V, 5-1 non-slip ratio threshold value Bsz for judging transition from phase V to phase I, etc. It is set for each parameter.

In this case, the deceleration threshold value which has a great influence on the control force is such that the braking performance when the road surface μ is large and the control response when the road surface μ is small are compatible with each other at a high level. The smaller the level of the state value Mu, that is, the smaller the road surface μ, the closer to 0G. Here, when the control unit 24 selects LM2 for medium speed / low friction road surface as the traveling state parameter, as shown in the column of LM2 in the control threshold setting table of FIG. Speed threshold B ₁₂ , 2-3 intermediate non-slip ratio threshold Bsg, 3
-5 Intermediate deceleration threshold value B ₃₅ , 5-1 Non-slip rate threshold value Bsz, -0.5G, 90%, 0G, 90%
Each value of is read out.

Next, the control unit 24 sets S3.
At 3, it is determined whether or not the frictional state value Mu is set to 3, which indicates a high friction road surface, and when Yes is determined, at S34, it is determined whether or not the rough road flag Fak is set to 0. As a result of the determination, the rough road flag F
When ak is 0, the process proceeds to S35, in which it is determined whether the absolute value of the steering angle θ detected by the steering angle sensor 26 is smaller than 90 °, and the absolute value of the steering angle θ is smaller than 90 °. If not, in S36, the control threshold value is corrected according to the steering angle θ. This control threshold correction processing is shown in FIG.
It is performed based on the control threshold value correction table illustrated in FIG.

That is, in the control threshold value correction table of FIG. 8, in order to ensure the steerability 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 each of the 3 intermediate non-slip ratio threshold Bsg and the 5-1 intermediate non-slip ratio threshold Bsz is the final 2-3 non-slip ratio threshold Bs.
g and the final 5-1 non-slip rate threshold value Bsz, and other intermediate threshold values are set as they are as the final threshold value.

On a rough road with a high friction (flag Fak = 1), in order to ensure the running performance when the steering wheel operation amount is small, 2-3 intermediate non-slip ratio threshold values Bsg and 5-
The values obtained by subtracting 5% from the 1 intermediate slip ratio threshold Bsz are set as the final 2-3 non-slip ratio threshold Bsg and the final 5-1 non-slip ratio threshold Bsz. Next, when the determination result in S35 is NO,
Each of the above intermediate threshold values is directly set as the final threshold value.

On the other hand, the control unit 24 uses S3
If it is determined that the rough road flag Fak is set to 1 in step 4, the process proceeds to step S37, and the relation between the rough road flag Fak and the steering angle θ is 2 based on the control threshold value correction table of FIG. -3 Intermediate non-slip ratio threshold Bs
g and the 5-1 non-slip rate threshold value Bsz are respectively corrected to obtain the final 2-3 intermediate non-slip rate threshold value Bs.
g and the final 5-1 non-slip rate threshold value Bsz are set. Then, in step S38, based on the control threshold value correction table of FIG.
Performing correction processing for setting the intermediate deceleration value obtained by subtracting 1.0G from the threshold B ₁₂ as the final 1-2 deceleration threshold B _12.

This is because the wheel speed sensors 27 to 30 are likely to make an erroneous detection at the time of determining a bad road, so that the response of the control is delayed and a good braking force is secured.
Incidentally, other intermediate threshold values are set as they are as final threshold values. Furthermore, the control unit 24
When it is determined in S33 that the frictional state value Mu is not 3, the process proceeds to S35. The control thresholds are set for the second and third channels as in the case of the first channel.

Next, regarding the control signal output processing of determining the above-mentioned phase and outputting the braking control signal of each phase to the valve unit, taking the first channel as an example, the flowcharts of FIGS. 9 to 13 and FIGS. The description will be made with reference to 18. Note that this process is a process that is repeated, for example, every 4 ms.

First, various data are read (S40 in FIG. 9), then it is determined in S41 whether or not the brake switch 25 is ON. If the determination is NO, the process returns through S42 and the above determination is YES. If it is, the vehicle body speed Vr is a predetermined value C1 (for example, 5.0 km / h) in S43.
Below, and the wheel speed Vw1 is a predetermined value (for example, 7.5).
km / h) Judge whether it is less than or equal to. If the determination is YES, it is in a sufficiently decelerated state, and there is no need for ABS control, so the process returns via S42, but the determination in S43 is No.
If so, the process proceeds to S44.

In S42, the phase flag P1, the lock flag Flok1, the continuation flag Fcn1, and the flag F are set to 0.
Respectively, and then returns to S40.

Next, in S44, the lock flag Flok is set.
It is determined whether 1 is 0 or not, and the flag F is set before the ABS control is started.
When lok1 is 0, the process proceeds to S45 and the wheel speed Vw
The deceleration DVw1 of 1 (provided that DVw1 ≦ 0) is a predetermined value D ₀ , that is, the 0-2 deceleration threshold value B described above.
₀₂ (for example, -3G) or less is determined, and the determination is Y
If ES, the process proceeds to S46. On the other hand, when the determination in S44 is NO, the process proceeds to S49.

Next, if the determination in S45 is YES, S
The lock flag Flok1 is set to 1 in 46, then the flag P1 is set to 2 in S47, and the process proceeds to phase II (holding phase after pressure increase), and then preset in S48 for phase II. The braking control signal is output to the first valve unit 20, and then the process returns.

After the ABS control is started, the flag Flok1 is set to 1. Therefore, the process proceeds from S44 to S49, and it is determined whether the flag P1 is 2. If the flag P1 is 2, the process proceeds to S50. When P1 is not 2, the process proceeds to S54.

At S50, it is determined whether or not the slip ratio S1 is equal to or less than the 2-3 slip ratio threshold value Bsg. Since it is determined as NO at the beginning, the process shifts from S50 to S48. The slip ratio S1 is the threshold value Bs
When it becomes g or less, the process proceeds from S50 to S51. This S
In 51, the flag P1 is set to 3 and the process moves to phase III (phase of pressure reduction).

Next, in S52, the timer T for counting the elapsed time after the start of the phase III is reset and then started, and then in S53, the braking control signal for the phase III is output to the first valve unit 20. Is
Then return. However, the subroutine of S53 will be described later with reference to FIGS.

When the flag P1 is not 2 as a result of the determination in S49, the process proceeds from S49 to S54 and the flag P1 is set to 3
If the determination is YES, the process proceeds to S55, and if the determination is NO, the process proceeds to S59 in FIG.

In S55, it is determined whether or not the deceleration DVw1 is equal to the 3-5 intermediate deceleration threshold value B ₃₅ , and it is determined to be NO at the beginning, so the process proceeds from S55 to S53. By repeating the above, when the deceleration DVw1 becomes equal to the threshold value B ₃₅ , the process proceeds to S56, the flag P1 is set to 5 in S56, and the process proceeds to the phase V (holding phase after depressurization). Next, in S57, S
The flag F used in the subroutine 53 is reset to 0.

Next, in S58, a braking control signal preset for phase V is output to the first valve unit 20, and then the process returns.

Next, when the determination in S54 is NO, the process shown in FIG.
In S59 of 0, it is determined whether or not the flag P1 is 5, and if the determination is YES, the process proceeds to S60, and if NO, the process proceeds to S67. When the flag P1 is 5, S60
In, it is determined whether the slip ratio S1 is 5-1 slip ratio threshold Bsg or more.

At the beginning, since NO is determined, S6
The transition from 0 to S58 in FIG. 9 is repeated. And
In phase V, the non-slip rate S1 increases and S
When the determination result in 60 is YES, the process proceeds to S61, in which 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.
Is set to

Next, in S62, the rapid pressure increase time Tpz of the initial rapid pressure increase executed at the beginning of the phase I (pressure increase phase) is calculated. This rapid pressure increase time Tpz is S7.
It is set as a value proportional to the pressure increase time Ti of the previous cycle calculated and stored at 0. Next, in S63, the timer T1 that counts the elapsed time after the start of the phase I is reset and then started, and then in S64, it is determined whether the count time T1 of the timer T1 is equal to or less than the rapid pressure increase time Tpz set in S62. If it is determined that the sudden pressure increase time Tpz is the first time or less, the process proceeds from S64 to S65, and a braking control signal preset for the initial rapid pressure increase of phase I is output to the first valve unit 20 in S65. , Then return.

Next, after the shift to phase I, the determination in S59 is NO, so the flow shifts from S59 to S67.
In 67, it is determined whether or not the flag P1 is 1, and the flag P
When 1 is 1, the deceleration DVw1 is 1 in S68.
-2 It is determined whether or not the intermediate deceleration threshold value B _{12 is} less than or equal to, and the determination is NO at the beginning, so S68 to S64
Transition to S64 and before the rapid pressure increase time Tpz elapses from S64 to S
The process of shifting to 65 is repeated. While repeating this,
After the transition to phase I, when the rapid pressure increase time Tpz elapses,
Since the determination in S64 is NO, the process proceeds from S64 to S65, where a braking control signal preset for the slow pressure increase in phase I is output to the second valve unit 20, and then the process returns.

Next, when the determination in S68 is YES, S
The flag P1 is set to 2 in 69, and then S70.
At time t1, the pressure increase time T is calculated based on the time measured by the timer T1.
i (phase I period) is calculated and stored, and then the process proceeds to S48.

Thus, after the ABS control is started, the phase II, the phase III, the phase V, the phase I, the phase II, the phase III, ... Are executed in this order over a plurality of cycles, and the determination in S43 is YES. If the brake switch 25 is turned off, ABS
The control ends (see FIG. 15).

Next, the subroutine of S53 of FIG. 9 will be described with reference to the flowcharts of FIGS. 11 to 13 and FIGS. 14 to 16.

As shown in FIG. 16, the depressurization in the phase III of the first cycle is carried out by opening the relief valve 20b intermittently in five times from the first time to the fifth time. The reduced pressure amount is set by the opening time of the valve 20b.

In the table of decompression level / decompression amount shown in FIG. 14, decompression start time of each decompression, decompression level,
The reduced pressure amount of each reduced pressure is described.

The decompression levels DL, DM, DS and DVS are
It is set from the reduced pressure conversion DV calculated by the following equation.

DV = slip amount Sm + kc × absolute value of wheel deceleration In the above equation, the slip amount Sm is (vehicle body speed Vr-wheel speed Vw) and kc is a predetermined constant.

When k3≤DV, the pressure reduction level = L
D, (large decompression level) When k2 ≦ DV <k3, decompression level = DM, (during decompression level) When k1 ≦ DV <k2, decompression level = DS, (small decompression level) When DV <k1, decompression Level = DVS, (small decompression level) For example, k3 = 0.25Vr, k2 = 0.10V
r, k1 = 0.05 Vr.

In this way, the pressure reduction conversion DV is calculated from the slip amount Sm and the wheel speed deceleration, and this pressure reduction conversion DV is calculated.
And the vehicle speed Vr from the decompression level DL, DM, DS, D
The VS is determined, the decompression amount is determined from the decompression level based on the map of FIG. 14, and the decompression is executed by outputting the braking control signal for opening the relief valve 20b for the decompression amount time at each decompression.

In the flow chart of FIG. 11, first, the pressure reduction conversion DV and the pressure reduction level are calculated in S80, then it is determined in S81 whether the continuation flag Fcn1 is 0, the flag Fcn1 is 0, and the first flag In the phase III of the cycle, the flow shifts to S82, the determination of the flag F is executed in S82 to S84, and when the flag F is 0 for the first time, the flow shifts to S86, and the control signal for the first pressure reduction is output.

This first pressure reduction is a pressure reduction of a predetermined amount (for example, pressure reduction time 8 ms, pressure reduction time 16 ms when road surface μ is high) regardless of the pressure reduction level, and a control signal for opening the relief valve 20b for 8 ms or 16 ms is used. Then, the flag F is set to 1 in S87, and the process returns.

When the flag F is 1, the process proceeds from S82 to S88, the depressurization amount of the second depressurization is calculated based on the depressurization level and the map of FIG. 14, and then in S89, the timer started in S52. Time T of T is 8
It is determined whether or not ms is reached, and when T = 8 ms is reached, S9
At 0, a control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output, and then at S91, the flag F is opened.
Set to 2 and return. That is, the second decompression is
It is executed subsequent to the first depressurization of a predetermined amount.

When the road surface μ is high, the depressurization amount of the second depressurization is +3 ms as described in [Note] in FIG.
Only the increase is corrected.

Next, when the flag F = 2, the flow shifts from S83 to S92 to determine whether or not the time T counted by the timer T is 40 ms, and repeats returning for T <40 ms until T = 40 ms. Then, in S93, the pressure reduction amount of the third pressure reduction is calculated based on the pressure reduction level and the map of FIG. 14, and then in S94, a control signal for opening the relief valve 20b for the time of the pressure reduction amount is output, and then S95
Then, the flag F is set to 3, and the process returns. In other words, the third depressurization is 40m after the start of timer T
It is executed from the time when s has elapsed. Note that [Note] in FIG.
As described in (1), when the road surface μ is low, the decompression amount of the decompression for the third time and thereafter is increased and corrected by +2 ms.

Next, when the flag F = 3, the flow shifts from S84 to S96 to determine whether the time T of the timer T is 80 ms, and repeats returning for T <80 ms until T = 80 ms. , S97, the pressure reduction amount of the fourth pressure reduction is calculated based on the pressure reduction level and the map of FIG. 14, then a control signal for opening the relief valve 20b for the time of the pressure reduction amount is output in S98, and a flag is output in S99. Set F to 4 and return. That is,
The fourth depressurization is executed when 80 ms has elapsed after the start of the timer T start.

Next, when the flag F = 4, the process shifts from S85 to S100 and the time measured by the timer T is 120 ms.
If T = 120 ms, the pressure reduction amount for the fifth deceleration is calculated based on the pressure reduction level and the map of FIG. 14, and then S102. At, the control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output, and then at S103, the flag F is reset to 0 and the process returns. That is, the fifth depressurization is executed when 120 ms have elapsed after the start of the timer T start.

As a result of the determination in S81, the continuation flag Fcn1
Is 1, that is, Phase III after the second cycle
If so, the process proceeds to S104 of FIG.

In S104 to S106, the flag F is determined, and when the flag F is initially 0, the process proceeds to S107 and the pressure reduction amount of the initial pressure reduction is calculated. However, after the second cycle, as shown in FIG. 14, the decompression amount of the first decompression is also calculated based on the decompression level and the map of FIG. Next, in S108, a control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output,
Next, in step S109, the flag F is set to 1, and the process returns. When the road surface μ is high, the decompression amount of the initial decompression is increased and corrected by +3 ms.

Next, when the flag F is 1, the process proceeds from S104 to S110, and the time T counted by the timer T is 40 ms.
If T = 40 ms, the pressure reduction amount of the second pressure reduction is calculated based on the pressure reduction level and the map of FIG. 14, and then S112. At, a control signal for opening the relief valve 20b is output for the time corresponding to the pressure reduction amount, and then the flag F is set to 2 in S113, and then the process returns. In other words, the second depressurization is executed when 40 ms has elapsed after the start of the timer T start. When the road surface μ is low, the decompression amount for the second and subsequent decompressions is increased and corrected by +2 ms.

Next, when the flag F = 2, S105
To S114, the time T of the timer T is 80 m
It is determined whether or not s, and the process is repeatedly returned for T <80 ms. When T = 80 ms, 3 is obtained in S115.
The depressurization amount of the second depressurization is calculated based on the depressurization level and the map of FIG. 14, then a control signal for opening the relief valve 20b for the time of the depressurization amount is output in S116, and then the flag F is set to 3 in S117. Return after setting. That is, the third depressurization is executed when 80 ms has elapsed after the start of the timer T start.

Next, when the flag F = 3, S106
To S118, the measured time T of the timer T is 120
It is determined whether or not it is ms and returns for T <120 ms. When T = 120 ms, the pressure reduction amount of the fourth pressure reduction is calculated in S119 based on the pressure reduction level and the map of FIG. In S120, a control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output, and then in S121, the flag F is reset to 0 and the process returns. That is, the fourth depressurization is executed when 120 ms has elapsed after the start of the timer T.

Here, as a measure against the case where the road surface μ suddenly changes from high μ to low μ, the subroutine of FIG. 13 is executed in parallel with the subroutines of FIGS. 11 and 12.

By the determination of S130, the timer T repeats returning before the measured time T of 40 ms has elapsed. Then, in S131, it is determined whether 40 ms ≦ T <80 ms. If the determination is Yes, The process proceeds to S132.

In S132, it is determined whether or not the pressure reduction level is DL. When the pressure reduction level is DL and the degree of pressure reduction is high, a control signal for continuously opening the relief valve 20b for continuously reducing the pressure is output in S133. And then return. If the pressure reduction level is lowered by the continuous pressure reduction and the determination in S132 is NO, a control signal for stopping the continuous pressure reduction is output in S134, and then the process returns.

Next, when T ≧ 80 ms, the process proceeds from S131 to S135, in S135, it is determined whether the pressure reduction level is DL, and when the pressure reduction level is DL and the degree of pressure reduction is high, the operation is continuously performed in S136. A control signal for continuously opening the relief valve 20b to reduce the pressure is output, and then the process returns. When the pressure reduction level is lowered by the continuous pressure reduction and the determination in S135 is NO, S1 is set.
Move to 37.

In S137, it is determined whether or not the pressure reduction level is DM, and when the pressure reduction level is DM and the degree of pressure reduction is still high, a control signal for continuously opening the relief valve 20b for continuous pressure reduction is given in S138. It is output and then returns. When the pressure reduction level is lowered by the continuous pressure reduction and the determination in S137 is NO, a control signal for stopping the continuous pressure reduction is output in S139, and then the process returns.

Next, regarding the operation of the ABS control described above, the ABS control for the first channel will be taken as an example.
This will be described with reference to the time chart of FIG.

In the ABS uncontrolled state during deceleration, the braking pressure generated by the depression operation of the brake pedal 16 gradually increases, and the rate of change of the wheel speed Vw1 of the left front wheel 1 (deceleration DVw1) reaches -3G. At this time, the lock flag Flok1 of 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, 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.

Next, the non-slip ratio S1, the wheel deceleration DVw1, and the wheel acceleration AVw1 obtained from the wheel speed Vw1 are compared with various control threshold values, the phase 0 is changed to the phase II, and the braking pressure is increased. It will be maintained at the level immediately after.

When the non-slip ratio S1 falls below the 2-3 intermediate slip ratio threshold value Bsg, the phase shifts from phase II to III, the relief valve 20b is turned on / off with the pressure reducing characteristic as described above, and from that time tb. The braking pressure decreases at a predetermined gradient, the braking force gradually decreases, and the rotational force of the front wheels 1 begins to recover. When the wheel pressure deceleration DVw1 continues to decrease to the threshold value B ₃₅ (0G), the phase III shifts to V and the braking pressure is maintained at the reduced pressure level from time tc. .

In this phase V, the non-slip rate S1
Becomes 5-1 non-slip rate threshold value Bsz or more, the continuation flag Fcn1 is set to 1, and the ABS control shifts from the time td to the second cycle. At this time, the phase is forcibly shifted to the phase I, and immediately after the shift to the phase I, the opening / closing valve 20a, as described above, has the rapid pressure increase time T set with the pressure increase time Ti of the previous cycle as a parameter.
During pk, the relief valve 20b is closed and the on-off valve 20a is 1
The opening and closing valve 20 is opened at a duty ratio of 00% to increase the braking pressure steeply, and after the rapid pressure increase time Tpz has elapsed.
a is turned on / off at a predetermined duty ratio, and the braking pressure gradually increases with a gentler gradient. Thus, immediately after the shift to the second cycle, the braking pressure is reliably increased, and a good braking pressure is secured.

On the other hand, even after the second cycle, the appropriate friction state value Mu is determined, and the friction state value Mu is determined.
Since various control threshold values corresponding to the traveling state parameters corresponding to the vehicle speed Vr and the vehicle body speed Vr are selected from the control threshold value setting table in FIG. 7, precise control of the braking pressure according to the traveling state is performed.

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.

In the ABS control of this embodiment, FIG.
, The continuation flag Fcn1 is 0, that is, the first flag
In the depressurizing phase of the cycle, in S86, the depressurizing amount of the initial depressurizing is set to a predetermined amount (the opening time of the relief valve 20b is 8 m).
s, but 16 ms when high μ) is set and the pressure reduction is executed. Therefore, the minimum required amount is not affected by the unstable slip ratio and wheel speed deceleration at the start of ABS control. The first decompression of can be executed.

Next, the passage control of the step or the protrusion will be described with reference to the flowchart of FIG.

In the case of this embodiment, the 0-2 deceleration threshold value B ₀₂ for judging the transition from the phase 0 showing the ABS non-controlled state to the phase II showing the holding state after the pressure increase, that is, AB
Two S control start threshold values are set, and for example, −
A first control start threshold B ₀₂ 1 set to 3G and a second control start threshold B ₀₂ 2 set to, for example, -5G are prepared. Then, usually, the first control start threshold value B ₀₂ 1 is set for each channel, and the positive change in the acceleration / deceleration of the wheel is larger than 1 G (for example, when the change from -3 G to -1.5 G, or , 0G to 1.5G, the positive change in acceleration / deceleration is 1.5G each), the second control start threshold value B ₀₂ 2 is changed. There is.

In FIG. 17, the control unit 24 first determines whether or not the ABS control is in progress (S14).
0), if ABS control is not in progress (S140: N
O), it is determined whether or not the positive change in the wheel acceleration / deceleration is larger than 1 G (G is the gravitational acceleration) (S141). In this determination, if the positive change in the acceleration / deceleration of the wheels is larger than 1 G (S141: YES), the control unit 24 determines that the malfunction occurs (S142), and sets the ABS control start threshold value B ₀₂ to −. 3G (first control start threshold value B ₀₂
The value is changed from 1) to -5G (second control start threshold value B ₀₂ 2) (S143). As a result, a larger wheel deceleration needs to be detected in order to start the ABS control, and the ABS control start condition is limited accordingly.

When the wheel deceleration exceeds the ABS control start threshold value and the ABS control is started (S1
44: YES), the control unit 24 sets the value of the flag F to 1 (S145) and permits the second pressure reducing operation.

If the ABS control is already underway in the determination at S140 (S140: YE
S), the control unit 24 further sets the flag F to 1
It is determined whether or not (S146). Then, when the value of the flag F is 1 (S146: YES), the control unit 24 determines whether or not the initial depressurization time is shorter than a predetermined value (for example, 8 ms) (S147).
This depressurization time corresponds to the magnitude of the value of the depressurization variable DV in this embodiment. When the calculated initial depressurization time is shorter than the predetermined value (S147: YES), it is determined that the malfunction has occurred (S148), and the ABS control is stopped (S1).
At the same time, the flag F is reset to 0 (S15).
0).

As described above, the fact that the depressurization time is short when the ABS control is started means that the depressurization request in the ABS control is low. In this embodiment, in such a case, It is configured to stop the ABS control. Even if the depressurizing operation is canceled in this manner, the request is originally low, so that no problem occurs.

Next, another embodiment of the malfunction determination will be described with reference to FIGS. 18 and 19.

In this embodiment, when there is a positive change in the wheel acceleration / deceleration more than a predetermined value during the non-ABS control, the timer limits the ABS control for a predetermined time.

Referring to FIG. 18, when the vehicle passes through a protrusion on the road surface, the acceleration / deceleration of the wheels changes as shown by the solid line in the figure. That is, when the vehicle travels on a substantially horizontal road surface while the wheels receive a constant braking force, the wheels are decelerated with a substantially constant deceleration (negative acceleration) (see part A in the figure). Then, when the wheel hits a projection on the road surface, the deceleration slightly increases as shown by B in the figure. Next, since the wheel travels around the protrusion and travels on a path longer than the locus of the vehicle body, the wheel acceleration / deceleration changes positively (see part C in the figure). When the wraparound of the wheel protrusion is completed, the wheel deceleration reaches the peak value P. After that, since the rotation of the wheel is suddenly restricted, the deceleration increases (see the part D in the figure). When it completely passes through the protrusion, it returns to a state of almost constant deceleration similar to that before riding on the protrusion (see E portion in the figure).

In the present embodiment, when the difference between the acceleration / deceleration level of the portion A in the figure and the end of the portion C, that is, the peak value P exceeds 1 G as a positive change in the acceleration / deceleration, it is detected that the acceleration / deceleration of the wheel is From the time when the peak value P of the speed (deceleration in this embodiment) (change in acceleration / deceleration is zero) is detected until a predetermined time (100 ms in this embodiment) elapses, A
Limit the start of BS control.

That is, in the flowchart of FIG. 19, S151 and S152 are the same as S140 of FIG.
And S141, but in S153, the control unit 24 determines whether or not 100 ms has elapsed after the peak value P was detected, and when it has not elapsed (S153: NO), It is determined that the malfunction has occurred (S154), and the start of the ABS control is prohibited (S155). Then, after 100 ms has elapsed, A
When the BS control start condition is satisfied (S153: Y
ES) and ABS control will be started (S15).
6). The processing of S157 to 162 is the same as the processing 1 of S145 to 150 in the flowchart of FIG.

Further, as a method of detecting the step, it is also possible to detect it as follows in addition to the above.

It is known that when the wheel gets over a projection on the road surface, the difference between the speed of the wheel passing through the projection and the pseudo vehicle body speed temporarily increases. Therefore, it is configured such that the deviation between the wheel speed and the pseudo vehicle body speed is monitored, and the ABS control is not started if the time to return to the pseudo vehicle body speed is fast even if the deviation temporarily increases. May be. For example, if the deviation between the wheel speed and the pseudo vehicle body speed exceeds the predetermined value and falls within the predetermined deviation within 50 ms, it is possible that the wheel has passed over a small obstacle such as a protrusion on the road surface. Therefore, the start of ABS control is suppressed. However, if the deviation does not fall within the predetermined range even after the elapse of 50 ms, the control is started on the condition that the ABS control start condition is satisfied.

Next, with reference to the flow charts of FIG. 20 and subsequent figures, the processing for limiting or prohibiting the malfunction determination corresponding to each claim of the present invention will be described.

FIG. 20 is a flow chart showing the processing corresponding to claims 1 and 2. First, it is judged whether or not the vehicle is running (S171). If the vehicle is running (S171 :).
YES), it is determined whether or not the malfunction is determined in the front wheel side control channel (S172), and if the malfunction is determined in the front wheel side control channel (S1).
72: YES), a predetermined time corresponding to the vehicle speed (for example, 40
It is determined whether or not about 250 ms at km / h has elapsed (S173), and if a predetermined time has elapsed (S173:
(YES), the control channel on the rear wheel side is forcibly set as the malfunction determination condition.

By executing such processing, it is possible to prevent unnecessary malfunction determination in the control channel on the rear wheel side, and prevent occurrence of erroneous determination regarding malfunction determination in the control channel on the rear wheel side. As a result, the initiation and / or continuation of ABS control when truly ABS control is required will not be disturbed. Then, the predetermined time is S1
As shown in the graph added to 73, the predetermined time can be set according to the vehicle speed by decreasing the vehicle speed as the vehicle speed increases.

FIG. 21 is a flow chart showing the processing corresponding to claim 3. First, it is judged whether or not the vehicle is traveling (S181), and if it is traveling (S181: YE).
S), it is determined whether the vehicle speed is in the high speed range equal to or higher than the set vehicle speed (S182), and if it is in the high speed range (S182: YE
S), the malfunction determination is prohibited (S183). On the other hand, if it is not in the high speed range (S182: NO), the malfunction determination is permitted (S184).

By executing such processing, A in a scene where ABS control is truly required in the high speed range is performed.
The BS control start is not obstructed, and the running stability of the vehicle in the high speed range is improved.

FIG. 22 is a flow chart showing the processing corresponding to claim 4. First, it is judged whether or not the vehicle is running (S191). If the vehicle is running (S191: YE).
S), it is determined whether the slip amount is larger than the set value (S192), and if it is larger than the set value (S192: YE
S), the malfunction determination is prohibited (S183). On the other hand, if the slip amount is less than or equal to the set value (S192: NO), the malfunction determination is permitted (S194).

By executing such processing, the ABS can be operated even if it is a malfunction, so that a large slip can be quickly recovered and the running stability is improved.

FIG. 23 is a flow chart showing a process corresponding to claims 7 and 8. First, it is judged whether or not the ABS control is started (S201). If the ABS control is being executed (S201: YES), the skid is executed. The time Ts and the return acceleration are measured (S202). Then, when the return acceleration is equal to or greater than a predetermined value (for example, +10 G) (S203: YES),
If the skid time Ts is less than or equal to a predetermined value (for example, 50 ms) (S204: YES), it is determined to be a malfunction and AB
The S control is ended (S205), and the brake hydraulic pressure is rapidly increased to the hydraulic pressure of the master cylinder. On the other hand, when the return acceleration is smaller than the predetermined value (S203: NO) or when the skid time Ts is larger than the predetermined value (S20).
4: NO), the malfunction determination is prohibited, and the normal ABS control is continued (S206).

By carrying out such a processing, there is an advantage that the malfunction can be surely judged and the ABS control when the ABS control is truly required is not hindered.

FIG. 24 is a flow chart showing the processing corresponding to claim 9. First, all control channels are ABS.
It is determined whether or not control is being performed (S211), and if all channels are not under ABS control (S211: NO), it is determined whether or not at least one control channel is under ABS control (S212). If at least one control channel is under ABS control (S212: YES), the malfunction determination of the non-ABS control channel is prohibited (S21).
3).

By executing such processing, it is possible to prevent the control channel in the non-ABS control state from stopping the ABS control immediately after the ABS control is started.

FIG. 25 is a flow chart showing the processing according to claim 10, and when two control channels, for example, a control channel for the left front wheel and a control channel for the right front wheel share a reservoir, It is determined whether only one of the front wheel control channels is under ABS control (S221), and if it is under control, the malfunction determination of the other front wheel control channel is prohibited (S22).
2).

By performing such processing, it is possible to prevent the control channel in the non-ABS control state from stopping the ABS control immediately after the ABS control is started, and it is possible to avoid the occurrence of the pressure reduction defect and the pressure increase defect.

FIG. 26 is a flow chart showing the processing corresponding to claim 12. First, it is judged whether or not the brake pedal is depressed (S231), and if the brake pedal is depressed (S231: YES), A positive change in the wheel acceleration / deceleration, which is the error degree determination condition, is set to + 1G as in S141 of FIG. 17 and S152 of FIG. 19 (S2).
32). If the brake pedal is not depressed (S23
1: NO), change the error degree judgment condition to + 8G (S2
33) Make the malfunction determination sensitive.

By carrying out such a processing, there is an advantage that the ABS control becomes difficult to start when the brake pedal is not depressed, and the malfunction does not easily occur.

[Brief description of drawings]

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

[Fig.2] Diagram of μ table

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

FIG. 4 is a diagram of a map of vehicle speed correction values.

FIG. 5 is a flowchart of control threshold setting processing.

FIG. 6 is a diagram of a table in which driving state parameters are set.

FIG. 7 is a diagram of a table in which various control thresholds are set.

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

FIG. 9 is a part of a flowchart of control signal output processing

FIG. 10: Remaining part of flowchart of control signal output processing

11 is a part of a flowchart of a control signal output subroutine of S53 of FIG.

12 is the rest of the flowchart of the control signal output subroutine of S53 of FIG.

13 is a flowchart of a control signal output subroutine executed in parallel with FIG. 11 and FIG.

[Fig. 14] Diagram of decompression level / decompression amount table

FIG. 15 is an operation time chart of the anti-skid brake device.

16 is an operation time chart of Phase III in the first cycle of FIG.

FIG. 17 is a flowchart of control when a wheel passes through a protrusion or the like.

FIG. 18 is an explanatory view of control when passing through a protrusion according to another embodiment.

FIG. 19 is a flowchart similar to FIG. 17 according to another embodiment.

FIG. 20 is a flowchart showing a process corresponding to claims 1 and 2;

FIG. 21 is a flowchart showing a process corresponding to claim 3.

FIG. 22 is a flowchart showing a process corresponding to claim 4;

FIG. 23 is a flowchart showing a process corresponding to claims 7 and 8;

FIG. 24 is a flowchart showing a process corresponding to claim 9;

FIG. 25 is a flowchart showing a process corresponding to claim 10.

FIG. 26 is a flowchart showing a process corresponding to claim 12;

[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 (14)

[Claims] 1. A control channel for variably controlling a wheel braking pressure to perform anti-skid control is provided for each of front wheels and rear wheels, and each control channel includes a wheel speed detecting means for detecting a wheel rotation speed. A braking pressure adjusting means for adjusting the braking pressure of the wheels, and an anti-skid control means for operating the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means to periodically increase or decrease the braking pressure. In an anti-skid brake device for a vehicle, which is provided with malfunction determination means for determining malfunction of the anti-skid control means, if the malfunction determination is made by the malfunction determination means in the control channel on the front wheel side. , The control channel on the rear wheel side is forcibly determined after a lapse of a predetermined time from the time when the malfunction determination is made. Antiskid brake apparatus for a vehicle, characterized in that the working erroneous determination due stage is provided with means for the state was made. 2. The antiskid brake device for a vehicle according to claim 1, wherein the predetermined time is changed according to a vehicle speed. 3. 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 the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In an anti-skid brake device for a vehicle, which is provided with an anti-skid control unit that operates to cyclically increase and decrease the braking pressure, and a malfunction determination unit that determines a malfunction of the anti-skid control unit, in a high speed range, An anti-skid brake device for a vehicle, comprising means for prohibiting the malfunction determination by the malfunction determination means. 4. 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 the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In an anti-skid brake device for a vehicle, which is provided with an anti-skid control means for operating the anti-skid control means for periodically increasing and decreasing the braking pressure, and an erroneous operation determination means for deciding an erroneous operation of the anti-skid control means, An anti-skid brake device for a vehicle, comprising means for prohibiting the malfunction determination by the malfunction determination means when the amount is larger than a set value. 5. A non-anti-skid control is provided with means for making it difficult to start the anti-skid control for a predetermined time when the malfunction determination is made by the malfunction determining means during the non-skid control. 4. An anti-skid brake device for a vehicle according to any one of 4 above. 6. A non-anti-skid control is provided with means for prohibiting the anti-skid control from being started for a predetermined time when the malfunction determination means makes a malfunction determination. Item 5. An anti-skid brake device for a vehicle according to any one of items 1 to 4. 7. 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 the braking pressure adjusting means 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 unit that is activated to periodically increase or decrease the braking pressure; and a malfunction determination unit that determines a malfunction of the anti-skid control unit. The determining means determines an erroneous operation when the skid time of the wheel is a predetermined time or less, and prohibits the erroneous operation determination by the erroneous operation determining means when the return acceleration of the wheel speed after depressurization is smaller than a predetermined value. An anti-skid brake device for a vehicle, which is equipped with. 8. The malfunction determination means makes a malfunction determination when the skid time of the wheel is a predetermined time or less and the return acceleration of the wheel speed after decompression is a predetermined value or more. 7. An anti-skid brake device for a vehicle according to item 7. 9. A plurality of control channels are provided for variably controlling the braking pressure of the wheels to perform anti-skid control, and the plurality of control channels include wheel speed detecting means for detecting the rotation speed of the wheels, and wheel control means. Braking pressure adjusting means for adjusting the braking pressure, anti-skid control means for operating the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means to periodically increase or decrease the braking pressure,
In an anti-skid brake device for a vehicle, each of which is provided with malfunction determination means for determining malfunction of the anti-skid control means, when at least one control channel of the plurality of control channels is under anti-skid control. An anti-skid brake device for a vehicle, comprising means for prohibiting malfunction determination by the malfunction determination means in another control channel. 10. When the two control channels share a reservoir of brake fluid and a pump for pumping the brake fluid from the reservoir and supplying the brake fluid to the brake device of the wheel through the braking pressure adjusting means, 10. The anti-skid brake device for a vehicle according to claim 9, wherein when one of the control channels is under anti-skid control, the malfunction determination by the malfunction determining means in the other control channel is prohibited. 11. When the malfunction determination is made by the malfunction determining means after the anti-skid control is started,
11. An antiskid brake device for a vehicle according to claim 7, further comprising means for immediately stopping the antiskid control. 12. Wheel speed detecting means for detecting the rotational speed of the wheel, and braking pressure adjusting means for adjusting the braking pressure of the wheel.
A plurality of control channels are provided, each of which has an anti-skid control means for operating the braking pressure adjusting means based on the wheel speed detected by the wheel speed detecting means to periodically increase or decrease the braking pressure, and each control channel. In each of the above, in a vehicle anti-skid braking device provided with malfunction determination means for determining malfunction of anti-skid control, a brake sensor for outputting an ON signal when the brake pedal is depressed is provided, An anti-skid brake device for a vehicle, wherein when the signal from the brake sensor is off, the malfunction determination by the malfunction determining means is more sensitive than when the signal is on. 13. In the non-anti-skid control, if a positive change in acceleration / deceleration of a wheel that is equal to or more than a predetermined value is detected, the malfunction determination means makes a malfunction determination, and the brake sensor detects that the malfunction is detected. 13. The antiskid brake device for a vehicle according to claim 12, wherein the predetermined value is set to be smaller when the signal is OFF than when the signal is ON. 14. The anti-skid brake for a vehicle according to claim 13, further comprising means for preventing the anti-skid control from being started for a predetermined time when the malfunction determination is made by the malfunction determining means. apparatus.