JPH04163264A - Antiskid brake control method - Google Patents

Abstract

PURPOSE:To reliably prevent the lock of a wheel by continuing an antiskid control by using an average value of deceleration of a car body right before the occurrence of a trouble instead of deceleration of a wheel when a deceleration sensor is failed in operation during antiskid control. CONSTITUTION:Sensor values from wheel sensors 19 and a deceleration sensor 21 and the switching state of switches 22-24 are stored in the memory of a controller 20, and an average value GAVE of car body deceleration GS is calculated and stored. It is then discriminated whether abnormality occurs to the switches 22-24 and the deceleration sensor 21, and it is discriminated whether the drive system of an automobile is 4WD or 2WD. When the deceleration sensor 21 is failed in operation and a drive system at a point of time when a trouble occurs is 4WD, the average value GAVE of the car body deceleration GS is employed as the car body deceleration GS to be read. A pseudo car body speed VREF is then computed and estimation of a road surface mu is effected to continue antiskid control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an anti-skid brake control method for preventing wheels from locking during braking, and in particular to an anti-skid brake control method suitable for automobiles running with four-wheel drive. Regarding control method.

(Prior Art) According to an anti-skid brake control method applied to this type of four-wheel drive vehicle, during braking, the wheel speed of each wheel is detected by a wheel speed sensor, while the vehicle body deceleration is reduced. The speed is detected by a speed sensor, and a pseudo vehicle speed of the vehicle body is calculated based on these wheel speeds and vehicle body deceleration. When the wheel speed of a wheel decreases too much relative to the simulated vehicle speed and its rotational tendency tends to lock, the braking force of that wheel, that is, the braking force, is reduced to eliminate the tendency. After that, based on the rotational trend of the wheels, the brake pressure is increased, maintained, or decreased repeatedly to control the wheel speed of each wheel to follow the pseudo vehicle speed, thereby preventing each wheel from locking. I try to do that. When the anti-skid control described above is performed during braking, steering performance can be ensured and the braking distance can also be greatly reduced.

(Problems to be Solved by the Invention) In the anti-skid brake control method described above, the pseudo vehicle speed is calculated by taking into consideration the vehicle deceleration in addition to the wheel speed. In other words, in a four-wheel drive vehicle, locking is likely to occur when braking or between four wheels, so if one of the wheel speeds is used as the reference wheel speed and the pseudo vehicle speed is calculated based on this reference wheel speed. However, there is a risk that the pseudo vehicle speed may be calculated based on the reference wheel speed that tends to lock, and the pseudo vehicle speed may not be calculated accurately. For this reason, it is decided based on the vehicle body deceleration whether or not a slip that indicates a lock tendency has occurred in the reference wheel speed, and if the above-mentioned slip has also occurred in the reference wheel speed itself, In this system, a pseudo vehicle speed is calculated based on the vehicle deceleration rather than the wheel speed, so that anti-skid control, that is, brake control for each wheel can be optimally performed.

As mentioned above, in the anti-skid brake control method for four-wheel drive vehicles, the sensor signal from the deceleration sensor is important in controlling the brake pressure of each wheel, so there is no possibility that the deceleration sensor is malfunctioning. Conventionally, when a failure occurs, the operation of the anti-skid control system is immediately stopped at the time the failure occurs.

For this reason, in the conventional anti-skid brake control method, when a car is running in four-wheel drive on a low μ road such as a snow-covered road or an icy road, anti-skid control is applied when braking in such a situation. If a failure occurs in the deceleration sensor while the anti-skid control is being carried out, the anti-skid control will be immediately stopped. Therefore, under the above-mentioned driving conditions, if anti-skid control is stopped and normal brake control is resumed, the braking force of each wheel, that is, the brake pressure, may become excessive. This increases the possibility that all four wheels will lock up at the same time.

This invention was made based on the above-mentioned circumstances, and
The purpose of this is that even during anti-skid control,
To provide an anti-skid brake control method that secures steering performance by reliably preventing locking of each wheel even when a failure occurs in a deceleration sensor of a vehicle body, and is excellent in safety.

(Means for Solving the Problems) This invention detects the wheel speed of each wheel with a wheel speed sensor, and detects the deceleration of the vehicle body with a deceleration sensor. By calculating a pseudo-vehicle speed based on the speed, when a wheel lock tendency occurs with respect to the pseudo-vehicle speed, anti-skid control is implemented to control the braking force of that wheel according to the lock tendency. Accordingly, in the anti-skid brake control method in which the wheel speed of the wheels follows the pseudo vehicle body speed, in the method of the present invention, when a failure occurs in the deceleration sensor during anti-skid control, the vehicle body deceleration immediately before the failure occurs. The average value of speed is used in place of vehicle deceleration, and anti-skid control is continued until the end of the anti-skid control.

(Function) As described above, according to the anti-skid brake control method of the present invention, even if the deceleration sensor of the vehicle body fails during anti-skid control, the anti-skid control continues until the end of the anti-skid control. , there is no undesirable transition from anti-skid control to normal brake control.

Therefore, the anti-skid control can be effectively operated until the vehicle stops or the tendency of the wheels to lock is resolved. Even if it becomes impossible to obtain the vehicle deceleration due to a failure of the deceleration sensor, the average value of the vehicle deceleration immediately before the failure of the deceleration sensor is used instead of this vehicle deceleration to prevent anti-skid. Since the control is continued, this anti-skid control can be carried out appropriately.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

Referring to FIG. 1, an anti-skid brake device applied to a 2WD/4WD selective type automobile is schematically shown. First, to briefly explain the power transmission path of an automobile, in the case of 4WD, the driving force of the engine 1 is transmitted to the left and right front wheels 4 via the transmission 2, front differential (not shown), and front wheel drive shaft 3. ．． L,
It is transmitted to 4R, and then to the left and right rear wheels 5L and 5R.
The driving force of the engine 1 is transmitted through a transmission 2, a center differential (not shown), a propeller shaft 6, a rear differential 7, and a rear wheel drive shaft 8. Furthermore, in the case of 2WD, the driving force of the engine 1 is transmitted to one of the front wheels 4L, 4R1 or the rear wheels 5L, 5R.

Wheel brakes 9 are attached to each of the front wheels 4 and the rear wheels 5, and these wheel brakes 9 are connected to a hydraulic brake circuit 10.

The hydraulic brake circuit 10 includes a tandem mask cylinder 12 equipped with a vacuum brake booster operated by a brake pedal 11, and a front wheel brake line 1 is connected to one pressure chamber (not shown) of the mask cylinder 12.
3 extends, and a rear wheel brake pipe 14 extends from the other pressure chamber (not shown). These front wheel and rear wheel brake lines 13 and 14 extend through the control valve device 15, and the front end side of the front wheel brake line 13 is branched left and right and connected to the wheel brake 9 of each front wheel 4. At the same time, the rear wheel brake conduit 14 is also connected to the wheel brake 9 of each rear wheel 5 by branching left and right at its tip side.

In the front wheel brake pipe 13, an anti-skid valve device 16 is inserted in each portion branched toward the wheel brake 9 of the corresponding front wheel.
In the rear wheel brake line 14, one anti-skid valve device 16 is inserted at a portion before branching.

Further, a hydraulic pump 17 is connected to the control valve device 15, and this hydraulic pump 17 pressurizes the pressure fluid sucked from the pressure fluid tank 18 to a predetermined pressure, and during anti-skid brake control, It can be supplied to the wheel brakes 9 of each wheel via the control valve device 15.

That is, when anti-skid control is started during braking, each wheel brake 9 is supplied with dynamic pressure from the hydraulic pump 17 instead of pressure fluid from the mask cylinder 2 due to the action of the control valve device 15. By appropriately operating each anti-skid valve device 16, the brake pressure within the wheel brake 9, that is, the braking force thereof, can be controlled.

In order to control the brake pressure of each wheel brake 9 by the above-mentioned anti-skid control, a wheel speed sensor 19 is arranged on each wheel 4, 5, and wheel speed signals from these wheel speed sensors 19 are sent to the controller. 20.

In addition to the wheel speed sensor 19, the controller 20 is also connected to a deceleration sensor 21 for detecting vehicle deceleration GS and various switches for setting the vehicle drive system. These switches include a 4WD select switch 22 for selecting 2WD and 4WD, a center differential lock switch 23 for locking the function of the center differential, and a rear differential lock switch 2 for locking the function of the rear differential 7.
Therefore, the controller 20 is also supplied with sensor signals and switching signals from the deceleration sensor 21 and each switch.

In addition, in FIG. 1, the return pipes from each wheel brake 9 to the pressure fluid tank 18 are not shown in order to simplify the drawing.

The controller 20 performs the anti-skid control described above, that is, the operation of the control valve device 15 and each anti-skid valve device I6, based on sensor signals from the wheel speed sensor 19 and deceleration sensor 21 and the switching states of various switches. An example of the anti-skid control routine, ie, the ABS main routine, is shown in FIG.

Therefore, the ABS main routine will be explained below with reference to FIG.

In the ABSBS main routine, step S1, the wheel speed VW of each wheel is read by each wheel speed sensor 19, and the next step S2. In S3, it is determined whether the first failure flag F1 and the first failure flag F1 are set, that is, whether these flags F2. It is determined whether F3 is set to 1 or not. Here, step S2. Discrimination of S3 is negative (N
O), and in the next step S4, the deceleration sensor 21
The vehicle body deceleration GS is read.

After this, in step S5, it is determined whether or not the first failure flag F1 is set to 1, but the determination is still negative here, so the process proceeds to step S6, and the aforementioned 4WD select After the switching states of the switch 22, center differential lock switch 23, and rear differential lock switch 24 are read, in the next step S7, one of the wheel speeds VW of each wheel read in step S1 is selected as the reference wheel speed ■WS. . Here, as the reference wheel speed vW, for example, when the car is running in 4WD, the second or third wheel speed from the top is selected among the respective wheel speeds VW; When the vehicle is traveling at a speed of 1, the wheel speed of the non-driving wheel is selected.

In step S8, anti-skid control, that is, ABS
It is determined whether or not control should be started, specifically,
Other wheel speeds V with respect to the already determined standard wheel speed VWS
The determination is made based on whether at least one of the wheels W has decreased to a predetermined value ΔvW or more and the wheel has a tendency to lock. Here, if the brake pedal (not shown) of the automobile is not depressed, that is, if braking has not started, the determination in step S8 is negative, so step S
1 and the steps described above are repeated.

When the determination in step S8 is positive (Yes), at least one wheel has a tendency to lock, and anti-skid control is started, in the next step S9, the pseudo vehicle speed V REF and the coefficient of friction of the road surface, That is, the road surface μ is estimated. In this example, the pseudo vehicle speed V REF is
As shown in the block diagram of Fig. 3, the reference wheel speed is
WS, calculated deceleration Gk obtained from this reference wheel speed VW
It is calculated by taking into account the vehicle body deceleration GS obtained by the deceleration sensor 21. That is, the wheel speed V of each wheel
After the reference wheel speed ■WS selected from W is filtered, it is used as the reference vehicle speed VF and the pseudo vehicle speed VRF,
The reference vehicle speed VF is supplied to the arithmetic unit 25 that calculates F, and is subjected to differentiation processing to obtain the calculated deceleration Gk.
It is supplied to the arithmetic unit 25 as .

On the other hand, the vehicle body deceleration GS obtained by the deceleration sensor 21 is also
After passing through filter processing, the signal is supplied to the calculation section 25. In addition, in Fig. 3, the subscripts PL, PR, RL, and RR attached to the wheel speed VW indicate that the wheel speed is the left front wheel,
These represent the right front wheel, left rear wheel, and right rear wheel, respectively.

The calculation unit 25 calculates the pseudo vehicle speed V REF in consideration of the reference vehicle speed VF, the calculated deceleration Gk, and the vehicle deceleration GS, and estimates the road surface μ. Specifically, the pseudo vehicle speed V RBF is usually set to the reference vehicle speed VF, or immediately after the start of ABS control,
If the calculated deceleration Gk is so large that it would be impossible for normal braking, it can be estimated that the reference wheel speed VWS itself is also slipping. Therefore, in the above-mentioned situation, the reference vehicle speed VF is changed to the pseudo vehicle speed V REF
Instead of setting it as After a predetermined period of time has elapsed since the start of ABS control, the vehicle body deceleration G from the deceleration sensor 21 is
The pseudo vehicle speed V REF is calculated based on S. Furthermore, when the values of the calculated deceleration Gk and the vehicle body deceleration GS return to the normal range, the pseudo vehicle body speed V REF
The reference vehicle speed VF will be adopted as the standard vehicle speed VF.

As described above, according to this embodiment, the pseudo vehicle speed V
When calculating RBF, we take into account not only the wheel speed VW but also the calculated deceleration Gk and the vehicle body deceleration GS, so even when braking in 4-wheel drive, where it is easy to slip when between 4 wheels, the pseudo It becomes possible to accurately calculate the vehicle speed V REF.

Further, the road surface μ is estimated from the magnitude of the calculated deceleration Gk or the vehicle body deceleration GS and its change trend. That is, if the value of deceleration is large, it can be estimated that the road surface μ is also large, and conversely, if the deceleration is small, it can be estimated that the road surface μ is also small.

As described above, in step S9, the pseudo vehicle speed V RE
Once F and road surface μ are estimated, in the next step SIO and step S11, a slip rate is calculated based on the wheel speed VW of each wheel with respect to the pseudo vehicle speed VREF, and based on the slip rate, each wheel The brake pressure control for each wheel, that is, the operation control of the control valve device 15 and each anti-skid valve device 16, is carried out so that the slip ratio of the wheels is at an optimum value. It can be resolved.

After this, in the next step 312, the abnormality flag FO is set to 1.
is set, it is determined whether or not, but here, the determination is negative, and step S13, which will be described later, is determined.
By repeating the above-mentioned steps through the failure diagnosis routine in , the brake pressure of each wheel is controlled to increase, maintain, or decrease depending on the rotational trend of that wheel.
As a result, each wheel speed VW can be made to follow the pseudo vehicle body speed V REF, and each wheel can be prevented from locking.

In this embodiment, in step 811, when controlling the brake pressure of each wheel, not only the road surface μ estimated in step S9 but also the switching state of each switch read in step S6 is taken into consideration. It has become. Specifically, when the anti-skid control described above is started while the vehicle is running in 4WD, the front wheel drive system and the rear wheel drive system are connected, so the front wheel drive system and the rear wheel drive system If the braking forces of the two wheels are controlled independently, the torsional torque in the drive system increases, which may cause the wheel speeds VW of the front wheels and the rear wheels to oscillate. Therefore, in this embodiment, when controlling the brake pressure of each wheel, for example, the rear wheel 5R tends to lock as shown in FIG. When the brake pressures of both SRs are reduced, the brake pressures of the front wheels 4R on the same side as the rear wheels 5R are simultaneously reduced by a predetermined pressure DP. In this way, during anti-skid control, brake pressure reduction control can be carried out in the same phase for the front wheels and the rear wheels, so each wheel speed VW
vibration can be effectively suppressed. In addition, 2WD
In this case, it goes without saying that the brake pressures of the left and right front wheels 4 and both rear wheels 5 are controlled independently during anti-skid control.

In the above case, the 4WD select switch 22 is turned on, but in addition to the 4WD select switch 22, the center differential lock switch 23 is also turned on and the center differential is locked. For the reasons mentioned above, vibrations are likely to occur in each wheel speed VW, so when the switch is in such a switching state, when controlling the brake pressure of each wheel, the brake pressure must be relaxed compared to the case described above. Furthermore, in addition to the two switches 22 and 23 mentioned above, the rear differential lock switch 24 is also turned on.
When the rear differential 7 is locked, the brake pressure of each wheel is controlled to be more relaxed.

Next, the details of the above-mentioned fault diagnosis routine executed in step S13 are shown in FIG. 5, and below,
This failure diagnosis routine will be explained.

Fault Diagnosis Routine First, in step S20 shown in FIG. 5, sensor values from each wheel speed sensor 19 and deceleration sensor 21, and
The switching state of each switch 22, 23, 24 is stored in the memory, and in the next step S21, the average value GAVE of the vehicle body deceleration GS obtained by the deceleration sensor 21 is calculated and stored in the memory. . Here, the average value GAVE of the vehicle body deceleration GS is calculated by adding the value of the vehicle body deceleration GS up to a predetermined time each time step S21 is executed when the ABS main routine in FIG. 1 is repeatedly executed. It can be obtained by taking the average value.

In each of the next steps S22 to S25, whether or not there is an abnormality in the 4WD select switch 22, the center differential lock switch 23, the rear differential lock switch 24, and the deceleration sensor 21, for example, each switch and the controller 20 are checked.
It is determined whether there is a failure such as a disconnection in the signal line connecting the two.

If all of the determinations in steps S22 to S25 are negative, the process returns to step S1 and the aforementioned steps are repeated.

However, if any of the determinations in steps S22 to S25 is positive (Yes), the process advances to step S26, where the type 1 failure flag F1 is set. , step S27
At this point, the abnormality flag FO is set to 1.

On the other hand, if the determination in step S25 is positive, it is determined in the next step S28 whether the driving force type of the automobile is 4WD or 2WD. Here, if the drive system is 4WD, the process advances to step S29, where the second type failure flag F2 is set to 1, and then step S27 is executed. On the other hand, the drive method is 2W
In the case of D, the type 3 failure flag F3 is set to 1 in step S30, and then step S27 is executed.

Therefore, the above-mentioned step S26. S29. After any of S30 is executed, the process returns to the ABS main routine of FIG. 1, and when this main routine is executed, steps S2. S3. Since any judgment in S5 is positive,
As a result, step S31 is determined according to the failure flag.
to 833, that is, type 1 to type 3 fail-safe control will be implemented. That is, the first type flag F1
is set to 1 and the determination in step S5 is positive, the ABS main routine is executed to proceed from step S5 to step S9 through implementation of the first type fail-safe control in step 31. On the other hand, the second
species and type 3 failure fraction F2. F3 is set to 1, and step S2. If one of the determinations in S3 is positive, the process proceeds from that step to the corresponding step S32.
Or A to proceed to step S6 after performing S33.
The BS main routine will be executed.

In the above-described failure diagnosis routine, the first to third type failure flags Fl, F2. If any of F3 is set to 1, the abnormality flag FO is set to 1 in step 827 of FIG. 5, so if the ABS main routine is executed after this, Step 8
Since the determination in step S12 is positive, the failure diagnosis routine in step S13 is bypassed and executed.

The first to third type fail-safe controls are shown in FIGS. 6 to 8, respectively, and these fail-safe controls will be sequentially explained below.

1st Type Fail Safe Contest As is clear from the above explanation, this 1st Type Fail Safe control uses 4W in the fault diagnosis routine shown in Figure 5.
D select switch 22, center differential lock switch 2
This is carried out when a failure occurs in either the rear differential lock switch 24 or the rear differential lock switch 24. First, in step S40 in FIG. 6, it is determined whether or not ABS control is being performed.

For example, this determination is performed by checking whether the wheel speed VW of each wheel has converged within a predetermined deviation with respect to the pseudo vehicle speed V RBF.

If the determination in step S40 is positive, the next step S41 is executed, so that even if any of the 4WD select switch 22, center differential lock switch 23, and rear differential lock switch 24 is malfunctioning,
Each switch 22, 23 before the failure occurs
．． 24 switching states are maintained. Specifically, in step S20 of FIG. 5, the switching states of each switch 22, 23, 24 before the failure are maintained by reading the switching state of each switch 22, 23, 24 stored in the memory. can do.

From step S41, the process advances to step S9 in the ABS main routine of FIG. 2, and the steps after this step are repeatedly executed.

In the process in which the ABS main routine via the first type fail-safe control in step S31 is repeatedly executed in this way, if the determination in step S40 in FIG. 6 is negative, the process proceeds to step S42. In this step, the warning lamp 26 (see Figure 1) is turned on to activate or stop the anti-skid brake system, that is, the system, and a failure code corresponding to the failure flag is output. The ABS main routine is forcibly terminated.

As is clear from the above-mentioned type 1 fail-safe control,
During ABS control, the 4WD select switch 22.
Even if a failure occurs in either the center differential lock switch 23 or the rear differential lock switch 24, the ABS control will not be stopped immediately, and the various switches 22, 23, 24 that were in place before the failure will be The control will continue taking into account the switching state of the switch. That is, as shown in FIG. 9, which shows the change in wheel speed VW during ABS control, even if a failure occurs in any of the various switches 22, 23, 24 at time t1 during ABS control,
The control of the wheel speed VW by the ABS control is continued until the end of the control, as shown by the broken line.

Therefore, according to this embodiment, even if a failure occurs in the various switches 22, 23, 24 while ABS control is being performed, the ABS control can be continued until the end of the failure. At this point, even if the car is traveling in 4WD on a low-μ road, ABS control will not be canceled unexpectedly, thus ensuring that all four wheels are locked at the same time. This can be prevented, sufficient steering performance can be ensured at that point, and the braking distance can also be shortened.

Type 2 fail-safe control This type 2 fail-safe control is performed when the deceleration sensor 21 fails, as explained in the failure diagnosis routine of FIG.
Moreover, this is carried out when the drive system at the time of the failure is 4WD, and in this case, in step S50 of FIG. 7, as in step S40 of FIG. 6, it is determined whether ABS control is in progress or not. If the determination is positive, the next step S51 is executed. In this step S51, the average value GAYE of the vehicle body deceleration GS stored in the memory in step S21 in FIG. 5 is adopted as the vehicle body deceleration GS to be read in step S4 in FIG. Step S of the ABS main routine in Figure 1
Returning to step 9, after the pseudo vehicle speed V REF is calculated and the road surface μ is estimated, the steps after this step are repeated. Therefore, even if the deceleration sensor 21 fails in this way, the vehicle body deceleration GS
Instead, by using the average value G AVE immediately before the failure, it is possible to accurately determine the pseudo vehicle speed V REF and the road surface μ and continue anti-skid control.

In the process of repeatedly executing the ABS main routine via the second type fail-safe control, step 8
If the determination of 50 is negative, step 4 in FIG.
After performing step S52 similar to step 2, the ABS main routine is forcibly terminated.

Type 3 fail-safe control This type 3 fail-safe control is executed when the deceleration sensor 21 fails, similar to the type 2 fail-safe control described above, but the difference is that This means that the drive system at the time of failure is not 4WD but 2WD. In this case, step S60 in FIG.
Now, step S40 in FIG. 6 and step S in FIG.
As in the case of 50, it is determined whether or not ABS control is in progress.
If the determination is positive, the next step S61 is executed. In this step S61, step S4 in FIG.
As the vehicle body deceleration GS to be read in, the calculated deceleration Gk shown in FIG. 3 is adopted.

That is, in this case, the calculated deceleration Gk is the reference wheel speed ■WS
In the case of 2WD, the wheel speed of the non-driving wheel is selected as the reference wheel speed vWS, so the calculated deceleration Gk accurately represents the vehicle deceleration. Become. After this, from step S51, the ABS of FIG.
Returning to step S9 of the main routine, the pseudo vehicle speed V
After REF is calculated and the road surface μ is estimated, the steps after this step are repeated. Therefore, even in this case, by using the calculated deceleration Gk instead of the vehicle deceleration GS, it is possible to accurately obtain the pseudo vehicle speed V REF and the road surface μ, and continue the anti-skid control.

In the process where the ABS main routine via the third type fail-safe control is repeatedly executed, step S
If the determination in step 60 is negative, step 4 in FIG.
2 and step S62 similar to step S52 in FIG.
After the execution of the ABS main routine, the ABS main routine is forcibly terminated.

Therefore, as is clear from the above explanation, even if a failure of the deceleration sensor 21 occurs at time t1 in FIG. 9 during ABS control, the second type fail-safe control or the third type fail-safe control The ABS main routine will continue via the control until the end of the control. And A
To continue the BS main routine, instead of the vehicle deceleration GS detected by the deceleration sensor 21, a calculated deceleration obtained by differentiating the average value GAVE of the vehicle deceleration GS immediately before the failure or the reference vehicle speed VF is used. Since the speed Gk is used, even if the deceleration sensor 21 cannot obtain the vehicle deceleration GS, the pseudo vehicle speed V R obtained in step S9
Since EF and road surface μ are appropriate values, even in this case, it is possible to optimally control the brake pressure of each wheel. Therefore, even if the vehicle is traveling on a low-μ road when a failure occurs, optimal ABS control can be continued until the end of ABS control without undesirably stopping it, and wheel locking can be reliably prevented. The steering performance can be sufficiently ensured and the braking distance can also be shortened.

This invention is not limited to the one embodiment described above, and various modifications are possible. For example, as an apparatus for carrying out the anti-skid brake control method of the present invention,
The method of the present invention is not limited to the configuration shown in FIG. 1, and can be implemented by appropriately changing the structure of the device.

(Effects of the Invention) As explained above, according to the anti-skid brake control method of the present invention, even if the deceleration sensor that detects the deceleration of the vehicle body fails during anti-skid control, the brake control method immediately Instead of stopping the anti-skid control, the average value of the vehicle body deceleration immediately before the failure is used instead of the wheel deceleration, and the anti-skid control is continued until the end, for example. If anti-skid control is unexpectedly stopped during anti-skid control when driving on a low μ road, the control will not return to normal brake control, thus reliably preventing wheel locking.
It has excellent effects, such as ensuring sufficient steering performance and greatly reducing the braking distance.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an anti-skid brake device, and FIG. 2 is an ABS brake system.
A flowchart showing the main routine, FIG. 3 is a block diagram for explaining calculation of pseudo vehicle speed VREF and estimation of road surface μ, FIG. 4 is a diagram showing an example of brake pressure control in 4WD, and FIG. , a flowchart showing the failure diagnosis routine, FIG. 6 is a flowchart showing the first type fail safe control, FIG. 7 is a flowchart showing the second type fail safe control, and FIG. 8 is a flowchart showing the third type fail safe control. The flowchart shown in FIG. 9 is a graph showing the behavior of wheel speed and vehicle body deceleration during ABS control. 4... Front wheel, 5... Rear wheel, 9... Wheel brake, 12... Mask cylinder, 15... Control valve device, 16... Anti-skid valve device, 19... Wheel speed Sensor, 20... Controller, 21... Deceleration sensor, 22... 4WD select switch, 23...
Center differential lock switch, 24...Rear differential lock switch, 26...Warning lamp. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagado 2r

Claims (1)

[Claims] While the wheel speed of each wheel is detected by a wheel speed sensor,
By detecting vehicle deceleration with a deceleration sensor and calculating a pseudo vehicle speed based on these wheel speeds and vehicle deceleration during braking, if a wheel lock tendency occurs with respect to the pseudo vehicle speed, the locking tendency is detected. According to the anti-skid brake control method, the anti-skid control is performed to control the braking force of the wheel, thereby causing the wheel speed of the wheel to follow the pseudo vehicle body speed. An anti-skid brake characterized in that when a failure occurs in a sensor, the average value of vehicle body deceleration before the failure is used instead of the vehicle body deceleration, and anti-skid control is continued until the end of the failure. Control method.