JPH04163266A - Antiskid brake control method - Google Patents

Abstract

PURPOSE:To surely prevent the lock of a wheel by continuing antiskid control based on a switch changing-over state before the occurrence of a trouble even when a trouble occurs during antiskid control of various switches for setting the drive system of an automobile. CONSTITUTION:Sensor values from wheel speed sensors 19 and a deceleration sensor 21 and the changing-over states of switches 22-24 are stored in a memory, and an average value GAVE of car body deceleration GS is calculated and stored in a memory. It is then discriminated whether or not a trouble 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 a trouble occurs to one of the 4WD select switch 22, the center flock switch 23, and the rear diff-lock 24, the changing over states of the switches 22-24 before the occurrence of a trouble is maintained. Namely, the changing-over states, stored in the memory, of the switches 22-24 are read and antiskid control is continued as usual.

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 capable of running with four-wheel drive. This invention relates to a brake control method.

(Prior Art) According to this type of anti-skid brake control method, during braking, the wheel speed of each wheel is detected by a wheel speed sensor, and the deceleration of the vehicle body is detected by a deceleration sensor, and,
Based on these wheel speeds and vehicle deceleration, a pseudo vehicle speed of the vehicle body is calculated.

When the wheel speed of a wheel decreases too much with respect to the pseudo 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 locking tendency. Based on the rotational trend of the wheels, the brake pressure is repeatedly increased, maintained, or decreased to control the wheel speed of each wheel to follow the pseudo vehicle speed, and thereby,
This prevents each wheel from locking. 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.

On the other hand, some four-wheel drive (4WD) vehicles to which the anti-skid brake control method described above is applied, switch their drive system from four-wheel drive to two-wheel drive (2WD), or lock the center differential. Some vehicles are equipped with a 4WD select switch, a center differential lock switch, etc. in order to achieve this. Therefore, when implementing anti-skid control, the switching status of these switches, that is, the drive system of the vehicle, must be taken into account when controlling each wheel. brake pressure is controlled.

(Problem to be Solved by the Invention) By the way, in the above-mentioned anti-skid brake control method, anti-skid control has conventionally been carried out in consideration of the switching states of the 4WD select switch and the center differential lock switch. Even if a failure occurs in either the select switch or the center differential lock switch, anti-skid control is not performed to ensure driving safety. In other words, 4
If a failure occurs in the WD select switch or center differential lock switch, anti-skid control, that is, the operation of the system is immediately stopped.

Therefore, in the conventional anti-skid brake control method,
If a car is running in four-wheel drive on a low μ road such as a snow-covered road or frozen road, and anti-skid control is being implemented in response to braking in such a situation,
If a failure occurs in the 4WD select switch or center differential lock switch, the anti-skid control will be immediately stopped. Therefore, under the above-mentioned driving conditions, when anti-skid control is stopped and normal brake control is resumed, the braking force of each wheel, that is,
The brake pressure will be excessive, so if you're driving in four-wheel drive, there's an increased chance 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,
It is an object of the present invention 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 the various switches described above, and is excellent in safety.

(Means for Solving the Problems) The present invention is applied to an automobile that can drive by selecting a drive method, and the wheel speed of each wheel is detected by a wheel speed sensor, while the deceleration of the vehicle body is detected by a deceleration sensor. When braking, a pseudo-vehicle speed is calculated based on these wheel speeds and vehicle deceleration, and when a lock tendency occurs in the rotational trend of the wheels with respect to the pseudo-vehicle speed, the locking tendency and drive system can be detected. In an anti-skid brake control method, anti-skid control is carried out to control the braking force of the wheel according to the switching state of various switches that select In this invention, when a failure occurs in at least one of the various switches during anti-skid control, the switching state of the various switches is set to the switching state immediately before the failure, and the anti-skid control is continued until the end of the anti-skid control. I have to.

(Function) As described above, according to the anti-skid brake control method of the present invention, even if one of the various switches fails during anti-skid control, the switching states of the various changeover switches can be maintained at the switching states immediately before the fault. Since the anti-skid control is continued until the end according to the switching state immediately before the failure, there is no undesirable transition from anti-skid control to normal brake control during braking. Therefore, the anti-skid control can be effectively operated until the vehicle stops or the tendency of the wheels to lock is resolved.

(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 4L via a transmission 2, a front differential (not shown), and a front wheel drive shaft 3. , 4
The driving force of the engine 1 is then transmitted to the left and right rear wheels 5L and 5R via the transmission 2, center differential (not shown), propeller shaft 6, rear differential 7, and rear wheel drive shaft 8. It has become so.

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.

Furthermore, 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 12 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 senku 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 above-mentioned anti-skid control, that is, the operation of the control valve device 15 and each anti-skid valve device 16, 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.

First, in step S1, the wheel speed VW of each wheel is read by each wheel speed sensor 19, and at the same time, in step S2. In S3, it is determined whether or not the type 2 failure flag F2 and the type 3 failure flag F3 are set, that is, whether or not the type 2 failure flag F2 and the type 3 failure flag F3 are set. It is determined whether F3 is set to 1 or not. Here, step 32. The determination in S3 is negative (No), and in the next step S4, the vehicle body deceleration GS is read by the deceleration sensor 21.

After this, in step S5, it is determined whether or not the first failure flag FT 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 vWS. 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 from among the respective wheel speeds VW; When the vehicle is traveling at a speed of 1, the wheel speed of that non-driven wheel is selected.

In step S8, anti-skid control, that is, ABS
It is determined whether or not control should be started, specifically,
For the reference wheel speed ■WS that has already been determined, other wheel speeds V
The determination is made based on whether at least one of the wheels W has decreased to a predetermined value Δ■W 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 VREF and the friction coefficient of the road surface are determined. , the road surface μ is estimated. In this embodiment, the pseudo vehicle speed V REF is equal to the reference wheel speed VW, as shown in the block diagram of FIG.
S, the calculated deceleration Gk obtained from this reference wheel speed VW and the vehicle body deceleration GS obtained by the deceleration sensor 21 are calculated. That is, the wheel speed VW of each wheel
The reference wheel speed ■WS selected from is subjected to filter processing and then supplied as the reference vehicle speed VF to the calculation unit 25 that calculates the pseudo vehicle speed V REF, and the reference vehicle speed VF is subjected to differentiation processing. Thus, the calculated deceleration Gk is supplied to the calculation unit 25. On the other hand, the vehicle body deceleration GS obtained by the deceleration sensor 21 is also supplied to the calculation unit 25 after passing through filter processing. In addition, in Fig. 3, the subscripts PL, PR, RL, and R attached to the wheel speed VW are
R represents that the sono wheel speed is that of the right front wheel, the right front wheel, the left rear wheel, and the 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, normally, the pseudo vehicle speed VREF is set to the reference vehicle speed VF, but immediately after the start of ABS control, if the calculated deceleration Gk is so large that it cannot be achieved with normal braking. , it can be estimated that slip has also occurred in the reference wheel speed VWS itself. Therefore, in the above-mentioned situation, the reference vehicle speed VF is not set as the pseudo vehicle speed VRBF, but in this case, immediately after the start of ABS control, the vehicle body is at a predetermined deceleration and a predetermined deceleration. Assuming that the vehicle decelerates for a certain period of time, a pseudo vehicle speed V REF is calculated, and after a predetermined time has elapsed from the start of ABS control, the vehicle body deceleration GS from the deceleration sensor 21 is calculated.
The pseudo vehicle speed VRIEF is calculated based on the following. 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 REF, not only the wheel speed VW but also the calculated deceleration Gk and the vehicle body deceleration GS are taken into account, so even when braking with 4-wheel drive, which is prone to slipping when moving between 4 wheels, the pseudo It becomes possible to accurately calculate the vehicle body speed VREF.

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 deceleration value is large, it can be estimated that the road surface μ is also large, and conversely, if the deceleration is small, the road surface μ can also be estimated to be small.

As described above, in step S9, the pseudo vehicle speed VR,
Once EF and road surface μ are estimated, in the next step SIO and step Sll, the slip rate is calculated based on the wheel speed VW of each wheel with respect to the pseudo vehicle speed VREF, and the slip rate of each wheel is calculated based on the slip rate. Brake pressure control for each wheel, that is, operation control of the control valve device 15 and each anti-skid valve device 16, is carried out so that the slip ratio is at an optimum value, thereby eliminating the locking of the wheels that tend to lock. can do.

After this, in the next step S12, 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 the case of this embodiment, when controlling the brake pressure of each wheel in step Sll, not only the road surface μ estimated in step S9 but also the switching state of each switch read in step S6 are 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, as shown in FIG. 4, the rear wheel 5R tends to lock, and according to the so-called select low principle, the rear wheels 5L, When the brake pressures of both the rear wheels 5R and 5R 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 performed in the same phase for the front wheels and the rear wheels, so vibrations in each wheel speed VW can be effectively suppressed. be able to. In addition, 2
In the case of WD, 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 should be adjusted to the ratio of the above case. In addition to the above-mentioned two switches 22 and 23, 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, the sensor values of each wheel speed sensor 19 and deceleration sensor 21 are
The switching state of each switch 22, 23, 24 is stored in the memory, and in the next step S21, the average value GAVB 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 drive system of the vehicle is 4WD or 2WD. Here, if the drive system is 4WD, the process advances to step S29, and after the type 2 failure flag F2 is set to 1, step S27 is executed. On the other hand, the drive method is 2'W
In the case of D, the third type failure flag F3 is set to 1 in step S30, and then step S27 is executed.

Therefore, steps 326', 329 . 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 of the determinations in S5 is positive, step S3 is performed according to the failure flag.
1 to S33, that is, type 1 to type 3 failsafe control will be implemented. That is, the first type flag F
If l 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, type 2 and type 3 failure flag F2. F3 is set to 1 and step S2. If one of the determinations in S3 is positive, the process from that step to the corresponding step S3
2 or S33, the ABS main routine is executed to proceed to step S6.

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 S27 of FIG. 5, so if the ABS main routine is executed thereafter, Step S
Since the determination in step SI3 is positive, the failure diagnosis routine in step SI3 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.

Type 1 fail-safe control As is clear from the above explanation, this type 1 fail-safe control is performed using 4W in the fault diagnosis routine shown in FIG.
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 ■W of each wheel has converged within a predetermined deviation with respect to the pseudo vehicle speed V REF.

If the determination in step 340 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 has a failure,
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 FIG. 1) is turned on to stop the operation of the anti-skid brake device, that is, the system, and a fault code corresponding to the fault 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 consideration 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, or 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. is determined, and if the determination is positive, the next step S51 is executed. In this step S51, the average value GAVE of the vehicle body decelerations 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 S
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 8 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 body 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 determine the pseudo vehicle speed VREF 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 the ABS control without undesirably stopping the ABS control, thereby reliably preventing wheel locking. 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 various switches for setting the drive system of the automobile should fail during anti-skid control,
Based on the switching state of the switch before the failure, the anti-skid control continues until the end of the anti-skid control.
For example, when anti-skid control is performed while driving on a low-μ road, the anti-skid control will not be stopped unexpectedly and return to normal brake control, and the wheels will lock. It has excellent effects such as reliably preventing this, 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.
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, FIG. is a flowchart showing a failure diagnosis routine, FIG. 6 is a flowchart showing type 1 fail-safe control, FIG. 7 is a flowchart showing type 2 fail-safe control, and FIG. 8 is a flowchart showing type 3 fail-safe control. FIG. 9 is a graph showing the behavior of wheel speed and vehicle deceleration during ABS control. 4... Front wheel, 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 2f

Claims (1)

[Claims] Applicable to automobiles that can drive by selecting a drive method, the wheel speed of each wheel is detected by a wheel speed sensor, and the deceleration of the vehicle body is detected by a deceleration sensor, and when braking By calculating a pseudo vehicle speed based on these wheel speeds and vehicle deceleration, when a lock tendency occurs in the rotational trend of the wheels with respect to the pseudo vehicle speed, the lock tendency and the switching state of various switches for selecting the drive method are calculated. Accordingly, anti-skid control is implemented to control the braking force of that wheel, thereby
In an anti-skid brake control method in which the wheel speed of a wheel follows a pseudo-vehicle speed, when a failure occurs in at least one of the various switches during anti-skid control, the switching state of the various switches is changed to the switching state immediately before the failure. An anti-skid brake control method characterized in that the anti-skid control is continuously performed until the end of the anti-skid control.