JPH06107156A - Antiskid controller - Google Patents

Abstract

PURPOSE:To provide an antiskid controller that is able to improve the braking property of a vehicle as controlling the extent of yaw torque to be added to the vehicle on a split road. CONSTITUTION:Each solenoid valve individually regulating each braking hydraulic pressure of symmetrical front wheels operates both differences in each time turning to a booster mode and a decompressing mode (206), and on the basis of this operation, a high hydraulic pressure side wheel is judged (207). After each individual solenoid valve control mode is set on the basis of a slip state of each wheel (209), select low control is selected for rear wheels (211), independent control, independent limiting control and the selector low control are selected for the front wheels, in proportion as a difference in the slip state grows larger (217). Imbalance in front wheel braking force on a split road means that large yaw torque is added to a vehicle, but the extent of braking force is improvable as controlling this imbalance in a sufficient manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device for preventing wheel lock during wheel braking,
Particularly, the present invention relates to achieving both braking performance and steering stability on a traveling road (hereinafter referred to as a split road) having different friction coefficients with wheels on the left and right.

[0002]

2. Description of the Related Art In conventional anti-skid control,
For example, the control as described in Japanese Patent Publication No. 59-19863 is considered with emphasis on steering stability on a split road. That is, the braking force of the left and right wheels is controlled by so-called select low control in which the braking force of the other wheel is controlled in accordance with the wheel on the side where the slip is large. By doing so, it is possible to prevent a large braking force from being applied to the wheels on the high friction coefficient side and improve the steering stability of the vehicle.

[0003]

However, in a device adopting select low control, a relatively large slip occurs on a wheel on the low friction coefficient side (hereinafter referred to as a low μ wheel). Therefore, it is necessary to absorb this slip. Control is frequently performed to reduce the braking force of the low μ wheels. Then, the braking force of the wheel on the high friction coefficient side (hereinafter referred to as the high μ wheel) with relatively small slip is also similarly reduced, so that the braking force of the vehicle is reduced.

Therefore, in the conventional vehicle, the select low control is applied only to the rear wheels, and the front wheels, which generate a relatively large braking force at the time of braking, are independent of the braking force of each wheel in accordance with the slip state of each wheel. The so-called independent control for controlling the above is adopted. In the independent control, the braking force of each wheel is independently controlled, so that each wheel can generate the largest braking force.

However, as described above, since the front wheels generate a larger braking force than the rear wheels, a large yaw torque is applied to the vehicle when the braking forces of the left and right front wheels differ when traveling on a split road. Especially in a vehicle with a small wheelbase, a large yaw torque was applied, which sometimes impaired steering stability. If select low control is adopted for the front wheels, sufficient braking force cannot be obtained as described above.

Therefore, the present invention has been made for the purpose of providing an anti-skid control device capable of improving the braking performance of a vehicle while suppressing the yaw torque applied to the vehicle on a split road.

[0007]

DISCLOSURE OF THE INVENTION The present invention, which has been made to achieve the above object, has a braking force adjusting means for individually adjusting the braking forces of the left and right front wheels, as shown in FIG.
As the difference between the slip state detecting means for individually detecting the slip state of each of the front wheels and the slip state of the left and right front wheels detected by the slip state detecting means increases, the control of each front wheel is controlled by each of the front wheels. Independent control that independently controls the braking force of each front wheel according to the slip condition, independent limit control that controls the braking force increase tendency of the other front wheel by the front wheel with large slip, or the other according to the front wheel with large slip The gist of an anti-skid control device is characterized by further including front wheel control selection means for sequentially selecting a select low control for controlling the braking force of the front wheels.

[0008]

In the present invention thus constituted, the slip state detecting means detects the slip states of the left and right front wheels individually,
The front wheel control selecting means sequentially selects the independent control, the independent limiting control and the select low control for the control of each front wheel as the difference between the slip states of the left and right front wheels detected by the slip state detecting means increases.

For this reason, when the vehicle runs on a road where the road surface friction coefficient is substantially uniform on the left and right (hereinafter referred to as a uniform road), that is, when the left and right front wheels have substantially equal slip conditions, independent control is selected for the control of each front wheel. As a result, a sufficient braking force can be obtained. At this time, almost no yaw torque is applied to the vehicle except for the one operated by the steering wheel.

When traveling on a split road where the road surface friction coefficient is slightly different between left and right, that is, when the slip states of the left and right front wheels are slightly different, the independent limiting control is selected for the control of each front wheel as follows. The braking force can be improved while suppressing the yaw torque applied to the vehicle.

Here, the independent limiting control is a control method for limiting the tendency of the other wheel to increase the braking force by the wheel with large slip. Therefore, the braking force corresponding to the slip of the low-μ wheel is applied to the low-μ wheel, but the braking force of the low-μ wheel is smaller than the braking force corresponding to the slip of the high-μ wheel to the high-μ wheel. Greater braking force is applied.

Since the slip generated in the high μ wheels is relatively small, the braking force is improved by making the braking force of the high μ wheels larger than that of the low μ wheels. Further, since the increasing tendency of the braking force of the high μ wheel is limited by the low μ wheel, it is possible to prevent the application of the braking force which is largely biased to the high μ wheel side. Therefore, it is possible to prevent a large yaw torque from being applied to the vehicle.

Further, when traveling on a split road where the left and right road surface friction coefficients are greatly different, the independent limiting control may not be able to sufficiently suppress the yaw torque. This is because in the independent limiting control, the increasing tendency of the braking force of the high μ wheels is limited only by the low μ wheels, and the braking force is not the same. Then, on a split road where the left and right road surface friction coefficients greatly differ, a significant difference may occur in the braking force between the high μ wheel and the low μ wheel.

Therefore, when the vehicle runs on a split road where the left and right road surface friction coefficients greatly differ, that is, when the left and right front wheels greatly differ in slip condition, select low control is selected for the control of each front wheel. This makes it possible to equalize the braking forces applied to the left and right front wheels and favorably suppress the yaw torque applied to the vehicle.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the antiskid control device of the present invention will be described below. FIG. 1 shows the configuration of an anti-skid control device as an embodiment of the present invention.
The present embodiment is an example in which the present invention is applied to a front-wheel steering / front-wheel drive four-wheel vehicle.

In FIG. 1, the brake pedal 20 is connected to a master cylinder 28 via a vacuum booster 21. Therefore, by depressing the brake pedal 20, hydraulic pressure is generated in the master cylinder 28, and this hydraulic pressure is
Wheel cylinders 31, 32, 3 provided on each wheel (left front wheel FL, right front wheel FR, left rear wheel RL, right rear wheel RR)
It is supplied to 3, 34 and generates a braking force.

The master cylinder 28 has two pressure chambers (not shown) which generate brake hydraulic pressures of the same pressure, and supply pipes 40 and 50 are connected to the respective pressure chambers. The supply pipe 40 is branched into communication pipes 41 and 42. The communication pipe 41 is connected to the brake pipe 43 communicating with the wheel cylinder 31 via the solenoid valve 60a. Similarly, the communication pipe 42 is connected to the brake pipe 44 that communicates with the wheel cylinder 34 via the electromagnetic valve 60c.

The supply pipe 50 also has the same connection relationship as the supply pipe 40 and is branched into communication pipes 51 and 52. Communication pipe 51
Is connected to a brake pipe 53 communicating with the wheel cylinder 32 via an electromagnetic valve 60b. Similarly, the communication pipe 52 is connected to the wheel cylinder 3 via the solenoid valve 60d.
3 is connected to a brake pipe 54 that communicates with 3.

Known proportioning valves 59 and 49 are installed in the brake pipes 54 and 44 connected to the wheel cylinders 33 and 34, respectively. The proportioning valves 59 and 49 control the brake hydraulic pressure supplied to the rear wheels RL and RR to bring the braking force distribution of the front and rear wheels FL to RR close to ideal.

Electromagnetic pickup type wheel speed sensors 71, 72, 73 and 74 are installed on the respective wheels FL to FR, and the signals thereof are inputted to the electronic control circuit ECU. The electronic control circuit ECU outputs a drive signal to the solenoid valves 60a to 60d so as to control the brake hydraulic pressure of each wheel cylinder 31 to 34 based on the input wheel speed of each wheel FL to FR.

Solenoid valves 60a, 60c, 60b, 60d
Is a 3-port 3-position solenoid valve, and at the position A in FIG. 1, the communication pipes 41, 42, 51, 52 and the brake pipe 4 are shown.
3, 44, 53, 54, respectively, and at the B position, the communication pipes 41, 42, 51, 52, the brake pipe 4
3, 44, 53, 54 and branch pipes 47, 48, 57, 58 are all blocked. Further, in the C position, the brake pipes 43, 44, 53, 54 and the branch pipes 47, 48, 57, 5 are
8 and 8 respectively.

The branch pipes 47 and 48 are both connected to the discharge pipe 81, and the branch pipes 57 and 58 are both connected to the discharge pipe 91. These discharge pipes 81 and 91 are respectively connected to the reservoirs 93a and 9a.
It is connected to 3b. The reservoirs 93a and 93b temporarily store the brake fluid discharged from the wheel cylinders 31 to 34 when the solenoid valves 60a to 60d are in the C position. Therefore, in the solenoid valves 60a-60d,
The brake hydraulic pressure of the wheel cylinders 31 to 34 can be increased at the A position, the brake hydraulic pressure can be maintained at the B position, and the brake hydraulic pressure can be reduced at the C position. That is, the solenoid valves 60a and 60b correspond to braking force adjusting means.

The pumps 99a and 99b are provided with a reservoir 93.
The brake fluid accumulated in a and 93b is pumped up and returned to the master cylinder 28 side. Also, check valve 97
a, 98a, 97b, 98b are reservoirs 93a, 93b
The brake fluid pumped up from the reservoir 93a,
This is to prevent backflow to the 93b side. The stop switch 100 detects whether or not the driver is stepping on the brake pedal 20.

Next, the anti-skid control executed in the apparatus of this embodiment constructed as described above will be described with reference to FIG.
This will be described with reference to the flowcharts of FIG. First, FIG. 2 is a flow chart showing the main routine of the anti-skid control of the embodiment. Note that this process is a process that is started when an ignition switch (not shown) is turned on. In addition, this process is sequentially performed for each wheel FL to RR,
For example, left front wheel FL → right front wheel FR → left rear wheel RL → right rear wheel R
It is executed in the order of R.

When the processing is started, first, in step 201, various flags and various counters to be described later are initialized. In the following step 203, the wheel speed sensors 71 to 71
Based on the signal input from the control unit 74, the wheels to be controlled (F
Wheel speed and acceleration of any of L to RR) are calculated. Further, in the following step 205, the solenoid valves 60a, 6
0b control mode (electronic control circuit EC
(Set in U) is the time for pressure boost mode TupFL,
The difference between TupFR and the difference between times TdwFL and TdwFR during which the control modes of the solenoid valves 60a and 60b are in the pressure reducing mode are calculated.

Next, when the routine proceeds to step 207, based on the calculation result of step 205, either of the front wheels FL and FR is the high hydraulic side wheel (the wheel on the high brake hydraulic pressure side) by the high hydraulic side wheel determination routine described later. Determine if there is.
Further, in the following step 209, based on the wheel speeds and accelerations of the wheels FL to RR calculated in step 203, the control modes (pressure increase, pressure increasing, Hold, depressurize). Since this process is a well-known process, detailed description thereof will be omitted. The control mode set here is simply numerical data in the electronic control circuit ECU. That is, in this step, the solenoid valves 60a-
Do not drive 60d. Further, in this step, all the control modes of the solenoid valves 60a to 60d are set to the pressure increasing mode during normal traveling when the stop switch 100 is not operating.

At the following step 211, it is determined whether the wheel to be controlled is one of the rear wheels RL and RR.
Step 2 if the controlled object is the rear wheel RL or RR
13, the select low control is selected for controlling the rear wheels RL, RR, and the process proceeds to step 215. On the other hand, when the controlled object is the front wheel FL or FR, the following step 2
Go to 17.

In step 217, the control of the front wheels FL, FR is switched by the control switching routine described later based on the determination result in step 207. When the mode is switched to the select low control, the routine proceeds to step 213, where the front wheels FL, F
When the select low control is selected for the R control and the control is switched to the independent control, the process proceeds to step 221, the independent control is selected, and when the control is switched to the independent limit control, the step 2 is performed.
In step 19, the independent limiting control is selected.

After the control of the wheels FL to RR to be controlled is selected in steps 213 to 221, the process proceeds to step 215, and the corresponding solenoid valve 60 is selected based on the selected control.
Drive a to 60d. After step 215, the process moves to step 203 again, and the above processing is repeated.

Next, FIG. 3 is a flow chart showing the high hydraulic pressure side wheel determination routine of step 207. When the process is started, first, in step 301, the brake pedal 20
Is operated to determine whether the stop switch 100 is operating. If the stop switch 100 is not operating and the determination is negative, the routine proceeds to step 303, where the right front wheel FR indicates that the right front wheel FR is a high hydraulic side wheel.
R and the left front wheel flag FFL indicating that the left front wheel FL is the high hydraulic side wheel are both reset and the process returns to the main routine. As described above, when the stop switch 100 is not operated, all the solenoid valves 60a to 60d are in the pressure increasing mode regardless of whether the left and right front wheels FL and FR are high hydraulic side wheels. Control switching at 217 does not make sense. Therefore, for the sake of convenience, the left and right front wheels FL, F
R is not a high hydraulic side wheel (it is a low hydraulic side wheel)
And

When the stop switch 100 is operating, the process proceeds to step 305. In step 305,
Based on the calculation result in step 205, the sum of the differences between the time TupFR during which the control mode of the solenoid valve 60b is in the pressure increasing mode and the time TupFL during which the control mode of the solenoid valve 60a is in the pressure increasing mode is calculated, and is increased. The pressure time difference is ΔTup.
In the following step 307, similarly, the solenoid valves 60b, 60
Time TdwFR, Td when the control mode of a is the depressurization mode
The sum of the differences in wFL is calculated, and this is defined as the depressurization time difference ΔTdw.

Subsequently, in step 309, it is determined whether or not a value obtained by subtracting the pressure reduction time difference ΔTdw from the pressure increase time difference ΔTup is equal to or larger than a predetermined value Ta. When it is Ta or more, the process proceeds to step 311, and the right front wheel flag F
The FR is set and the left front wheel flag FFL is reset to return to the main routine. That is, ΔTup−ΔT
The larger dw means that the control mode of the solenoid valve 60b is in the pressure increasing mode longer than that of the solenoid valve 60a.
Alternatively, it means that the time during which the control mode of the solenoid valve 60b is in the pressure reducing mode is shorter than that of the solenoid valve 60a. Therefore, if an affirmative decision is made at 309, the right front wheel FR
Is a high hydraulic side wheel. The control modes of the solenoid valves 60a and 60b are the corresponding wheels FL and F.
Since R is set so as not to be locked, the fact that the right front wheel FR is a high hydraulic wheel indicates that the vehicle is traveling on a split road and the wheels are high μ wheels.

When a negative determination is made in step 309 and the process proceeds to the following step 313, it is determined whether or not ΔTup−ΔTdw is less than or equal to a predetermined value −Ta. When it is −Ta or less, it is determined that the left front wheel FL is a high hydraulic side wheel, and in step 315, the right front wheel flag FFR is reset and the left front wheel flag FFL is set to return to the main routine. If a negative determination is also made in step 313, there is no significant difference in the brake hydraulic pressure applied to the left and right front wheels FL, FR.
That is, it is determined that the vehicle is traveling on a uniform road, and at step 303, the flags FFL and FFR are reset and the process returns to the main routine.

Next, FIG. 4 is a flow chart showing the control switching routine of step 217. As described above, in this process, the control object of the main routine is the front wheel FL.
Or it is executed only when FR. When the process is started, first, at step 401, it is judged if the vehicle speed V is smaller than a predetermined value Va. Here, the vehicle speed V is step 20.
It is possible to use those obtained by various methods such as a method of obtaining from the wheel speed detected in 3, a method of providing a vehicle speed sensor on the vehicle body, a method of providing a sensor on a speedometer cable (not shown), and the like.

When the vehicle speed V is smaller than the predetermined value Va, the counter CT1 is reset in step 403, and then, as shown in FIG.
In step 219, the independent control is selected. That is, when the vehicle speed V is sufficiently low, even if the braking force applied to the front wheels FL and FR is different between the left and right, the influence of the yaw torque generated thereby on the steering stability can be ignored. Therefore, the independent control is selected as the control of the front wheels FL and FR that are the targets, and the braking force is improved.

When the vehicle speed V is equal to or higher than the predetermined value Va, the routine proceeds to the following step 405, where the front wheel F to be controlled is controlled.
It is determined whether L (or FR) is a high hydraulic side wheel. When the wheel is a low hydraulic side wheel, that is, the right front wheel flag F
When FR (or the front left wheel flag FFL) is reset, the routine proceeds to step 219 via step 403. When the wheel is a high hydraulic side wheel (flag FFR or F
When FL is set), the process proceeds to the following step 407. In step 407, it is determined whether the control mode set in step 209 of FIG. 2 is the pressure increasing mode. If it is in the pressure increasing mode, the process proceeds to the following step 409. If it is not in the pressure increasing mode, that is, if it is the holding or pressure reducing mode, the process proceeds to step 2 through step 403.
Move to 19.

As will be described later, when the control mode of the high hydraulic side wheels is the pressure increasing mode, the select low control and the independent limiting control are based on the control mode of the low hydraulic side wheels, and are actually applied to the high hydraulic side wheels. This is a control for prohibiting or limiting the increase of the applied brake hydraulic pressure. Therefore, steps 405 and 4
By the processing of 07, the front wheel FL (or F
R) is a low hydraulic side wheel or its front wheel FL (F
When the control mode of R) is not the pressure increasing mode, the independent control is selected to improve the braking performance. Also, when the vehicle is traveling on a uniform road and both flags FFL and FFR are reset, a negative determination is made in step 405, and the independent control is similarly selected.

Next, at step 409, it is judged if the control mode of the low hydraulic pressure side wheel is the pressure reducing mode. In the pressure reducing mode, the counter CT1 is incremented in the following step 411, and then the step CT413 is performed.
Move to. In step 413, it is determined whether or not the value of the counter CT1 is in the range of the predetermined value K1 or more and less than the predetermined value K2. If the counter CT1 is within the above range, the process proceeds to step 213 in FIG. 2 to select the select low control, and if not within the above range, step 221 in FIG.
Move to and select independent limit control. On the other hand, the control mode of the low hydraulic pressure side wheel is the pressure increasing mode or the holding mode, and if a negative determination is made in step 409, the counter CT1 is reset in step 415 and then the process proceeds to step 221.

That is, the counter CT1 measures the period in which the control mode of the high hydraulic side wheels is kept in the pressure increasing mode and the control mode of the low hydraulic side wheels is kept in the depressurizing mode. Such a period becomes longer as the road friction coefficients on the left and right differ greatly. Therefore, CT1 <K1
If it is, it is judged that the left and right road surface friction coefficients are slightly different, and the independent limiting control is selected. If K1 ≦ CT1, it is judged that the left and right road surface friction coefficients are significantly different and select low control is selected. Of. Further, when the above period becomes further longer and K2 ≦ CT1, the independent limiting control is selected in order to prevent the braking performance of the vehicle from being significantly deteriorated by selecting the select low control for a long time.

In this way, in the control switching routine of this embodiment, the independent control is selected for controlling the front wheels FL and FR on a uniform road where the left and right road surface friction coefficients are not substantially different, and the left and right road surface friction coefficients are slightly different. Independent limiting control can be selected on the road, and select low control can be selected on the split road where the left and right road surface friction coefficients differ greatly.

Next, FIGS. 5 to 8 are flow charts showing the driving routine of the solenoid valves 60a to 60d in step 215. When the independent control is selected in step 219, the process shown in FIG. 5 is executed. That is, first, in step 501, the control mode set in step 209 is read into the wheel to be controlled (any one of FL to RR). In the following step 503, the solenoid valves 60a-60d corresponding to the target wheels FL-RR are driven in that control mode to return to the main routine. That is, when the control mode is the pressure increasing mode, the solenoid valves 60a to 60d are moved to the A or B position in order to perform the pressure increasing output or the duty increasing output of the pressure increasing and holding, and to the B position in the holding mode, to reduce the pressure. In the mode, it is driven to the C or B position in order to output the reduced pressure or output the reduced pressure and hold the duty. As described above, in the independent control, the solenoid valves 60a to 60d are driven in the control mode set in step 209, so that the target wheels FL to RR can be favorably prevented from being locked and the maximum braking force can be obtained.

If the select low control is selected in step 213, the process shown in FIG. 6 is executed. That is,
First, in step 601, the control mode set in step 209 is read into the wheels FL to RR to be controlled. In the following step 603, it is determined whether the control mode of the low hydraulic pressure side wheel is the pressure reducing mode and the control mode of the high hydraulic pressure side wheel is the pressure increasing mode. If an affirmative determination is made here, in the following step 605, the solenoid valves 60a to 60d corresponding to the target wheels FL to RR are driven in the pressure reducing mode, and the process returns to the main routine.

If a negative determination is made in step 603, the process proceeds to step 607. In step 607,
It is determined whether the control mode of the low hydraulic pressure side wheels is the holding mode and the control mode of the high hydraulic pressure side wheels is the pressure increasing mode.
If an affirmative decision is made here, in a succeeding step 609, the corresponding solenoid valves 60a to 60d are driven in the holding mode, and the process returns to the main routine. When a negative determination is made in step 607, the process proceeds to step 611, and the corresponding solenoid valves 60a-60d are driven in the control mode set in step 209 to return to the main routine.

As described above, in the select low control, the solenoid valves 60a to 60d are driven in the control mode of the low hydraulic pressure side wheels (low μ wheels), so that the yaw torque applied to the vehicle during braking on the split road can be well suppressed. The steering stability can be sufficiently improved. When the independent limit control is selected in step 221, the process shown in FIG. 7 is executed. That is, first, at step 701, the wheels FL, F to be controlled are
The control mode set in step 209 is read into R (high hydraulic side wheel as described in step 405). In the following step 703, it is determined whether or not the control mode of the high hydraulic side wheels is the pressure increasing mode. When not in the pressure increasing mode, the routine proceeds to step 705, where the solenoid valves 60a and 60b corresponding to the target wheels FL and FR are driven in the control mode set at step 209 to return to the main routine.

If an affirmative decision is made in step 703, the operation proceeds to the following step 707. In step 707, it is determined whether the control mode of the low hydraulic pressure side wheel is the pressure reducing mode. If in depressurization mode, continue to step 7
At 09, the corresponding solenoid valves 60a-60d are driven in the holding mode to return to the main routine. If a negative determination is made in step 707, the process proceeds to step 711,
The corresponding solenoid valves 60a to 60d are driven in the gentle pressure increasing mode to return to the main routine. Here, driving in the gentle pressure increase mode means that the solenoid valves 60a to 60d are set to A
This is a mode in which the hydraulic pressure of the wheel cylinders 31 to 34 is gradually increased by moving between the position and the B position with a predetermined duty ratio.

As described above, in the independent limiting control, the increase of the brake hydraulic pressure on the high hydraulic wheel side is limited in the control mode of the low hydraulic side wheel (low μ wheel), so that the yaw torque applied to the vehicle during braking on the split road is reduced. It is possible to obtain good braking force while suppressing and ensuring steering stability.

In the above processes, the process of step 209 of FIG. 2 corresponds to the slip state detecting means, and the process of step 217 of FIG. 2, that is, the process of the control switching routine of FIG. 4 corresponds to the front wheel control selecting means. As described above, in the anti-skid control device of the present embodiment, sufficient braking force can be obtained by selecting the independent control for the control of the front wheels FL, FR when traveling on a uniform road. At this time, the yaw torque is hardly applied to the vehicle. In addition, when traveling on a split road where the left and right road surface friction coefficients are slightly different, the front wheels FL, F
By selecting the independent limiting control for the R control, it is possible to improve the braking force while suppressing the yaw torque applied to the vehicle. Further, when traveling on a split road where the left and right road surface friction coefficients differ greatly, the yaw torque applied to the vehicle can be favorably suppressed by selecting the select low control for controlling the front wheels FL, FR.

That is, in this embodiment, it is possible to obtain as much braking force as possible while sufficiently suppressing the yaw torque applied to the vehicle on various split roads. Therefore,
In the vehicle adopting this embodiment, it is possible to suppress the application of yaw torque to improve the steering stability and the braking performance of the vehicle.

In the above embodiment, the slip state of the front wheels FL, FR is detected based on the control mode of the front wheels FL, FR. However, the slip state of the front wheels FL, FR can be detected by various other methods. Can be detected. For example, the slip state may be detected by comparing the wheel speed detected by the wheel speed sensors 71, 72 with the vehicle speed.

In this embodiment, the counter CT1 counts the period during which the control mode for the high hydraulic side wheels is the pressure increasing mode and the control mode for the low hydraulic side wheels is the depressurizing mode.
Although the control is selected by comparing the slip states of the front wheels FL and FR based on the value, the slip states can be compared by various methods other than this. For example, the slip states of the left and right front wheels FL and FR may be compared based on the pressure increase time difference ΔTup and the pressure decrease time difference ΔTdw calculated in steps 305 and 307 of FIG.

[0051]

As described above in detail, in the anti-skid control device of the present invention, sufficient braking force can be obtained by selecting the independent control for the control of each front wheel when traveling on a uniform road. At this time, the yaw torque is hardly applied to the vehicle. Further, when traveling on a split road where the left and right road surface friction coefficients are slightly different, it is possible to improve the braking force while suppressing the yaw torque applied to the vehicle by selecting the independent limiting control for the control of each front wheel. Furthermore, when traveling on a split road where the left and right road surface friction coefficients differ greatly, the yaw torque applied to the vehicle can be suppressed well by selecting the select low control for the control of each front wheel.

That is, in the present invention, while sufficiently suppressing the yaw torque applied to the vehicle on various split roads,
It is possible to obtain as much braking force as possible. Therefore, in the vehicle adopting the present invention, it is possible to suppress the application of the yaw torque to improve the steering stability and the braking performance of the vehicle.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an anti-skid control device of an embodiment.

FIG. 2 is a flowchart showing a main routine of anti-skid control of the embodiment.

FIG. 3 is a flowchart showing a high hydraulic side wheel determination routine of anti-skid control.

FIG. 4 is a flowchart showing a control switching routine of anti-skid control.

FIG. 5 is a flowchart showing an independent control solenoid valve drive routine.

FIG. 6 is a flowchart showing a select low control solenoid valve drive routine.

FIG. 7 is a flowchart showing a solenoid valve drive routine of independent limitation control.

FIG. 8 is a diagram illustrating the configuration of the present invention.

[Explanation of symbols]

20 ... Brake pedals 31, 32, 33,
34 ... Wheel cylinder 60a, 60b, 60c, 60d ... Solenoid valve 71, 72, 73, 74 ... Wheel speed sensor 100 ... Stop switch ECU ... Electronic control circuit FL, FR ... Front wheel RL, RR ... Rear wheel

Claims (1)

[Claims] 1. A braking force adjusting means for individually adjusting the braking force of the left and right front wheels, a slip state detecting means for individually detecting a slip state of each of the front wheels, and the left and right sides detected by the slip state detecting means. As the difference in the slip state of the front wheels increases, independent control is performed to control the braking force of each front wheel independently according to the slip state of each front wheel, and the braking force of the other front wheel is controlled by the front wheel with the larger slip as the front wheel is controlled. Front wheel control selecting means for sequentially selecting independent limiting control for limiting and controlling the increasing tendency, or select low control for controlling the braking force of the other front wheel in accordance with the front wheel with large slip, Anti-skid control device.