JPH0885441A - Antiskid device for automobile - Google Patents

Abstract

PURPOSE: To reconcile the braking property and stability by providing a control reference wheel selecting means selecting a wheel showing the lock tendency the most as the control reference wheel, excluding the locked wheel from the selection subject when any wheel is locked, and selecting the control reference wheel from the remaining wheels. CONSTITUTION: An ECU 26 judges whether a vehicle is under antiskid control or not and whether the estimated vehicle body speed is the prescribed judgment value VH (travel load judgment level) or below or not during the travel of the vehicle. When either judgment is 'NO', one of four wheels showing the lock tendency the most is selected as a reference, and the control mode is determined. When both judgments are 'YES', lock judgment is made for all four wheels, and various low selections are switched according to the number of locked wheels. When all four wheels are not locked, the control mode is determined by the low selection of four wheels. When only one wheel is locked, the control mode is determined by the low selection of the remaining three wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile antiskid device.

[0002]

2. Description of the Related Art In this type of anti-skid device, a wheel speed sensor for detecting the wheel speed is provided for each wheel.
From the wheel speed information obtained by the sensor, the wheel having the most locking tendency (the wheel having the lowest wheel speed) is selected as the control reference wheel (so-called low-selection type). Then, the braking pressure is controlled to increase / decrease with reference to the control reference wheel. More specifically, for example, in the case of a 1-channel type control device that simultaneously controls the braking pressures of all four wheels, a control reference wheel is selected from the wheel speed information for each wheel, and the control reference wheel is used as a reference,
The pressure increasing / decreasing control valves (braking control actuators) that control the braking pressures of all four wheels are driven (four-wheel low select control).

[0003]

However, in the above-described conventional anti-skid device, control is performed by four-wheel low select (in the case of four-wheel one-channel control type), so that stability during braking is reduced. Although excellent, it causes a problem that the braking force is reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an anti-skid device for an automobile capable of achieving both braking performance and stability. .

[0005]

In order to achieve the above object, the invention according to claim 1 is a braking control actuator for simultaneously controlling braking pressure for a plurality of brake wheel cylinders provided for each wheel. A wheel speed detecting means for detecting a wheel speed for each wheel, and a control reference wheel selecting means for selecting a wheel having the most locking tendency from the wheel speed information for each wheel by the wheel speed detecting means as a control reference wheel. A control reference wheel selected by the control reference wheel selection means is used as a reference, and a braking control means for operating the braking control actuator to obtain a desired braking pressure. When one of the wheels is locked, the wheel selecting means excludes the locked wheel from the selection target of the control reference wheel and determines whether the wheel speed information of the remaining wheels is used. It is summarized in that selecting control criteria wheel.

According to a second aspect of the invention, in the first aspect of the invention, when two wheels are locked, whether the locking occurs on the same side on the left or right side or on the different sides on the left and right sides of the vehicle body. When the lock occurs on the same side on the left and right of the vehicle body, the control reference wheel selection means selects a control reference wheel from the wheels on the side different from the lock generation side to lock the control reference wheel. Is generated on the left and right sides, the control reference wheel is selected from the wheels other than the first lock wheel.

According to a third aspect of the present invention, in the first or second aspect of the present invention, there is provided a traveling state discriminating means for discriminating whether or not the traveling state of the vehicle body is within a predetermined traveling load range. The control reference wheel selection means is configured to prohibit the lock wheel from being excluded from the selection targets of the control reference wheel when the traveling state of the vehicle body deviates from the traveling load range.

[0008]

According to the first aspect of the present invention, the control reference wheel selecting means selects the wheel having the most locking tendency from the wheel speed information for each wheel by the wheel speed detecting means as the control reference wheel. At this time, when any of the wheels is locked, the control reference wheel selecting means removes the locked wheel from the selection target of the control reference wheel and selects the control reference wheel from the wheel speed information of the remaining wheels. Then, the braking control means operates the braking control actuator to obtain a desired braking pressure with reference to the control reference wheel selected by the control reference wheel selection means.

In short, in the so-called low-select type anti-skid device that selects the wheel having the most locking tendency among the wheels whose braking pressures are simultaneously controlled as the control reference wheel, braking is performed so as to eliminate the locking tendency of the control reference wheel. It is controlled by reducing the pressure. However, once the control reference wheel is locked, the locked wheel is used as a control reference thereafter, which causes a problem that it is difficult to secure the braking force. On the other hand, according to the present configuration, by excluding the lock wheel from the selection target of the control reference wheel, a desired braking force is secured even in the low-select type. As a result, both the braking performance and the stability are realized by a simple method.

In this specification, "lock tendency"
Means that the wheel speed relatively decreases with respect to the vehicle body speed, and the greater the degree of decrease, the greater the locking tendency. Also, "lock" means
This means that the rotation of the wheels is stopped before the vehicle body is stopped during the brake operation (in this case, the wheel speed is almost 0, and the wheel speed is very close to “0”).

According to the second aspect of the present invention, the lock determining means determines, when the two wheels are locked, whether the lock is generated on the same side on the left and right sides or on the left and right sides of the vehicle body. To do. The control reference wheel selection means selects the control reference wheel from the wheels on the side different from the lock generation side when the lock occurs on the same side on the left and right sides of the vehicle body, and when the lock occurs on the left and right sides, Select a control reference wheel from the other wheels except the first lock wheel.

That is, when the wheels on the same side on the left and right sides of the vehicle body are continuously locked (for example, when the front right wheel and the right rear wheel are locked in this order), the vehicle body has left and right wheels with different μ (friction coefficient) road surfaces. It is assumed that the vehicle is traveling on a (crossing road) and that only the wheels on the low μ side are locked. In this case, by selecting the control reference wheel from the wheel on the side different from the lock generation side, that is, the wheel on the high μ side, the anti-skid control ensuring the braking performance is realized. In addition, when the lock occurs on the left and right sides (for example, when locking in the order of right front wheel → left rear wheel), the vehicle body is traveling uniformly on a low μ road surface and randomly (depending on load and tire condition etc.) ) It is assumed that a lock has occurred. In this case, highly stable anti-skid control is realized by selecting the control reference wheel from the wheels other than the first lock wheel.

According to the third aspect of the present invention, the traveling state determining means determines whether the traveling state of the vehicle body is within a predetermined traveling load range. At this time, the traveling state of the vehicle body is determined by, for example, one of the vehicle body speed, the longitudinal acceleration of the vehicle body, and the lateral acceleration of the vehicle body. The control reference wheel selection means is
When the traveling state of the vehicle body is out of the predetermined traveling load range, it is prohibited to exclude the lock wheel from the selection target of the control reference wheel.
That is, in the inventions described in claims 1 and 2, the braking pressure is controlled in the increasing direction when the wheels are locked. However, in the invention described in claim 3, when the traveling state of the vehicle body deviates from a predetermined traveling load range. In the above, it is important to release the wheel lock when the wheel is locked, and the braking pressure is controlled in the pressure reducing direction.
As a result, it is possible to secure the behavior with high stability of the vehicle body when the traveling load is large.

[0014]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a hydraulic circuit diagram showing an outline of an automobile antiskid device constituted by two hydraulic systems of X piping (diagonal piping). In the anti-skid device of FIG. 1, a brake booster 2 that boosts the depression force of the pedal 1 is connected to the brake pedal 1, and a tandem master cylinder 12 is connected to the brake booster 2. The brake booster 2 utilizes the pressure difference between the negative pressure of the intake manifold (intake negative pressure) generated in the engine 28 and the atmospheric pressure, and uses the brake pedal 1
Adjust the pressure difference with the depression of the master cylinder 12
The force applied to the piston (not shown) is increased.

More specifically, the brake booster 2 has a first power cylinder 4 and a second power cylinder 4 which are partitioned by a diaphragm 3.
The power cylinder 5 is formed. The intake negative pressure of the engine 28 is introduced into the first and second power cylinders 4 and 5 through the negative pressure ports 6 and 7, and the negative pressure level thereof is the electromagnetic 2-position control valve. The negative pressure control valve 1 and the second negative pressure control valve 9 are controlled according to the communication / cutoff operation. First and second negative pressure control valves 8, 9
Is controlled in position by the ECU 26,
When there is no input signal from (no coil excitation), the first negative pressure control valve 8 is held in the communicating position and the second negative pressure control valve 9 is held in the shut-off position (state shown in the figure).

Atmospheric pressure is introduced into the second power cylinder 5 through the atmospheric pressure port 10. At this time, the atmospheric pressure is adjusted by a pressure adjusting valve (not shown) according to the depression of the brake pedal 1 and is introduced into the second power cylinder 5. Therefore, the second power cylinder 5 is
A large pressure difference is generated with respect to the first power cylinder 4.
The opening / closing of the atmospheric pressure port 10 is controlled by an atmospheric pressure control valve 11 which is an electromagnetic two-position control valve. Atmospheric pressure control valve 11
Is held in the communication position when there is no input signal from the ECU 26 (when the coil is not excited) (state shown in the figure).

The master cylinder 12 is the first hydraulic port 1
3 and a second hydraulic pressure port 14, of which the first hydraulic pressure port 13 is connected to the right front (F
The wheel cylinder 17 for the (R) wheel and the wheel cylinder 18 for the left rear (RL) wheel are in communication. In addition, the second hydraulic port 14 is connected to the right rear (R
The wheel cylinder 19 for the (R) wheel and the wheel cylinder 20 for the left front (FL) wheel are in communication. Hydraulic piping 15,
A P valve (proportioning valve) 21 for generating a hydraulic pressure difference between the front wheels and the rear wheels is provided on the left and right rear (RL, RR) wheels of the vehicle 16.

Each wheel is provided with a wheel speed sensor 22, 23, 24, 25 for detecting the wheel speed of each wheel, and each sensor signal has an electronic control device (hereinafter referred to as EC
U) 26. These wheel speed sensors 2
As 2 to 25, an electromagnetic pickup type sensor or a photoelectric conversion type sensor is used. Further, the brake pedal 1 is provided with a brake switch 27 for detecting whether or not the pedal is depressed, and a detection signal thereof is input to the ECU 26.

The ECU 26 is mainly composed of a microcomputer, and calculates the estimated vehicle body speed based on the input signals from the wheel speed sensors 22 to 25. And E
The CU 26 determines the lock tendency of each wheel from the estimated vehicle body speed and the wheel speed, and also determines the anti-skid control mode of each wheel. At this time, the ECU 26 carries out the anti-skid control based on the control mode of the wheel showing the most locking tendency for all four wheels (four-wheel low select control). That is, the wheel having the most locking tendency becomes the control reference wheel. The ECU 26 determines that the wheel is locked when the rotation of the wheel is stopped before the vehicle body is stopped during the brake operation.

In this embodiment, the brake booster 2, the first and second negative pressure control valves 8 and 9, and the atmospheric pressure control valve 11 are used.
The master cylinder 12 constitutes a braking control actuator, and the wheel speed sensors 22 to 25 constitute wheel speed detecting means. Further, the ECU 26 constitutes a control reference wheel selection means, a braking control means, and a traveling state determination means.

The operation of the antiskid device in each antiskid control mode (pressure increasing mode, holding mode, pressure reducing mode) will be briefly described. First, in the pressure increase mode (state of FIG. 1), the ECU 26 determines that the first negative pressure control valve 8 is in the communicating position, the second negative pressure control valve 9 is in the shut-off position, and the atmospheric pressure control valve 11 is in the communicating position. Located in. Then the first
Intake negative pressure from the engine 28 acts on the power cylinder 4 and atmospheric pressure acts on the second power cylinder 5, and the brake booster 2 causes the brake pedal 1 to operate according to the pressure difference between the intake negative pressure and the atmospheric pressure. The force applied to the master cylinder 12 by the depression operation of is boosted. As a result, the hydraulic pressure generated by the master cylinder 12 rises, and the wheel cylinders 17 to 20 are pressurized.

In the holding mode, the ECU 26 positions the first negative pressure control valve 8 in the shutoff position, the second negative pressure control valve 9 in the shutoff position, and the atmospheric pressure control valve 11 in the shutoff position. Then, the intake negative pressure and the atmospheric pressure to the first and second power cylinders 4 and 5 are shut off, and the master cylinder 12
The braking pressures of the wheel cylinders 17 to 20 are held together with the hydraulic pressure generated at.

Further, in the depressurization mode, the ECU 26
The first negative pressure control valve 8 is in the shut-off position, and the second negative pressure control valve 9 is
To the communicating position and the atmospheric pressure control valve 11 to the shut-off position. Then, the first and second power cylinders 4 and 5 are communicated with each other, and the hydraulic pressure of the master cylinder 12 decreases. as a result,
The wheel cylinders 17 to 20 are depressurized.

Next, the unique operation and effect of this embodiment will be described with reference to FIGS. Here, FIG. 2 and FIG.
FIG. 4 is a flowchart showing an anti-skid control routine executed by the ECU 26, and FIGS. 4 and 5 are timing charts showing the behavior of the routine more specifically.

First, the outline of this operation will be briefly described. At the beginning (before all wheels are locked), the anti-skid control is executed based on the control mode of the wheel showing the most locking tendency among all the four wheels. (4 wheel low select control). Further, if any of the wheels locks regardless of the four-wheel low-selection control, the locked wheel is excluded from the selection target thereafter, and the control mode of the wheel showing the most locking tendency among the remaining wheels is used as a reference. Then, the anti-skid control is executed. At this time, the control method is switched according to the number of lock wheels, such as 4-wheel low select ⇔ 3-wheel low select ⇔ 2-wheel low select ⇔ 1-wheel select.

Next, an anti-skid control routine for realizing the above control will be described in detail with reference to FIGS. Now, when the same routine starts, EC
U26, first in step 100 of FIG. 2 to enter the wheel speed V _W obtained from the detection result of the wheel speed sensors 22-25. Then, the ECU 26 calculates the wheel acceleration G _W on the basis of the wheel speed V _W in step 101, and in the subsequent step 102, the estimated vehicle body speed V _SO and the estimated vehicle body acceleration G _W.
Calculate _SO and. Further, the ECU 26 executes step 103
Then, the slip ratio S is calculated for each wheel based on the estimated vehicle speed V _SO and the wheel speed V _W (S = (V _SO −V _W ) /
V _SO ). After that, the ECU 26 determines in step 104 whether or not the brake switch 27 is on, and if the switch = off, returns to step 100. If the switch is on, the ECU 26 proceeds to step 105 of FIG.

After that, the ECU 26 executes step 1 of FIG.
At 05, the control mode is determined for each wheel. At this time, E
The CU 26 determines the threshold value of the slip ratio S and the wheel acceleration G.
Using the mode determination map represented by the threshold value of _W (deceleration), one of the pressure increasing / holding / pressure reducing control modes is determined for each wheel.

Subsequently, the ECU 26 determines in step 106 whether or not the anti-skid control is being performed, and in the following step 107, the estimated vehicle body speed V _SO is equal to or lower than a predetermined determination value V _H (running load determination level). Or not. At this time, if either of steps 106 and 107 is NO, the ECU 26 proceeds to step 108 and uses the determination result of step 105 to control the wheel at that time based on the wheel having the most locking tendency among the four wheels. Determine the mode (4-wheel low select). Further, the ECU 26 turns off the _first to third timers T _{1 to} T ₃ in the following step 109.
Here, the first timer T ₁ indicates the lock duration of the first wheel,
The second timer T ₂ measures the lock duration of the second wheel, and the third timer T ₃ measures the lock duration of the third wheel.

On the other hand, steps 106 and 107 are both YE
If S, the ECU 26 proceeds to step 110, and thereafter, in steps 110 to 130, lock determination is performed for all four wheels, and various low selections are switched according to the number of locked wheels. That is, the ECU 26 determines in steps 110 to 113 how many of the four wheels are locked. In this case, if all four wheels are unlocked, steps 110 to 113 are all NO, and the ECU 26
In step 108, the control mode at that time is determined by four-wheel low select. Further, in the following step 109, the first to third timers T _{1 to} T ₃ are turned off.

When one of the four wheels is locked and step 113 becomes YES, the ECU 26 determines the control mode at that time by the three-wheel low select in steps 126 to 130. That is, the ECU 26 determines in step 126 whether or not the first timer T ₁ is “0”, and if T ₁ = 0, the first timer T _{1 in} step 127.
Turn on. In step 128, the ECU 26 determines whether or not the elapsed time of the first timer T ₁ is equal to or longer than the predetermined time T _D. If T ₁ ≧ T _D , the process proceeds to step 129, and the determination result of step 105 is obtained. Is used to determine the control mode at that time based on the wheel having the most locking tendency among the three wheels excluding the lock wheel (three-wheel low select). After that, the ECU 26 turns off the timers T ₂ and T ₃ in step 130.

The second wheel locks after the first wheel,
When step 112 becomes YES, the ECU 26 determines the control mode at that time by the two-wheel low select in steps 121 to 125. That is, the ECU 26 determines in step 121 whether or not the second timer T ₂ is “0”, and if T ₂ = 0, the second timer T ₂ is determined in step 122.
Turn ₂ on. The ECU 26 also executes step 123.
Elapsed time second timer T ₂ is determined whether a predetermined time T _D above in, if T ₂ ≧ T _D proceeds to step 124, using the determination result of step 105, except for locked wheel The control mode at that time is determined based on the wheel with the larger locking tendency of the two wheels (two-wheel low select). After that, the ECU 26 turns off the timer T _{3 in} step 125.

In addition, the third wheel is locked following the second wheel,
When step 111 becomes YES, the ECU 26 determines the control mode at that time by selecting one wheel in steps 117 to 120. That is, the ECU 26 executes step 1
At 17, it is determined whether or not the third timer T ₃ is "0",
If T ₃ = 0, the third timer T ₃ is turned on at step 118. Further, the ECU 26 makes a first determination in step 119.
It is determined whether the elapsed time of the timer T ₃ is a predetermined time T _D or more, and if T ₃ ≧ T _D , the process proceeds to step 120,
Using the determination result of step 105, the control mode at that time is determined on the basis of one wheel in the unlocked state (one wheel select).

Further, when all four wheels are locked and step 110 becomes YES, the ECU 26 determines that step 11
In step 4, it is determined whether or not the current road surface is an extremely low μ road (for example, an icy road), and in step 115, it is determined whether it is a bad road (for example, a gravel road). Where step 1
In 14, if the deceleration is smaller than the predetermined level, the μ is extremely low.
It is determined that the road is a road, and if the fluctuation of the wheel speed is larger than a predetermined level in step 115, the road is a bad road. In this case, if both steps 114 and 115 are NO, the ECU 26 sets the control mode to the pressure increasing mode so that the braking pressure is forcibly increased in step 116. That is, since the maximum braking force is exerted at the time of locking on an extremely low μ road or an extremely bad road, when the four wheels are locked by the extremely low μ road or the extremely bad road, the forced pressure increase is allowed.

After the control mode is determined as described above, E
The CU 26 proceeds to step 131 in FIG. 2, outputs a control signal according to the determined control mode, and then returns to step 100.

In the above routine, step 107 is NO when the vehicle body speed exceeds the predetermined level even if any wheel is locked and control other than the four-wheel low select control is executed. Immediately returned to 4-wheel low-select control. That is, in this case, switching such as 4-wheel low select ⇔ 3-wheel low select ⇔ 2-wheel low select ⇔ 1-wheel select is prohibited. This is because when the vehicle body travels at high speed, stable traveling is emphasized.

Next, the operation of the above routine will be described more specifically with reference to the timing charts of FIGS. Note that this chart is based on the assumption that the wheels are locked one by one (wheel speed = 0). In FIG. 4, the first one of the four wheels is locked at time t2, and It shows that the second wheel locks at t4, the third wheel locks at time t6, and the last fourth wheel locks at time t8. Lines ~ lines show speed changes of the first to fourth lock wheels.

Explaining FIG. 4 over time, the braking force is generated at time t1 by the depression operation of the brake pedal 1. At this time (before time t2), step 11 in FIG.
The determination results of 0 to 113 are all NO, and step 10
The control mode is determined based on the wheels indicated by the lines by the 4-wheel low select of 8.

After that, at the time t2 when the first wheel is locked, steps 110 to 112 in FIG. 3 are NO, step 1
13 becomes YES. Further, at the time t3 when the delay time T _D (for example, about 0.1 seconds) has elapsed, step 128 of FIG. 3 becomes YES, and in the following step 129, the four-wheel low-select control until then is switched to the three-wheel low-select control. To be In this case, of the three wheels excluding the lock wheel, the control mode is determined based on the wheel indicated by the line.

Further, at time t4 when the second wheel is locked, steps 110 and 111 in FIG.
12 becomes YES. Further, at the time t5 after the delay time T _{D has} elapsed, step 123 in FIG. 3 becomes YES, and in the following step 124, the three-wheel low-select control up to then is switched to the two-wheel low-select control. In this case, of the two wheels excluding the lock wheel, the control mode is determined based on the wheel indicated by the line.

Further, at time t6 when the third wheel is locked, step 110 in FIG. 3 is NO and step 111 is Y.
It becomes ES. Further, at the time t7 after the delay time T _{D has} elapsed, step 119 of FIG. 3 becomes YES, and in the following step 120, 1 is selected from the two-wheel low select control up to that point.
Switch to wheel select control. In this case, the control mode is determined based on the wheels shown by the unlocked line.

According to the above control, 4-wheel low select ⇒ 3
At each switching of wheel low select ⇒ two wheel low select ⇒ one wheel select (time t3, t5, t7), immediately before that, the braking force decreases as the speed of the low-selected wheel decreases, but After that, it can be seen that the braking force is again increased by performing the control based on the low-selected wheels excluding the lock wheels. Here, in the conventional control (indicated by a broken line) that does not perform the above switching, the reduced pressure state is maintained by the locking of the first wheel and the braking force remains reduced. I can know.

On the other hand, the operation when the first lock wheel is unlocked due to the road surface becoming a high μ road surface after switching from 4-wheel low-sect to 3-wheel low-select will be described with reference to the timing chart of FIG. explain.

That is, as in the case of FIG. 4, the time t of FIG.
After the first wheel (the wheel indicated by the line) is locked at 11, at time t12, switching from 4-wheel low select to 3-wheel low select is performed. After time t12, the anti-skid control is performed with the wheel (wheel indicated by the line) selected by the three-wheel low select as a reference.

Then, when the lock of the first wheel is released at time t13, the four-wheel low select control is resumed. After that, when the time t14 at which the wheels are locked again is reached, the delay time T _D elapses. At time t15,
Switching from 4-wheel low select to 3-wheel low select is performed again.

As described above, according to the routines of FIGS. 2 and 3, it is possible to easily reduce the number of wheels to be selected according to the number of lock wheels as described with reference to FIG. In addition, as described with reference to FIG. 5, the wheel to be selected can be easily returned when the lock wheel is unlocked.

The anti-skid device of this embodiment described in detail above can obtain the following effects. That is, in the low-select type anti-skid device that simultaneously controls a plurality of wheels as in the present embodiment, the braking pressure is controlled in a direction to eliminate the lock tendency, but the lock tendency is locked and the lock is not released. This causes a problem that it becomes difficult to secure the braking force. However, according to this configuration, when the lock occurs, the control is performed for the wheels other than the lock wheels, so that a desired braking force can be secured even in the low-select type in which a plurality of wheels are simultaneously controlled.

On the other hand, conventionally, for example, Japanese Patent Laid-Open No. 5-6
As shown in Japanese Patent Laid-Open No. 53-53, a selection map is prepared in advance that defines the correspondence relationship between the types of sequences in which the slip states of a plurality of wheels exceed the set state and the control reference wheels at that time, and the control reference is set according to the map. Some decide the ring,
In such a device, it is necessary to prepare a selection map in advance, and the map may become enormous with the expected traveling pattern. On the other hand, in the device of this embodiment, it is not necessary to prepare a special map,
It is possible to achieve both braking performance and stability by a simpler method.

Further, in this embodiment, it is judged from the vehicle speed whether or not the traveling state of the vehicle body is within a predetermined traveling load range (step 107 in FIG. 3), and the traveling state of the vehicle body deviates from the traveling load range. If (NO in step 107), switching from normal four-wheel low select control to other control is prohibited. That is, when the traveling state of the vehicle body deviates from the predetermined traveling load range, it is important to release the wheel lock when the wheels are locked, and the braking pressure is controlled in the pressure reducing direction. As a result, it is possible to ensure the stability of the vehicle body when the traveling load is large.

In step 107 of FIG. 3, the estimated vehicle body acceleration G _SO is changed so as to be compared with a predetermined traveling load determination level, or the lateral acceleration (lateral G) is compared with a predetermined traveling load determination level. You can also change it. In this case, when the vehicle body acceleration or the lateral G is large, the pressure increase due to the switching of the low select control is not performed, so that the wear of the tire and the like are also prevented.

(Second Embodiment) Next, an automobile anti-skid device according to a second embodiment will be described with a focus on differences from the first embodiment. FIG. 6 is a flowchart showing a part of the anti-skid control routine in the second embodiment, which is replaced by FIG. 3 in the first embodiment.

The difference from FIG. 3 will be briefly described. In FIG. 3, it is determined that one wheel to four wheels are locked and four wheel low select to one wheel select are appropriately switched. , In FIG. 6, the lock determination is limited to one wheel and two wheels,
It is designed to switch between 4 wheel low select and 2 wheel low select. That is, when the first wheel is locked, switching from 4-wheel low select to 3-wheel low select is performed as in FIG. Further, when the second wheel is locked, it is selected whether to switch from three-wheel low select to two-wheel low select or hold three-wheel low select depending on whether the lock wheels are on the same side or on the different side. Further, the third timer T ₃ that operates with the lock of the three wheels is omitted.

The antiskid control routine in the second embodiment will be described with reference to FIG. Now, the ECU 26
Determines the control mode for each wheel in step 200 of FIG. Further, the ECU 26 determines in step 201 whether or not the anti-skid control is being performed, and then in step 2
In 02, it is determined whether or not V _SO ≦ V _H. in this case,
If either of steps 201 and 202 is NO, E
The CU 26 proceeds to step 203, determines the control mode at that time by the four-wheel low select in step 203, and in the following step 204, the first and second timers T ₁ ,
Turn off T ₂ .

On the other hand, if both of the steps 201 and 202 are YES, the ECU 26 proceeds to step 205 and determines in step 205 whether or not the two wheels are locked, and in step 206 whether or not the one wheel is locked. . in this case,
If all four wheels are unlocked, the ECU 26 performs a four-wheel low select (steps 203 and 204), and if one of the four wheels is locked, a three-wheel low select (steps 212 to 216). Up to this point, the processing is almost the same as that in FIG. 3 of the first embodiment.

When the second wheel is locked, the ECU 2
In step 6, it is determined whether or not the two wheels locked in step 207 are on the same side on the left and right. In this case, step 20
If 7 is NO, the process directly proceeds to step 131 in FIG. 2 and the three-wheel low select till then is continuously executed. If YES in step 207, the ECU 2
In step 208 to 211, 6 performs two-wheel low select. Here, the process of step 207 corresponds to a lock determination means.

That is, when the wheels on the left and right sides of the vehicle body are continuously locked (when step 207 is YES),
It is assumed that the left and right wheels of the vehicle travel on different road surfaces (crossing roads) with different μ, and the two locked wheels are on the low μ side and the two unlocked wheels are on the high μ side. Therefore, in this case, it is preferable to perform the two-wheel low-select control on the two wheels on the high μ side. If the lock occurs on the left and right sides (NO in step 207), the vehicle body is traveling on a uniform low μ road and randomly (depending on the load or tire condition).
It is assumed that wheel locking has occurred. Therefore, in this case, it is preferable to perform the three-wheel low-selection control with the wheels other than the first lock wheel.

Next, the above processing will be described more specifically with reference to the timing charts of FIGS. Note that FIG.
Represents the case where the vehicle body is traveling on a crossroad, and FIG.
Indicates that the vehicle body is traveling on a uniform low μ road.

In FIG. 7, the low μ shown by the line at time t21.
The wheel on the side (for example, the right front wheel) is locked, and at time t22, the four-wheel low-select control up to then is switched to the three-wheel low-select control. Further, at time t23, the wheel on the low μ side indicated by the line (for example, the right rear wheel) is locked, and at time t24, the three-wheel low select control up to then is switched to the two-wheel low select control. In other words, when traveling on such a straddle road, the two wheels that remain unlocked have a high μ
Since the vehicle is running on the side, it is difficult to lock, and after time t24, the two-wheel low select control is continuously performed.

On the other hand, in FIG. 8, the wheel indicated by the line (for example, the right front wheel) is locked at time t31, and at time t32, the four-wheel low-select control up to then is switched to the three-wheel low-select control. At time t33, the wheel indicated by the line (for example, the left front wheel) locks, but the three-wheel low select control up to that point is continuously performed. That is, when traveling on such a low μ road, all the wheels are easily locked, so that the three-wheel low select control is continued even after the second wheel is locked. Further, at time t34, the lock of the first wheel is released, and the four-wheel low select control is performed again.

According to the anti-skid device of the second embodiment, the object of the present invention is to achieve both braking performance and stability by using a simple method, as in the first embodiment. Can be achieved. Further, particularly in the second embodiment, the running road surface state of the vehicle body is estimated from the order in which the wheels are locked, and the low select control is performed according to the estimated state. Therefore, the antiskid control is performed more appropriately and practically. be able to.

The present invention can be embodied in the following modes other than the above embodiment. (1) In each of the above-described embodiments, the control mode is determined for each wheel, and then the control mode to be actually used is determined based on the wheel having the most locking tendency. However, this method is changed. May be. For example, the control reference wheel may be directly selected from the wheel speeds of the four wheels, and the actual control mode may be determined from the wheel speeds of the control reference wheels.

(2) In each of the above embodiments, the one-channel control system of the braking pressure is constructed by controlling the pressure acting on the first and second power cylinders 4, 5 of the brake booster 2. You can change this. For example, a one-channel hydraulic control circuit may be configured on the downstream side of the master cylinder 12.

[0063]

According to the invention described in claim 1, the excellent effect that both the braking property and the stability can be achieved is exhibited.

According to the second aspect of the present invention, the control reference wheel can be selected according to the traveling road surface of the vehicle body assumed from the order in which the wheels are locked, and the antiskid control can be performed more properly. It can be carried out.

According to the third aspect of the present invention, when the traveling state of the vehicle body deviates from the predetermined traveling load range, it is important to release the wheel lock when the wheels are locked, and the behavior of the vehicle body with high stability is emphasized. Can be secured.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing a configuration of an automobile anti-skid device according to a first embodiment.

FIG. 2 is a flowchart showing an anti-skid control routine in the first embodiment.

FIG. 3 is a flowchart showing an anti-skid control routine subsequent to FIG.

FIG. 4 is a timing chart showing how the row select control is switched.

FIG. 5 is a timing chart showing how the row select control is switched.

FIG. 6 is a flowchart showing a part of an anti-skid control routine in the second embodiment.

FIG. 7 is a timing chart showing how low-select control is switched when the vehicle body is traveling on a straddle road.

FIG. 8 is a timing chart showing how the low select control is switched when the vehicle body is traveling on a uniform low μ road.

[Explanation of symbols]

2 ... Brake booster as braking control actuator, 8 ... First negative pressure control valve as braking control actuator, 9 ... Second negative pressure control valve as braking control actuator, 11 ... Atmospheric pressure control as braking control actuator Valves, 12 ... Master cylinders as braking control actuators, 17-20 ... Wheel cylinders, 22-25
A wheel speed sensor as a wheel speed detecting means, a control reference wheel selecting means, a braking control means, a lock determining means, and an ECU as a traveling state determining means.

Claims (3)

[Claims] 1. A braking control actuator for simultaneously controlling braking pressure for a plurality of brake wheel cylinders provided for each wheel, wheel speed detection means for detecting a wheel speed for each wheel, and the wheel speed detection. Based on the control reference wheel selected by the control reference wheel selection means and the control reference wheel selection means for selecting the wheel showing the most locking tendency from the wheel speed information for each wheel by the means as the control reference wheel, the desired reference wheel In an automobile anti-skid device including a braking control unit that operates the braking control actuator to obtain a braking pressure, the control reference wheel selecting unit controls the locked wheel when the wheel is locked. The anti-skid device for automobiles is characterized in that the control reference wheel is selected from the wheel speed information of the remaining wheels excluding the wheel selection target. . 2. When the two wheels are locked, lock control means is provided for determining whether the lock occurs on the same side on the left or right of the vehicle body or on the different sides on the left and right, and the control reference wheel selection means. When the lock occurs on the same side on the left and right of the vehicle body, the control reference wheel is selected from the wheels on the side different from the lock generation side, and when the lock occurs on the left and right sides, the first lock wheel is selected. The anti-skid device for automobiles according to claim 1, wherein the control reference wheel is selected from the other wheels. 3. A running state determination means for determining whether or not the running state of the vehicle body is within a predetermined running load range, wherein the control reference wheel selecting means has a running state of the vehicle body outside the running load range. The anti-skid device for automobiles according to claim 1 or 2, wherein, in the case of being locked, it is prohibited to exclude the lock wheel from the selection target of the control reference wheel.