JP2002012142A - Antiskid control method for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antiskid control method for a vehicle capable of surely coping with the case where a synchronous tendency of brake hydraulic control appears between right and left front wheels and at least one rear wheel to prevent synchronization. SOLUTION: The period from the start time of intensifying control in the antiskid control of brake fluid pressure of a left front wheel FL to the end of the intensifying control is taken as T1L, the time from the start time of intensifying control in the antiskid control of brake fluid pressure of a right front wheel FR to the end of intensifying control is taken as T1R, and the time when the period T1L and T1R overlap is taken as T1. When the period T1 is formed, intensifying control of brake fluid pressure of at least one rear wheel R in the period T1 is inhibited.

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 method for a vehicle that performs anti-skid control by controlling brake fluid pressure of wheels when braking the vehicle.
The present invention relates to an anti-skid control method for a vehicle in which a pressure increase control and a pressure reduction control of a brake fluid pressure are not synchronized between right and left front wheels and a rear wheel.

[0002]

2. Description of the Related Art In anti-skid control, all wheel braking systems (for example, three channels of a front left wheel braking system, a front right wheel braking system, and left and right rear wheel braking systems) increase or decrease brake fluid pressure synchronously. If this occurs, the vehicle body deceleration changes greatly, and the vehicle vibrates back and forth, giving the driver discomfort.

Further, when the anti-skid control is performed, the slip periods of the respective wheels are overlapped. At this time, when the pseudo vehicle speed calculated from the wheel speed is used to obtain the slip ratio of each wheel, particularly, On a low μ road surface, the pseudo vehicle speed is calculated as a value that is significantly lower than the actual vehicle speed. That is, the pseudo vehicle body speed is obtained by following the largest one among the wheel speeds of all the wheels (select high), but if all the wheels are slipping, the wheel speeds of all the wheels are low, and Even if the wheel speed is selected, the wheel speed is low, and therefore, the pseudo vehicle speed is also required to be significantly lower than the actual vehicle speed. The operation of reducing the brake fluid pressure is performed when the wheel speed falls by a certain threshold value or more with respect to the simulated vehicle speed. Therefore, it is usually performed that the simulated vehicle speed is lower than the actual vehicle speed. Since the decompression is performed after the wheel speed is further reduced, which is later than the time required for decompression, the state of slipping of the wheels becomes longer, the stability of the vehicle is not ensured, and in the worst case the wheels are locked It becomes impossible to control.

For example, in Japanese Patent Application Laid-Open No. 4-110263, in a four-wheeled vehicle, the braking force control phase of the left front wheel braking system and the right front wheel braking system shifts to the pressure increasing phase within a predetermined time T1, and both are in the pressure increasing phase. Even if the left and right rear wheel braking systems are ready to shift to the pressure increase phase,
2. Until one of the right front wheel and the left front wheel becomes a phase other than the pressure boosting phase, the shift to the pressure boosting phase of the left and right rear wheel braking system is prohibited, and the brake fluid for the left and right front wheels and the rear wheel is prohibited. The pressure control phase is prevented from synchronizing.

[0005]

SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 4-110 is disclosed.
In Japanese Patent Publication No. 263, the increase in the brake fluid pressure of the rear wheels is prohibited only when both the left and right front wheels shift to the pressure increasing phase within the predetermined time T1. This is because when the left front wheel and the right front wheel are shifted to the pressure increasing phase after a predetermined time T1 or more, that is, after a certain period of time, either the left front wheel or the right front wheel immediately shifts to another phase. This is because there is no inconvenience caused by the coincidence of the pressure increasing phases.

However, even if each of the wheels makes various movements according to the road surface condition and the like, and the other front wheel shifts to the pressure increasing phase after a lapse of a predetermined time T1 or more after one front wheel shifts to the pressure increasing phase. In some cases, the period in which both front wheels are in the pressure increasing phase may be long, and if the pressure increase of the rear wheel brake fluid pressure is permitted at this time, the pressure increasing phases of the respective wheels may all coincide. For example, after the left front wheel shifts to the pressure increasing phase on a low μ road, even if the right front wheel shifts to the pressure increasing phase after a predetermined time T1 or more, a slip that is not enough to reduce the pressure on the left front wheel occurs and the pressure increasing control is performed. Is interrupted and the holding period is lengthened, the period of the pressure increasing phase becomes longer by that amount, and the pressure increasing phases of the left and right front wheels coincide. In that case, in the above conventional example, the pressure increase prohibition process of the rear wheel brake fluid pressure is not performed. Further, when the predetermined time T1 is set to a large value, even when the phases of the pressure increase phases of the left and right front wheels are not synchronized, the brake fluid pressure increase prohibition processing of the rear wheels is performed, and the rear wheels exert braking force. There is a risk of shortage.
Therefore, in the case where the increase of the rear wheel brake hydraulic pressure is prohibited only at a certain limited time as in the above-described conventional example, a plurality of wheels that perform various movements in accordance with various conditions are provided. It is considered difficult to prevent the synchronization of the brake fluid pressure control and to avoid the insufficient braking force.

In Japanese Patent Application Laid-Open No. 62-146768, in order to prevent simultaneous locking between the left and right front wheels, the brake fluid pressure of one wheel is held for a set time ΔT just before the lock pressure. When shifting from a low μ road to a high μ road, one of the front wheels holds the hydraulic pressure near the lock pressure at the time of traveling on the low μ road, and the braking distance may be extended due to insufficient braking pressure on the high μ road surface. . Further, a yaw moment may be generated on a high μ road. Until the latter half of the pressure-increasing phase immediately before the wheel lock, at which the brake fluid pressure of one of the wheels starts to be held, the two wheels are synchronously increasing the brake fluid pressure. The decline is inevitable, and the unstable state of the vehicle will continue.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to reliably cope with a case where a synchronization tendency of brake fluid pressure control appears between the left and right front wheels and at least one of the rear wheels to prevent synchronization. It is an object of the present invention to provide an anti-skid control method for a vehicle that can perform the control.

[0009]

In order to solve the above problems, according to the first aspect of the present invention, the pressure increase control of the brake fluid pressure of the left front wheel is terminated from the start of the pressure increase control in the anti-skid control. T1L, the period from the start of the pressure increase control in the anti-skid control of the brake fluid pressure of the right front wheel to the end of the pressure increase control is T1R, and the period T1L overlaps with the period T1R. Is defined as T1, and when the period T1 is formed, the increase in the brake fluid pressure of at least one rear wheel during the period T1 is prohibited.

According to a third aspect of the present invention, the brake fluid pressure of the front left wheel reaches a second predetermined ratio with respect to a lock pressure of the wheel after the pressure increase control in the anti-skid control is started. T2L is the period up to the point
The period from the time when the brake fluid pressure of the right front wheel reaches the first predetermined ratio to the lock pressure of the wheel after the start of the pressure increase control in the anti-skid control to the time when it reaches the second predetermined ratio is T2R, These periods T2L and T2
A period in which R overlaps is defined as T2, and when the period T2 is formed, an increase in brake fluid pressure of at least one rear wheel during the period T2 is prohibited.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 shows a brake piping system of a vehicle according to the present embodiment.

Two hydraulic pressure generating chambers are defined in the cylinder body 3 of the master cylinder 1, and when the brake pedal 4 is depressed, hydraulic pressure is generated in these chambers. This hydraulic pressure is supplied to the left front wheel F via the line 5a and the supply valve 17a (electromagnetic switching valve).
L is supplied to the wheel cylinder of the right front wheel FR via a pipe 6a branched from the pipe 5a and a supply valve 20a (an electromagnetic switching valve), and is supplied to the pipe 5b and a supply valve 17b (an electromagnetic switching valve). ) Through the left and right rear wheels RL, R
R is supplied to each wheel cylinder.

The wheel cylinders of the left and right front wheels FL and FR are respectively provided with discharge valves 23a and 24a (electromagnetic switching valves).
Are connected to the slack duct 8a through the left and right rear wheels RL and RR.
Each wheel cylinder is connected to the slack pipe 8b via a discharge valve 23b (electromagnetic switching valve). Relaxing pipeline 8
a, 8b are connected to low pressure reservoirs 25a, 25b, respectively. The low-pressure reservoirs 25a and 25b have a known structure, and a piston urged by a relatively weak spring is slidably fitted in the casing. The brake fluid storage chamber is located on the suction side of the hydraulic pump 10. It is connected to the.

The hydraulic pump 10 is constructed in a known manner,
It comprises a motor 11, an eccentric mechanism 12, and check valves 15a, 15b and 13a, 13b. When the pair of plungers reciprocate in opposite directions, the check valves 13a,
3b is opened to supply the pressurized liquid to the pipelines 5a and 5b.

Each of the wheels FL, FR, RL, RR is provided with a wheel speed sensor (not shown). When the vehicle is running, the rotation speed of these wheels is detected. Supply. The control unit evaluates the skid state of these wheels and evaluates the above-mentioned electromagnetic switching valves 17a, 17b, 20
a, 23a, 23b and 24a are selectively excited.

The brake pipe according to the present embodiment is configured as described above. Next, this operation will be described. For simplicity of explanation, it is assumed that all four wheels are in the same skid state.

When the brake pedal 4 is depressed, the hydraulic fluid from the master cylinder 1 is supplied to the pipelines 5a, 5b, the supply valves 17a,
The brakes are supplied to the wheel cylinders of the wheels FL, FR, RL and RR through 0a and 17b and brakes are applied. When the control unit determines that the brake fluid pressure should be maintained, the solenoids of the supply valves 17a, 20a, 17b are energized and switch to the shut-off position. This allows
The pressure fluid is confined in the wheel cylinder of each wheel, and the braking force is kept constant. When it is determined that the brake fluid pressure should be released, the supply valves 17a, 20a, 17b
And the solenoids of the discharge valves 23a, 24a, 23b are excited, and the pressure fluid in the wheel cylinders of each wheel is discharged to the discharge valve 2
The brakes are released through the low pressure reservoirs 25a and 25b through 3a, 24a and 23b and the pipelines 8a and 8b.

When the control unit determines that refilling should be performed, in the present embodiment, the discharge valves 23a,
The solenoids 24a and 23b are not excited, and intermittently excite the solenoids of the supply valves 17a, 20a and 17b. Thereby, the hydraulic pressure of the wheel cylinder of each wheel rises stepwise.

In this embodiment, the left and right front wheels FL,
The brake fluid pressure of the FR is independently controlled, and the brake fluid pressure of the left and right rear wheels RL and RR is a three-channel control in which the brake fluid pressure is commonly controlled.

Next, details of the anti-skid control operation according to the present embodiment will be described.

When the driver depresses the brake pedal 4 at time t in FIG. 1 while the vehicle is traveling on a low μ road surface, the left front wheel FL, the right front wheel FR, and the commonly controlled left and right rear wheels RL, R
The hydraulic pressures of the wheel cylinders of R (hereinafter collectively referred to as rear wheels R) increase, and the wheel speed VFL of the front left wheel, the wheel speed VFR of the front right wheel, the wheel speed VR of the rear wheel R, and the pseudo vehicle speed V
Decrease as shown. The pseudo vehicle speed V is calculated by following the largest wheel speed (select high).

Then, the slip ratio of each wheel obtained based on the pseudo vehicle speed V and each wheel speed VFL, VFR, VR reaches the slip ratio threshold value,
If this is exceeded, the brake fluid pressure of each wheel (the fluid pressure of the wheel cylinder) is reduced.

When each wheel turns from deceleration to acceleration by this pressure reduction and the wheel speeds VFL, VFR, VR start to recover, the brake fluid pressure is kept constant.

When the wheel speeds VFL, VFR, VR of each wheel recover to near the pseudo vehicle speed V, the brake fluid pressure is increased again. At this time, the brake fluid pressures of the left and right front wheels FL and FR are controlled to increase according to the respective wheel speeds.
The pressure increase of the rear wheel R brake fluid pressure is controlled according to the flowchart shown in FIG.

When the control unit determines that the wheel speed of the rear wheel R has recovered and the pressure of the brake fluid should be increased, it is determined in step S1 whether the rear wheel R has been in the second control cycle or later in the anti-skid control. A determination is made as to whether or not it is. Assuming that the control of the rear wheels is the first control cycle, the determination in step S1 becomes No, and the timer counted during the pressure increase of the left and right front wheels FL and FR is cleared in the processing block B1, and the processing block In B2, normal control, that is, hydraulic control (pressure reduction, holding or pressure increase control) according to the wheel speed of the rear wheel R is performed. In addition,
One control cycle during the anti-skid control is from the start of pressure reduction to the end of pressure increase (at the start of the next pressure reduction).

According to the determination in step S1, the increase in the brake fluid pressure of the rear wheels R is not prohibited in the first control cycle. This is because the pseudo vehicle speed formed in the first control cycle is unstable. Therefore, the slip state of the wheel determined based on the pseudo vehicle body speed and the control of the wheel brake hydraulic pressure performed accordingly become unstable, and in this state, the brake hydraulic pressure of the rear wheel R is increased. This is because if prohibited, the braking force may be insufficient.

Also, during braking, the influence of the rear wheel braking force on the braking of the vehicle is smaller than the braking force of the front wheels due to the movement of the load to the front wheels, but the initial force before the load movement still occurs. During the braking (first control cycle), the braking force of the rear wheels plays a large role in braking the vehicle. Therefore, at this time, if the increase of the rear wheel brake fluid pressure is prohibited, the braking force becomes insufficient. Therefore, by the determination in step S1, the increase in the brake fluid pressure is prohibited only for the rear wheels R after the second control cycle.

Next, in step S2, it is determined whether or not the vehicle deceleration calculated from the pseudo vehicle speed is less than a predetermined value. Here, μ of the road surface is determined. The vehicle deceleration serving as a reference for determination is, for example, 0.4 g. When the vehicle deceleration is less than 0.4 g, it is determined that the vehicle is traveling on a low μ road surface. That is, according to the determination in step S2, the increase in the brake fluid pressure of the rear wheel R is prohibited only when traveling on a low μ road surface. On a high μ road surface, the wheel slip is small, and even if the slip of each wheel has the same phase, the decrease in the pseudo vehicle speed with respect to the actual vehicle speed is small, so that it is not necessary to prohibit the increase in the rear wheel brake fluid pressure. Also, if the increase in the rear wheel brake fluid pressure is prohibited even though a large deceleration is obtained on a high μ road surface, the deceleration is reduced and the braking efficiency is deteriorated. Therefore, in the present embodiment, the brake fluid pressure of the rear wheel R is prohibited from increasing only on the low μ road surface to prevent the synchronization of the slip of each wheel.

When the pseudo vehicle speed is calculated in an unstable state at the initial stage of control while traveling on a high μ road surface, the vehicle deceleration at the initial stage of the control (first control cycle) may be calculated to be low. is there. That is, there is a possibility that the condition is satisfied in step S2 despite the high μ road surface and the determination of Yes is made, and the increase of the rear wheel brake fluid pressure is prohibited, but the second control cycle has already been performed in step S1. In the first control cycle, the increase in the rear wheel brake fluid pressure is not prohibited, and therefore the braking force is not limited. There is no shortage.

Next, in step S3, it is determined whether or not the left front wheel FL is in the pressure increasing mode. If the determination is Yes, the FL wheel timer is counted up in processing block B3. If not in the pressure increase mode, the FL wheel timer is cleared in processing block B4.

Next, in step S4, it is determined whether or not the right front wheel FR is in the pressure increase mode. If the determination is Yes, the FR wheel timer is counted up in a processing block B5. If not in the pressure increase mode, the FR wheel timer is cleared in processing block B6.

Then, in step S5, it is determined whether both the FL wheel timer and the FR wheel timer are not 0, that is, whether both the FL wheel and the FR wheel are increasing the pressure. That is, in FIG. 1, assuming that a period of the left front wheel FL in the pressure increasing mode is T1L and a period of the right front wheel FR in the pressure increasing mode is T1R, whether or not a period T1 in which these periods T1L and T1R overlap is formed. Is determined.

Here, if the determination is Yes, the process proceeds to step S6. In step S6, it is determined whether both the FL wheel timer and the FR wheel timer are within a predetermined value. That is, it is determined whether or not a time limit (for example, 500 ms) has elapsed from the start of the pressure increase control for each of the left and right front wheels FL and FR. If the time limit has elapsed before the pressure increase control ends, the periods T1L and T1R are set to the time limit. Time (500m
s). Therefore, the period T1 in which these periods T1L and T1R overlap is also limited.

In the processing block B7, when the period T1 is formed, even if the brake fluid pressure of the rear wheel R should be increased during this period, the increase is prohibited. That is, during the period T1, the rear wheel R is maintained at the brake fluid pressure P1 at the start of the period T1, and if the period T1 ends and the pressure should be increased, the pressure increase control is performed from the end point. .

This makes it possible to widely cope with a case where the wheels tend to be synchronized, without being limited to certain conditions.

Next, a second embodiment of the present invention will be described with reference to FIGS. The brake pipe system has the same configuration as that of the first embodiment, and the brake fluid pressures of the left and right front wheels FL and FR are independently controlled, and the brake fluid pressures of the left and right rear wheels RL and RR are commonly controlled. 3 channel control.

In the present embodiment, the brake fluid pressure is increased again in the anti-skid control by a sudden increase and a subsequent gentle increase. FIG. 4 shows a brake fluid pressure increase mode on a low μ road surface, and a period t ′ is a rapid pressure increase period,
For example, three pressure increases are performed stepwise. Thereafter, the pressure is gradually increased in a stepwise manner with a longer holding period than during the rapid pressure increase.

When the control unit determines that the pressure of the brake fluid for the rear wheel R has to be increased, in the flowchart of FIG. 3, first, in step S11, the rear wheel R is in the second and subsequent control cycles in the anti-skid control. Is determined. If the determination here is No, a timer described later is cleared in processing block B11, and normal control, that is, hydraulic control according to the wheel speed of the rear wheel R is performed in processing block B12. By the determination in step S11, as in the first embodiment,
In the first control cycle, the increase in the brake fluid pressure of the rear wheel R is not prohibited.

Next, in step S12, it is determined whether or not the vehicle body deceleration calculated from the pseudo vehicle body speed is less than a predetermined value, thereby determining μ on the road surface. Based on the determination in step S12, the brake fluid pressure increase of the rear wheels R is prohibited only when the vehicle is traveling on a low μ road surface, as in the first embodiment.

Next, in step S13, the left front wheel F
If the rapid pressure increase of L is completed, the process proceeds to the next step S14, where it is determined whether or not the number of times of the stepwise gentle pressure increase in the left front wheel FL is within a predetermined value. The FL wheel timer is counted up. That is, if the answer is Yes in steps S13 and S14, the FL wheel timer is counted up from the end of the rapid pressure increase. If No at step S13 or S14, FL is reached at processing block B14.
The wheel timer is cleared.

Next, at step S15, the right front wheel F
If the rapid pressure increase of R is completed, the process proceeds to step S16, where it is determined whether or not the number of times of the step-like gentle pressure increase in the right front wheel FR is within a predetermined value. The timer counts up. That is, in steps S15 and S16, Ye
When s is reached, the FR wheel timer is counted up from the end of the rapid pressure increase. Step S15 or Step S
If No at 16 the FR wheel timer is cleared at processing block B16.

In step S17, both the FL wheel timer and the FR wheel timer are not 0, and
It is determined whether both the wheel and the FR wheel are slowly increasing the pressure and before the predetermined number of pressure increases. That is, FIG.
, The second time during the slow pressure increase from the end point of the rapid pressure increase at which the brake fluid pressure of the left front wheel FL reaches the first predetermined rate to the lock pressure (start time of the slow pressure increase), T2L is the period up to the time when the pressure increase is performed (including the start time and end time of the second pressure increase).
The end point of the rapid pressure increase in which the brake fluid pressure of the right front wheel FR reaches the first predetermined ratio with respect to the lock pressure (the time point of the start of the gentle pressure increase)
From the above, assuming that the period up to the point of time when the second pressure increase is performed during the gradual pressure increase reaching the second predetermined ratio is T2R, it is determined whether or not a period T2 in which these periods T2L and T2R overlap is formed. A decision is made. Note that the lock pressure here is the wheel cylinder pressure before the pressure reduction is performed before the brake pressure is reduced.

If the answer is "Yes" here, step S
Proceed to 18. In step S18, it is determined whether both the FL wheel timer and the FR wheel timer are within a predetermined value. That is, it is determined whether a time limit (for example, 500 ms) has elapsed from the time when each of the left and right front wheels FL and FR has reached the first predetermined ratio (when the rapid pressure increase ends), and before the second predetermined ratio has been reached. When the time limit elapses, the periods T2L and T2R are set to the time limit (500
ms). Therefore, these periods T2L, T2R
Are also limited.

In the processing block B17, when the period T2 is formed, even if the brake fluid pressure of the rear wheel R should be increased during this period, the increase is prohibited. That is, during the period T2, the rear wheel R is maintained at the brake fluid pressure immediately before the start of the period T2, and if the period T2 ends and the pressure should be increased, the pressure increase control is performed from the end point.

In this embodiment, the period T2 during which the increase of the rear wheel brake fluid pressure is prohibited is limited as compared with the first embodiment, so that the brake fluid pressure is held for an unnecessarily long time. It does not cause braking force shortage.

In the first and second embodiments, the time limit (for example, 500 ms) is set for the periods T1L, T1R, T2L, and T2R, so that the increase in the rear wheel brake fluid pressure should be prohibited. Without unnecessarily lengthening the periods T1 and T2, the shortage of the braking force does not occur.

This is because, for example, the condition that the vehicle body deceleration is less than a predetermined value may be satisfied on a downhill on a middle μ road surface, and all other conditions are satisfied, and the rear wheels are driven downhill on a middle μ road surface. If the increase of the brake fluid pressure is prohibited, the braking force may be insufficient and the braking distance may be extended. Further, when a small wheel slip which is not enough to reduce the pressure during the brake fluid pressure increase of the front wheels occurs and the holding time in the stepwise pressure increase is lengthened, the periods T1L, T1R, T2L, T
There is a possibility that the end point of the 2R is extended, so that the periods T1 and T2 are lengthened and the braking force becomes insufficient. Since it is more important to stop the vehicle than the instability of the vehicle due to the synchronization of the brake fluid pressure control mode of each wheel, as described above, do not prohibit pressure increase beyond the time limit. I have.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited to these embodiments.
Various modifications are possible based on the technical idea of the present invention.

In the above embodiment, the brake pipe is connected as shown in FIG.
As shown in the above, three-channel control is performed with the H pipe, but X pipe may be used, or four-channel control in which all four wheels are independently controlled may be used. In the case of the four-channel control, the pressure increase of at least one of the rear wheels is prohibited during the periods T1 and T2.

In the above embodiment, the periods T1 and T1
The brake fluid pressure of the rear wheel immediately before the step 2 is a holding mode after the pressure reduction mode. If the pressure increase mode is set, the pressure increase inhibition processing is not performed. This is because when the brake fluid pressure of the rear wheels is in the pressure increasing mode at the start of the periods T1 and T2, a phase difference in the pressure increasing mode has already occurred between the front and rear wheels. Alternatively, if the brake fluid pressure of the rear wheels is in the pressure increasing mode before the start of the periods T1 and T2, the hydraulic pressure at this time is set at the start of the periods T1 and T2 during the periods T1 and T2. May be held, and if the pressure should be increased at the end of the periods T1 and T2, the pressure increase may be restarted from the end.

Steps S2 and S2 in FIGS.
The determination in step 12 may be unnecessary and applied to a high μ road surface.

The first predetermined ratio and the second predetermined ratio in the second embodiment are based on road surface conditions (for example, low μ road, high μ road, bad road, right and left μ split road, etc.), vehicle conditions (for example, It is variable according to the magnitude of the vehicle deceleration, the magnitude of the wheel deceleration, the straight running, the turning, etc.) and the vehicle specifications (eg, the magnitude of the inertia of the wheels). In the second embodiment, the low μ road surface is used. Or a high μ road surface. As described above, by changing the first predetermined ratio and / or the second predetermined ratio in accordance with various situations, it is possible to appropriately prohibit the control of increasing the rear wheel brake pressure and shorten the braking distance. It is possible to secure the stability of the vehicle and not to give the driver any discomfort.

Also, instead of using the pseudo vehicle speed obtained based on the wheel speed in the calculation of the slip ratio, for example, using the vehicle speed obtained by a Doppler sensor for directly detecting the ground speed, the synchronization of the wheel cycle is used. For the purpose of preventing the fluctuation of the vehicle body deceleration, the determination in steps S1 and S11 may be omitted, and the increase in the brake fluid pressure of the rear wheels may be prohibited in the first control cycle.

In the second embodiment, whether or not the first predetermined ratio and the second predetermined ratio have been reached is determined by the number of stepwise pressure increases. The pressure gain may be obtained by multiplying the pressure gain by the pressure increase time.
Alternatively, the voltage for exciting the solenoid of the supply electromagnetic switching valve may be pulse-modulated, or the current for exciting the solenoid may be controlled to increase the pressure continuously instead of the stepwise pressure increase.

[0056]

As described above, according to the present invention, it is possible to always cope with a case where the displacement of the brake fluid pressure of all the wheels tends to be synchronous, without being limited to a certain condition, and therefore various changes can be made. Even in a four-wheeled vehicle having a plurality of wheels, it is possible to calculate a stable pseudo vehicle speed, and furthermore, the brake fluid pressure can be increased or decreased all at once during a certain time. The deceleration fluctuation of the vehicle can be suppressed so as not to be performed.

[Brief description of the drawings]

FIG. 1 is a time chart of an anti-skid control operation according to an embodiment of the present invention.

FIG. 2 is a flowchart of control for increasing the brake fluid pressure of the rear wheels according to the first embodiment of the present invention.

FIG. 3 is a flowchart of control for increasing the brake fluid pressure of a rear wheel according to a second embodiment of the present invention.

FIG. 4 shows a second embodiment of the present invention, in which the brake hydraulic pressures of the left and right front wheels are increased, and a period T for this mode.
2 is a time chart showing a pressure increasing mode of a rear wheel in which the pressure increase during the period 2 is prohibited.

FIG. 5 is a brake piping diagram of a four-wheeled vehicle according to the embodiment of the present invention.

[Explanation of symbols]

FL Left front wheel FR Right front wheel RL Left rear wheel RR Right rear wheel V Pseudo vehicle speed VFL Left front wheel speed VFR Right front wheel speed VR Rear wheel speed t 'Rapid pressure increase period T1 Overlap period of period T1L and T1R ( T2 period T2L and T2R overlap period (prohibition period of rear wheel brake fluid pressure increase)

Claims (9)

[Claims] 1. An anti-skid control method for a vehicle, wherein brake fluid pressures of left and right front wheels are controlled independently and brake fluid pressures of left and right rear wheels are controlled independently or commonly, respectively. The period from the start of the pressure increase control in the anti-skid control to the end of the pressure increase control is defined as T1L, and the pressure increase control of the brake fluid pressure of the right front wheel ends from the start of the pressure increase control in the anti-skid control. T1R, a period in which the periods T1L and T1R overlap with each other is T1, and when the period T1 is formed, an increase in the brake fluid pressure of at least one rear wheel during the period T1 is prohibited. An anti-skid control method for a vehicle, comprising: 2. A time limit from the start of the pressure increase control is set in each of the periods T1L and T1R, and when the time limit elapses before each pressure increase control of the left and right front wheels ends, 2. The anti-skid control method for a vehicle according to claim 1, wherein time periods T1L and T1R are the time limits. 3. An anti-skid control method for a vehicle in which the left and right front wheel brake fluid pressures are controlled independently and the left and right rear wheel brake fluid pressures are controlled independently or commonly, respectively. The period from the time when the first predetermined ratio to the lock pressure of the relevant wheel reaches the second predetermined ratio to the time when the second predetermined ratio is reached after the start of the pressure increase control in the anti-skid control is defined as T2L. A period from the time when the first predetermined ratio to the lock pressure of the wheel reaches the second predetermined ratio to the second predetermined ratio after the start of the pressure increase control in the skid control is defined as T2R, and the overlapping period of the periods T2L and T2R is defined as T2R. When the period T2 is formed, an increase in the brake fluid pressure of at least one rear wheel during the period T2 is prohibited. Kid control method. 4. The first predetermined ratio and / or the second predetermined ratio.
4. The anti-skid control method for a vehicle according to claim 3, wherein the predetermined ratio is variable. 5. The pressure increase control of each of the brake fluid pressures of the left and right front wheels is performed in a stepwise manner by a rapid pressure increase and a subsequent gentle pressure increase.
The time point when the first predetermined ratio is reached is the end point of the rapid pressure increase, and the time point when the second predetermined ratio is reached is when a predetermined number of stepwise pressure increases are performed. The vehicle anti-skid control method according to claim 3 or 4. 6. A time limit from when the first predetermined ratio is reached is set for each of the periods T2L and T2R,
4. The period T2L, T2R is the time limit if the time limit elapses before each of the brake fluid pressures of the left and right front wheels reaches the second predetermined ratio. Item 6. An anti-skid control method for a vehicle according to any one of Items 5. 7. Even if the period T1 or T2 is formed,
7. The anti-skid control for a vehicle according to claim 1, wherein when the first control cycle of the anti-skid control is in progress, the pressure increase control of the brake fluid pressure of the rear wheel is permitted. Method. 8. Even when the period T1 or T2 is formed,
2. The control system according to claim 1, wherein when the vehicle body deceleration is equal to or greater than a predetermined value, pressure increase control of the brake fluid pressure of the rear wheels is permitted.
An anti-skid control method for a vehicle according to claim 7. 9. At the start of the period T1 or T2, if the brake fluid pressure of the rear wheel is under pressure increase control in anti-skid control, the brake fluid pressure of the rear wheel during the period T1 or T2 is increased. The anti-skid control method for a vehicle according to any one of claims 1 to 7, wherein pressure control is permitted.