JPH026256A - Method for controlling anti-lock brake of vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A0 Object of the Invention (1) Industrial Application Field The present invention relates to an anti-lock brake control method for a vehicle that independently controls the braking oil pressure of left and right wheel brakes based on the corresponding wheel speeds. Regarding.

(2) Prior Art Conventionally, such an anti-lock brake control method is known, for example, from Japanese Patent Laid-Open No. 60-38239.

(3) Problems to be Solved by the Invention However, in the conventional system described above, the left and right wheel brakes are controlled individually, so if the friction coefficients of the road surface that the left and right wheels contact are different, anti-lock brake control is required. Sometimes, the braking force on the side with a higher friction coefficient is high, and the braking force on the side with a lower friction coefficient is low, creating a rotational moment on the vehicle body.In this case, if the generation of the rotational moment is gradual, the driving This makes it easier for the operator to make steering corrections.

The present invention has been made in view of the above circumstances, and it alleviates the sudden generation of rotational moment during anti-lock brake control when the friction coefficients of the road surface that the left and right wheels contact are different, thereby facilitating the driver's steering correction. An object of the present invention is to provide a method for controlling anti-lock brakes for a vehicle.

B1 Structure of the Invention (1) Means for Solving the Problem The invention described in claim (1) provides a method for controlling the braking oil pressure of at least one of the wheel brakes until a set time elapses from the start of the anti-lock control of the braking oil pressure of at least one of the wheel brakes. , the braking oil pressure of both wheel brakes is controlled based on the lower of both wheel speeds.

Further, the invention described in claim No. (2) is based on the invention described in claim No.
The invention described in item (2) is characterized in that the setting time is increased as the vehicle speed increases above a certain vehicle speed.

Further, the invention as set forth in claim (3) provides a method for reducing the braking oil pressure of at least one of the wheel brakes by a first time.
It is characterized by controlling the braking oil pressure of both wheel brakes based on the lower of both wheel speeds from when the first set time has elapsed until the second set time has elapsed when the set time has lasted longer than the set time. The invention as set forth in claim (4) provides that, when the time to reduce the brake hydraulic pressure of at least one of the front wheel brakes lasts for a first set time or more, the second set time is applied after the first set time has elapsed. Until the set time elapses,
The invention as set forth in claim (5) is characterized in that the braking oil pressure of both rear wheel brakes is controlled based on the lower of both rear wheel speeds, the first set time is such that the brake pressure of both rear wheel brakes is controlled based on the lower of both rear wheel speeds. Particularly, the invention as set forth in claim (6) is characterized in that the distance is shortened as the vehicle speed increases.
The set time is lengthened as the vehicle speed increases above a certain vehicle speed.

(2) Effect According to the invention described in the above claim (11), when at least one of both wheel brakes starts anti-lock brake control, both wheel brakes are collectively low-selected, so that the left and right wheels are free from friction. When antilock brake control is started while driving on road surfaces with different coefficients, the braking oil pressure of both wheel brakes is kept the same for a set time, thereby suppressing the generation of rotational moment.

According to the invention described in claim (2), the set time is changed in accordance with the vehicle speed, thereby making it possible to perform control in accordance with the vehicle speed.

Further, according to the invention described in claim (3), the braking hydraulic pressure of both wheel brakes on the road surface side, which has a lower coefficient of friction, is first reduced.
By continuing for a set period of time, both wheel brakes are controlled at once to low select, so when the friction coefficients of the road surface of the left and right wheels become different in the anti-lock brake control state, the braking hydraulic pressure of both wheel brakes is set to low select control. By making the two set times the same, the generation of rotational moment can be suppressed to a small level.

According to the invention described in claim (4), when the brake hydraulic pressure reduction of at least one front wheel brake continues for a first set time, both rear wheel brakes are collectively low-selected for a second set time. , when the friction coefficients of the road surfaces that the left and right wheels touch become different under anti-lock brake control, it is determined that the front wheels have entered a road surface with a lower friction coefficient, and both rear wheels approach the same road surface. sometimes,
Since the braking oil pressure on the rear wheel side is already the same, the generation of rotational moment can be suppressed to a small level.

Furthermore, according to the invention described in claims (5) and (6), the first and second set times are changed in accordance with the vehicle speed, thereby making it possible to perform control in accordance with the vehicle speed.

(3) Examples Examples of the present invention will be explained below with reference to the drawings.
First, in FIGS. 1, 2, and 3 showing an embodiment of the invention as set forth in claim (1), both the left and right wheels, for example, the left and right front wheels, have their wheel speeds VWL+
wheel speed detectors IL, 1M for individually detecting the
Wheel brakes 2L and 2+t are individually mounted. In addition, a hydraulic control circuit 3゜3e corresponding to each wheel brake 2L, 2R individually receives control signals from anti-lock brake control circuits 4L, 48 to control each wheel brake 2L.
.

Controls the 2R brake oil pressure. Furthermore, a wheel speed signal is input from the switching circuit 6 to the anti-lock brake control circuits 4c, 4*. This switching circuit 6 is
Wheel speed detected by both wheel speed detectors IL and IK ■.

Anti-lock brake control circuit 4L corresponding to L, ■□
, the switching mode individually input to 4R, and the wheel speed selected by the low select circuit 5. The switching mode of inputting the anti-lock brake control circuits 4L and 4R to the anti-lock brake control circuits 4L and 4R is changed by a switching control signal from the switching control circuit 7.

The switching circuit 6 has a first input contact 6. connected to the left wheel speed detector IL. and right wheel speed detection”
a second input end contact 6b connected to J'jr I R;
A third input end contact 6c connected to the low select circuit 5 and a first input end contact 6c connected to the anti-lock brake control circuit 4L.
Output side contact 6. and anti-lock brake control circuit 4R
The second output side contact connected to 6. Equipped with. When the control signal from the switching control circuit 7 is at a high level, the switching circuit 6 connects to the third input end contact 6c.
When the control signal from the switching control circuit 7 is at a low level, the first input terminal contact 6
．． This is a switching mode in which the first output contact 6d is electrically connected and the second input end contact 6b is electrically electrically connected to the second output contact 6°.

A both wheel speed detector 1LIR is connected to the low select circuit 5, and the low select circuit 5 detects the wheel speed detected by the both wheel speed detectors IL and 1*.
The lower one of these is output as wheel speed ■8.

The switching control circuit 7 outputs a high-level signal for a set time T2 determined by the time setting circuit 8 in response to at least one of the anti-lock brake control circuits 4L and 411 outputting a signal to start anti-lock brake control. and both anti-lock brake control circuits 4L.

an OR gate 9 which outputs a high level signal when a signal to start anti-lock brake control is output from at least one of 4; and an OR gate 9 which outputs a high level signal when the signal to start antilock brake control is output; Set time T2
The switching mode of the switching circuit 6 is changed by the output of the monostable circuit 10.

The time setting circuit 8 includes a vehicle speed corresponding time setting circuit 11, a fixed time setting circuit 12, a comparison circuit 13 that compares the time set by both setting circuits 1112, and changes the switching mode based on the output signal of the comparison circuit 13. and a holding circuit 15 that holds a set time T2 that is input via the switch 14 when the output of the OR gate 9 becomes high level. It is connected to the stabilizing circuit 10 to set its high level output time.

The vehicle speed corresponding time setting circuit 11 calculates a set time 72m corresponding to the vehicle speed Vv, and the circuit 11 calculates the following equation.

Tzs=kt' Vv+at Here, the sign kZ+aZ is a constant.

On the other hand, the fixed time setting circuit 12 sets a fixed time T2, and the output signal of the fixed time setting circuit 12 is input to the non-inverting input terminal of the comparison circuit 13, and the output signal of the vehicle speed corresponding time setting circuit 11 is inputted to the non-inverting input terminal of the comparison circuit 13. is input to the inverting input terminal of the comparison circuit 13. Therefore, the comparison circuit 13 calculates the set time T2. When Tzm exceeds the set time Tzm, a high level signal is output.

The switch 14 has 14 first individual contacts connected to the vehicle speed corresponding time setting circuit 11 and 14 second individual contacts connected to the fixed time setting circuit 12. and a common contact 14c connected to the holding circuit 15, and when the output of the comparison circuit 13 becomes high level, the second individual contact 14. conducts to the common contact 14c, and when it becomes low level, the first individual contact 141 conducts to the common contact 14c. Therefore, the output of the switch 14, that is, the set time T2 input to the holding circuit 15 is as shown in FIG. In other words, the set time T2 remains at a constant value T until the vehicle speed Vv reaches a certain value.
2b, and when the vehicle speed ■9 exceeds the above-mentioned certain value, it increases in accordance with the vehicle speed ■9.

Next, the operation of this embodiment will be explained with reference to FIG. In FIG. 3, the output oil pressure of the mask cylinder is indicated by reference numeral P, the braking oil pressure of the left wheel brake 2L is indicated by reference numeral PL, and the braking oil pressure of the right wheel brake 2R is indicated by reference numeral P.

For example, assume that the front left wheel is about to lock up during braking while the vehicle is running on a road surface where the front left wheel is on a road surface with a lower coefficient of friction than the road surface where the front right wheel is on contact. When the front left wheel is about to lock, a signal to start anti-lock brake control is input from the anti-lock brake control circuit 4L to the hydraulic control circuit 3L, and the hydraulic control circuit 3L controls the braking hydraulic pressure of the wheel brake 2L accordingly. However, the anti-lock control start signal from the anti-lock brake control circuit 4L is output from O of the switching control circuit 7.
It is also input to R gate 9. Therefore monostable circuit 10
outputs a high-level signal that lasts for a set time T2 in response to the anti-lock brake control start signal being output from the anti-lock brake control circuit 4L, and in response, the switching circuit 6 outputs a high-level signal that lasts for a set time T2. ■ Wheel speed selected at. Both anti-lock brake control circuits 4. ．． This is the switching mode that is input to 4R.

As a result, during the set time T2, both wheel brakes 2L and 2
The ++ braking oil pressure is collectively controlled by low selection, so that the difference in braking force between the left and right wheels is kept small. Therefore, during this period, the rotational moment of the vehicle body is generated slowly, and the driver can easily make steering corrections.

Furthermore, the set time T2 is a constant value T'zb until the vehicle speed vv reaches a certain value, and increases in accordance with the vehicle speed vv after exceeding that constant value, so the higher the speed, the more time there is for steering correction. Thus, fine control according to the vehicle speed Vv becomes possible.

FIG. 4, FIG. 5, and FIG. 6 show an embodiment of the invention as set forth in claim (3), and parts corresponding to the above embodiment are given the same reference numerals.

In this embodiment, the switching control circuit 7' that controls the switching mode change of the switching circuit 6 includes both anti-lock brake control circuits 4L.

4R outputs a brake oil pressure reduction signal that lasts longer than the first set time T1 set by the first time setting circuit 16, the second set time T2 is set by the second time setting circuit 8'. Outputs a signal that becomes high level only when Further, the switching circuit 6 switches the low select circuit 5 to both the anti-lock brake control circuits 4L and 4 in response to the output of the switching control circuit 7' becoming high level.
The switching mode is such that the anti-lock brake control circuits 4t and 4i are connected to the low select circuit 5 in a switching mode. Anti-lock brake control is performed based on

The switching control circuit 7' includes a clock pulse source 1
The clock pulses input from 8 are counted until the fall of the brake hydraulic pressure reduction signal from the anti-lock brake control circuits 4L and 4□, and the count time is the first
a counter 17L that outputs a high level signal when the first set time T set by the time setting circuit 16 is exceeded;
171 and their counters 17L, 17. A high level signal that lasts for a second set time T2 set by a second time setting circuit 8' after the output of the OR gate 9 becomes high level. The monostable circuit 10 is equipped with a monostable circuit 10 that outputs
The switching mode of the switching circuit 6 changes depending on the output.

The first time setting circuit 16 includes a vehicle speed corresponding time setting circuit 19, a constant time setting circuit 20, a comparison circuit 21 that compares the time set by the reset circuit 19.20, and the comparison circuit 2.
A switch 22 whose switching mode changes according to the output signal of 4.1, and both anti-rotator brake control circuits 4L, 4.
an OR gate 23 whose output becomes high level in response to at least one of outputting a brake hydraulic pressure reduction signal;
The holding circuit 24 holds the set time T input through the switch 22 when the output of the gate 23 becomes high level, and the holding circuit 24 sets the count time to the counter 17L17m in the switching IIN control circuit 7'. connected to set up.

The vehicle speed corresponding time setting circuit 19 sets a set time T1. corresponding to the vehicle speed ■9. The circuit 19 calculates the following equation.

T+m=　k+　・Vv+a1 Here, the sign kl+al is a constant.

On the other hand, a constant time Tl is set in the constant time setting circuit 20, the output signal of the constant time setting circuit 20 is input to the non-inverting input terminal of the comparison circuit 21, and the output signal of the vehicle speed corresponding time setting circuit 19 is It is input to the inverting input terminal of the comparison circuit 21. Therefore, the comparison circuit 21 outputs a high level signal when the set time T+b exceeds the set time 'T'1m.

The switch 22 has a first individual contact 22 . connected to the vehicle speed corresponding time setting circuit 19 . and a second individual contact 22 . connected to the fixed time setting circuit 20 . and a common contact 22e connected to the holding circuit 24, and when the output of the comparison circuit 21 becomes high level, the second individual contact 22. conducts to the common contact 22c, and when it becomes low level, the first individual contact 22□ conducts to the common contact 22c. Therefore, the output of the switch 22, ie, the set time T input to the holding circuit 24, becomes as shown in FIG. That is, the set time T decreases with the vehicle speed (2) until the vehicle speed (9) reaches a certain value, and becomes constant when the vehicle speed (9) exceeds the above-mentioned value.

The second time setting circuit 8' is configured similarly to the time setting circuit 8 shown in FIG.
2 is the same as the set time shown in FIG.

Next, the operation of this embodiment will be explained with reference to FIG. 6. In FIG. 6, the output oil pressure of the mask cylinder is indicated by reference numeral P, and the braking oil pressure of the left wheel brake 2L is indicated by reference numeral P4, Right wheel brake 2. The brake oil pressure of 1 is designated by the reference symbol PR.

For example, when anti-lock brake control is being performed in a braking state where there is no difference in the coefficient of friction between the left and right wheels, the vehicle is driving on a road where the front left wheel is on a road with a lower coefficient of friction than the front right wheel. Assume that the vehicle starts running. At this time, when driving onto a road surface with different coefficients of friction on the left and right sides, if the braking oil pressure is reduced by the wheel brake 2L of the wheel on the road surface with the lower coefficient of friction, that is, the left wheel, then the brakes 2L and 2J1 of the left and right wheels are controlled. This results in a large difference in power and a sudden rotational moment on the vehicle body. However, when the brake oil pressure reduction signal is input from the anti-lock brake control circuit 4L to the oil pressure control circuit 3L, and the brake oil pressure reduction signal continues beyond the first set time TI, the output of the counter 17L becomes high level. , therefore, the monostable circuit 10 has the first set time T
, after which the switching circuit 6 outputs a high-level signal that lasts for a second set time T2, and in response to this, the switching circuit 6 changes the wheel speed o selected by the low select circuit 5 to both anti-long brake control circuits 4L, 4. This is the switching mode that is input to the

As a result, during the second set time T2, both wheel brakes 2L
, 2R braking oil pressure is collectively controlled by low selection, and the difference in braking force between the left and right wheels is kept small. Therefore, during this period, the rotational moment of the storage body is generated slowly, and the driver can easily make steering corrections. Moreover, the first and second set times T,
,T.

is determined according to the vehicle speed ■9, so the higher the speed, the more quickly the low selection can be performed all at once, and more time can be given for steering correction, making it possible to perform fine control according to the vehicle speed ■9. .

7 and 8 show an embodiment of the invention as set forth in claim (4), and parts corresponding to the embodiment of FIGS. 4 to 6 are given the same reference numerals. .

Wheel speed detectors 111L+1++a are installed on the left and right rear wheels to individually detect both rear wheel speeds Vw*L and V□8.
and rear wheel brake 2 RLI 21R are installed individually. In addition, each rear wheel brake 211L + 2
Hydraulic control circuit 3RL+ 31 individually compatible with 11R
111 is anti-lock brake control circuit 4 RLI
Each rear wheel brake 2 receives the control signal from 411J1.
RLI 2 Controls the braking oil pressure of R11. Furthermore, anti-lock brake control circuit 411LI 4111
1 receives a wheel speed signal from the switching circuit 6. This switching circuit 6 includes both wheel speed detectors I
Rear wheel speed detected by RLI I RN■. L,■
Anti-lock brake control circuit 411L corresponding to □7
I 4 The switching mode individually input to m11 and the wheel speed selected by the low select circuit 5 ■. The switching mode inputted to the anti-lock brake control circuit 4 RLI 411M is changed by a switching control signal from the switching control circuit 7'.

The wheel brakes mounted on both front wheels are anti-lock controlled by the control circuit of the embodiment shown in FIG. 4, and anti-lock brake control circuits 4FL and 4□ included in this front wheel brake control circuit. A brake hydraulic pressure reduction signal from the rear wheel brake 211LI 2** is used to lower the anti-lock brake l1li. In other words, the switching control circuit 7' that controls the change in the switching mode of the switching circuit 6 controls the anti-lock brake control circuits 4FL and 4□ for both front wheels so that at least one of the anti-lock brake control circuits 4FL and 4□ sets the first set time T1 or more in the first time setting circuit 16. When a sustained brake oil pressure reduction signal is output, the second
A signal that remains at a high level for a second set time T2 set by the time setting circuit 8' is output. Further, the switching circuit 6 switches the low select circuit 6 to both rear wheel anti-lock brake control circuits 411L, 41. in response to the output of the switching control circuit 7' becoming high level. The switching mode is such that both anti-rotator brake control circuits 411LI 4 +u+ are connected to the wheel speed ■ output from the low select circuit 5. Anti-lock brake control is performed based on

The switching control circuit 7' and the first time setting circuit 16
The second time setting circuit 8' is basically the same as the embodiment shown in FIG. ' counter 17!11.
It is inverted and input to 171111.

The operation of this embodiment will be explained with reference to Fig. 8. In Fig. 8, reference symbol P is the output hydraulic pressure of the mask cylinder, PFL is the left front wheel brake, P□ is the right front wheel brake, and PIIL is the left rear wheel brake. Wheel brake and pHll indicate the braking oil pressure of the right rear wheel brake, respectively.

As shown in FIG. 8(a), at least one of both front wheel brakes, for example, the left front wheel brake, has a first brake hydraulic pressure P, L.
When the pressure is reduced for a set time T1 or more, as the first set time T1 elapses, the braking oil pressure of both rear wheel brakes PRL, P1 as shown in FIG. 8(b).
ljl is collectively controlled for a second set time T2 in accordance with the lower brake hydraulic pressure, for example, the left rear wheel brake.

With such anti-lock control, for example, when performing anti-lock brake control in a braking state where there is no difference in the coefficient of friction of the road surface where the left and right wheels are in contact, one of the left and right wheels may be placed on a road surface with a low coefficient of friction. When the vehicle is entered, the braking oil pressure of the rear wheel brakes 28□ is controlled by the collective low selection. For example, if the vehicle is traveling on a road surface where the left wheel contacts the road surface with a lower coefficient of friction than the road surface where the right wheels contact the road surface, the braking oil pressure of the left front wheel brake will be reduced due to the lower friction coefficient. When the brake oil pressure decrease continues for the first set time T1 or more, the brake oil pressure of both front wheel brakes becomes as shown in Fig. 8 (a).
), both rear wheel brakes 211L,
2 The braking oil pressure of R11 is also the second as shown in Fig. 8(b).
Control is performed by collective low selection for a set time T2.

As a result, the front wheels determine that at least one wheel has entered a road surface with a low coefficient of friction, before the rear wheels approach that road surface, and control is carried out early with collective low selection. The difference in braking force can be reduced, the generation of rotational moment of the vehicle body can be made gentler, and the driver can easily make steering corrections during this time.

Moreover, as in the embodiment shown in FIG. 4 above, the first and second set times T+ and Tz are determined according to the vehicle speed 9, so that the higher the speed, the more quickly the low selection is performed, and the more time is required for steering correction. You can give yourself some leeway,
Fine-grained control according to the vehicle speed ■7 is possible.

As yet another embodiment of the present invention, both front wheel brakes may be collectively controlled in the embodiments shown in FIGS. 7 and 8.

In the above embodiment, one example is when performing anti-lock brake control while driving on a road surface with different coefficients of friction on the left and right sides,
We have explained two separate examples of when the vehicle enters a road surface with different coefficients of friction on the left and right sides while performing anti-lock brake control, but by combining them with each other, it is possible to drive onto a road surface with different coefficients of friction on the left and right sides. This makes it possible to deal with both when performing anti-lock brake control while driving and when the vehicle enters a road surface with different coefficients of friction on the left and right sides while performing anti-lock brake control.

Effects of C6 Invention As described above, according to the invention described in claim (1), both wheel speeds are maintained at least until the set time elapses from the start of anti-lock control of the braking oil pressure of at least one of the wheel brakes. Since the braking oil pressure of both wheel brakes is controlled based on the lower of The driver can easily make steering corrections.

Further, according to the invention described in claim (2), since the set time is increased as the vehicle speed increases above a certain vehicle speed, fine control according to the vehicle speed becomes possible.

According to the invention recited in claim (3), when the time for the brake hydraulic pressure of at least one of the wheel brakes to decrease continues for a first set time or more, the first set time is 2. Until the set time elapses, the braking oil pressure for both wheel brakes is controlled based on the lower speed of both wheels, so if one of the left and right wheels enters a road surface with a low coefficient of friction during anti-lock brake control, The rotational moment generated in the vehicle body can be reduced (suppressed) for a certain period of time, and the driver can easily make steering corrections during that period.

According to the invention set forth in claim (4), when the time to reduce the braking oil pressure of at least one of the front wheel brakes lasts for a first set time or more, the first set time is elapsed and the first set time is reduced. 2. Until the set time has elapsed, the braking oil pressure for both rear brakes is controlled based on the lower speed of both rear wheels, so if one of the left or right front wheels enters a road surface with a low coefficient of friction during anti-lock brake control. In some cases, the rear wheel brakes can be immediately subjected to collective low selection control for a second set time to moderate the generation of rotational moment during that time, thereby facilitating steering correction by the driver.

Furthermore, according to the invention described in claims (5) and (6), the first setting time is shortened as the vehicle speed increases until a certain vehicle speed is reached, and the second setting time is
Since the length is increased as the vehicle speed increases above a certain vehicle speed, fine control according to the vehicle speed is possible.

[Brief explanation of the drawing]

1 to 3 show an embodiment of the invention as set forth in claim (1), in which FIG. 1 is a control circuit diagram and FIG. 2 is a graph showing the time set by the time setting circuit. , FIG. 3 is a graph showing changes in braking oil pressure, and FIGS. 4 to 6 show an embodiment of the invention as set forth in claim (3).
The figure is a control circuit diagram, Figure 5 is a diagram showing the time set by the first time setting circuit, Figure 6 is a graph showing changes in braking oil pressure, and Figures 7 and 8 are according to claim (4). FIG. 7 is a control circuit diagram, and FIG. 8 is a graph showing changes in braking oil pressure. 2L 2. +1...Wheel brake, 21L+2
**...Rear wheel brake, T...1st set time, T2...2nd set time 2nd
figure

Claims (6)

[Claims] (1) In a vehicle anti-lock brake control method in which the braking oil pressure of left and right wheel brakes is independently controlled based on the corresponding wheel speed, the braking oil pressure of at least one of the wheel brakes is set from the start of anti-lock control. 1. A method for controlling an anti-lock brake for a vehicle, comprising controlling the braking oil pressure of both wheel brakes based on the lower of both wheel speeds until a time elapses. (2) The anti-lock brake control method for a vehicle according to item (1), wherein the set time is increased as the vehicle speed increases above a certain vehicle speed. (3) In a vehicle anti-lock brake control method in which the braking hydraulic pressure of the left and right wheel brakes is independently controlled based on the corresponding wheel speed, the first setting is the time for reducing the braking hydraulic pressure of at least one of the wheel brakes. If the duration lasts for a period of time or more, the second set time after the first set time has passed.
A method for controlling anti-lock brakes for a vehicle, characterized in that, until a set time elapses, the braking oil pressure of both wheel brakes is controlled based on the lower of both wheel speeds. (4) In a vehicle anti-lock brake control method in which the braking hydraulic pressure of the left and right rear wheel brakes is independently controlled based on the corresponding rear wheel speed, a time period for reducing the braking hydraulic pressure of at least one of the front wheel brakes is determined. When the duration lasts for more than one set time, the second set time elapses and the second
An anti-lock brake control method for a vehicle, comprising controlling the braking oil pressure of both rear wheel brakes based on the lower of both rear wheel speeds until a set time has elapsed. (5) Anti-lock brake control for a vehicle according to item (3) or item (4), wherein the first set time is shortened as the vehicle speed increases until a certain vehicle speed is reached. Method. (6) The anti-lock brake control method for a vehicle according to item (3) or item (4), wherein the second set time is increased as the vehicle speed increases above a certain vehicle speed. .