JPH04110262A - Anti-skid controller - Google Patents

Abstract

PURPOSE:To carry out the anti-skid control with high precision even in turn by judging the frictional coefficient between a wheel and a road surface from the result of the detection of a longitudinal accelerating speed detecting means and a lateral accelerating speed detecting means and correcting the result of the judgement to a less value when the accelerating speed in the lateral direction is larger than that in the longitudinal direction. CONSTITUTION:The output of a longitudinal accelerating speed sensor 3a is inputted into a car body speed calculation part 52 and a frictional coefficient judging part 53 through an input processing part 51a, and the output of a lateral accelerating speed sensor 3b is inputted through an input processing part 51b. The car body speed calculating part 52 and frictional coefficient judging part 53 calculates the accelerating speed of the sum of the accelerating speed in the longitudinal direction of the car body and the accelerating speed in the lateral direction of the car body. An anti-skid control part 54 sets the slip standard in correspondence with the car body speed obtained in the car body speed calculation part 52 and the frictional coefficient obtained in the frictional coefficient judging part 53, and when the wheel speed becomes less than this slip standard, each decompression signal is outputted into actuators 13a-13d, and decompression control for the brake hydraulic pressure is performed, and anti-skid control is realized.

Description

[Detailed Description of the Invention] Overview A longitudinal acceleration detection means for detecting the longitudinal acceleration of the vehicle body and a lateral acceleration detection means for detecting the lateral acceleration of the vehicle body are provided, and based on the sum of these detection results, It determines the coefficient of friction between the wheels and the road surface, calculates the speed of the main body, and controls the braking force of the wheels based on the results of these determinations and calculations.

The friction coefficient is corrected to be small, particularly for the inner wheels, when the vehicle turns in a turn where the acceleration in the lateral direction is greater than the acceleration in the longitudinal direction.

In this way, the friction coefficient determination results are corrected in response to the difference in load bearing between the inside wheel and the outside wheel when turning, and highly accurate anti-skid control is achieved even with the difference in load bearing, and braking Try to shorten the distance.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device that controls braking force to increase the coefficient of friction between wheels and a road surface to shorten braking distance.

A conventional anti-skid control device is a device that controls braking force based on wheel speed, vehicle body speed, etc. so that the coefficient of friction between the wheels and the road surface increases, thereby shortening the braking distance.

Therefore, when a braking operation is performed by depressing the brake pedal, and the wheels are locked, and the slip ratio between the wheels and the road surface becomes large, pressure reduction control of the braking oil pressure is performed. When the wheel speed is recovered by this pressure reduction control, the braking oil pressure is increased again, and such pressure reduction/pressure increase operation and holding operation are repeated to control the braking force so that the slip ratio is reduced.

The pressure reduction control is started when the wheel speed becomes equal to or less than a predetermined slip reference. In typical prior art, the slip criterion is determined based on the vehicle body speed determined from, for example, the maximum value of each wheel speed of four wheels or the integrated value of the longitudinal acceleration of the vehicle body detected by an acceleration sensor. has been done. That is, for example, the vehicle speed is determined by multiplying the vehicle body speed by a predetermined coefficient, for example, 0.85.

Problems to be Solved by the Invention Therefore, in the above-mentioned prior art, there is a problem in that when turning, it is not possible to perform optimal control for each wheel due to the difference in the turning radius between the inner wheel and the outer wheel.

In other words, the inner wheel has a smaller turning radius than the outer wheel, so the wheel speed is lower, and if pressure reduction control is performed based on the same slip standard, the inner wheel's braking hydraulic pressure will be lower than that of the outer wheel. It feels a little weird. Therefore, the braking distance becomes longer and the vehicle body becomes unstable.

Generally, the control system of the anti-skid control device is composed of three systems: the left and right front wheels, and the rear wheels. The so-called select low control, in which all wheels are controlled together, is used to ensure the stability of the vehicle body. Therefore, in the above-mentioned conventional technology, when turning, both the left and right rear wheels
Because pressure reduction is controlled based on the wheel speed of the inside rear wheel,
This also increases the braking distance.

An object of the present invention is to provide an anti-skid control device that can perform highly accurate anti-skid control even when turning.

Means for Solving the Problems The present invention provides: a wheel speed detection means for detecting the rotational speed of the wheels; a longitudinal acceleration detection means for detecting the longitudinal acceleration of the vehicle body; and a lateral acceleration detection means for detecting the lateral acceleration of the vehicle body. a detection means, and determines at least a friction coefficient between the wheels and the road surface from the detection results of the longitudinal acceleration detection means and the lateral acceleration detection means, and when the lateral acceleration is larger than the longitudinal acceleration, the determination is made. An anti-skid control device comprising: a determination means for correcting the result to a smaller value; and a control means for controlling the braking force of the wheels based on the detection result of the wheel speed detection means and the determination result of the determination means. .

Further, the determination means of the present invention determines the sum of the acceleration in the longitudinal direction and the acceleration in the lateral direction as jc! I tJl! It is characterized by being used for determining coefficients.

Furthermore, the present invention provides: wheel speed detection means for detecting the rotational speed of the wheels; acceleration detection means for detecting the acceleration of the vehicle body; turning detection means for detecting that the vehicle body is in a turning state; determining means that determines at least a friction coefficient between the wheels and the road surface based on the detection results, and responds to the detection results of the turning detection means, and corrects the determination results to a smaller value when the vehicle body is in a turning state; The anti-skid control device includes a control means for controlling the braking force of the wheels based on the detection result of the wheel speed detection means and the determination result of the determination means.

Further, the turning detection means of the present invention is characterized in that it is a lateral acceleration detection means for detecting acceleration in the lateral direction of the vehicle body.

Furthermore, the determination means of the present invention is characterized in that the correction is performed with respect to the inner wheel at the time of turning.

According to the present invention, the longitudinal acceleration of the vehicle body is detected by the longitudinal acceleration detection means, and the lateral acceleration of the vehicle body is detected by the lateral acceleration detection means, which is the turning detection means. The determining means calculates the acceleration of the vehicle body in the running direction by adding the detection results of the two acceleration detecting means, calculates the vehicle speed etc. based on the calculation result, and determines at least the gap between the wheels and the road surface. Further, the determining means for determining the friction coefficient of the vehicle corrects the friction coefficient to be smaller, especially for the wheels that are on the inside during turning, when the acceleration in the lateral direction is larger than the acceleration in the longitudinal direction.

The judgment results and calculation results of the judgment means are given to a control means, and the control means, based on the judgment results and the vehicle speed, responds to the rotational speed of the wheels detected by the wheel speed detection means. , controls the braking force of the wheels.

Therefore, even when the lateral acceleration of the vehicle body, that is, the turning force is large, such as during sudden braking and sudden turning, the friction coefficient determination result is corrected in accordance with the load burden between the inner and outer wheels. However, highly accurate anti-skid control is performed even for the difference in load burden.

Embodiment FIG. 1 is a functional block diagram for explaining the principle of an embodiment of the present invention. The output from the longitudinal acceleration sensor 3a that detects the longitudinal acceleration of the vehicle body is sent to the input processing section 51.
It is input to the vehicle body speed calculating section 52 and the friction coefficient determining section 53 via a.

Similarly, the output from the lateral acceleration sensor 3b, which detects the lateral acceleration of the vehicle body and is a turning detection means, is sent to the input processing unit 5.
1b, it is input to the vehicle body speed calculation section 52 and the friction coefficient determination section 53.

The vehicle speed calculating unit 52 and the friction coefficient determining unit 53 calculate the sum of the acceleration in the longitudinal direction of the vehicle body and the acceleration in the lateral direction of the vehicle body. Furthermore, the vehicle body speed calculating section 52 integrates the vehicle body accelerations obtained in this manner, calculates the vehicle body speed, and outputs the result to the anti-skid control section 54 .

On the other hand, each wheel is provided with a wheel speed sensor 1a to 1d, and the wheel speed signal from each of these wheel speed sensors 1a to 1d is converted into the wheel speed of each wheel by a wheel speed calculation section 55, and then It is input to the anti-skid control section 54.

Further, the output from the wheel speed calculating section 55 is input to the friction coefficient determining section 53, and the friction coefficient determining section 53 calculates the following from the vehicle body acceleration determined from the outputs of the acceleration sensors 3a and 3b and the wheel speed. The friction coefficient between the wheels and the road surface is determined, and the determination result is output to the anti-skid control section 54.

The anti-skid control section 54 calculates, for example, the vehicle speed calculated by the vehicle speed calculation section 52 and the friction coefficient determination section 3.
A slip standard is set in accordance with the friction coefficient determined in , and when the wheel speed becomes equal to or less than this slip standard, a pressure reduction signal is output to actuators 13a to 13d, which will be described later, to perform pressure reduction control of the braking oil pressure. Anti-skid control is thus achieved.

FIG. 2 is a block diagram showing the electrical configuration of an anti-skid control device in which the present invention is implemented, and FIG. 3 is a piping route diagram for braking oil pressure in the anti-skid control device. Wheel speed sensor 1 provided on each wheel 34a to 34d
a to 1d detect the rotational speeds of the wheels 34a to 34d, respectively.

These wheel speed sensors 1a to 1d are, for example, provided with a large number of notches and protrusions at equal intervals in the circumferential direction of a ferromagnetic detection plate fixed to a wheel shaft, and provided near the circumference of the detection plate. by electromagnetic pickup or optical sensor, etc.
The wheel speed signal is configured to derive a wheel speed signal having a frequency proportional to the rotational speed of the wheel. These wheel speed sensors 1a
The wheel speed signals from 1 to 1d are given to waveform shaping circuits 5a to 5d in the anti-skid control circuit 4, and after being waveform-shaped into pulse signals, they are input to the processing circuit 2.

The acceleration sensors 3a and 3b (hereinafter collectively referred to as reference numeral 3) output analog signals of a level corresponding to acceleration, as will be described later. The output signals from these acceleration sensors 3 are respectively given to analog/digital conversion circuits 6a and 6b (indicated by reference numeral 6 when referred to collectively), converted into digital values, and then given to the processing circuit 2. Digital filter processing is performed to remove unnecessary components. The processing circuit 2 processes these acceleration sensors 3
A calculation operation is performed based on the outputs from the wheel speed sensors 1a to 1d to perform anti-skid control.

The processing circuit 2 also receives an output from the switch 7 that detects that the brake pedal 30 has been depressed, after being converted by a level conversion circuit 8 to a voltage level suitable for the anti-skid control circuit 4. Ru. Each circuit in the anti-skid control circuit 4 is supplied with voltage from the battery 11 that is input via the power switch 10 after being stabilized by the power supply circuit.

The processing circuit 2 drives and controls actuators 13a to 13d constituted by three-position electromagnetic control valves 32a to B2d and wheel cylinders 33a to 33d, which will be described later, based on the input results input as described above, and performs anti-skid control. Perform control actions. That is, the relay coil 15a of the relay 15 is connected via the solenoid relay drive circuit 14.
is excited, thereby making the relay switch 15b conductive. A high level voltage is commonly applied to one input of each of the actuators 13a to 13d via this relay switch 15b. The control output from the processing diagram 111F2 is given to the other input of these actuators 13a and 13d via solenoid drive circuits 12a to 12d, respectively.

As a result, the three-position electromagnetic control valves 32a to 32d control the braking oil pressure to either increase or decrease the pressure, or maintain it, as will be described later.

The processing circuit 2 also outputs an output to the relay coil 16a of the relay 16 via the motor relay drive circuit 18, thereby driving the motor 17 for generating braking oil pressure connected to the relay switch 16b of the relay 16. controlled. Furthermore, in process diagram F#I2, the warning light 19 is turned on via the lamp drive circuit 20 when an abnormality occurs in the anti-skid control.

Referring to FIG. 3, when the brake pedal 30 is depressed, braking oil pressure is generated in the master cylinder 31, and the braking oil pressure is transmitted through the three-position electromagnetic control valves 32a to 32a through the pipes P1 to P4. 32d, and further supplied to wheel cylinders 33a to 33d via pipes P5 to P8.

As a result, the wheels 34a to 34d are braked, and the vehicle speed is reduced.

The rotational speed of the wheels 34a to 34d is measured by a wheel speed sensor la.
~1d, respectively, and inputted to the anti-skid control circuit 4. Further, an output signal representing the vehicle body acceleration detected by the acceleration sensor 3 fixed to the vehicle body is also input to the anti-skid control circuit 4.

When the anti-skid control circuit 4 determines that the conditions for starting anti-skid control are met, the anti-skid control circuit 4 controls the motor 17.
The braking hydraulic pressure generated by is applied to the master cylinder 31 via the pipe P9, and the three-position electromagnetic control valves 32a to 32d are controlled to increase, decrease, or hold the brake pressure to the wheel cylinders 33a to 33d. Controls the braking oil pressure. Thereby, the slip ratios of the wheels 34a to 34d are controlled to a value at which a high frictional braking force acts on the road surface.

The fourth section is a block diagram showing the electrical configuration of the acceleration sensor 3, and FIG. 5 is a diagram for explaining the principle of acceleration measurement by the acceleration sensor 3. Acceleration sensor 3
The acceleration detection unit 41 is composed of three metal plates 41a, 41c, and 41b that are arranged parallel to each other in a direction that intersects the traveling direction of the vehicle body indicated by an arrow A. Therefore, adjacent metal plates 41a, 41c: 4],
Two capacitors 41ac41.c41. cb
is configured.

The metal plates 41a and 41b are fixed, and the metal plate 41c
is configured to be movable in the direction of the arrow A. Therefore, when the metal plate 41c is displaced due to acceleration in the direction of arrow A, the capacitance Cac of the capacitor 41ae and the capacitance Ccb of the capacitor 41cb change as shown in FIG.

Therefore, acceleration can be detected from changes in the capacitances Cac and Ccb. A rectangular wave pulse as shown in FIG. 7(1) is applied from the oscillator 42 to one capacitor 41ac of the acceleration detecting section 41 configured as described above, and the rectangular wave pulse as shown in FIG. 7(1) is applied to the other capacitor 41cb. The pulse is applied after being inverted in the inversion buffer 43 as shown in FIG. 7(2).

The output of the acceleration detection section 41 is connected to a capacitor 41ac41c.
After being amplified by, for example, about 20 dB in an amplifier 44, it is led out from a switch 45 to the analog/digital conversion circuit 6 via a low-pass filter (abbreviated as LPF) 46.

A rectangular wave pulse from the oscillator 42 shown in FIG. 7(1) is applied to the switch 45. When this pulse is at a high level, the switch 45 conducts l-,
Shuts off when the level is low.

Therefore, as shown in FIG. 7(3), before time 10 when no acceleration is applied, a 0 level output is derived from the connection point 41e, and after time 10 when acceleration is applied, An output of a corresponding level is derived. This output is connected to the oscillator 4 at the switch 45.
After the output during a period in which no pulse is derived from 2, that is, the 0 level output is cut off, it is smoothed by the LPF 46 and output.

Therefore, when a sudden braking and sudden turn such as a J-turn or a U-turn is performed, the longitudinal acceleration of the vehicle body detected by the longitudinal acceleration sensor 3a indicates that the braking starts at time t1 in Fig. 8 (1). It increases to the negative side from the time t2, turns to recovery at the time when the turn shown at time t2 starts, and reaches the minimum value at time 3, when the attitude of the vehicle body is displaced by 90 degrees. Thereafter, it increases again until time t4 when the turn ends, and then recovers when the turn ends.

On the other hand, the lateral acceleration of the vehicle body detected by the lateral acceleration sensor 3b increases from the time t2 when the turn is started, as shown in FIG. 8(2), and the attitude of the vehicle body changes. It reaches a maximum value at the time 3 when the rotation is displaced by 90 degrees, and then decreases until the time t4 when the turn ends.

Therefore, in this embodiment, the friction coefficient μ is determined based on the sum of the longitudinal acceleration of the vehicle body shown in FIG. 8(1) and the lateral acceleration shown in FIG. 8(2). The result of the determination is indicated by the reference numeral 1 in FIG. 8(3), for example. On the other hand, if the friction coefficient μ is determined only based on the acceleration in the longitudinal direction of the vehicle body, even on a high μ road, as shown by reference numeral 2 in Fig. 8 (3), During the period from time t2 to t4, it is erroneously determined to be medium μ or low μ.

Therefore, the anti-skid control device according to the present invention, which determines the friction coefficient μ based on the sum of accelerations in the longitudinal direction and the lateral direction of the vehicle body, can accurately determine a high μ.

Note that the determination of the friction coefficient μ as described above is performed as follows. In other words, the negative acceleration α in the longitudinal direction of the vehicle body
1 and the lateral acceleration α2, the acceleration α3 is 0.7
G (G is gravitational acceleration) or more, a high μ determination is made, and if it is less than 0.7 G and 0.4 G or more, a medium μ determination is made, and if it is less than 0.4 G and 0.2 G or more. Sometimes a low p determination is made, and when it is less than 0.2G, an extremely low μ determination is made.

However, when turning, a load difference occurs between the inner and outer wheels. Therefore, for example, if a wheel is about to lock up, the outer wheel will recover its wheel speed by just slightly relaxing the brake hydraulic pressure, while the inner wheel will recover its speed by reducing the pressure! 0: If the wheel speed is not set to a large value, it will be difficult to recover the wheel speed. Therefore, in this embodiment, when it is determined that a turning condition is occurring, the friction coefficient μ obtained as described above is used to control the outer wheel, and the inner wheel speed is For wheel control, a friction coefficient μ that is one step lower than the friction 1 series coefficient μ obtained as described above is used. That is, when the determination result of the friction coefficient μ is high μ, the outer wheels are controlled based on the high μ determination, whereas the inner wheels are controlled based on the medium μ determination. In this way, the difference in load burden is compensated for by the friction coefficient μ.

FIG. 9 shows T! for each wheel 34a to 34d! 1 is a flowchart for explaining the setting operation of the friction coefficient μ.

In step m1, the longitudinal acceleration α1 of the vehicle body detected by the longitudinal acceleration sensor 3a is read, and in step m2, the lateral acceleration α2 detected by the lateral acceleration sensor 3b is read. In step m3, the acceleration α1. The acceleration α3 of the sum of α2 is determined, and thus the acceleration of the vehicle body in the running direction is determined. In step m4, the step m
The friction coefficient μ is determined based on the acceleration α3 obtained in step 3, and the determination result is determined as a control parameter for all wheels 34a to 34d.

At the step pressure I5, it is determined whether the lateral acceleration α2 is larger than the longitudinal acceleration α1, and if so, that is, when a sharp turn is being made, the process moves to step m6, and the friction of the inside wheel is determined. The coefficient μ is the step m
The operation is terminated by resetting the friction coefficient μ to one step lower than the friction coefficient μ set in step 4. Otherwise, when it is not turning, the direct operation is terminated, and all wheels 34a to 34d are Control is performed based on the friction coefficient μ set in step m4.

FIG. 10 is a timing chart for explaining the anti-skid control operation. When the brake pedal 30 is depressed at time tll, the braking oil pressure starts to rise as shown in FIG. 10 (4). As a result, the wheel acceleration increases to the negative side and becomes less than the predetermined pressure reduction start reference Gll at time t12 as shown in FIG. , slip reference LL1 determined by the wheel speed in advance
If the value is below, from time t13, pressure reduction control of the braking oil pressure is started as shown in FIG. 10 (3) in accordance with the friction coefficient μ.

The slip reference Lll is indicated by reference numeral 12, and is, for example, 8 of the vehicle speed Vs determined as described later.
Set to 5%. Further, the pressure reduction control is a duty control in which pressure reduction and holding are alternately switched in a short time, and the duty of the pressure reduction pulse is set lower as the friction coefficient μ becomes higher.

When the wheel acceleration and wheel speed become uneven due to the pressure reduction control and the wheel acceleration exceeds the pressure reduction start reference G11,
At time t14, the pressure reduction control is ended and the process moves to holding control. However, when the drop in wheel speed is large, the wheel acceleration does not converge even with the pressure reduction/holding control, and at time t15, the pressure increase start reference G1
After reaching the peak value at time t16, time t
At 17, the pressure becomes less than the pressure increase start reference G12 again. At this time, the anti-skid control circuit 4 increases the brake oil pressure by a pressure increase time W2 corresponding to the peak value of the wheel acceleration at the time t16 and the friction coefficient μ.

The pressure increase time W2 is set longer as the friction coefficient μ is higher and as the peak value of the wheel acceleration at time t16 is higher. In this way, the wheel acceleration becomes the reference G1
1. If it falls within G12, then time t18. As indicated by t19, the braking oil pressure is increased in pulses at every predetermined period Wll.

FIG. 11 is a flowchart for explaining the anti-skid control operation. In step n1, initialization processing is performed, and in step n2, it is determined whether or not a predetermined calculation operation timing, for example every 55 seconds, has arrived, and when the calculation operation timing has arrived, the process moves to step n3.

In step n3, each of the wheel acceleration sensors 1a to 1d
The speed of each wheel is calculated from the detection results. step n
4, it is determined from the output of the switch 7 whether or not the brake pedal 30 is depressed, and if so, the process moves to step n5, and the maximum value of the respective wheel speeds determined in step n3 is determined as the estimated vehicle body speed. If not, the process moves to step n6, and the minimum value of the respective wheel speeds is set as the estimated vehicle speed Vsi.

After the estimated vehicle speed Vsi from which the influence of slip between the wheels and the road surface has been removed is obtained in steps n4 to n6, the process moves to step n7, where the acceleration α3 obtained in step m3 is integrated and the vehicle body speed Vsi is calculated. The speed Vs is determined. Once the parameters for the anti-skid control have been determined in this way, the process moves to step n8, where the braking oil pressure is controlled as will be described later. In step n9,
It is determined that the acceleration sensor 3 is abnormal, and if the determination result is abnormal, one warning light is turned on to notify the driver, and the estimated vehicle speed Vsi is substituted for the vehicle speed Vs. Self-safe processing such as

FIG. 12 is a flowchart for explaining in detail the braking oil pressure control operation in step n8.

When the anti-skid control operation is performed, step S1
In step S2, it is determined whether anti-skid control is currently being executed, and if not, in step S2,
It is determined whether the conditions for starting anti-skid control are satisfied. The control start condition is, for example, when the wheels 34a to 34d are locked, or when the wheel speed becomes equal to or less than the predetermined slip reference Lll.

When the anti-skid control start condition is satisfied, the process moves to step S3, where a pressure reduction flag for causing the wheel cylinders 33a to 33d to perform a pressure reduction operation is set in a predetermined memory area of the processing circuit 2, and the process proceeds to step s.
Move on to 4. If anti-skid control has already been performed in step s1, step s4 is performed directly.
Move to.

In step s4, it is determined whether the conditions for terminating the anti-skid control are satisfied.

This control termination condition is, for example, when the operation of the brake pedal 30 is released, or when the vehicle body speed Vs is 5.
km/h or less.

When the anti-skid control end condition is satisfied in step S4, and when the anti-skid control start condition is not satisfied in step S2, the process moves to step s18, and the actuators 13a to 13d
The three-position electromagnetic control valves 32a to 32d are set to the pressure increasing position, and anti-skid is not controlled. Therefore, when the brake pedal 30 is depressed, the master cylinder 3
The braking oil pressure generated in wheel cylinders 33a to 3
3d, and a normal braking operation is performed.

In step S4, if the anti-skid control termination condition is not satisfied, the process moves to step s5, where flags that control increases and decreases in the braking oil pressure of the wheel cylinders 33a to 33d are determined. At the start of the anti-skid control, the pressure reduction flag is set as shown in step s3, so the process moves to step 56. In step $6, it is determined whether or not to end the pressure reduction control. If not, in step s7, the friction coefficient μ
Pulse width control of the pressure reduction pulse is performed with a duty corresponding to , and pressure reduction control is performed in which the ratio between the pressure reduction output and the holding output is changed.

Further, when the pressure reduction control should be ended in step s6, that is, when the wheel speed starts to recover, the process moves to step s8, where a holding flag for keeping the braking oil pressure of the wheel cylinders 33a to 33d constant is set, and the process proceeds to step s8. Move to s9. Even when such anti-skid control operation is repeated and the holding flag has already been set in step s5, the process moves to step s9. In step s9, it is determined whether the holding end condition is satisfied, and if not, in step slo, the three-position electromagnetic control valves 32a to 32d are set to the holding position, holding control is performed, and then the operation is ended.

In step s9, if the holding end condition for determining that the wheel speed has not recovered is satisfied, in step sll a pressure increase flag for increasing the braking oil pressure in the wheel cylinders 33a to 33d is set, and in step s12 Move to. Further, when the pressure increase flag is already set in step s5, the process moves directly to step s12. In this step s12, it is determined whether the pressure increase end condition is satisfied or not, and if not, step s13
After the three-position electromagnetic control valves 32a to 32d are set to the pressure increase position and pressure increase control is performed, the operation ends.

As described above, this pressure increase control is performed based on the peak value of the wheel acceleration recovered by the pressure decrease control and the 1 friction coefficient μ set in step m4 or m6. The pressure increase end condition is, for example, when the pressure increase time determined by the wheel acceleration obtained when the wheel speed is restored has elapsed.

When the pressure increase end condition is satisfied in step S'12, the process moves to step s14, where a pulse pressure increase flag for gradually increasing the brake oil pressure in the wheel cylinders 33a to 33d is set, and the process moves to step s15. Further, when the pulse pressure increase flag has already been set in step S5, directly step s1
Move on to 5.

In step s15, it is determined whether the conditions for ending the pulse pressure increase control are satisfied, and if not, in step s16, the three-position electromagnetic control valves 32a to 32
The pulse pressure increase control of d is continued and the operation is completed. If the conditions for ending the pulse pressure increase control are satisfied in step s15, the pressure reduction flag is set in step s17, and then the process moves to step s7, where pressure reduction control is performed.

As described above, in the anti-skid control device according to the present invention,
Since the friction coefficient μ is determined based on the acceleration α3, which is the sum of the longitudinal acceleration α1 and the lateral acceleration α2 of the vehicle body, the friction coefficient μ may be incorrectly determined during sudden braking on high μ roads or sharp turns. It is possible to prevent this and achieve highly accurate anti-skid control.

Further, when the lateral acceleration α2 is larger than the longitudinal acceleration α1, the friction coefficient μ of the inside wheel is corrected to be lower by one step, so even if the turning force is large as in the case of sudden braking or sharp turning, Also, it is possible to perform highly accurate anti-skid control corresponding to the load sharing between the inner and outer wheels. This makes it possible to shorten the braking distance and ensure the stability of the vehicle body.

Note that in the above embodiment, when a sharp turn is determined,
Although the friction coefficient μ of the inner wheel was corrected to be one step lower, in another embodiment of the present invention, the outer wheel is also controlled with a friction coefficient one step lower in the same manner as the inner wheel.
Stability may be ensured.

Further, in the above-described embodiment, although it is determined that the vehicle body is turning when the lateral acceleration α2 of the vehicle body becomes larger than the longitudinal acceleration α1, as another embodiment of the present invention, it is determined that the vehicle body is turning The determination as to whether the vehicle is in the current state may be made based on other parameters such as the difference between the left and right wheel speeds.

Effects of the Invention As described above, according to the present invention, the coefficient of friction between the wheels and the road surface is determined based on the sum of the acceleration in the longitudinal direction and the acceleration in the lateral direction of the vehicle body, and the coefficient of friction between the wheels and the road surface is determined. When the acceleration in the longitudinal direction is greater than the acceleration in the longitudinal direction, the determined friction coefficient is corrected to a smaller value for the inner wheel when turning, so high accuracy is achieved that corresponds to the difference in load burden between the inner wheel and the outer wheel when turning. It is possible to perform effective anti-skid control, shorten the braking distance, and ensure the stability of the vehicle body.

[Brief explanation of drawings]

FIG. 1 is a functional block diagram for explaining the principle of an embodiment of the present invention, FIG. 2 is a block diagram showing the electrical configuration of an anti-skid control device in which the present invention is implemented, and FIG. 3 is a functional block diagram for explaining the principle of an embodiment of the present invention. FIG. 4 is a block diagram showing the electrical configuration of the acceleration sensor 3; FIG.
The figure is a diagram for explaining the measurement principle of the acceleration sensor 3, FIG. 6 is a graph for explaining the measurement principle of the acceleration sensor 3, and FIG. 7 is a waveform diagram for explaining the measurement principle of the acceleration sensor 3. Fig. 8 is a timing chart showing changes in acceleration during sudden braking layer turning and judgment results of friction coefficient μ, Section 9 is a flowchart for explaining the setting operation of friction coefficient μ, and Fig. 10 is anti-skid control operation. 11 is a timing chart for explaining the anti-skid control operation, and FIG. 11 is a flow chart for explaining the anti-skid control operation.
FIG. 2 is a flowchart for explaining in detail the braking oil pressure control operation. 1a to 1d...Wheel speed sensor, 2...Processing circuit,
3a, 3b...Acceleration sensor, 4...Anti-skid control circuit, 13a-13d...Actuator, 51
a, 51b...input processing section, 52-vehicle speed calculation section,
53...Friction coefficient determination section, 54.Anti-skid control section, 55..Wheel speed calculation section Box 4 Fig. 1 Fig. s 5 Fig. 6 Fig. 1c Fig. 1 Fig. 1c Fig. fig.

Claims (5)

[Claims] (1) Wheel speed detection means for detecting the rotational speed of the wheels; longitudinal acceleration detection means for detecting the longitudinal acceleration of the vehicle body; lateral acceleration detection means for detecting the lateral acceleration of the vehicle body; and the longitudinal acceleration detection means for detecting the longitudinal acceleration of the vehicle body. determining means for determining at least the coefficient of friction between the wheels and the road surface from the detection results of the means and the lateral acceleration detecting means, and correcting the result of the determination to a smaller value when the lateral acceleration is greater than the longitudinal acceleration; An anti-skid control device comprising: a control means for controlling a braking force of a wheel based on a detection result of the wheel speed detection means and a determination result of the determination means. (2) The anti-skid control device according to claim 1, wherein the determining means uses an added value of the acceleration in the longitudinal direction and the acceleration in the lateral direction to determine the friction coefficient. (3) wheel speed detection means for detecting the rotational speed of the wheels, acceleration detection means for detecting the acceleration of the vehicle body, turning detection means for detecting that the vehicle body is in a turning state, and from the detection results of the acceleration detection means. determining means that determines at least a coefficient of friction between the wheels and the road surface, responds to the detection result of the turning detection means, and corrects the determination result to a smaller value when the vehicle body is in a turning state; and the wheel speed detection An anti-skid control device comprising: control means for controlling braking force of a wheel based on a detection result of the means and a determination result of the determination means. (4) The anti-skid control device according to claim 3, wherein the turning detection means is a lateral acceleration detection means for detecting acceleration in the lateral direction of the vehicle body. (5) The anti-skid according to any one of claims 1, 2, 3, and 4, wherein the determining means performs the correction with respect to an inner wheel when turning. Control device.