JPH0771931B2 - Anti-skid controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid control device that controls the rotational speed of the wheels of an automobile during brake operation, and is particularly preferably applied to control for reducing the hydraulic pressure of hydraulic braking means.

2. Description of the Related Art An anti-skidding control device is a device that hydraulically controls a wheel slip ratio by hydraulic braking means so that a frictional braking force generated between a wheel and a road surface when the brake pedal is depressed is maximized. Here, when the traveling speed of the automobile is VS and the rotation speed of the wheels (hereinafter referred to as "wheel speed") is VW, the slip ratio S is defined by the formula (1).

When the driver rapidly depresses the brake pedal, the braking hydraulic pressure supplied to the hydraulic braking means for braking the rotation of the wheels rapidly increases. Due to the sudden increase in the braking hydraulic pressure, the wheel rotation speed is reduced, and the wheel speed becomes zero, resulting in a locked state. In this locked state, the braking distance increases and the steerability is lost.

Therefore, in order to prevent the wheels from becoming locked, the conventional anti-skidding control device performs pressure reduction control for reducing the braking hydraulic pressure supplied to the hydraulic braking means when the wheel speed approaches the locking state. By this pressure reduction control, the wheel speed is recovered, the friction braking force between the wheel and the road surface is increased, and the steerability is maintained. Then, when the wheel speed is sufficiently recovered, the pressure increasing control is performed again to increase the braking hydraulic pressure to the hydraulic braking means, and as described above, the slip rate S of the wheel is set to a value at which the highest braking force is exerted. Therefore, the hydraulic braking means is controlled by a combination of pressure increasing control, holding control and pressure reducing control.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional anti-skidding control device, for example, between the wheel and the road surface due to the change of the friction coefficient between the wheel and the road surface due to the change of the road surface state or the change of the traveling speed of the automobile. The control is also performed uniformly with respect to the change of the friction coefficient, and it cannot be said that the anti-skidding control is necessarily performed in the optimum state.

That is, on the high friction coefficient road, the braking hydraulic pressure at which the wheels are locked becomes higher than on the low friction coefficient road, so that in order to maintain the same slip ratio S, it is necessary to increase the wheel cylinder pressure. The same thing happens when the traveling speed of the automobile decreases.

FIG. 9 is a μ-S curve for explaining changes in the friction coefficient μ and the slip ratio S with respect to changes in the traveling speed of the automobile. It is understood that as the running speed of the vehicle decreases from the high speed region to the low speed region, the friction coefficient μ increases for the same slip ratio as shown by lines l11 to l13 in FIG. Therefore, since the friction coefficient μ between the wheel and the road surface increases as the traveling speed of the automobile decreases, the braking hydraulic pressure at which the wheel starts to lock increases. Therefore, the anti-skidding control device needs to increase the braking hydraulic pressure supplied to the hydraulic braking means in order to maintain the slip ratio S that exhibits the highest braking force.

However, as the wheel cylinder pressure supplied to the hydraulic braking means increases, the hysteresis possessed by the hydraulic braking means also increases. FIG. 10 is a graph showing that the hysteresis increases, and is a graph for explaining the relationship between the wheel cylinder pressure and the braking torque generated by the hydraulic braking means. That is, the wheel cylinder pressure is line l14.
The braking torque, that is, the torque applied in the direction opposite to the rotation direction of the wheel because the hydraulic braking means reduces the rotation of the wheel, also increases. The wheel cylinder pressure is
For example, even if the wheel cylinder pressure is reduced to P2 after reaching P1 along the line l14, the braking torque is maintained at T1, and the braking torque does not decrease according to the reduction of the wheel cylinder pressure. That is, even if the wheel cylinder pressure is reduced from the pressure P1 to the pressure P2, the operating point of the hydraulic braking means is the line l1.
5 The braking torque does not decrease just by moving up, and T1 is maintained. When the wheel cylinder pressure is further reduced from P2, the operating point moves along the line 16 and the braking torque begins to decrease. Thus, there is a hysteresis phenomenon between the wheel cylinder pressure and the braking torque. Further, when the wheel cylinder pressure is increased along the line 14 and the pressure reduction is started at the pressure P3 smaller than the pressure P1, the operating point of the hydraulic braking means is only moving on the line l17 until the pressure P4, and the braking torque is increased. Does not decrease and maintains T2. When the wheel cylinder pressure is further reduced from the pressure P4, the operating point moves along the line l16, and the braking torque can be reduced.

Therefore, even if the pressure reduction control is performed by the same pressure for the hydraulic braking means, due to the wheel cylinder pressure at the start of pressure reduction, the size of the dead region differs as shown by lines l15 and l17, Will have different effects.

Therefore, especially on a high friction coefficient road, there is a problem that due to the above-mentioned hysteresis, the amount of pressure reduction to the hydraulic braking means is insufficient, the decrease in wheel speed is significantly increased, and the braking distance is increased. .

Therefore, an object of the present invention is to provide an anti-skid control device that avoids the shortage of the pressure reduction amount due to the above-mentioned hysteresis, prevents the increase of the braking distance, and prevents the wheel speed from significantly decreasing.

Means for Solving the Problems The present invention is an anti-skid control device that increases or decreases the hydraulic pressure of hydraulic braking means for a wheel to increase the friction coefficient between the wheel and the road surface. The anti-skidding control device is characterized in that a large amount of pressure reduction is selected at the time of pressure reduction.

Further, the present invention changes the hydraulic pressure of the hydraulic braking means by a periodic pulse, and when reducing the pressure after the number of pulses of the pulse pressure increase continues to be a predetermined value, the pressure reduction duration of the pulse pressure reduction is increased by the pulse pressure increase. When the number of pulses is less than the predetermined value, the decompression duration of the pulse decompression is selected to be longer.

Furthermore, the present invention is an anti-skid control device that increases or decreases the hydraulic pressure of the hydraulic braking means for a wheel to increase the friction coefficient between the wheel and the road surface. The anti-skidding control device is characterized in that it is selected to be larger than the pressure reduction amount selected when the vehicle speed is equal to or higher than a predetermined vehicle speed.

Operation According to the present invention, the anti-skid control operation for controlling the hydraulic pressure of the hydraulic braking means provided in association with each wheel so as to increase or decrease the hydraulic pressure between the wheels and the road surface is performed. Therefore, the larger the hydraulic pressure of the hydraulic braking means at the time of pressure reduction, the larger the pressure reduction amount is selected.

Therefore, due to the hysteresis characteristic of the hydraulic braking means, the hydraulic pressure of the hydraulic braking means is large at the start of pressure reduction, and even if pressure reduction control is performed, it is not possible to obtain a reduction in braking torque by a value corresponding to the amount of pressure reduction. At this time, the pressure reduction amount is selected to be large so that the corresponding torque can be obtained. Therefore, regardless of the hydraulic pressure of the hydraulic braking means at the start of the pressure reduction, the braking torque can be reduced corresponding to the pressure reduction amount. it can.

According to the invention, when pulse pressure increase is performed in which the hydraulic pressure of the hydraulic braking means is changed by periodical pulses, the greater the number of pressure increase pulses until the time of pressure reduction, the greater
Since the hydraulic pressure of the hydraulic braking means is large, when the pressure reducing control is performed after the number of pulses for increasing the pressure is equal to or more than the predetermined value, the pressure reducing duration is less than the predetermined value when the pulse pressure is increased. Choose longer than the decompression duration.

Therefore, due to the hysteresis characteristic of the hydraulic braking means, the hydraulic pressure of the hydraulic braking means is large at the start of pressure reduction, and even if pressure reduction control is performed, it is not possible to obtain a reduction in braking torque by a value corresponding to the amount of pressure reduction. At this time, the pressure reduction amount is selected to be large so that the corresponding torque can be obtained. Therefore, regardless of the hydraulic pressure of the hydraulic braking means at the start of the pressure reduction, the braking torque can be reduced corresponding to the pressure reduction amount. it can.

Further, according to the present invention, in performing the anti-skid control, the smaller the vehicle speed at the time of pressure reduction, the larger the friction coefficient between the wheel and the road surface, and the larger the hydraulic pressure of the hydraulic braking means. Therefore, the pressure reduction amount is selected to be larger than that when the vehicle speed is high.

Therefore, in this case, due to the hysteresis characteristic of the hydraulic braking means, the hydraulic pressure of the hydraulic braking means at the start of pressure reduction is large, and even if the pressure reduction control is performed, it is not possible to obtain a reduction in the braking torque by a value corresponding to the pressure reduction amount. When
A large amount of pressure reduction is selected so that the corresponding torque can be obtained, and the braking torque can be reduced corresponding to the amount of pressure reduction regardless of the magnitude of the hydraulic pressure of the hydraulic braking means at the time of starting the pressure reduction. it can.

Embodiment FIG. 1 is a block diagram of an anti-skidding control device according to an embodiment of the present invention. The anti-skidding control circuit 1 is
For example, it is provided in the passenger compartment or the rear trunk. The wheel speed sensors 2a to 2d are provided for each wheel and are sensors for detecting the wheel speed. Wheel speed sensor 2a ~
2d is, for example, a detection plate made of a ferromagnetic material having a large number of notches and projections formed at equal intervals in the circumferential direction is fixed to the wheel shaft, and is provided near the circumference of the detection plate, for example, an electromagnetic wave. The pickup is configured to detect a signal having a frequency proportional to the wheel speed. Wheel speed sensor 2a ~
The wheel speed signal detected by the 2d is the waveform shaping circuit 3a-
After being shaped into a pulse signal by 3d, it is given to processing circuits 4a and 4b realized by a micro computer or the like.

The switch 2e is, for example, a brake switch that sends out a signal indicating that the brake pedal is stepped on. The output signal of the switch 2e is given to the level conversion circuit 3e, and the signal level is a voltage level suitable for the anti-skidding control circuit 1. Is converted to. The output of the level conversion circuit 3e is sent to the processing circuits 4a and 4b.

The processing circuit 4a includes a wheel speed sensor 2a provided on the right front wheel.
Also, after determining the respective wheel speeds based on the wheel speed signal from the wheel speed sensor 2b provided on the left rear wheel, the larger wheel speed is transferred to the processing circuit 4b via the signal line sl1. Similarly, the processing circuit 4b calculates the respective wheel speeds based on the wheel speed signals from the wheel speed sensor 2c provided on the left front wheel and the wheel speed sensor 2d provided on the right rear wheel, and then the larger one is obtained. The wheel speed of the is transferred to the processing circuit 4a via the signal line sl2.

From the transferred wheel speeds and the wheel speeds calculated in the respective processing circuits, the processing circuits 4a and 4b estimate, for example, the wheel speed of the higher wheel speed as the vehicle speed. An anti-skid calculation is performed based on the vehicle speed and each wheel speed to control the wheel cylinder oil pressure.

The control signals output from the processing circuits 4a and 4b are power-amplified by the solenoid drive circuits 5a to 5d, and then the switching valves 6a to 6a.
It is given to the solenoid coil provided in 6d.
Solenoid relay drive signals sent from the processing circuits 4a and 4b are given to the AND circuit 7, the output of which is amplified by the solenoid relay drive circuit 8 and then given to the relay coil 9a of the solenoid relay 9. . When the contact 9b becomes conductive, the battery voltage of the battery 11 is applied to the other ends of the solenoid coils incorporated in the switching valves 6a to 6d via the contact 9b and the connection point 10.

The motor 12a is a motor for driving a hydraulic pump, and when the motor relay 13 is turned on, electric power is supplied from the battery 11 and control hydraulic pressure is generated. The motor drive signals from the processing circuits 4a and 4b are given to the logical sum circuit 14, and are processed by the processing circuits 4a and 4b.
When any of the motor drive signals from b goes high, the motor relay drive circuit 15 turns on and the motor relay 13
Also turn on. When the lamp drive signal from the processing circuit 4a or 4b is given to the lamp drive circuit 16, the alarm lamp 17 is turned on. The alarm lamp 17 lights up when any abnormality occurs in the anti-skidding control device, and warns the driver.

The positive electrode of the battery 11 is connected to the power circuit 19 via the power switch 18.
Connected to. The power supply circuit 19 converts the battery voltage into a desired voltage and then supplies the converted voltage to each circuit. Further, the negative electrode of the battery 11 is connected to the vehicle body, and so-called body grounding is performed.

FIG. 2 is a block diagram for explaining a hydraulic path of the anti-skidding control device according to the embodiment of the present invention. By operating the brake pedal 20, the master cylinder
The hydraulic pressure generated in 21 is applied to the wheel cylinders 22a to 22d via the switching valves 6a to 6d, and reduces the rotation speed of the wheels 23a to 23d.

During the anti-skid control, the braking hydraulic pressure generated by driving the motor 12a is supplied to the P valves 24b and 24d.
When the pressure increase control signal is sent from the anti-skidding control circuit 1 to the switching valve 6a, the braking hydraulic pressure generated by the hydraulic pressure reduction 12 is applied to the pipeline 25.
It is supplied to the wheel cylinder 22a via a and 26a. Further, when the pressure reduction control signal is sent to the switching valve 6a, the hydraulic pressure in the wheel cylinder 22a is returned to the reservoir tank 28 via the pipelines 26a, 27, and the hydraulic pressure in the wheel cylinder 22a is reduced. Further, when the hold control signal is sent to the switching valve 6a, all of the pipelines 25a, 26a and 27 are shut off, and the hydraulic pressure in the wheel cylinder 22a is maintained constant. The above switching is the same for the switching valves 6b to 6d.

The P valves 24b and 24d are valves for limiting the gradient of the braking hydraulic pressure supplied to the wheel cylinders 22b and 22d of the rear wheels from a predetermined value or more.

FIG. 3 is a functional block diagram for explaining the correction calculation of the pressure reducing time of the pulse pressure reducing control in the processing circuits 4a and 4b. As already mentioned, the hysteresis increases as the wheel cylinder pressure in the hydraulic braking means increases. Therefore, in the present embodiment, among the control signals output to the hydraulic braking means, the number of output times of the pulse pressure increase control signal or the total pressure increase time of the pulse pressure increase control signal is detected,
The wheel cylinder pressure is estimated from the detected value. Here, the "pulse pressure increase control signal" is a signal for performing pressure increase control only during the period in which the pulse signal is being output, and the other holding control. Further, the “pulse pressure reduction control signal” is a signal that performs pressure reduction control only during the period in which the pulse signal is output and the other that performs holding control.

Therefore, in this embodiment, the pulse pressure reducing control signal output after the number of times the pulse pressure increasing control signal is output or the total pressure increasing time of the pulse pressure increasing control signal exceeds a predetermined value has a hysteresis that the hydraulic braking means has. A correction time for canceling out is added, and the pressure reduction duration of the pulse pressure reduction is lengthened.

In FIG. 3, a wheel speed calculated based on a wheel speed signal of one of the wheel speed sensors 2a to 2d and a wheel acceleration which is a time change rate of the wheel speed are introduced into a control unit 31,
Anti-skidding operation is performed. The decompression time correction unit 32 is a unit that determines whether or not the correction time should be added when the pulse decompression control signal is output to the hydraulic braking means.
The control signal output to the hydraulic braking means is input to detect the number of times the pulse pressure increase control signal is output or the total pressure increase time of the pulse pressure increase control signal. Then, when the pressure reduction request signal is sent from the control unit 31 to the pressure reduction time correction unit 32, the pressure reduction time correction unit 32 causes the control unit 31 to correct the pressure reduction control signal when the detected value is equal to or greater than a predetermined value. A correction signal to which is added is output. In this way, the control unit 31 outputs the pulse pressure reducing control signal to which the correction time for canceling the hysteresis of the hydraulic braking means is added.

FIG. 4 is a timing chart for explaining the operation of this embodiment. 4 (1) shows changes in wheel speed, FIG. 4 (2) shows changes in wheel acceleration, FIG. 4 (3) shows changes in wheel cylinder pressure, and FIG. 4 (4) shows changes in control signal. The output states are shown respectively. In addition, in FIG. 4 (2), G means gravitational acceleration. In Fig. 4 (1), the line
l1 represents changes in wheel speed, and line l2 represents processing circuits 4a and 4b.
Represents the change in the vehicle speed calculated within the line, and the line l3 represents a speed 10% lower than the vehicle speed (hereinafter referred to as "slip reference speed"), which is the output reference of the control signal in the anti-skidding control calculation. is there.

As shown in FIG. 4 (1), at time t1, the wheel speed falls below the slip reference speed, and the wheel acceleration shown in FIG. 4 (2) falls below the pressure reduction reference acceleration G ₁ which is the output judgment of the pulse pressure reduction control signal. When turned, a pulse pressure reduction control signal is output as shown in FIG. 4 (4). However, the number of output times of the pulse pressure increase control signal output at time t1 is 4 times or less, which is the reference time for adding the correction time to the pulse pressure decrease control signal, so the output time T of the pulse pressure decrease control signal is corrected. No time is added. The same applies to the pulse pressure reduction control signal output at time t2.

However, when the pulse pressure increase control signal is output six times before the time t3, the correction time ΔT1 is added to the output time T of the normal pulse pressure decrease control signal and is output to the hydraulic braking means.

In the embodiment described above, the correction time is added when the number of times the pulse pressure increase control signal is output exceeds the predetermined number of times, but the total pressure increase time of the pulse pressure increase control signal is equal to or longer than the predetermined time. The correction time may be added in some cases.

FIG. 5 is a functional block diagram of another embodiment for explaining the correction calculation of the pressure reduction time of the pulse pressure reduction control signal in the processing circuits 4a and 4b. The wheel speed and the wheel acceleration, which is the time change rate of the wheel speed, are introduced into the control unit 41. The control unit 41 performs anti-skidding control calculation from the wheel speed and the wheel acceleration, and outputs a control signal to the hydraulic braking means. The control unit 41 further sends the vehicle speed calculated in the control unit 41 to the decompression time correction unit 42. The decompression time correction unit 42 determines whether or not the vehicle speed is less than a predetermined speed, and if it is less than this, outputs a correction signal to the control unit 41. When the correction signal is input, the control unit 41 adds a correction time to the pulse pressure reduction control signal and outputs it to the hydraulic braking means.

FIG. 6 is a schematic flow chart of the anti-skid control in the processing circuits 4a and 4b of this embodiment. The processing of each step will be described below. Note that the control for the right front wheel 23a will be described below to simplify the description, but the control for the other wheels is exactly the same.

When the anti-skidding control is started in the processing circuit 4a,
First, in step s1, it is judged whether or not the anti-skidding control is currently being executed. If it is under control, it is not necessary to judge whether or not the anti-skidding control is started, so that the process proceeds to step s4. If the anti-skidding control is not performed in step s1, the process proceeds to step s2, and it is determined whether or not the condition for starting the anti-skidding control is satisfied. As the anti-skidding control start condition, for example, it is determined whether or not the wheel is locked, or the wheel speed is lower than a predetermined rotation speed and the wheel deceleration (negative wheel acceleration) is higher than a predetermined deceleration. Then, when the condition for starting the anti-skidding control is satisfied, the process proceeds to step s3, and a pressure reducing flag for causing the wheel cylinder to perform the pressure reducing operation is set in a predetermined memory area of the processing circuit 4a.

If it is determined in step s2 that the conditions for starting the anti-skidding control are not satisfied, the process proceeds to step s19, in order to directly transmit the hydraulic pressure generated in the master cylinder by the depression of the brake pedal to the wheel cylinders. The switching valve 6a is set to the pressure increasing position.

At step s4, the condition for ending the anti-skidding control is judged, and for example, when the foot is released from the brake pedal,
Alternatively, if the vehicle speed falls below 5 km / h, the anti-skidding control is released. If the anti-skidding control end condition is not met in step s4, step s5
Then, the determination of the flag for increasing / decreasing the wheel cylinder oil pressure is performed.

At step s5, the flag set in the memory area is determined, and the process is moved to each control of pressure reduction, holding, pressure increase, or pulse pressure increase. Further, in step s5, the total calculation of the number of times the pulse pressure increase control signal is output or the pressure increase time of the pulse pressure increase control signal is performed, and the result is stored in the memory.

When the anti-skidding control is started, the pressure reduction flag is set in step s3, so the process proceeds to step s6,
Further, in step s7, the pulse pressure reduction control of the wheel cylinder 22a is performed. In step s6, the condition for ending the pulse pressure reduction control, that is, the acceleration G ₂ determined by the wheel acceleration
When it starts to show the sign that the wheel speed is recovering, go to step s8. In step s8, wheel cylinder 22a
A flag is set to keep the hydraulic pressure of the constant. When the holding flag is set, the process proceeds from step s9 to step s10, a holding control signal is output to the switching valve 6a, and the wheel cylinder pressure is kept constant.

In step s9, the wheel acceleration exceeds the acceleration G _2, then it falls below the acceleration G _2, holding end condition is satisfied. When the holding end condition is satisfied, the process proceeds from step s9 to step s11, and a pressure increase flag for increasing the oil pressure of the wheel cylinder 22a is set. The output time of the control signal for increasing the pressure of the wheel cylinder 22a is set by the value of the wheel acceleration after the pressure reduction. Then, from step s12 to step s
Proceeding to 13, the hydraulic pressure in the wheel cylinder 22a is increased. When the pressure increase setting time ends, the process proceeds from step s12 to step s14, and the pulse pressure increase flag for gently increasing the oil pressure in the wheel cylinder 22a is set. Then, from step s15 to step s16, a pulse pressure increase control signal having a predetermined time width is sent from the processing circuit 4a to the solenoid drive circuit 5a, and the switching valve 6a has the pulse width given by the solenoid drive circuit 5a. The pressure increase control is performed for a corresponding time. In step s15, if the condition for ending the pulse pressure increase, that is, if the wheel starts to lock, or if the wheel speed falls below the slip reference speed and the wheel acceleration falls below the depressurization reference acceleration G ₁ , steps s15 to s17
Then, the pulse pressure reduction flag is set.

When the pulse pressure reduction flag is set, the process proceeds to step s18, and the correction calculation of the output time of the pulse pressure reduction control signal described later is performed. When the correction calculation of the pulse pressure reducing control signal is completed, the process proceeds to step s7, and the pulse pressure reducing control signal is output to the hydraulic braking means.

FIG. 7 is a processing flow chart for correcting the output time of the pulse pressure reduction control signal according to the number of times the pulse pressure increase control signal is output in this embodiment. In step m1,
It is determined whether or not the counter C1 that counts the number of times the pulse pressure increase control signal is output exceeds the pulse pressure increase determination reference number K1 (for example, 9). If it exceeds, the process proceeds from step m1 to step m2, and the first correction time ΔT1 is added to the contents of the memory M1 in which the pulse pressure reduction control time is set. For example, 8 msec is selected as the first correction time ΔT1.
If the value of the counter C1 does not exceed the first pulse pressure increase determination reference number K1 in step m1, the process proceeds to step m3
Pulse pressure increase determination reference number K2 (for example, 4). When the value of the counter C1 exceeds the reference number K2, the process proceeds to step m4, and the second correction time ΔT2 is added to the contents of the memory M1. For example, 4 msec is selected as the second correction time ΔT2.

If the value of the counter C1 does not exceed the reference number K2 in step m3, the process proceeds to step m5, and the correction calculation is not performed on the content of the memory M1 in which the output time of the pulse pressure reducing control signal is stored.

FIG. 8 is a processing flow chart for correcting the output time of the pulse pressure reducing control signal according to the vehicle speed, which is another embodiment of the present invention. In step n1, it is judged whether or not the vehicle body speed exceeds the high speed judgment speed KV1, and if it exceeds, the routine proceeds to step n2, where the output time of the pulse pressure reducing control signal is stored in the memory M2, The correction time ΔT3 of is reduced. As the third correction time, for example, 8 mse
c is selected. If the vehicle body speed does not exceed the high speed determination speed KV1 in step n1, the process proceeds to step n3, and it is further determined whether or not the vehicle body speed is lower than the low speed determination speed KV2. When the speed is lower than the low speed judgment speed KV2, the process proceeds to step n4, and the fourth correction time ΔT4 is added to the contents of the memory M2. For example, 4 msec is selected as the fourth correction time ΔT4.

If the vehicle speed is not lower than the low speed judgment speed KV2 at step n3, that is, if the vehicle speed is between the low speed judgment speed KV2 and the high speed judgment speed KV1, the correction calculation of the output time for the pulse pressure reduction control signal is performed at step n5. Is not done.

Thus, in the anti-skidding control device according to the present invention,
When the pulse pressure increase control signal is output many times, or when the vehicle speed is low and the friction coefficient between the wheel and the road surface is considered to be high, the hydraulic pressure of the hydraulic braking means is increasing, and the hysteresis characteristic Since the dead region at the time of pressure reduction is expected to be large, the output time of the pulse pressure reduction control signal is corrected to be long. Therefore, it is possible to perform the optimum control in consideration of the influence of the hysteresis characteristic of the hydraulic braking means.

In the above-described embodiment, the output time of the pulse pressure reducing control signal is corrected by providing two determination criteria, but more determination criteria may be provided for the correction, and the pulse pressure boosting control is performed. If the correction calculation is performed in proportion to the total number of times the signal is output or the pressure increasing time, smoother control can be realized.

As described above, according to the present invention, when the anti-skidding control operation is performed, the larger the hydraulic pressure of the hydraulic braking means at the time of pressure reduction, the larger the pressure reduction amount is selected. Therefore, the hydraulic braking at the time of pressure reduction is performed. The higher the pressure of the means, the larger the dead area due to the hysteresis characteristic of the hydraulic braking means, and the smaller the reduction amount of the braking torque even if the same pressure is reduced, the longer the decompression time is corrected. And then
It is possible to determine the optimum pressure reduction amount by compensating for the hysteresis characteristic of the hydraulic control means.

Further, according to the present invention, in performing the anti-skidding control operation, when it is determined that the hydraulic pressure of the hydraulic braking means is large from the number of pulses of pulse pressure increase until the pressure reduction start time,
Since the depressurization duration is selected to be long, it is possible to determine the optimum depressurization amount by compensating for the hysteresis characteristic of the hydraulic braking means.

Further, according to the present invention, when the vehicle body speed at the time of depressurization is small and the friction coefficient between the wheel and the road surface is large, the amount of depressurization is selected to be large when the hydraulic pressure of the hydraulic braking device is large. By compensating for the hysteresis characteristic, the optimum pressure reduction amount can be determined.

[Brief description of drawings]

FIG. 1 is a block diagram of an anti-skidding control device according to an embodiment of the present invention, FIG. 2 is a block diagram for explaining a hydraulic path of this embodiment, and FIGS. 3 and 5 are processing circuits 4
Functional block diagrams for explaining the correction calculation of the pressure reduction time of the pulse pressure reduction control signals in a and 4b, FIG. 4 is a timing chart for explaining the operation of this embodiment, and FIG. 6 is the processing of this embodiment. FIG. 7 is a schematic flow chart of the anti-skidding control in the circuits 4a and 4b, and FIG. 7 is a process flow chart for correcting the output time of the pulse pressure reduction control signal according to the output frequency of the pulse pressure increase control signal in this embodiment.
FIG. 8 is a processing flow chart in the case where the output time of the pulse pressure reducing control signal is corrected and calculated according to the vehicle speed in another embodiment of the present invention, and FIG. 9 is a friction coefficient μ and slip with respect to changes in the traveling speed of the automobile. A μ-S curve for explaining the change in the ratio S, and FIG. 10 is a graph for explaining the relationship between the wheel cylinder pressure and the braking torque generated by the hydraulic braking means. 1 ... Anti-skid control circuit, 2a-2d ... Wheel speed sensor, 4a, 4b ... Processing circuit, 5a-5d ... Solenoid drive circuit, 6a-6d ... Switching valve, 8 ... Solenoid relay drive circuit, 9 ...... Solenoid relay, 11 …… Battery, 12 ……
Hydraulic power source, 13 …… Motor relay, 15 …… Motor relay drive circuit, 19 …… Power supply circuit, 21 …… Master cylinder, 22a
~ 22d …… Wheel cylinder

Claims (3)

[Claims] 1. An anti-skid control device for increasing / decreasing a hydraulic pressure of hydraulic braking means for a wheel to increase a friction coefficient between a wheel and a road surface. An anti-skidding control device characterized by selecting a large amount of decompression. 2. The pressure reduction duration of pulse pressure reduction is pulse increased when the pressure change of the hydraulic braking means is changed by a periodic pulse and the pressure is reduced after the pulse number of the pulse pressure increase continues to a predetermined value. 2. The anti-skidding control device according to claim 1, wherein the pulse reduction pressure is selected to be longer than the pressure reduction duration when the number of pulses is less than the predetermined value. 3. An anti-skid control device for increasing or decreasing the hydraulic pressure of hydraulic braking means for a wheel so as to increase a friction coefficient between the wheel and a road surface. An anti-skid control device, characterized in that the pressure reduction amount is selected to be greater than a predetermined vehicle speed or higher.