JPH01309865A - Device for controlling anti-skid - Google Patents

Abstract

PURPOSE:To prevent the vibration of a vehicle body accompanying the variation of oil pressure by detecting the peak value in the rise in wheel speed at the time of braking and preventing the lowering of the friction braking force of a friction braking means for a certain time from the point of time of detecting the peak value. CONSTITUTION:When a brake pedal 20 is stepped in, oil pressure generated in a master cylinder 21 is given to a plurality of wheel cylinders 22a-22d via a plurality of actuators 6a-6d to lower the rotating speed of a plurality of wheels 23a-23d. As the braking oil pressure of a motor 12 is fed to the master cylinder 21, each of the actuators 6a-6d is controlled by an anti-skid control circuit 1 to control the rotating speed of each of the wheels 23a-23d. In this case, the peak value in the rise in wheel speed at the tie of braking is detected, and the lowering of the friction braking force of each wheel cylinder 22a-22d is prevented for a certain time from the point of time of detecting the peak value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an anti-skid control device that prevents vibrations in wheel speed that occur on roads with high friction coefficients.

Conventional technology An anti-skid control device is a device for preventing a decrease in braking ability and steering ability caused by a lock-like R of the wheels (a condition in which the rotational speed of the wheels is almost zero) during sudden braking. Then, the slip rate of the wheels is calculated based on the vehicle's running speed (hereinafter referred to as ``vehicle speed'') and the rotational speed of the wheels (hereinafter referred to as ``wheel speed''), and the slip rate at which the wheels exert the highest braking force is determined. (For example, 10% to 20
This is a device that hydraulically controls the braking device of each wheel so that

When the brake pedal is strongly pressed while driving, the oil pressure inside the wheel cylinder that applies braking force to the braking device installed on each wheel increases, and the wheel speed decreases.An anti-skid control device is installed on each wheel. The wheel speeds are calculated based on the wheel speed signals from the wheel speed sensors provided, and the vehicle speed is estimated from these wheel speeds. Then, when the wheel deceleration (negative wheel acceleration) determined from the wheel speed and the slip rate determined from the wheel speed and vehicle body speed exceed a predetermined value, anti-skid control is started. When the anti-skid control starts, the anti-skid control device reduces the hydraulic pressure in the wheel cylinder and restores the wheel speed in order to prevent the wheels from becoming locked. After the pressure is reduced, when the wheel speed begins to show signs of recovery, the anti-skid control device outputs a control signal to gradually increase the pressure in the wheel cylinder.

Then, when the hydraulic pressure inside the wheel cylinder increases, the wheel speed starts to decrease again. If the wheel speed decreases significantly, the pressure reduction operation is performed again and the wheel speed starts to recover. On roads with a high friction coefficient, the wheel speed recovers quickly after the pressure reduction operation, and the wheel speed oscillates greatly. If the wheel speed fluctuates significantly, the pressure will be reduced, and this pressure reduction will cause the wheel speed to oscillate again.

This vibration causes the M-control of pressure reduction and pressure increase to be repeated, which causes the vehicle body to vibrate, resulting in extremely poor ride comfort.

The above-mentioned wheel speed vibration phenomenon will be explained in more detail as follows. FIG. 8 shows the relationship between wheel speed and wheel cylinder oil pressure when vibration occurs in wheel speed in conventional anti-skid control. It is a time chart for explaining Section A. When the accelerator pedal is depressed, the oil pressure in the wheel cylinder increases and the wheel speed decreases. Then, when the anti-skid control start condition is satisfied at time tll, the anti-skid control device performs a pressure reduction operation, and the wheel cylinder oil pressure decreases. Then, the decrease in wheel speed is suppressed and recovery begins thereafter.

The anti-skid control device detects signs of recovery and gradually increases the wheel cylinder oil pressure.

On roads with high friction coefficients, the wheel speed recovers quickly and the wheel speed oscillates significantly. Therefore, at time t13, the anti-skid control device again performs a pressure reduction operation to suppress a decrease in wheel speed. Thereafter, the anti-skid control device operates at time t14. t1
5, the pressure reduction operation is performed and the wheel speed exhibits an oscillating phenomenon.

In order to prevent the above-mentioned wheel speed vibration phenomenon, conventionally, after the wheel speed has recovered, for example, after time t12 in FIG. 8(1), a pressure reduction operation is difficult to be performed. That is, unnecessary pressure reduction operations are avoided by setting the level of wheel deceleration, which is one of the criteria for starting the pressure reduction operation fF at time t13, to be larger.

Problems to be Solved by the Invention As mentioned above, even if the level of wheel deceleration, which is the condition for starting a pressure reduction operation for a certain period of time after the wheel speed has recovered, is set high, if the fluctuation in wheel speed is large, There is a risk of unnecessary pressure reduction operation being performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an anti-skid control device that effectively prevents wheel speed vibrations that occur on roads with a high friction coefficient after a pressure reduction operation.

Means for Solving the Problems The present invention provides anti-friction braking means for controlling the slip rate between the wheels and the road surface based on the output from the wheel speed detection means so that the frictional force between the wheels and the road surface increases. The skid control device includes means for detecting the peak value of the wheel speed while the wheel speed is increasing during braking in response to the output of the wheel speed detection means; The anti-skid control device is characterized in that it includes means for preventing a decrease in the frictional braking force in the braking means for a predetermined time from the time of detection.

Further, the present invention includes a means for detecting vehicle speed, a wheel speed detecting means, a peak value detecting means, and an output from the vehicle speed detecting means, and the wheel speed decreases after the peak value is detected within the predetermined time. The anti-skid control device is characterized in that when the difference between the wheel speed and the vehicle body speed exceeds a predetermined value, the friction braking force of the friction braking means is reduced.

In the present invention, during anti-skid control, the peak value when the wheel speed increases after the pressure reduction operation and starts to decrease is detected, and the braking means provided at each wheel is activated for a predetermined time from the peak value. prevents a decrease in frictional braking force.

Further, in the present invention, when the wheel speed after detecting the peak value decreases by a predetermined value or more, the frictional braking force by the braking means is decreased by degrees.

Embodiment FIG. 1 is an electrical block diagram of an anti-skid control device which is an embodiment of the present invention. The anti-skid control circuit 1 is provided, for example, in a vehicle interior or a rear trunk. The wheel speed sensors 2a to 2d are provided for each wheel, and are sensors for detecting the rotational speed of the wheel, that is, the wheel speed. The wheel speed sensors 2a to 2d are, for example, a detection type made of a ferromagnetic material in which a large number of notches and protrusions are formed at equal intervals in the circumferential direction, and are fixed to the wheel shaft, and a detection plate is mounted near the circumference of the detection plate. An electromagnetic pickup provided detects a signal with a frequency proportional to the wheel speed. The wheel speed signals detected by the wheel speed sensors 2a to 2d are waveform-shaped into pulse signals by waveform shaping circuits 3a to 3d, and then provided to processing circuits 4a and 4b realized by a microcomputer or the like.

The switch 2e is, for example, a flake switch that sends out a signal indicating that the brake pedal has been depressed, and the output signal of the switch 2e is given to a level conversion circuit 3e, so that the signal level is adjusted to a voltage that is compatible with the anti-skid control circuit 1. converted to level. The output of the level conversion circuit 3e is sent to processing circuits 4a and 4b.

The processing circuit 4a includes a wheel speed sensor 2a attached to the front right wheel and a wheel speed sensor 2 attached to the rear left wheel.
After determining the respective wheel speeds on the basis of the wheel speed signals from b, the higher 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 attached to the left front wheel and the wheel speed sensor 2d attached to the right rear wheel, and then selects the larger one. The wheel speed is transferred to the processing circuit 4a via the signal line s12.

The processing circuits 4a and 4b estimate, for example, the larger wheel speed from the transferred wheel speeds and the wheel speeds calculated within each processing circuit as the controlled vehicle body speed. Anti-skid control calculations are performed based on this controlled vehicle speed and each wheel speed, and wheel cylinder oil pressure is controlled.

The control signals output from the processing circuits 4a and 4b are power amplified by the solenoid drive circuits 5a to 5d, and then applied to the solenoid coils provided in the actuators 6a to 6d. The solenoid relay drive signals sent from the processing circuits 4a and 4b are given to an AND circuit 7, whose output is power amplified by a solenoid relay drive circuit 8, and then sent to the solenoid relay relay coil 9.
given to a. 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 actuators 6a to 6d via the contact 9b and the connection point 1o.

The motor 12 is a motor for driving a hydraulic pump, and when the motor relay 13 is turned on, power is supplied from the battery 11 and control hydraulic pressure is generated.

The motor drive signals from the processing circuits 4a, 4b are given to the OR circuit 14, and when the motor drive signal from either of the processing circuits 4a, 4b becomes high level, the motor relay drive circuit 15 is turned on, and the motor relay 13 is turned on. Also turns on. When a lamp drive signal from the processing circuit 4a or 4b is applied to the lamp drive circuit 16, the alarm lamp 17 is turned on. The warning lamp 17 lights up when any abnormality occurs in the anti-skid control device to alert the driver.

A positive electrode of the battery 11 is connected to a power supply circuit 19 via a power switch 18 . The power supply circuit 19 converts the battery voltage into a desired voltage, and then supplies the converted voltage to each circuit.

FIG. 2 shows an anti-skid system (
FIG. 3 is a plot diagram for explaining a hydraulic path of the ear device.

The hydraulic pressure generated in the master cylinder 21 by pressing the brake pedal 20 is applied to the actuators 6a to 6d.
is applied to the wheel cylinders 22a to 22d via
The rotational speed of the wheels 23a to 23d is reduced.

During actuator control, the braking oil pressure generated by the motor 12 is supplied to the master cylinder 21,
Anti-skid control circuit 1 to actuators 6a to 6
By the control signal given to d, the wheel cylinder 2
2a to 22d (controls the brake oil pressure 3 supplied to control the rotation speed of the wheels 23a to 23d. P, pulp 2
4b and 24d are rear wheel cylinders 22b and 22d
This valve limits the upward slope when the hydraulic pressure supplied to the cylinder exceeds a predetermined value.

FIG. 3 is a functional block diagram for explaining the present invention in detail. The vibration countermeasure means 30 responds to the outputs of the anti-skid control command and the wheel speed recovery determination means 31 which detects a peak value from which the pressure reduction operation command wheel speed recovers from the wheel speed and begins to decrease again, and the wheel speed recovery determination means 3. '61-, a timer 32 which outputs a decompression prohibition command for a predetermined period of time.

The wheel speed recovery determining means 31 memorizes that the output control command is a pressure reduction operation command at the end of the anti-skid control calculation, and then when the wheel speed recovers and the peak value is detected,
The wheel speed recovery determining means 31 sends a timer dynamic f% start command to the timer 32.
Upon receiving the timer operation start command from 1, it sends a decompression prohibition command for a predetermined time to the anti-skid and Ti control calculation section.

Due to this prohibition command, the anti-skid control calculation unit does not perform the pressure reduction operation even if the conditions for the pressure reduction operation are satisfied.

The vibration countermeasure prohibition determining means 33 is a means for determining +, ('t-) which prohibits the operation of the vibration countermeasure means 30 described above, and is determined from the wheel speed and the controlled vehicle body speed. On the other hand, when the predetermined speed difference is exceeded, the vibration countermeasure prohibition determination means 33 sends a command to the timer 32 to end the timer operation, and the depressurization prohibition command is canceled. Perform normal anti-skid control calculations and perform depressurization operation.

FIG. 4 is a time chart showing the relationship between wheel speed and wheel cylinder oil pressure when the present invention is implemented. Figure 4 (1) shows changes in wheel speed, and Figure 4112I (
2> indicates a change in wheel cylinder oil pressure. When the accelerator pedal is depressed and a braking operation is performed at time to, the wheel cylinder oil pressure increases and the wheel speed decreases. At time t1, when anti-skid control start conditions are met, anti-skid control is started, and the wheel cylinder oil pressure is reduced by performing pressure reduction operation (%). At this time, a pulse pressure increase operation is performed to gradually increase the wheel cylinder oil pressure.This pulse pressure increase operation is a repetition of increasing the wheel cylinder oil pressure for a predetermined period of time. 4+1t
3, when a peak value at which the wheel speed changes from increasing to decreasing is detected, the pressure reduction operation is prohibited for a predetermined time W3+ from time t3 to time t4. Therefore, the pulse pressure increasing operation is continuously performed from time t3 to time t4, and large vibrations in wheel speed are prevented.

FIG. 5 is an output control flowchart 1 to 1 in a processing circuit in which an embodiment of the present invention is executed. Processing circuits 4a, 4
When the anti-skid control program is executed in step b, it is first determined in step s1 whether or not anti-skid control is currently being executed, and if it is under control, there is no need to determine whether to start anti-skid control. Therefore, the process proceeds to step S4. If the anti-skid control is not being performed in step s1, the process proceeds to step S2, where it is determined whether the conditions for starting the anti-skid control are satisfied. As anti-skid control starting conditions, it is determined whether the wheels are locked, for example, if the wheels are locked, the wheel speed is lower than a predetermined rotational speed, and the wheel deceleration is greater than the predetermined deceleration. If the conditions for starting the anti-skid control are met, the process proceeds to step s3, where a pressure reduction flag is set in a predetermined memory area of the processing circuit 4 to cause the wheel cylinder to perform a pressure reduction operation.

If it is determined in step S2 that the conditions for starting anti-skid control are not met, the process proceeds to step s18, in which the actuator is activated so that the hydraulic pressure generated in the master cylinder by depression of the brake pedal is transmitted to the wheel cylinder. The electromagnetic control valve 6 is set to the pressure increasing position.

In step S4, the conditions for ending the anti-skid control are determined, and the anti-skid control is canceled, for example, when the foot is released from the brake pedal, or when the vehicle speed becomes 5 km/h or less. If the anti-skid control termination condition is not satisfied in step S4, the process proceeds to step S5, where a flag for controlling increase/decrease in wheel cylinder oil pressure is determined.

When the anti-skid control starts, since the pressure reduction flag is set in step S3, the process advances to step s6, and then to step S7, where the wheel cylinder 22
is depressurized. In step S6, when the pressure reduction operation is completed, that is, when the wheel speed starts to show signs of recovery, the process proceeds to step S8, and a holding flag is set to keep the oil pressure of the wheel cylinder 22 constant. Then, the process advances from step s9 to step slo, and the wheel cylinder pressure is kept constant.

In step s9, when the wheel speed starts to increase and the wheel acceleration exceeds a predetermined value and satisfies the holding end conditions,
The process advances to step sll, where a flag for increasing the oil pressure of the wheel cylinder 22 is set. Then, the process advances from step s12 to step s13, and the wheel cylinder 2
The oil pressure in 2 is increased. In step s12, when the pressure increase end condition, for example, the oil pressure has recovered to a predetermined value, the process proceeds to step s14, where a pulse pressure increase flag for gradually increasing the pressure in the wheel cylinder 22 is set. Then, the process proceeds from step s15 to step s16, where a pressure increase pulse having a predetermined time width is sent from the processing circuit 4 to the solenoid drive circuit 5a, and the actuator is operated for a time corresponding to the pulse width given from the solenoid drive circuit 5. When the conditions for ending the pulse pressure increase are met in step s15, in which the pressure increase operation is performed, the process proceeds to step S17.
The process proceeds to step S7, where a pressure reduction flag is set, and a pressure reduction operation is performed in step S7.

FIG. 6 is a flowchart for executing wheel speed vibration countermeasure processing according to an embodiment of the present invention. This vibration countermeasure processing is performed in step S5 in the output control flow shown in FIG.
is executed before the flag determination process. If it is determined in step S4 of FIG. 5 that the anti-skid control termination condition is not satisfied, vibration countermeasure processing shown in FIG. 6 is performed. In step m1, it is determined whether or not the decompression flag is set, and if it is set, Stella 7m
Proceed to step 2. In step m2, a vibration countermeasure flag F1 for storing that a pressure reduction operation has been performed is set.

While the decompression flag is set, step m l
, step m2 is executed. Then, when the decompression flag is reset and the holding flag is set, step m
1, the process proceeds to step m3, where it is determined whether the vibration countermeasure flag is set. Since the vibration countermeasure flag F1 is set in step m2, step m
3 proceeds to step rn4, where it is determined whether the wheel speed has recovered, that is, whether a peak value at which the wheel speed changes from increasing to decreasing has been detected. When the peak time of the wheel speed is detected, the process proceeds from step m4 to step m5, and the vibration countermeasure flag F1 is reset, and at the same time, in step m6, a predetermined counter indicates a depressurization prohibition time that prohibits the output from depressurizing for a predetermined time from the peak time. A count value KT corresponding to is set.

In step m3, since the vibration countermeasure flag F1 has already been reset in step rn5, step rn
3, the process proceeds to step m7, where it is determined whether the vibration countermeasure counter M1 is zero, and if it is not zero, the process proceeds to step m7.
From step 7 to step m8, the vibration countermeasure counter M1 becomes 1.
will be reduced by Then, the process proceeds to step m9, where the difference between the controlled vehicle speed and the wheel speed is determined. If the difference is less than or equal to the predetermined speed ΔV, vibration countermeasure processing is continued, and if it exceeds, step m9 to step rn The process advances to step 10, where the vibration countermeasure counter M1 is set to zero, and the vibration countermeasure processing ends.

FIG. 7 is a flowchart of the pulse pressure increase process during the period when the vibration countermeasure process is being executed.

During the period when the vibration countermeasure process is being executed, step s15 in FIG. 5 is not executed, and a pulse pressure increase output is output as shown in the process flow in FIG. 7. In step n1, it is determined whether or not vibration countermeasure processing is being performed, that is, whether the vibration countermeasure counter M1 has become zero or not. If it is not zero, it is determined that it is a period in which vibration countermeasure processing is being performed, so the process advances from step n1 to step n3, and a pulse pressure increase signal is output.

In step n1, if the anti-vibration counter M1 is zero, the process proceeds to step n2, where it is determined whether the wheels have started to lock or have stopped. When the wheels are not locked, a pulse pressure increase signal is output in step n3, and when locking starts, a pressure reduction flag is set in step rI4, and the process proceeds to step s8 in FIG.

As described above, according to this embodiment, the anti-skid control device detects the first peak value after the pressure reduction operation and prohibits the pressure reduction output for a predetermined time from that peak value, so the wheel speed will fluctuate greatly. There is no.

Effects of the Invention As described above, according to the present invention, since a decrease in braking force is prevented for a predetermined period of time from the time when the peak value is detected, vibration of the vehicle body due to oil pressure fluctuations can be prevented.

In addition, since a decrease in braking force is prevented for a predetermined period of time,
It is possible to prevent the braking distance from becoming longer.

Furthermore, when the difference between the wheel speed and the vehicle speed exceeds a predetermined value, control is performed to reduce the frictional braking force, thereby preventing the wheels from locking, reducing the braking force and deteriorating steering performance. I can do it.

[Brief explanation of the drawing]

111J is a block diagram of an anti-skid control device which is an embodiment of the present invention, FIG. 2 is a block diagram for explaining the hydraulic path of the anti-skid control device according to the present invention, and FIG. 3 is a detailed diagram of the present invention. FIG. 4 is a time chart showing the relationship between wheel speed and wheel cylinder oil pressure when the present invention is implemented, and FIG. 5 is a process in which one embodiment of the present invention is executed. A flowchart of output control in the circuit, FIG. 6 is a flowchart for executing wheel speed vibration countermeasure processing according to an embodiment of the present invention, FIG. 7 is a flowchart for pulse pressure increase processing during a period in which vibration countermeasure processing is being executed, FIG. 8 is a time chart for explaining the relationship with wheel cylinder oil pressure when vibration occurs in wheel speed in conventional anti-skid control. DESCRIPTION OF SYMBOLS 1... Anti-skid control circuit, 2a-2d... Wheel speed sensor, 3a-3d... Waveform shaping circuit, 4a. 4b... Processing circuit, 5a-5d... Solenoid drive circuit, 6a-6d... Actuator, 9... Solenoid relay, 11... Battery, 12... Motor, 13... Motor relay , 15... Motor relay drive circuit, one... Power supply circuit, 21... Master cylinder, 22a-22d... Wheel cylinder, 30...
...Vibration countermeasure means, 31...Wheel speed recovery determination means, 3
2...Timer, 33...Vibration countermeasure prohibition judgment means Agent Patent attorney Keibu Saikyo Figure 2 Figure 3 Figure 4

Claims (2)

[Claims] (1) In an anti-skid control device that controls the friction braking means of the wheels so that the slip ratio between the wheels and the road surface is increased based on the output from the wheel speed detection means, the friction braking means of the wheels is controlled such that the friction force between the wheels and the road surface is increased. means for detecting the peak value of the wheel speed while the wheel speed is increasing during braking in response to the output of the means; An anti-skid control device comprising: means for preventing a decrease in frictional braking force in the braking means. (2) a means for detecting vehicle speed; and a means for detecting a wheel speed in response to the outputs from the wheel speed detecting means, the peak value detecting means, and the vehicle speed detecting means, and detecting that the wheel speed decreases after the peak value is detected within the predetermined time. An anti-skid control device characterized in that when the difference between wheel speed and vehicle body speed exceeds a predetermined value, the friction braking force of the friction braking means is reduced.