JPH01160764A - Anti-skid control device - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an anti-skid control device provided in a braking system of a four-wheeled vehicle.

"Prior Art" In recent years, vehicles equipped with anti-skid control devices that aim to prevent wheels from locking during vehicle braking and obtain the shortest braking distance have become popular.

As one method of anti-skid control, the increase or decrease in wheel speed is grasped from the data obtained from the wheel speed sensor, and for example, if the wheel speed suddenly decreases, it is determined that there is a significant tendency to lock. There is a method that controls the pressure of the braking hydraulic system.

The above anti-skid control methods can be further categorized into a 4-sensor, 4-channel method that detects the speed of each wheel and controls the hydraulic system for each wheel, and a simplified version of the 4-sensor, 4-channel method that detects the speed of each wheel and controls the hydraulic system for each wheel. A 4-sensor, 3-channel system is used to connect the rear wheels to the hydraulic system for individual control, and connect the rear wheels to a single hydraulic system for collective control.The rear wheel hydraulic system is equipped with a pressure control valve (PCV). By limiting the braking force on the rear wheels, the front wheels have the characteristic of locking before the rear wheels, and the presence or absence of a tendency to lock can be determined from the wheel speed. 4 sensors 2 connected to the brake hydraulic system for control
A channel method (X piping method) is known.

By the way, in any of the above anti-skid methods, in order to perform appropriate anti-skid control, it is necessary to accurately detect the speed of each wheel. By configuring the device, wheel speed data for each wheel is obtained.

Symbols I A - I D in the figure are wheel speed sensors, and these wheel speed sensors 1 detect the circumferential speed in response to changes in the circumferential speed of the right front wheel, left front wheel, right rear wheel, and left rear wheel, respectively. If the period is large, the pulse is emitted in a short period, and if the period is small, the pulse is emitted in a long period. These wheel speed sensors I
The outputs of A to ID are supplied to waveform shaping circuits 2A to 2D, each shaped into a predetermined waveform, for example, a rectangular wave, and then supplied to trigger input terminals T of latches (holding circuits) 3A to 3D, respectively. There is. Further, the latches 3A to 3D are configured to hold the count value of the counter 4 connected to the data input terminal by inputting a pulse to the trigger input terminal T.

The latches 3A to 3D are ROM, RAM, I
It is connected by bus to a microprocessing unit (hereinafter referred to as MPU) 5 which stores lo, counters, timers, latches, etc. in one package, and stores its retained data in MPU.
It can be read into the PU5 arbitrarily. Moreover, the outputs of the waveform shaping circuits 2A to 2D are output from the MPUI
are supplied to interrupt input terminals INTI-INT4, respectively. The latched data is then taken into the MPUI by inputting a signal from the waveform shaping circuit to the MPUI.

"Problem to be Solved by the Invention" By the way, since anti-skid control is executed based on subtle increases and decreases in wheel speed, accurate wheel speed data is required to perform appropriate anti-skid control. From this point of view, in the above anti-skid control device, the count value of the counter 4 is set to the MPU 5.
The count value is reliably latched based on the pulse from the wheel speed sensor IA~ID instead of being read directly.
A method is adopted in which the data is held in 3D, read into the MPU 5 as necessary, and processed as wheel speed data.

That is, in the method of directly reading the count value into the MPU 5, depending on the operation timing of the control program of the MPU 5, it may not be possible to read the count value immediately in response to a pulse interrupt input.
There is a possibility that an error may occur in the input wheel speed data.

Therefore, in order to obtain accurate wheel speed data, it is necessary to provide latches 3A to 3D for each wheel speed sensor lA-ID and to have the ability to process the data supplied from these latches 3A to 3D. The MPU5 was required, which caused an increase in the cost of the anti-skid control device.

In addition, in the anti-skid control system that has a two-channel hydraulic system using X piping, under normal driving conditions, that is,
Since the front wheels always tend to lock up before the rear wheels, a two-sensor system that uses only the front wheel speed data includes rear wheel speed sensors IC and ID, waveform shaping circuits 2C and 2D,
It is also possible to omit the latches 3C and 3D. However, in rare cases when the following adverse conditions occur, the rear wheels may tend to lock even if the front wheels do not, and it is difficult to perform appropriate control based only on wheel speed data from the front wheels. There was no possibility that it would not be possible.

a. So-called split, 1 (II
is the coefficient of friction).

b. When the μ of the brake pads on each wheel becomes uneven due to wear, etc.

C9 When μ is different for each wheel due to spikes or chain attachment on some wheels.

d. Excessive wear on some wheels (not only due to the use of defective tires, but also due to some wear due to not rotating the tires, installation of spare tires whose wear conditions are extremely different from the tires in use, etc.) When μ is different for each wheel due to

The present invention was proposed in view of the above circumstances, and maintains reliability of anti-skid control even under special conditions.
Furthermore, the present invention aims to reduce the cost of a 4-sensor, 2-channel type anti-skid control device.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides a two-system hydraulic system that is arranged diagonally and controls the braking hydraulic pressure of both wheels in conjunction with each other. In the anti-skid control device, the anti-skid control device is provided with a hydraulic pressure control valve that regulates brake fluid pressure on the rear wheel side so that the front wheels lock before the rear wheels, and the anti-skid control valve is provided on each of the wheels and corresponds to the wheel speed. a wheel speed sensor that outputs a pulse that outputs a pulse, a holding means that holds the count value of a counter using the pulse supplied from each of the wheel speed sensors of both front axles as a trigger, and a wheel speed of the front wheels held by the holding means. and a microprocessor that controls the pressure of the two hydraulic systems based on data, and the microprocessor reads the count value of the counter using pulses supplied from the two rear wheels as a trigger, thereby controlling the pressure of the rear wheels. In addition to obtaining wheel speed data, the control content of the hydraulic system is corrected based on the wheel speed data for the rear wheels, if necessary.

"Operation" According to the above configuration, under normal road surface conditions or tire conditions, anti-skid control is executed based on accurate wheel speed data regarding the front wheels, and in parallel with this,
Using the wheel speed data regarding the rear wheels, it is possible to estimate the vehicle speed or perform corrective control such as whether the rear wheels are locked in advance of the front wheels.

"Example" An embodiment of the present invention will be described below with reference to FIG.

As in the conventional example shown in FIG.
They are connected to NTl to INT4, respectively. Further, among the waveform shaping circuits 2A to 2D, a waveform shaping circuit 2A and a waveform shaping circuit 2A, which shapes the output pulses of the wheel speed sensors IA and IB for the front wheels, are also provided.
The output of 2B is connected to the trigger input terminals T of latches 3A and 3B, and these latches 3A and 3B detect the edges of the pulses supplied to the trigger input terminals T from the waveform shaping circuits 2A and 2B. , each latches the count value of the counter 4 and supplies it to the MPU 5 as necessary.

In the wheel speed detection device configured as described above, the count value of the counter 4 is latched in the latches 3A and 3B by pulses supplied from the wheel speed sensors IA and IB, and the latched wheel speed data is required. is supplied to the MPU 5. Based on the supplied accurate wheel speed data about the front wheels, the MPU 5 controls, for example, the hydraulic pressure of each of the diagonal wheel braking hydraulic systems interconnected by the X pipe, that is, the deceleration of the wheel speed is controlled. If the brake fluid pressure exceeds a predetermined value, the hydraulic system valve is operated to reduce the brake fluid pressure, and if the wheel speed deceleration falls below the predetermined value, the hydraulic system valve is operated to restore the brake fluid pressure. to recover the wheel speed from the tendency to lock.

In addition, in parallel with the control based on the wheel speed data regarding the front wheels, the MPU 5 detects the edges of the pulses supplied from the waveform shaping circuits 2C and 2D of the speed sensor IC and ID of the rear wheels, and calculates the count value of the counter 4. The control based on the front wheel speed data can be read and modified by the rear wheel speed data. That is, even if it is determined that the wheel speed has recovered through control based on the wheel speed data of the front wheels, for example, if the rear wheels tend to lock due to the various causes described in the prior art section, Since wheel speed data to that effect is supplied to MPU5, in this case, even if the wheel circumferential speed of the front wheels tends to recover, control is performed such that the hydraulic pressure in that system is maintained at a reduced level.

In addition, the brake hydraulic system for the rear wheels is equipped with a hydraulic pressure control valve.
In the case of a channel type, the wheel circumferential speed of the rear wheels can be regarded as the closest value to the vehicle body speed, except in special situations where only the rear wheels tend to lock, so data on the wheel circumferential speed of the rear wheels can be can be used as auxiliary data when estimating vehicle speed.

"Effects of the Invention" As is clear from the above explanation, according to the present invention, only two holding means for the front wheels are provided for latching wheel speed data using pulses supplied from the wheel speed sensor, and based on this data, Since the brake hydraulic system is controlled by determining whether or not the front wheels have a tendency to lock, the number of holding means is reduced. The configuration of the processor can be simplified. In addition, the microprocessor can directly read speed data using the pulses supplied from the rear wheel speed sensor and correct the hydraulic control based on the front wheel speed data. This has the effect that it is possible to reliably grasp the locking tendency of the rear wheels and execute appropriate control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of an example of a speed detection device applied to an anti-skid control device. I A -LD...Wheel speed sensor, 2A~2
D... Waveform shaping circuit, 3A/3B...
Latch (holding means), 4... Counter, 5...
・・・・MPU (Micro Processing Unit)
.

Claims (1)

[Claims] The two hydraulic systems control the brake fluid pressure of a pair of diagonally arranged wheels in conjunction with each other, and the brake fluid pressure of the rear wheels changes so that the front wheels lock before the rear wheels. In the anti-skid control device, the anti-skid control device is provided with a hydraulic pressure control valve that regulates the wheel speed, and a wheel speed sensor that is provided on each wheel and outputs a pulse corresponding to the wheel speed, and a wheel speed sensor that outputs a pulse corresponding to the wheel speed, and a wheel speed sensor that outputs a pulse corresponding to the wheel speed. The microprocessor is comprised of a holding means that holds each count value of a counter using a pulse as a trigger, and a microprocessor that controls the pressure of the two hydraulic systems based on the wheel speed data of the front wheels held in the holding means. The processor reads the count value of the counter using the pulses supplied from the rear wheels as a trigger to obtain wheel speed data about the rear wheels, and, if necessary, adjusts the hydraulic pressure based on the wheel speed data about the rear wheels. An anti-skid control device characterized by modifying control contents of a system.