JPH02136362A - Antiskid controller - Google Patents

Abstract

PURPOSE:To attain the shortest braking distance while preventing the reduction of the excess brake liquid pressure by properly changing the threshold value when performing the antiskid control based on the measured value of the wheel peripheral speed or the acceleration/deceleration. CONSTITUTION:The wheel speed signal romega is inputted to a pseudo car speed generator 11 and a wheel acceleration/deceleration generator 12 respectively. The wheel speed romega, pseudo car speed Vref, and wheel acceleration/deceleration are inputted to a judging unit 13 respectively, when the relationship with the preset threshold value is satisfied, the modulator drive signal is outputted to a modulator, and the oil pressure of a brake is reduced. On the other hand, the wheel acceleration/deceleration signal is fed to a peak detector 14, and the peak value on the plus side is detected. The peak value signal is fed to an augmentation setter 15 together with other signals. The augmentation is fed to the judging unit 13 via a delay unit 16 and a decreasing unit 17 to increase the threshold value.

Description

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

``Prior art'' In general, anti-skid control devices have two functions: when detecting that the vehicle is in a skid state due to brake operation, the braking force is temporarily reduced to eliminate the skid state, and after the skid is resolved, While repeating the action of restoring braking force, the system brakes the vehicle over the shortest possible distance while avoiding skids.

As a conventional example of this anti-skid control, (a) A method in which a slip ratio is determined from the wheel circumferential speed and a predetermined simulated vehicle speed, and the hydraulic pressure of the braking system is controlled by comparing the slip ratio with the predetermined slip ratio.

A method that measures the circumferential speed of a wheel, calculates the acceleration/deceleration of the wheel from this circumferential speed, and controls the calculated acceleration/deceleration to be within a predetermined range (a range of deceleration that does not cause slippage).

C) - A method that uses both of the above methods in combination.

is generally adopted.

[Problem to be Solved by the Invention] By the way, the control described in item 1 is effective because it is performed based on the measured value of the wheel circumferential speed (or the acceleration/deceleration obtained by differentiating this value, or both). For anti-skid control, wheel circumferential speed (or wheel acceleration/deceleration)
However, it is inevitable that vibrations will be transmitted to the wheels from the drive system or from the road surface due to driving on rough roads, etc., through the wheels. This vibration causes an error in the measured wheel circumferential speed, which is the basis of anti-skid control, resulting in the problem of extended braking distance due to excessive braking force reduction.

The present invention was proposed in view of the above circumstances, and an object of the present invention is to perform appropriate anti-skid control regardless of the influence of vibrations applied to wheels.

"Means for Solving the Problems" In order to achieve the above object, the present invention provides an anti-skid control device that prevents wheel slippage by controlling the pressure of a braking hydraulic system. means, a calculation means for calculating at least one of a wheel slip amount and acceleration/deceleration from the wheel circumferential speed and the simulated vehicle speed obtained from the measuring means, and a comparison means for comparing the calculation result of the calculation means with a threshold value. a jump amount calculation means for calculating the jump amount of the wheel peripheral speed from the simulated vehicle speed; a threshold value control means for changing the threshold value according to the jump amount calculated by the calculation means; and operating means for operating the braking hydraulic system on the condition that the comparison means determines that the threshold value is exceeded.

[Effect-1] With the above configuration, even if a wheel circumferential speed (or acceleration/deceleration) different from the original wheel circumferential speed (or acceleration/deceleration) is measured due to the influence of vibrations applied to the wheel, the wheel circumferential Since the threshold value is changed according to the jump amount from the simulated vehicle speed, the brake fluid pressure will not be excessively reduced due to specific data due to the influence of vibrations, etc.

[Example 2] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a brake hydraulic system to which the anti-skid control of the present invention is applied. In this hydraulic system, hydraulic pressure is generated from a master cylinder 2 by depressing a brake pedal 1, and the generated hydraulic pressure is The pressure is supplied to the brake 4 via the pressure modulator 3 to perform a predetermined braking operation. Further, the modulator 3 is controlled by a controller 6 that detects the skid tendency of the wheels based on a wheel speed signal from a wheel speed sensor 5, and reduces the braking oil pressure according to various conditions described below. .

Next, the specific configuration of the controller 6 will be explained with reference to FIG.

The symbol rω indicates a wheel obtained by performing processing such as F/V conversion and amplification on the signal output from the wheel speed sensor 5 according to the wheel speed (generally a pulse signal with a period proportional to the speed). This signal rω is input to the simulated vehicle speed generator 1 and the wheel acceleration/deceleration generator 12, respectively. The simulated vehicle speed generator 11 generates a simulated vehicle speed based on the wheel speed signal rω using a predetermined calculation formula (from the speed curve, linearly changes the slope by +2G when accelerating and by −1.2G when decelerating). Calculate and output V ref. The wheel acceleration/deceleration generator 12 also generates a wheel acceleration/deceleration signal r by differentiating the wheel speed signal rω.
6) is output. These wheel speeds rω, simulated vehicle speed Vref
, wheel acceleration/deceleration rω are each supplied to the determiner 13,
If Vref-rω≧predetermined threshold value (S) or (if necessary) rr≦predetermined threshold chain (=b), this determiner 13 sends a modulator drive signal to the modulator 3. By outputting Ms, the hydraulic pressure of the brake 4 is reduced.

On the other hand, the output of the acceleration/deceleration generator 12 is transmitted to the peak detector 1.
4 is supplied. The peak detector 14 detects a positive peak value 1-r of the wheel acceleration/deceleration signal rω.
r] and supplies this signal to the threshold increase amount setting device 15. Further, the threshold increase amount setter 15 receives the speed signal rω and the simulated vehicle speed V ref supplied from the simulated vehicle speed generator 11.
and the peak value [r
From ω1, a threshold increase value is calculated based on a predetermined standard (the content of the standard will be described later), and the delay device 16 and the threshold Paul F Increase Village Decrease I7
Each threshold increase amount ΔS or (and as necessary) Δb is supplied to the judgment device 13 via. In the judgment device 13, the judgment standard for anti-skid control is changed as appropriate in accordance with the supplied threshold value ΔS. Note that the delay device 16 functions to cause a predetermined time delay in the control signal for increasing the threshold,
Further, the threshold increase amount reducer 17 functions to reduce the threshold increase amount in accordance with the amount of time delay caused by the delay device 16.

Next, the function of the threshold increase amount setter 15 will be explained with a focus on the slip threshold voltage.

For example, as shown in FIG.
and the difference between the wheel circumferential speed rω (rω−■ref) or the reference value δ.

The threshold increase amount Δ is conditional on exceeding
In the case of FIG. 3, the peak value [r6)] supplied from the acceleration/deceleration generator 12 is further compared with the reference value, and the first value is set according to the comparison result. The threshold increase amount is set to ΔS1 or the second value ΔS.

That is, the threshold increase amount setter 15a has the minimum value r6J. With the value of larger r(D) as the boundary, the amount of increase Δ
Select S or ΔS2.

r). If ≦[rme]<rω1, ΔS I= klX (r ωV ref−δ.)+△
S.

≦△S max r nights, ≦ [r 〈S 2= to 2X (r ω-V ref-δ.) ten to S.

≦△S□6x However, ΔS□8 is a predetermined upper limit value, and is designed to prevent the thread bold increase amount △S or ΔS2 from exceeding this two limit value.

Note that in the above, , and 2 are all constants, and k,=
It may be. Also, rme. , r r l + δ
.

ΔSo may be zero.

Also, ΔS − & (r (Z) −V ref − δ.) ten ΔS
.

Tatami k is a function of acceleration/deceleration rr As, k=f(rω)=-ρ1r Tatashi ρ, old constant k may be varied based on the following formula.

Therefore, the threshold increase amount setter 15 is
Vibrations transmitted from the road surface on rough roads, etc., and re-acceleration of the wheels after depressurization during anti-lock (causing vibrations in the drive system) may cause acceleration/deceleration exceeding a certain level (rr.), and as a result. The wheel circumferential speed rω is the simulated vehicle speed V ref by δ. A threshold increase amount ΔS is set on the condition that the threshold increase amount ΔS is greater than 2, and is supplied to the determination device 13. and judge 1
3 operates the modulator 3 of the brake hydraulic system when a slip exceeding S+ΔS occurs based on the set threshold increase amount ΔS, and reduces the brake hydraulic pressure in order to recover the wheel from skid tendency. . Therefore, when a wheel circumferential speed rω exceeding the simulated vehicle speed V ref is detected due to driving on a rough road or vibrations in the drive system, the anti-skid control is not started and the braking distance is maintained normally.

Note that the setting characteristics of the threshold increase amount ΔS are not limited to those shown in FIG. 3 (but may be changed as in other examples shown in FIG. 4).

In this case, the threshold value △S is △S - kX
I n (rω-Vref-δ.) 1△S.

Tashini=f(r6)) It increases exponentially according to the formula:

It is assumed that the threshold increase amount for the wheel deceleration threshold is also set in the same manner as in FIG. 3 or FIG. 4.

Next, the actual control by the anti-skid control device having the above configuration will be explained with reference to FIG. In addition, in this control, as shown in FIG.
Pressure increase control or pressure decrease control is selected by changing the boundary.

This example shows the situation of the threshold bold amount adjustment described above in response to drive system vibration that is likely to occur on a high μ road surface such as an asphalt road.

Figure 5 <a> shows the speed change over time in anti-skid control. In this speed change characteristic, the part indicated by chain line A indicates a decrease in wheel speed rω due to excessive braking force, and the part indicated by chain line B Some parts show lower speeds than reality due to vibrations in the drive system.

Therefore, if a constant threshold F value is adopted, the braking oil pressure will be excessively reduced in the portion indicated by chain line B, resulting in a decrease in braking force and an unavoidable increase in braking distance.

However, when the present invention is applied, based on the above-mentioned discrimination conditions, as shown by the solid lines in FIG. The brake fluid pressure is increased with a delay, so that the brake fluid pressure is not affected by specific speed fluctuations like the part B in FIG. 5(a).
It is controlled as shown in FIG. 5 (( )).

In addition, in the above example, as shown by the solid line, the threshold value increased by -1, linearly, that is, Δb=Δb
max −C+ t % △S−△ Smax−C2t (where C,,C, is a constant) It was designed to decrease according to the −order function, but as shown by the chain line in the figure, it decreases exponentially, that is, It may be decreased according to an exponential function: Δb=Δb max-e −”” ΔS-ΔS max-e ”t (C3, C, are constants).

In the above embodiment, the wheel deceleration "ω" and the slip amount S
Although both threshold values are increased, it is of course possible to operate either one of them.

Furthermore, although the first embodiment is constructed of an analog electric circuit, a microprocessor may be used to perform control equivalent to that of the electric circuit.

"Effects of the Invention" As is clear from the above description, according to the present invention, when performing anti-skid control based on measured values of wheel circumferential speed or its acceleration/deceleration, vibration of the drive system or If abnormal data (unrelated to the original anti-skid control) is input due to vibrations applied to the wheels from the road surface due to causes such as driving on a rough road, the threshold value can be changed to eliminate this. Particularly on a road surface where there are portions with a high coefficient of road friction, the present invention has the effect of being able to realize the shortest braking distance while preventing an excessive decrease in braking fluid pressure.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; Fig. 1 is a piping diagram of the braking hydraulic system to be controlled, Fig. 2 is a block diagram of the control system, and Fig. 3 is an example of threshold value change characteristics. Figure 4 is a diagram showing another example of threshold value change characteristics, and Figure 5 is a diagram showing changes in wheel circumferential speed and simulated vehicle speed in anti-skid control, wheel circumferential speed, amount of slips, and braking. FIG. 6 is a chart showing the relationship between the slip amount, threshold values of acceleration/deceleration, and the contents of hydraulic pressure control. 2... Master cylinder, 4... Brake,
5... Sensor, 11... Simulated vehicle speed generator,
12 Acceleration/deceleration generator, 13... Judgment device, I4...
Peak detector, 15... Increase amount setting device.

Claims (1)

[Claims] An anti-skid control device that prevents wheel slippage by controlling the pressure of a braking hydraulic system includes a wheel circumferential speed measuring means, and a wheel circumferential speed obtained from the measuring means and a simulated vehicle speed. a calculation means for calculating at least one of the slip amount and acceleration/deceleration; a comparison means for comparing the calculation result of the calculation means with a threshold value; and a jump amount calculation for calculating the jump amount of the wheel circumferential speed from the simulated vehicle speed. means, threshold value control means for changing the threshold value in accordance with the jump amount calculated by the calculation means, and said braking on the condition that said comparison means determines that said threshold value is exceeded. An anti-skid control device comprising an operating means for operating a hydraulic system.