JPS5826661A - Vehicle anti-skid unit - Google Patents

Abstract

PURPOSE:To enable the control of braking in dependence upon the condition of road surface, by estimating the deceleration of a vehicle body from the maximum value of recovered wheel speeds so that the reference value of the next wheel speeds are calculated. CONSTITUTION:A computer 46 calculates vehicle speeds of wheels 10, 14, 18, 20, taking account of output data from wheel speed sensors 12, 16, 24. Then, the maximum value of these wheel speeds is calculated. Further, a calculated speed is obtained by subtracting a reference speed from the maximum value of the wheel speeds. Then, a calculated speed after the time duration of DELTAt is obtained with the use of the previous reference wheel speed and reference deceleration. Brake units for repsective regulated wheels are controlled in dependence upon the deviation between this reference wheel speed and each of the wheel speeds of these regulated wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an anti-skid device for a vehicle, which is particularly suitable for use in an automobile, and which detects the state of deviation between the reference wheel speed determined from the wheel speed and the wheel speed of the control wheel when the vehicle is decelerating. The present invention relates to an improvement in an anti-skid device for a vehicle that prevents the controlled wheels from locking by controlling the brake device i1'fr of the controlled wheels in accordance with the above.

When a vehicle such as an automobile suddenly brakes, the brake system of the control wheel is controlled so that the speed of the single wheel of the control wheel does not become smaller than the reference wheel speed (7) by a predetermined value or more, and the control wheel is locked. Anti-skid devices for vehicles have been put into practical use to prevent this.

This anti-skid device is characterized in that the control wheels are prevented from locking, the stability of the vehicle body posture and the steering performance of the vehicle are ensured, and the braking stopping distance is shortened.

In such a heavy-duty anti-skid device, mll
Conventionally, in order to detect the locked state of a wheel, for example, the reference wheel speed is set to a value that is about 10% smaller than the wheel speed of the control wheel, and the wheel deceleration of the control wheel is set as expected from the ability of the brake system. i, the maximum value of vehicle deceleration, for example 1. If IG is exceeded, the deviation between the reference wheel speed and the wheel speed of the control wheel is determined by setting the differential value of the reference wheel speed to the maximum deceleration 1.1GK fixed A semi-deceleration regardless of the wheel speed. The brake device of the controlled wheel is controlled depending on the state. However, in the past, the reference deceleration was always the maximum value of the vehicle body deceleration expected from the ability of the brake system, so depending on the road surface condition, tire condition, etc., the wheels may lock or Alternatively, it has the disadvantage that the braking and stopping distance becomes longer than necessary.

In order to eliminate such drawbacks, it may be possible to modify the reference deceleration according to the time it takes for the wheel speed to recover, but the degree of modification may depend on factors such as tire inertia and transmission shift position. In some cases, it was not always possible to predict the deceleration of the vehicle.

The present invention has been developed in order to solve the above-mentioned conventional drawbacks, and it is possible to set an appropriate reference deceleration according to the deceleration state of the vehicle, thereby reliably preventing wheel locking. An object of the present invention is to provide an anti-skid device for a vehicle that can stop a vehicle with a minimum stopping distance.

The present invention prevents the controlled wheels from locking by fully controlling the brake devices of the controlled wheels in accordance with the deviation state between the reference wheel speed calculated from the wheel speed and the wheel speed of the controlled wheels when the vehicle is decelerating. anti-skid equipment for vehicles
At Vl, when the wheel deceleration exceeds the reference deceleration,
Regardless of the wheel speed 3, by fixing the differential value of the reference wheel speed to the reference deceleration, the reference wheel speed is determined and the brake device is controlled, and the deceleration of the base wheel speed is fixed to the reference deceleration. The current vehicle body deceleration is estimated from the slope of the straight line that connects the current wheel speed and the maximum value of the wheel speed when the wheel speed has recovered, and the reference deceleration is determined from the estimated current vehicle body deceleration. The revised value of the reference deceleration is set as the next reference deceleration, and the maximum value of the wheel speed of each control wheel is traced to correspond to π, and the corrected value of the reference deceleration is set as the next reference wheel speed. the maximum wheel speed at the time when the speed differential value is fixed to the reference deceleration Bvc;
Recovery is the most important thing.

Furthermore, if the elapsed time from the time when the differential value of the reference wheel speed is fixed to the reference deceleration to the time when the wheel speed of the wheel that recovers the fastest reaches the extreme value, the reference deceleration is This prevents malfunctions by not adjusting the speed.

Also, the initial value of the front d-pi reference deceleration is set to 1. IG.

Embodiments of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, this embodiment includes a wheel speed sensor 12 that generates a wheel speed pulse in accordance with the rotation of a right front wheel 10, which is a controlled wheel, and a wheel speed sensor 12 that generates a wheel speed pulse according to the rotation of a left front wheel 14, which is also a controlled wheel.
A wheel speed sensor 16 that generates a wheel speed pulse in accordance with 1jAw, a wheel speed sensor 24 that generates a wheel speed pulse in accordance with the rotation of the rear wheels 18 and 20 that are collectively controlled in accordance with the rotation of the propeller shaft 22, Hydraulic brake devices 26, 28, 3o and 32 are arranged on each wheel, a hydraulic cylinder 36 generates brake hydraulic pressure when the driver depresses the brake pedal 34, and a hydraulic cylinder 36 generates hydraulic pressure according to engine rotation. For example, the hydraulic pump 38 that also serves as a power steering pump and the hydraulic cylinder 36 are connected to hydraulic brake equipment [26, 28, 30 &
Hydraulic pipes 40, 42, 44 in contact with A computer 46 that generates its own control output.
and adjusting the hydraulic pressure of the hydraulic cylinder 36 and hydraulic pump 38 output according to the output of the computer 460, thereby creating brake hydraulic pressure, each hydraulic conduit 40.
Actuator 48.5 placed in the middle of 42.44
0.52, and the actuator 4g
, 50°52, as shown in Figure 8g2 (, hydraulic pump 3
A regulator section 53 that adjusts the hydraulic pressure of 8 outputs to a predetermined pressure, a control valve section 54 that includes an increase/decrease direction control solenoid for switching the increase/decrease direction of the brake hydraulic pressure, and an increase/decrease solenoid for switching the increase/decrease gradient of the brake hydraulic pressure into two levels, high and low. A brake oil pressure adjustment section 56 including a gradient control solenoid is provided. For example, the increase/decrease direction control solenoid of the control valve section 54 causes the oil pressure to decrease when energized, and the increase/decrease gradient control solenoid of the brake oil pressure adjustment section 56, for example,
It is twisted so that the gradient of increase/decrease in oil pressure is steep when electricity is applied.

The operation will be described below with reference to FIGS. 3 and 4. First, in the computer 46, as shown in the control flow of FIG.
The wheel speed %FRnVwF,n,vwRn is calculated. Next, this calculated wheel speed VwyByl,
VwyLn, VwBn (C), the maximum value Vwmax n is calculated using the following formula.

Vwmaxn = MAX (VwBn s Vwirn
n, Vw phn) ... Song (1) Furthermore, by subtracting the reference speed difference ΔV from the maximum value Vwmax n of the wheel speed, the first calculated speed V S A is calculated using the following formula.
Calculate n.

V 8 A11 = Vwmax n-△■・During the song・・
...(2) Here, the reference speed difference ΔVFi, fixed speed &V
It is calculated by the following formula using o and velocity coefficient Kv.

ΔV=Vo+Kv−Vwmax −=−−−−−−(
3) Next, the previous group #! Using the single wheel speed eVsn-1 and the reference deceleration dn, the second calculated speed Vsan, which is a time Δ after the previous time, that is, the current second calculated speed, is determined by the following equation.

Vaan = Vsn -1-cQnHΔt - Flexible (4) In the end, the reference wheel speed Van is determined by the following equation as the larger of the two calculated speeds.

Vsn = MAX (Vaan, Vsan) −
-(5) Reference wheel speed V8 determined in this way d)
n and the wheel speed of each controlled wheel Vwnn, Vwynn,
The brake device of each controlled wheel is controlled according to the deviation state from VwyLn. Specifically, as shown in Fig. 4, it is first compared whether the brake switch is on or not, and if the brake switch is off, there is no need to activate the anti-skid device, so the front 1C increase/decrease direction Both the control solenoid and the increase/decrease gradient/control solenoid H are turned off.On the other hand, when the n/rake switch is on, the reference wheel speed Van and the wheel speed Vwn of each control wheel are compared, and the corresponding Wheel speed V of the control wheel
If wn is smaller than the reference wheel speed Vsn,
The increase/decrease direction control solenoid of the corresponding actuator is turned on, and the corresponding brake device is released. On the other hand, when the wheel speed &Vwn of the controlled wheel is greater than the reference wheel speed Vsn, the increase/decrease direction control solenoid is turned off and the brake device is applied. )! ! Then, let the current wheel speed Vwn and the previous wheel speed Vwn-1 be (Vwn -
Vwn-1) Vwn = -・--・-(6) Next, the on/off state of the increase/decrease direction ratio control solenoid is checked, and if the increase/decrease direction ratio 11# solenoid is on, the wheel decrease is speed? wn is the first threshold G
TI (compared with 1, and if the wheel deceleration Own is less than or equal to the first threshold GTHI, 1'l'ij increase/decrease 6Q m
The control solenoid is turned on to ramp up the brake oil pressure and quickly lower the brake oil pressure. On the other hand, the wheel deceleration of the control wheel? wn is the threshold value GTHI of the whistle l
When VcFi exceeds VcFi, the increase/decrease gradient control renoids are turned off, and the brake oil pressure is gradually lowered by f(t).Also, when the decrease direction full eA renoids are off, the wheel deceleration': /wn and second threshold GTH2
are compared, and the wheel deceleration Vwn is determined by the second threshold value GTH
If it exceeds 2, the increase/decrease gradient control solenoid is turned on and the brake oil pressure is quickly increased, while the wheel deceleration?
If wn is less than the second threshold value GTH2, the increase/decrease gradient control solenoid is turned off and the control oil pressure is gradually increased.

Furthermore, when the wheel deceleration exceeds the reference deceleration 01n,
The corrected value of the standard deceleration (7n/) is determined as follows and is used as the standard deceleration at the time of the subsequent solenoid discharge.In other words, the differential value of the maximum wheel speed!Wnla
The maximum wheel speed when X becomes the reference deceleration ClIn is defined as V8TM. Next, let Vxsn be the local maximum value of 1 speed for the car whose wheel recovers the fastest. Further, the correction value 6n' of the reference deceleration is calculated from the following equation π, assuming that the time period during which the wheel speed changes from VSTm to Vinn is T(in).

Here, Kσ is a correction coefficient for υ.

In this way, the vehicle body deceleration is estimated from the change in the wheel speed, and control is continued using the reference deceleration correction value dnI obtained from the estimated vehicle body deceleration.

This makes it possible to perform appropriate brake control according to road surface conditions and tire conditions, reliably prevent wheel locking, and enable the vehicle to stop in the shortest stopping distance.

Incidentally, as the initial value of the base and semi-deceleration σn, that is, the first reference deceleration o1o after the start of braking.

For example, conventionally, the maximum deceleration expected from the maximum capacity of the braking system, for example 1.1 G, can be used.

Further, assuming the reference deceleration 6n, the correction value 01n/ of the reference deceleration obtained by calculation is, for example, 0.3.
If it is smaller than G, there may be a calculation error, etc., so the correction value of this reference deceleration is set to 0.3G, while the correction value Qn' is set to, for example, 1.3G. Even if it exceeds IG, it is still I.
? Since there are calculation errors, etc., the correction value C7n' is set to 1-
By fixing 1'G&, it is possible to prevent malfunctions caused by calculation errors and the like.

In this embodiment, the controlled wheels are the rear wheel, the right front wheel, the left front width, and the reference wheel speed Vs is set to each frame J'[i! Corresponding to the trace of the maximum values of the wheel speeds VWR, VWFR, and Vw+rt of the wheels), the correction value cIn' of the reference deceleration is such that the differential value of the wheel speed is equal to the reference deceleration. The standard deceleration was calculated based on the slope of the IH line that connects the maximum wheel speed when the speed is 1 and the thickest wheel speed of the wheel with the fastest rotation 1#, so the standard deceleration assuming the vehicle speed Ik was determined. Correction values can be determined with precision.

It should be noted that the application of the present invention is not limited to hK and hK, and it is clear that it can be similarly applied to, for example, a vehicle anti-skid device in which the control wheel is the rear wheel. In this case, the elapsed time from the time when the differential value of the rear wheel detour becomes the reference deceleration until the time when the rear wheel speed reaches the maximum value will not become so short that the elapsed time Even if the reference deceleration is corrected regardless, U4 is almost never activated.

Each wheel speed VWFR, VWFL, V in the above embodiment
Deceleration of WR and right front wheel 10? wp R1 same front right wheel
The relationship between the operational states of the increasing/decreasing direction control solenoid and the increasing/decreasing gradient control solenoid of the actuator 48 and the brake oil pressure output from the actuator 48 is shown in FIG.

As is clear from the figure, the reference wheel speed Vsu, the wheel speed V
wvR1VWFL is a value lower by a predetermined amount △V from the value Vwmax that traces the maximum value of VWR (7), and if Vwmax is the initial value of reference deceleration 60 or more, the deceleration is set to the reference deceleration crorc. It is assumed that it corresponds to a fixed value. The reference wheel speed Vs calculated in this way and the corresponding control wheel, for example, the right front wheel 1.
The magnitude relationship with the mold tank speed VwFRn of 0 is compared, and the time t when the wheel speed VWFR becomes smaller than the reference wheel speed Vs.
1. At t9°t's, the increase/decrease direction trend solenoid is turned on, and the brake oil pressure is set in the decrease direction. Furthermore, when this brake oil pressure is in the decreasing direction, the wheel deceleration VWF
Time ts, ts when R exceeds the first threshold GT old
At Vc, the increase/decrease slope control solenoid is turned off at t. Ki? At X/), the increase/decrease direction control solenoid is turned off and the brake oil pressure is increased. Furthermore, when the increase/decrease directional control mode is turned on,
Wheel deceleration? At time t6, L+1&r, when wk·n bs becomes less than the second threshold value GTH2, the increase/decrease gradient control solenoid is turned off, and the increase gradient of the brake oil pressure is made gentle.

Also, at time tt VC, when the differential value of the wheel speed exceeds the initial value o of the reference deceleration, the wheel speed of the C-th fastest wheel, that is, the right front wheel]0, is changed to VWF R(71t4'-
The slope of the straight line that contains the large value VIND is calculated using the equation (7) above, and the reference speed correction value l obtained from this calculation is the reference deceleration at the next fi control, that is, the reference deceleration at time tR% tit IC. It is said that

As explained above, according to the present invention, it is possible to estimate the optimal storage speed depending on the road surface condition and tire condition, thereby reliably preventing wheel lock and stopping the vehicle in the shortest stopping distance. It has the excellent effect of being able to

[Brief explanation of the drawing]

FIG. 1 is a pipeline diagram showing the overall configuration of an anti-skid device for a vehicle according to the present invention, FIG. This figure is a flowchart showing a control flow for operating the actuator, and FIG. 5 is a diagram showing an example of operation waveforms of each part in the actual example. 10... Right front wheel, 12.16.24... Wheel speed sensor, 14... Left front wheel, 18.20... Rear wheel, 22
・・・Propeller sea shaft, 26.28.3 (1°3
2...Hydraulic brake device, 34...Brake pedal, :(6...Hydraulic cylinder, 38...Hydraulic pump. 40.42.44...Hydraulic pipe line, 46...Computer, 48. 50152...actuator, 53...
- Regulator section, 54... Control valve section, 56,... Brake oil pressure adjustment section. Agent Takahiro Ron (and 1 other person)

Claims (1)

[Scope of Claims] (1,1 When the vehicle is decelerating, the brake device of the controlled wheel is controlled according to the deviation state between the reference wheel speed determined from the wheel speed and the wheel speed of the controlled wheel, and the controlled wheel is locked. In a vehicle anti-skid device that is designed to prevent wheel deceleration, when the wheel deceleration exceeds the reference deceleration, the differential value of the reference wheel speed is set to the reference deceleration [by fixing the reference deceleration] regardless of the wheel speed. The slope of a straight line connecting the wheel speed at the time when the wheel speed is determined and the brake device is controlled and the deceleration of the reference wheel speed is fixed to the reference deceleration and the maximum value of the wheel speed when the wheel speed is restored. The current car body deceleration is estimated from the current car body deceleration, and the correction value of the reference deceleration wave obtained from the estimated current car body deceleration is used as the next reference deceleration. It is assumed that it corresponds to the trace of the maximum value of the wheel speed, and 9.
The correction value of the reference deceleration is determined from the slope of a straight line connecting the maximum wheel speed at the time when the differential value of the reference wheel speed is fixed to the reference deceleration and the maximum value of the wheel speed of the wheel that recovers the fastest. Claim 1J'
Anti-skid device for vehicles listed in AK. (3) When the elapsed time from the time when the differential value of the reference wheel speed is fixed to the reference deceleration 'vc to the time when the wheel speed jlE of the wheel that recovers the fastest reaches its maximum value is less than a predetermined time. The anti-skid device for a vehicle according to claim 2, wherein the reference deceleration is not corrected. (4) Any one of claims 1 to 3, in which the initial value of the reference deceleration is 1.1G or −1k.
Anti-skid device for vehicles described in 4VC.