JPH0374248A - Antiskid control device - Google Patents

Abstract

PURPOSE:To properly perform hydraulic control by setting pressure reduction time approximately inversely proportional to the wheel acceleration average and controlling a hydraulic control valve device through a control means when the detected slipping degree of a wheel increases to the extent of the normal condition. CONSTITUTION:In an antiskid device, when the slipping degree of a wheel detected by a slip detecting means 1 increases to the extent of the normal condition under which the pressure reduction in brake oil is required, a pressure reduction time setting means 5 sets pressure reduction time approximately inversely proportional to the average time of wheel acceleration before increasing to the extent of the normal condition detected by a wheel acceleration average detecting means 4 and supplies a control means 2 with the set time. In addition, the control means 2 controls a hydraulic control valve device (pressure increasing and decreasing two position switch valve) 3 during pressure reduction time for reducing the pressure of brake oil. This makes it possible to properly control the pressure of brake oil regardless whether the pressure of brake oil, which will contribute to the friction factor on road surface, is high or not.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an anti-skid control device for preventing excessive wheel slip during braking in a vehicle equipped with a hydraulic brake device.

A conventional anti-skid control device generally includes (a) a hydraulic pressure control valve device that is provided between a brake cylinder of a brake that suppresses rotation of a wheel and a hydraulic pressure source, and that increases or decreases the hydraulic pressure of the brake cylinder; (b) a slip detection means for detecting slip of the wheel; and (C) controlling the hydraulic pressure control valve device based on the detection result of the slip detection means to prevent excessive slip of the wheel. The bottom of the tank includes a control means. The wheel slip is expressed by the difference between the vehicle speed and the wheel speed, the ratio between the difference and the vehicle speed, or the magnitude of the wheel deceleration (negative acceleration).

Conventionally, the above-mentioned hydraulic pressure control valve device is
As described in Publication No. 2158, a three-position valve is provided with a pressure-increasing position for increasing the hydraulic pressure of the brake cylinder, a pressure-reducing position for decreasing the hydraulic pressure, and a pressure-holding position for holding the hydraulic pressure constant;
As described in Japanese Utility Model Application Publication No. 61-87766, the combination of a pressure increase/decrease switching valve and a slow/slow switching valve can increase the pressure rapidly.
Slow pressure increase.

Types that could control hydraulic pressure in modes such as rapid pressure reduction and slow pressure reduction were used.

Problems to be Solved by the Invention These conventional hydraulic control valve devices inevitably have complicated structures and high costs. This problem can be solved by using a two-position pressure increase/decrease switching valve that can take only a pressure increase position and a pressure decrease position as a hydraulic control valve device.
It is not easy to properly control this switching valve. During anti-skid control, pressure reduction is normally performed more rapidly than pressure increase, but a two-position pressure increase/decrease switching valve has a pressure holding position and a gradual pressure reduction position, and has a pressure reduction gradient at the end of pressure reduction. Since it is not possible to increase the pressure after decreasing the slip, if the brake pressure is increased after the slip has actually decreased or signs of decrease have appeared, the brake fluid may be decreased too much due to control delays, etc. This is because it is difficult to reduce the pressure by an appropriate amount.

The first invention of the present application is based on the above-mentioned circumstances, and by devising the setting of the pressure reduction time of the two-position pressure increase/decrease switching valve,
The object of this invention is to provide an anti-skid control device that can appropriately control hydraulic pressure while using an inexpensive switching valve.

Further, the second invention has been made with the object of obtaining an anti-skid control device that can solve the problems of the first invention for a particularly wide range of road surfaces, from roads with a high friction coefficient μ to extremely low friction coefficients. It is something.

The third invention has been made with the aim of solving the problems of the second invention and obtaining a more reliable anti-skid control device.

Means for Solving the Problems And the gist of the first invention is, as shown in FIG. In the anti-skid control device including, a two-position pressure increase/decrease switching valve is used as a hydraulic control valve device, and (d) the average value of wheel acceleration until the slip detected by the slip detection means increases to a reference state. (e) a decompression time having a length that is approximately inversely proportional to the average value of wheel acceleration detected by the acceleration average value detection means when the slip detected by the slip detection means increases to the reference state; and a depressurization time setting means for setting and supplying the pressure to the control means.

As the reference state, it is desirable to adopt a state in which the wheel acceleration has decreased to the reference acceleration (negative acceleration) in order to detect an increase in slip at an early stage.

Furthermore, ``the average value j of wheel acceleration until the slip increases to the reference state is used as a value representing the magnitude of vehicle acceleration during braking, and when the braking effect begins to appear (for example, the wheel acceleration Although it is possible to calculate the average value after the wheel acceleration has decreased to a relatively small constant value (negative value), it is also possible to calculate a weighted average value that gives greater weight to newer values of a large number of sampled values of wheel acceleration. Then, an average value corresponding to the vehicle acceleration during braking can be obtained without specifying the sampling start time for obtaining the average value.

Moreover, the gist of the second invention is as shown in FIG. 1(b),
The apparatus in which the reference state, pressure reduction time, and pressure reduction time setting means of the first invention are replaced with the first reference state, first pressure reduction time TO, and first pressure reduction time setting means, respectively, further includes (
f) When the slip detected by the slip detection means decreases to the second reference state, the time T1 from when the slip increases to the first state to when it decreases to the second reference state.
is longer than the reference time C3, the second decompression time T2 is set to be longer as the difference between the time T1 and the reference time C3 is larger, and the second decompression time setting means is provided to supply the second decompression time T2 to the control means. That's true.

As the second reference state, a state in which the wheel speed has recovered to a speed lower than the vehicle body speed by a reference amount, a state in which the wheel acceleration has recovered to a reference acceleration that is equal to or different from the reference acceleration, etc. can be adopted. .

The gist of the third invention is that, as shown in FIG. (h) wheel acceleration recovery strength detection means for determining the recovery strength of wheel acceleration when a predetermined set time TCheck has elapsed;
and a second depressurization time setting means for setting a second decompression time T2 that is longer as the difference between the two strengths becomes larger when the wheel acceleration recovery strength is smaller than the reference recovery strength, and supplying the second decompression time T2 to the control means. be.

The above set time should be a relatively long time so that the wheel acceleration recovery strength has already recovered from the reference strength by the time the set time has elapsed, except on extremely low μ roads where the friction coefficient is less than 0.15. is desirable. Furthermore, the bipedal wheel acceleration recovery strength is, for example, the average value of wheel acceleration up to the time when the first decompression time is supplied to the control means, that is, the start of decompression, and the wheel acceleration up to the elapse of the set time. The difference between the acceleration and the average value can be used. As the latter average wheel acceleration value, it is preferable to use an average value of wheel accelerations during a certain period of time immediately before the elapse of the set time period. In particular, it is advantageous to set the certain period of time to a period close to or longer than the vibration period of the wheel due to the expansion and contraction of the suspension spring, since it is possible to reduce the influence of disturbances caused by vibration of the wheel. As the latter wheel acceleration average value, similarly to the detection of the acceleration average value by the acceleration average value detection means, a weighted average value is obtained by giving a large weight to a new one of a large number of sampled values of wheel acceleration, and then It is also possible to use

In the anti-skid device according to the first aspect of the invention, when the wheel slip increases to a reference state in which the brake fluid pressure needs to be reduced, it is approximately inversely proportional to the average value of the wheel acceleration until the brake fluid pressure increases to the reference state. The pressure reduction time TO set to the length is supplied to the control means, and the pressure reduction is performed by the amount control means of the pressure reduction time To.

The fact that the average value of the wheel acceleration until the wheel slip increases to the reference state is large means that the friction coefficient of the road surface is large and the brake fluid pressure is high. and,
The amount of pressure reduction when the pressure increase/decrease switching valve is kept in the pressure reduction position for a certain period of time increases as the brake fluid pressure increases, but the amount of pressure reduction due to one pressure reduction during anti-skid control is independent of the height of the brake fluid pressure. It is desirable that the value be approximately constant.

Therefore, if the pressure reduction time is set to a length that is approximately inversely proportional to the average value of wheel acceleration, the amount of pressure reduction per hour 1 2 will be approximately constant regardless of the level of brake fluid pressure or the road surface friction coefficient. , the decompression time can always be set to a substantially appropriate length.

That is, instead of terminating the pressure reduction by detecting that the slip has actually disappeared or started to disappear, the timing for terminating the pressure reduction is determined according to the situation at the start of the pressure reduction.

The brake fluid pressure of the front wheels, where the load increases during braking, is approximately proportional to the average value of wheel acceleration over a wide range, so the pressure reduction time set above for the front wheels is a reasonable length in most cases. It becomes Satoshi. However, when braking, the load on the rear wheels decreases as the friction coefficient of the road surface increases.When the friction coefficient exceeds a certain value, that is, when the absolute value of the average value of the wheel acceleration increases and its inversely proportional value decreases, the pressure decreases. It is necessary to ensure that the decompression time is not less than a certain value, as this may cause a shortage.

Moreover, in the anti-skid device according to the second invention,
The pressure reduction time of the first invention is supplied to the control means as the first pressure reduction time TO, and the time T1 from when the slip increases to the first reference state until it decreases to the second reference state is longer than the reference time C3. In this case, the larger the difference between the time TI and the reference time C3, the longer the second pressure reduction time T2 is set and supplied to the control means.

It is relatively easy to set the first decompression time TO to an approximately appropriate length for a road surface with a friction coefficient μ of about 1.0 to 0.15, but for road surfaces with a friction coefficient μ of about 1.0 to 0.15, It is not easy to appropriately set the first decompression time even for low μ roads. Therefore, in the second invention, the first decompression time is not forcefully set to an appropriate length even for an extremely low μ road, and the slip increases to the first reference state and then reaches the second reference state. An appropriate second pressure reduction time T2 is set according to the length of the time TI until the pressure decreases, and the entire pressure reduction time is set to T1+T2. The length of the time TI has a close relationship with the friction coefficient μ of the road surface, and the second decompression time T2 is made proportional to the difference between the time T1 and the reference time C3. By setting the second decompression time so that it becomes longer as the value increases, it is possible to set an appropriate decompression time of 3 4 for an extremely low μ road.

Further, in the anti-skid device according to the third invention,
The wheel acceleration recovery strength is detected when a set time has elapsed from the start of pressure reduction, and a second pressure reduction time is set based on the result. As in the second invention, if the second decompression time is determined at the time when the slip has decreased to the second reference state, there may be a delay or failure in detecting that the slip has recovered to the second reference state. Therefore, in order to improve the reliability of the device, it is necessary to perform special processing to deal with delays and failures, but in the anti-skid device according to the third invention, the second decompression time is Since the setting time is determined in advance, there is no need to perform such special processing.

Effects of the Invention Therefore, according to the first invention, by using an inexpensive 2-position pressure increase/decrease switching valve as a hydraulic pressure control valve device, it is possible to reduce the device cost while controlling the level of brake fluid pressure and the friction of the road surface. It becomes possible to appropriately control the brake fluid pressure regardless of the high or low coefficient, and it is possible to obtain an anti-skid control device that is inexpensive and has excellent performance.

Further, according to the second invention, in addition to the effects of the first invention, it becomes easy to set an appropriate depressurization time even when the coefficient of friction of the road surface changes over a wide range, and more accurate anti-skid control is performed. The effect that it is possible to achieve is obtained.

According to the third invention, since the setting timing of the second depressurization time is determined, it is possible to obtain the effect that the reliability of the apparatus can be easily improved compared to the second invention.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 is a diagram showing a part of an automobile hydraulic brake device including an anti-skid control device which is an embodiment of the first and second inventions of the present application. In the figure, reference numeral 10 denotes a brake pedal as a brake operating member, and hydraulic pressure corresponding to the operating force of the brake pedal 10 is generated in the mask cylinder 12 5 6 . The mask cylinder 12 is a tandem type having two pressurizing chambers, front and rear, and a hydraulic pressure circuit for the front wheel system and a hydraulic pressure circuit for the rear wheel system are connected to the two pressurizing chambers independently of each other. Only one wheel system 14 is shown. A brake cylinder 16 that operates the brakes of the wheels 14 is connected to the mask cylinder 12 by a main fluid passage 18 .

An on-off valve 20 is provided in the middle of this main liquid passage 18. The on-off valve 20 is an electromagnetic valve that switches between an open position for communicating with the main liquid passage 18 and a closed position for blocking it, and is normally in the open position. A bypass 24 including a check valve 22 is provided in parallel with the on-off valve 20, so that brake fluid quickly returns from the brake cylinder 16 to the mask cylinder 12 when the brake is released.

A series circuit including a pressure increase/decrease switching valve 26 and a check valve 28 is further connected to the main liquid passage 18 in parallel with the on-off valve 20 . The check valve 28 allows the brake fluid to flow from the mask cylinder 12 side to the pressure increase/decrease switching valve 26 side, but prevents the brake fluid from flowing in the opposite direction. In addition, the pressure increase/decrease switching valve 26
is a pressure reducing position where the brake cylinder 16 is communicated with the reservoir 30 to reduce the brake fluid pressure, and the accumulator 3 is in the pressure reducing position.
This is a solenoid valve that can be switched to a pressure increasing position in communication with 2 and increasing the pressure. When the pressure increase/decrease switching valve 26 is switched to the pressure reduction position, the brake fluid discharged into the reservoir 30 is pumped up by the pump 34 and stored in the accumulator 32. The accumulated liquid pressure of the accumulator 32 is set slightly higher than the maximum generated liquid pressure of the mask cylinder 12. A throttle 35 is provided on the inlet side of the pressure increase/decrease switching valve 26, and the flow rate of brake fluid when the pressure increase/decrease switch valve 26 is switched to the pressure increase position is 115 when switched to the pressure decrease position.
It is designed to be narrowed down to ~1/30.

Therefore, the pressure is reduced rapidly and the pressure is increased slowly.

The on-off valve 20, the pressure increase/decrease switching valve 26, and the pump 3
A motor 36 that drives 4 is controlled by a control device 37. A rotation sensor 38 is connected to the control device 37 . This rotation sensor 387 8 outputs one pulse-like signal every time the wheel 14 rotates by a certain angle. As shown in FIG. 3, the control device 37 includes a CPU 40. ROM42°RAM44 and■
It is mainly a microcomputer equipped with a /○ boat 46. The rotation sensor 38 is connected to the I10 boat 46 via a waveform shaper 50, and
The on-off valve 20 and the pressure increase/decrease switching valve 26 are connected via a drive circuit 52, and the motor 36 is connected via a drive circuit 54. The ROM 42 stores various control programs including the programs shown in the flowcharts of FIGS. 4(A) and 4(B). The flowchart in FIG. 4 shows only the part related to hydraulic pressure control of the brake cylinders 16 out of the program for creating control commands for controlling the hydraulic pressure of the brake cylinders of each wheel.

The operation of the present anti-skid control device will be described below with reference to the flowchart in FIG. 4, and each symbol in this figure indicates the following.

Time: Time cumulative value Time + Time2: Calculation time interval. Among a large number of calculation command pulses issued at predetermined time intervals, the fall of the pulse signal from the waveform shaper 50 immediately before the previous calculation command pulse and the rise of the pulse signal immediately before the subsequent calculation command pulse. It is the time until the fall, Time is the previous time interval of the two successive calculation time intervals, and Time2 is the subsequent time interval.

Pulse: Number of pulses of the pulse signal from the waveform shaper 50 within Time 2 TDow□: Decompression time V, 1. V,2: Wheel speed within Time 1 + Time 2 calculated based on the above pulse number (
Angular velocity) ΔVyu, ΔVwf: Wheel speed buffer and filter value 0. ΔVw+Vwr' Instantaneous value of wheel acceleration (angular acceleration), buffer, filter value 83:0. Long-term average value No1se 1: Low-pass filter value of wheel acceleration 90 Noise 2: Low-pass filter value of absolute value of No1se 1 Kv: Wheel speed determination coefficient 8: Wheel acceleration determination coefficient Kl, 2. 3: Low-pass filter coefficient 4. to 5
．． 6: Noise quantification coefficient GO: Reference acceleration for braking start detection G1: Anti-skid control start reference acceleration G21. G2
2: Reference acceleration for starting pressure reduction, G21 is for the first pressure reduction, and G22 is for the second pressure reduction.

G3: Reference value of positive peak value of wheel acceleration G4: Forced sudden pressure increase start reference acceleration G'22. G'4: G22 modified according to the noise level. 7 in G4. 8. 9. KIO, Kll, 12: Correction coefficient for each reference value based on noise Flag: Control mode flag, and each flight of this flag indicates the following mode.

O: Waiting until the 1st slip becomes excessive before starting anti-skid control 2: During anti-skid control 3: During extremely low μ road control 5 lip: Desired slip rate Valve Q: Control command for the on-off valve 20, 0 is when the slip is open , 1 represents closed.

Valve 1: Control command for the pressure increase/decrease switching valve 26, where 0 indicates pressure increase and 1 indicates pressure decrease.

VRsso: Target wheel speed of allowable slip rate Vwret
: Reference wheel speed V wbiss : Bias value ΔV w of Vwrer
rof' V wraf reduced slope T, 48□. : Decompression start time CI, C2, G3. C4, C5: Constant for decompression time calculation wa: Long-term average value of Vwr α: High AS of 0 Now, in FIG. 4, step Sl (hereinafter simply Sl
Expressed as The same applies to other steps), the control device 3
This is the initial 1 2 period setting that is performed at the same time as the power is turned on.Various values are reset to O.

At this time, Valve O and Valve 1 are reset and read by executing an interrupt routine (not shown), so that the on-off valve 20 is switched to the open position, the pressure increase/decrease switching valve 26 is switched to the pressure increase position, and the mask cylinder 1
2 is in a state where the hydraulic pressure is directly transmitted to the brake cylinder 16.

Subsequently, in S2, the values of Time2 and V,2 (here 0) are stored in Time1 and V,1, respectively. Also, the values of Time 2 and Pu1se are read, and Vw2=Kvl'ulse/Time2 HHHHH
The instantaneous value of the wheel speed is determined by the calculation of +-(t).

In S3, by determining whether Time 1 is O, it is determined whether S2 has already been executed twice or more, but initially, the result of the determination is Yes, and S2 is executed again. In this way, Time ITime2.
After the multiple values of Lrl and V,2 are determined, S4 is executed.

In S4, calculations of the following equations are performed.

Time-Time+Time2・・・・・・・・・
・(2)ΔT-(Time1+Time2)/2...
...(3) </, =, (Vw2-V, 41)/Δ
T・・・・・・(4)ΔV8−Δ■8・K1+(V
, 2 V-r) ・ ・ ・ (5) V wf =
V wf+ΔV8・K2 ・ ・ ・ ・ ・ ・ ・
・(6)Δi=Δ■8・K1 medium (0-9wt)・
...(7) 9wt = V wt+Δ, -2 -...
...-...(8),,,-8,+(-t v,a)K
3 ・ ・ ・ ・ ・ (9) Noise 1
=Note 1 + (Δ, -Noise 1)
K 4 ・O■No1se2=Noise2+(No
1sel・K5Noise2)K6・・・・
...(11) G'22=G22+w, ・K7 -Noise2・K8...02) G'4=
G4+No1se2・K9・・・・・・03)(5)
Equations (6), (7), and (8) are digital filters for wheel speed and wheel acceleration, respectively, and are a kind of Butterworth filter that averages the latest values with greater weight. Further, the formula 00) and the formula (I+) are low-pass filters of Δ0 and the absolute value of No1se 1, respectively. That is, the value of No1se2 obtained as a result of the calculation of equation (11) is a quantification of noise in the wheel acceleration 8, and according to equation 02), No1se2 is set to a predetermined constant depressurization start reference acceleration G22. A correction is made based on the magnitude of , and the corrected depressurization start reference acceleration G'22 that is actually used is determined. G22 is set to a smaller value (a negative value with a larger absolute value) as the noise becomes larger. Note that K7 can take a value from O to 1,
In particular, when 7 = 1, it can be interpreted that decompression is started when there is an imbalance of 022 based on the adhesion between the road surface and the tire (when K7 = 1, the amount of decompression per time is is constant). In addition, by using formula 03), the predetermined constant forced surge pressure start reference acceleration G4 is corrected based on the noise level, so that the actually used corrected forced surge pressure start reference acceleration G '4 is required. G'4 is set to a larger value as the noise becomes larger.

After execution of S4, branching of the operation based on the FlagO value is performed in S5. Initially, Flagi is set in the initial settings.
<Q is set, so S6 is executed.

It is determined whether the wheel acceleration filter value Vwr is smaller than the reference acceleration GO for braking start detection. This reference acceleration GO is set to a negative value with a small absolute value, and if braking is performed and the effect appears slightly, the determination result becomes Yes, and in S7, the target wheel speed V naso is calculated.

Vllaie=Vwf V, 4-31tp・HHHH
HH・Q'jJ Also, by setting Flag to 1, the vehicle enters a standby mode until the slip becomes excessive, and thereafter, hydraulic pressure control is performed in various patterns depending on the level of the friction coefficient μ of the road surface. .

The reason why the control pattern changes depending on the level of the friction coefficient μ of the road surface is as follows. In this embodiment, as will be described in detail later, when the wheel acceleration filter value becomes smaller than the reference acceleration G21 or G'22, S1
3, decompression time Tゎ. 8fi is set to be approximately inversely proportional to the long-term average value Vwi of the wheel acceleration filter values up to that point. The decompression time T thus set. ow+t is 5 6 the first decompression time To in the present invention, which is approximately appropriate for roads with high friction coefficients ranging from high friction coefficients to relatively low friction coefficient roads, but is not necessarily appropriate for extremely low friction coefficient roads. Therefore, for the extremely low μ road, the second pressure reduction time T2 is set in S20, and the pressure reduction time is reset. This is one of the reasons, and another reason is that on medium to very low μ roads, the wheel speed drops significantly during the first depressurization and does not recover easily, so additional gradual depressurization is performed. be. Each case will be explained in detail below.

First, the case of the high μ road shown in FIG. 5(a) will be explained. Note that the condition list in the figure shows the conditions for establishing the points represented by each number of each hydraulic pressure control pattern, and includes step numbers,
indicates a step in the flowchart of FIG. 4 in which the above-mentioned conditions are determined.

Now, after Flag is set to 1, S2, 53S4
．． S5. S8. S9 is repeatedly executed and it is waited for the filter value Vwf of the vehicle speed to become equal to or lower than the target wheel speed V11m5e. When f becomes smaller than the anti-skid control start reference acceleration G1, V
The value of alveO is changed from O to 1, the on-off valve 20 is switched to the closed position, and the supply of brake fluid from the mask cylinder 12 to the brake cylinder 16 is stopped by the check valve 28.
This is done only through the throttle 35 and the pressure increase/decrease switching valve 26, and from then on the hydraulic pressure in the brake cylinder 16 increases more slowly than before. In other words, the mode shifts to the slow pressure increase mode. At the same time, the morph 36 is activated and the pump 34 is ready to pump brake fluid from the reservoir 30.

This point is considered to be the start point of anti-skid control.

Then, when the wheel speed filter value V Wf becomes smaller than the target wheel speed V Ba5e, the wheel acceleration filter value is determined in 311. , is the decompression start reference acceleration G
It is determined whether or not the value has become smaller than 21, and while the result of the determination is No, gradual pressure increase is performed as before. However, if the result of determination is Yes, the pressure reduction time etc. are changed in S13. Settings are made. First, the pressure reduction time T D as the first pressure reduction time TO is determined by T, , , -C1/(,a+C2)-...q
A computation of W n is performed. That is, the decompression time T. In other words, the smaller the long-term average value 88 of the wheel acceleration filter value Vwt is (since it is a negative value, the larger its absolute value is), the shorter it is set. Wheel acceleration filter value Vw
The weighted average (1</
The magnitude of - corresponds to the magnitude of vehicle deceleration, and the fact that this long-term average value V- is small means that the friction coefficient μ of the road surface is high and the hydraulic pressure in the brake cylinder 16 is high. It is. The rate of change in brake fluid pressure during pressure reduction (pressure reduction gradient) increases as the brake fluid pressure increases, but the amount of brake fluid pressure reduction due to one pressure reduction is almost constant regardless of the brake fluid pressure level. Therefore, the pressure reduction time T Down is the long-term average value V of the wheel acceleration. It is desirable to set the pressure reduction time TDO-
is calculated. However, in this example, 1
The decompression time per cycle is limited to a maximum of 125 m5ec, and especially for the rear wheels, it is limited not to be shorter than 25m5ec.

In S13, in addition to calculating the above-mentioned pressure reduction time, Vwr
ar=Vwr+N04S+32 HK I O...
・・06) Vwbfss=11+No1se2 ・K
l 2 ...Q7) Reference wheel speed ■80
．． And the bias value V wbi++s is modified in accordance with the magnitude of wheel acceleration noise. In both cases, the larger the noise, the larger the value is corrected. In addition, 0.5G is the reduction gradient ΔV Wril of V Wrllf
f, and the time at that time is the decompression start time T□. , and Flag is set to 2.

As described above, after S13 is executed, S14 is executed, and the decompression time T. Since wn is set to a positive value in 313, Valvel is set to 1, and pressure reduction is started. Since this pressure reduction occurs more rapidly than the pressure increase performed through the throttle 35, it will be referred to as a rapid pressure reduction, and in contrast to this, the pressure increase will be referred to as a gradual pressure increase.

After the Flag is set to 2 in 313 as described above, S15 is executed following S5, and in this step, the reference wheel speed V wror and the pressure reduction time T are determined.

Wfi is decreased by l cycles. Note that this program is executed every 5 m5ec, so ΔT is 5 m5ec.
It is 5ec.

As described above, the reference wheel speed V wraf and the pressure reduction time T. After w7 is updated, S16 is executed, but since this determination result is Yes in a special case where the coefficient of friction of the road surface suddenly increases, we will discuss this in detail later, and here we will not Assume that the result is NO. Therefore, S17 is executed, but at the beginning of depressurization, T. 8o
Since it is normal that is positive, the result of the determination is Yes, and step 318 is executed. At this point, Flag is still set to 2 in S13, so 319
, the wheel speed filter value VWf is the reference wheel speed V
It is determined whether or not it is greater than or equal to Wrllf. At the beginning of depressurization, this judgment result is normally NO, and S13
The rapid depressurization started as a result of execution continues.

On a high μ road, it is normal for the determination result of 317 to become No before the determination result of S19 becomes Yes, and S
The pressure increase/decrease selection process from 21 onwards is performed. Immediately after the determination result in S17 is No, the determination results in subsequent steps 321 and S22 are also No, and To. Since w, , is negative, the slow pressure increase mode is set at S ], 4. Then, in the next cycle, S21 is Ye
s, and in S23, the wheel speed filter value ■. , is significantly smaller than the reference wheel speed Vwref, i.e. from the reference wheel speed Vwraf to the bias value V
It is determined whether it is even smaller than the value obtained by subtracting W b i a *, but on a high μ road, this determination result is usually N
It becomes O.

Further, immediately after S21 becomes YES, the determination result in S22 also becomes NO, so that the gradual pressure increase is continued.

Then, when S22 becomes Yes, S24 is executed, and if the result of this judgment is Yes, the wheel speed filter value V8f becomes the reference wheel speed V wra
If it is smaller than r, a depressurization time of 5 m5ec is set in S26, but when μ is high, the determination result is usually No, and in S25 it is determined whether the wheel acceleration filter value Vwt is smaller than the corrected depressurization start reference acceleration σ22. A determination is made. In other words, the determination in S25 is not made until 35 m5ec has passed after the transition from rapid pressure reduction to slow pressure increase. There is a lot of noise for a certain period of time after the sudden decompression ends, and within this time 32
If step 5 is executed, there is a risk that an erroneous determination will occur, so S25 is executed after waiting for this certain period of time to pass.

While the determination result in S25 is No, the gradual pressure increase is continued, but if the result is Yes, the rapid pressure reduction mode is set again in S13.

In this way, on high μ roads, hydraulic pressure control is performed in the pattern shown in Figure 5(a), while on medium and low μ roads, hydraulic pressure control is performed in the pattern shown in Figure 5(b). . During,
On a low μ road, the operation differs between the first and subsequent pressure reductions. The second and subsequent operations are similar to those on a high μ road, but the wheel speed decreases significantly the first time, so even if the pressure is reduced, the wheel speed does not recover easily. Therefore, during the first decompression, S
17, the determination result of S21 and 322 is NO, and the determination result of S24 is Y after the gradual pressure increase is performed.
es, and the pressure reduction time T is reached in S26. 8. , is 5
m5ec, and rapid depressurization is performed accordingly. Then, by executing S15, T. , ゎ becomes O, but in this case, S17. Since the determination results in S21 and 322 are both No, the Valve
1 is set to O, and the pressure shifts to gradual pressure increase. Next, S15
is executed again, TDown is -5m5ec
Therefore, S17. S21. The determination result in S22 becomes No in both cases, and the gradual pressure increase is continued. However, by executing 315 several more times, T Dowr+ becomes -3'5
If m5ec is reached, the determination result in S22 becomes Yes and 324 is executed, and if the determination result is Yes, rapid depressurization is executed again.

In other words, gradual pressure reduction is performed in which a gradual pressure increase of 35 m5ec and a rapid pressure reduction of 5 m5ec are performed alternately to wait for the wheel speed to recover, and this pressure reduction will be referred to as additional gradual pressure reduction.

If the wheel speed recovers, the determination result of S24 becomes NO, and the determination result of 325 becomes Yes as in the case of the high μ road.
Slow pressure increase is performed until the pressure reaches s.

If the determination result in step 325 is Yes, S13 is executed and the rapid pressure reduction mode is set.

Above, we have explained about medium and low μ roads, but even if the road surface suddenly changes to medium or low μ roads after anti-skid control is started on a high μ road, the determination result in S24 will be Yes.
A slow pressure increase of 35 m5ec and a rapid pressure reduction of 5 m5ec are performed alternately, and the brake cylinder hydraulic pressure is reduced to a height suitable for the road surface after the friction coefficient has been changed.

Even on an extremely low μ road, as shown in FIG. 5(c), the operation differs between the first and subsequent pressure reductions. 1
In the second time, as in the case of the high μ road, S17. S21
And the determination result of S22 is N.

Therefore, the determination result in S23, which is performed after the gradual pressure increase is performed, is Yes, and the pressure reduction time T D is determined in S26.
own is set to 5 m5ec and depressurization is performed. Therefore, on the extremely low μ road, slow depressurization of 10 m5 ec and rapid depressurization of 5 m5 ec are performed alternately.
This additional gradual pressure reduction is a steeper gradual pressure reduction than the additional gradual pressure reduction on the low μ road mentioned above. Then, the determination result in S23 is N
After reaching o, 35m5e as in the case of medium and low μ roads.
A gradual pressure increase of c and a rapid pressure reduction of 5 m5ec are performed alternately. When μ is extremely low, even if the brake fluid pressure reaches O by performing this additional gradual pressure reduction, the wheel speed does not recover and the determination result in S24 does not become NO, so the additional gradual pressure reduction continues and the brake cylinder fluid pressure The state of O continues for a while, but the wheel speed eventually recovers and the determination result in S24 becomes No. Therefore, step 325 is executed, but since the determination result is initially No, the slow pressure increase mode is set in S14. Then, when the determination result in S25 becomes Yes due to this gradual pressure increase, the pressure reduction time and the like are set in S13.

5 In the second rapid depressurization started as in 3, the depressurization time TI. Since the wheel speed recovers while , is positive, the determination result in S19 becomes Yes, and in S20, the elapsed time (
TI=T-Ti,. ) and the reference time C3, the pressure reduction time T2 is the pressure reduction time Tnow. is set as The pressure reduction time is reset from the first pressure reduction time TO to the sum TI+T2 of the elapsed time T1 and the second pressure reduction time T2. If this pressure reduction time T nown is negative, the slow pressure increase mode is set in S14, but if it is positive, the tendency to eliminate the slip is extremely slow.
It is determined that the friction coefficient μ of the road surface is extremely low, and the value of Flag is set to 3, which indicates that extremely low μ road control is being performed.

Therefore, after the next execution of 318, S19 and S20 are bypassed and S14 is executed, and the i and m pressures are performed for the time set in S20. The second pressure reduction time T2 has elapsed, and S17. The judgment results of S21 and S22 are No.
When this occurs, the mode shifts to the slow pressure increase mode, and when the result of the determination in S25 becomes Yes due to this slow pressure increase, the first pressure decrease time To (TDo, . . . ) and the like are set in S13.

Furthermore, even if the friction coefficient μ of the road surface suddenly decreases to an extremely low value after anti-skid control is started on a high μ road, medium or low μ road, additional gradual depressurization is executed in the same way as the first depressurization described above. The brake fluid pressure is then reduced to a level suitable for the changed low friction coefficient.

In addition, when anti-skid control is started on an extremely low μ road and then shifts to a medium or low μ road, the anti-skid control shown in Fig. 5 (dJ
Hydraulic pressure control is performed according to the pattern shown in .

When the friction coefficient increases rapidly, the wheel acceleration filter value 1
is larger than normal and larger than the corrected forced surge pressure start reference acceleration G"4, so S27 and S28 are executed. If the pressure is being reduced, T.o8. is positive, so the determination in S27 is made. The result is Yes, and at 328, the pressure reduction time T Down is set to O to shift to the slow pressure increase mode, and the long-term average value of wheel acceleration is changed to a bias value α &-1 smaller value. The time average value 8a is changed to a value suitable for a road surface with a high coefficient of friction 7 8 , and the pressure reduction time T D o w is set in 313 after the judgment result in 325 becomes Yes by executing the gradual pressure increase.
n becomes a value suitable for a road surface with a high coefficient of friction.

As described above, if the traveling speed of the vehicle decreases below a predetermined constant speed while hydraulic pressure control is performed in various patterns, or if the brake pedal 10 is released, the brake pedal 10 is released. The termination routine is executed and
There, FIag+ValveO and Valve
1 is reset to O.

As is clear from the above explanation, in this example,
S2 in FIG. 4 of the control device 37. The part that executes S3 and S4 cooperates with the rotation sensor 38 and the waveform shaper 50 to control the slip detection means, and the S of the control device 37
1, the part that executes SIO and S14 is the drive circuit 52.
The control means are jointly installed at the bottom of the tank. In addition, the control device 3
The part that executes SS4 of 7 is the acceleration average value detection means,
The part that executes Sll, S25, and S13 serves as the first decompression time setting means, and the part that executes S19 and 320 serves as the second decompression time setting means, respectively.

Figures 6 and 7 show wheel speed filter values when the anti-skid control device of this embodiment is operated on a high μ road and an extremely low μ road where the friction coefficient μ is 1 and 0.1, respectively. ■87. Changes in wheel acceleration filter value and brake fluid pressure P are shown.

In addition, in this experimental example, G1=-0.5G~0.7
5 G, G21 = -1, 5G ~ -20, G3 = 2G
, G4=30. 1=0.625~0.75. 2=0
．． 125-0.2. 3=0.02~0.03. ni 4=
2. 5=1~2. 6-(0,25~0.5)K4
．． 8ζ1. 9', 1. CI=15. C3-60m5
ec, C4=2.2, K7. G22 and C
2, any combination in the following table is 90. Note that there is a relationship of 7 to G22--1.5+, and a particularly desirable value of K7 is 0.75.

When the μ is high, the time required for pressure reduction is short, so as is clear from FIG. 6, the pressure reduction time T is determined by the long-term average value 88 of the wheel acceleration. . While pressure reduction is performed for w□ (first pressure reduction time To), when μ is extremely low, as is clear from FIG. 7, wheel speed filter value VWf is equal to reference wheel speed V.
Based on the fact that the pressure exceeds WrGf, the pressure is reduced for a time TI+T2 which is reset. In either case, good anti-skid control is performed. In addition, FIG. 7 shows that during the first pressure reduction at extremely low μ, the wheel speed filter value VWf becomes even smaller than the reference wheel speed VWrllf, which is corrected to be smaller by the bias value Vwbias, resulting in a gradual pressure increase. There are also signs that additional gradual decompression is being carried out by repeating rapid decompression.

FIG. 8 is a diagram showing the effect of quantifying wheel acceleration noise and correcting various reference values based on the quantified noise. Both are the results of experiments conducted on a road surface with a friction coefficient μ of 0.3, (a) with almost no noise, (b)
(C) shows the case where the peak-to-peak value is about 4G, and (C) shows the case where the peak-to-peak value is about 8G. From (b) and (c), the decompression start reference acceleration G22. Reference wheel speed V wraf and reference wheel speed bias value ■. , 89, etc. are modified according to the magnitude of the noise, and it can be seen that anti-skid control is performed satisfactorily despite the presence of large noise.

In the embodiment detailed above, 313 in 320
The elapsed time from the start of decompression to the time of execution at 320 TI
A second decompression time T2 with a length corresponding to the second decompression time T2 was set, and the process was to wait for the elapse of the second decompression time T2 before transitioning to slow decompression, but only the length corresponding to the second decompression time T2 was referred to. By increasing the wheel speed VWrGf, it is also possible to rapidly reduce the pressure by an appropriate amount.

For example, in the flowchart of FIG. 4, S30. S31 and S32 are added. S30 increases the reference wheel speed Vwref by an amount corresponding to the second pressure reduction time T2 (TD.0) calculated in S20, and increases the reduction gradient of the reference wheel speed to 0, 5G set in S313. This is the step of changing from 0.2 G to 0.2 G. After this step is completed, when 318 is executed in the next cycle, S31 is selected because the Flag has been changed to 3 in S20, and the wheel speed filter value V
, , are the reference wheel speeds increased in S30 ■
It is expected that the temperature will reach 8°. The judgment result of S31 is Y
Sudden pressure reduction is performed until es is reached, and if it becomes YES, the pressure reduction time Tl is reached in S32. ,,,, is 0
, and Flag is returned to 2, thereby shifting to the slow pressure increase mode.

According to this embodiment, when the road changes from a low μ road to a high μ road during anti-skid control, the time required for sudden pressure reduction is shortened, and the hydraulic pressure control is performed while well following changes in road surface μ. Effects can be obtained. FIG. 9 shows that when the friction coefficient μ of the road surface increases from 0.1 to 0.3 during depressurization, S30
It is a diagram comparing and showing cases where S30 to S32 are executed and cases where they are not executed, and when S30 to S32 are not executed, as shown in (a), despite the sudden increase in the friction coefficient, the setting is made before the sudden increase. The second decompression time T2, that is, Tl11. ,,= (T-T,,,.-C3) When C4 is depressurized and the wheel speed filter value VWf recovers too much, when S30 to S32 are executed, (b) As shown in Figure 2, after the rapid increase in the friction coefficient, the time for rapid depressurization is shortened (the wheel speed filter value ■) is prevented from recovering too much, and the slope of the vehicle speed decrease responds well to the rapid increase in the friction coefficient. Note that (c) shows the change in the wheel acceleration filter value Vwr, and (d) shows the change in the brake fluid pressure P, respectively.

An embodiment of the third invention is shown in FIG.

In this embodiment, in the embodiments shown in FIGS. 2 to 4,
Since this is a modified control program and the other parts are the same, a detailed explanation will be omitted and only the operation will be explained based on the flowchart.

In addition, each symbol in the flowchart is as follows. 4 Show things.

V, q: Long-term smoothed wheel speed obtained by smoothing the wheel speed filter value Vwf with a long time constant T9 G2: Decompression start reference acceleration G'2: G2C11 modified according to the size of noise
, C12, C13, C14, C15: constant V MIIIM for calculating decompression time. : Pseudo wheel acceleration average value T Cha.

k = set time ΔVMa+*o, which is the time interval between the start of pressure reduction and the time of detection of wheel acceleration recovery strength; V□ between the start of pressure reduction and the time of detection of wheel acceleration recovery strength; The wheel acceleration recovery strength S40, which is the difference between the two, corresponds to Sl in the flowchart of FIG. Further, although S41 corresponds to S2 to S4, the calculation of G'4 according to the formula 03) is not performed, but instead the calculation according to the following formula is performed.

Vw, -V,, +(Vl, f-V,,) Δt/τ,
-.-08) The time constant T9 in this equation is 100 m5ec in this embodiment. In the anti-skid control device of this embodiment, the vibration frequency of the wheel accompanying the expansion and contraction of the suspension spring is 10 to 15 Hz, and the vibration period is 100 to 67 m5.
Since it is used in a vehicle that is EC, the time constant T9 is set to the maximum vibration period of 100 m5ec. The reason will be explained later.

After execution of S41, branching of the operation is performed in S42 based on the value of Flag, but since Flag is initially set to O in the initial setting of 340, S43 is executed. Acceleration filter value 0. is smaller than the anti-skid control start reference acceleration G1, but the initial determination result is NO, and 341 is executed again. While the execution of S41 to S43 is repeated, S
If the determination result in step 43 is Yes, Fla
g is set to 1, and in 345, ValveO, which is a control command for the on-off valve 20, is set to 1, which indicates closing, and a pump start command is issued. Based on this, the on-off valve 20 is switched to the closed position, the rapid pressure increase mode is changed to the slow pressure increase mode, and the pump 34 is activated.

5 6 Since 11 Flags are set in S44 above,
In the next cycle, S46 is executed. It is waited until the filter value of the wheel acceleration becomes smaller than the corrected pressure reduction start reference acceleration G'2, and during this time, the gradual pressure increase is continued. Then, when the determination result in S46 is Yes, S47 is executed, and the pressure reduction time T D (l W wa and the pseudo wheel acceleration average value ■
□1o is calculated by the following formula.

T, O,,,=C11/v:7-・-・-・09)■
, 411ffi. -C12(Vllf-Vwq)+CI
1-C14・■, ・ ・ ・ Equation (2I09) looks different from the above θ equations, but they are essentially the same, Equation θ9) is the theoretical equation, and Equation 05) is This is the approximate formula.

Further, (V-t VW,) in the formula Cl1) is the difference in wheel speed between point Pl and point P'2 shown in FIG.

FIG. 11 shows the wheel speed filter values {circle around (2), , f} and the long-term smoothed wheel speed Vwa obtained by smoothing them using a long time constant I9 of 100 m5ec.

However, although both Vwf and V WQ actually contain noise, they are shown with the harmonics of that noise omitted, and the long-term smoothed wheel speed V8Q is different from the wheel speed filter value Vwf. 100m5e in the negative direction of the time axis
It is shown shifted by c. Therefore, the wheel speed filter value vwr at point 20 and the long-term smoothed wheel speed Vwr at point P'z are obtained at the same time. The average value of wheel acceleration at the start of decompression is 1
It is natural to use the difference between the wheel speed filter values VWf at points 1 and 22, but if this average wheel acceleration value is to be determined by a computer, a considerable amount of storage capacity will be required. If it is determined that point P corresponds to the start of decompression, then 22 l O0m5ec before that 18th point.
Although the point is uniquely determined, the wheel speed filter value V
At the point when wf is at 22 points, it is still 10 points from that point.
Since it is not known that the 11 points after 0m5ec correspond to the start of decompression, the computer uses the wheel speed filter value v
All calculation results of wf are memorized, and when the 23 points corresponding to the start of decompression are actually determined, the wheel speed filter value 100 m5ec before the point is determined using the many stored wheel speed filters. (This is because the value of the long-term smoothed wheel speed V wq at point P'2 is obtained at the same time as point P. There is approximately 1 pair between the difference in wheel speed filter values between point and point 22 and the difference between the magnitude of the wheel speed filter Vwf at point 11 and the long-term smoothed wheel speed ■w9 at point P'2. 1, and the latter can be used as the pseudo wheel acceleration average value ■□, . in place of the wheel acceleration average value at the start of pressure reduction.

However, 12 (in formula 11, Vl, , -Vw9 itself is not used as the pseudo wheel acceleration average value V Hers. Instead, a value modified using constants CI2, C13, CI4, etc. is used. .In particular, -C14・
Vwf is a correction term for making the absolute value of the pseudo wheel acceleration average value V Name larger as the wheel speed filter value Vwf becomes larger. Assuming that pressure reduction is started at approximately the same slip rate regardless of the magnitude of the wheel speed filter value vwf, the larger the wheel speed filter value Vwf, the greater the pseudo wheel acceleration average value V, 4. Since the absolute value of o is also supposed to be large, the correction is made to make it so using the term -014·Vwf.

Further, in S47, the timer value Tc is set to the set time T.
chock (65 m5ec in this embodiment), and the value of Flag is set to 2.

Subsequently, 34B is executed, but at this point T D
aw. is positive, the stain e1 is set to 1, and depressurization is started.

When 342 is executed next, the FlagO value is 2, so the program execution moves to S49 and the timer value T
. and decompression time T Down are respectively ΔT (5m
5ec) and T in S50.

A determination is made as to whether or not is positive. Initially, the result of this determination is Yes, and 351 is executed, but the Flag
Since the O value is 1, the result of this determination is No, and 348 is executed again.

9 0 and below, S41. S42. S49. S50. S51. S4
B is repeatedly executed and the timer value Tc becomes negative, but the pressure reduction time T calculated in S47. own is the set time T. Because it is shorter than , , ck,
T before the determination result of S50 becomes No. own becomes negative. As a result, Valve1 is set to O in 348, the rapid pressure reduction is ended, and the slow pressure increase is started.

Thereafter, the determination result in S50 becomes No, and it is determined in S52 whether or not the decompression time T 11 o w n is positive, but the decompression time T is set in 347 as described above. Since 8□ is shorter than the set time TChack, the determination result in S52 is naturally No, and the wheel acceleration recovery strength ΔVMa□ is determined in S53. is calculated by the following formula.

ΔV Ma++c+=Vwf Vwa VMI! I
f(+” ” (2+1 wheel acceleration recovery strength Δ■□a.

In this embodiment, T is the start time of decompression and the set time T. hac
Pseudo wheel acceleration average value after k elapsed■, 48□0
It is calculated as the difference between In S53, the value of Flag is further set to 3.

Subsequently, in S54, wheel acceleration recovery strength Δ■MIII
It is determined whether IO is positive or not, and if it is positive, S5
1 is executed, but at this point, Flag is 3.
is set to be greater than 2, and the decompression time T,.

Since 8n is negative, the determination result in S51 is Yes, and Flag is set to 1 in S55. On the other hand, S
If the determination result in step S54 is NO, the pressure reduction time T is set as the second pressure reduction time T2 in S56. ow. is calculated by the following formula.

T. , fi=−C15·ΔV Mllll.・・・・・・
(22) That is, at the time of determination in S54, ΔV M! , 1.
. If is positive, the wheel acceleration recovery strength is sufficient, and the second pressure reduction time is not set, and the gradual pressure increase is continued; however, if it is less than 0, the wheel acceleration recovery strength is insufficient. If there is, the second pressure reduction time is the wheel acceleration recovery strength ΔVlle□. The larger the absolute value of is, the longer it is set and additional depressurization is performed. In this embodiment, O is the reference recovery strength.

At S56, the pressure is reduced for a time T. If 1 2 S52 is executed after own is set, the determination result will be Yes, and S52 will be executed.
51 is executed. At this point, Flag is 3, which is greater than 2, but the decompression time is T. Since □ is positive, the judgment result is N.
o, Valve 1 is set to 1 at 348,
Rapid decompression is performed again. Then, when the decompression time T Down set in 356 becomes negative, steps 353 and 354 are executed again, but since the determination result in S54 is usually Yes and the determination result in S51 is also Yes, in 355 Flag is set to 1, and a transition to slow pressure increase is performed at 34B.

FIGS. 12 and 13 show examples of the results of braking experiments on a compressed snow road surface and an icy road surface for a vehicle equipped with the anti-skid control device of this embodiment. In these figures, (
(a) shows the experimental results on a compressed snow road surface, and (b) shows the experimental results on an icy road surface.

Figure 12 shows the experimental results when there is little noise, and the wheel acceleration recovery strength (ΔV
Homo) is positive (this can be seen from the fact that the straight line connecting point 13 and point P'4 has a gentler slope than the straight line connecting point p+ and point P'2), whereas It is negative on an icy road surface, and similarly in FIG. 13, which shows the experimental results when the noise is large, it is positive on a compressed snow road surface and negative on an icy road surface. As is clear from FIG. 13, wheel speed filter value V
, the gradient changes in a complicated manner, and when setting the decompression time based on the average value of wheel acceleration over a relatively short period of time, the decompression time on a compacted snow road surface is longer than the decompression time on an icy road surface. However, in this embodiment, the occurrence of such unreasonableness can be effectively avoided and the decompression time can be appropriately set. This is because, in this embodiment, when calculating the wheel acceleration average value, the long-term smoothed wheel speed VWQ whose time constant T9 is longer than the vibration period of the wheel, such as 100 m5ec, is used. This is because the average value of the wheel acceleration for a period longer than the vibration period of the wheel is obtained, so that the influence of noise due to wheel vibration can be effectively eliminated.

3 4 Although three embodiments of the present invention have been described in detail above, the present invention can be implemented in various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (C) are diagrams conceptually showing the configurations of the first invention, second invention, and third invention of the present application, respectively. FIG. 2 is a circuit diagram showing a part of a vehicle hydraulic brake device including an anti-skid control device, which is an embodiment common to the first invention and the second invention of the present application. FIG. 3 is a block diagram showing the configuration of the control device in FIG. 2. FIGS. 4A and 4B are flowcharts showing only portions of the control program stored in the ROM of FIG. 3 that are closely related to the present invention. FIG. 5 is an explanatory diagram showing a control pattern of the anti-skid control device. FIGS. 6 and 7 are graphs showing changes in wheel speed, wheel acceleration, and brake fluid pressure when the anti-skid control device is operated on a high μ road and an extremely low μ road, respectively. Figure 8(a),(b)
and (C) are graphs showing the wheel speed, wheel acceleration, and brake fluid pressure when the anti-skid control device is activated when the wheel acceleration includes noise. FIGS. 9(a) to 9(d) are graphs showing the effects of an embodiment in which steps indicated by broken lines in FIG. 4 are added in comparison with an embodiment in which no steps are added. 1st
FIG. 0 is a flowchart showing a control program in an embodiment common to the first invention and the third invention. FIG. 11 is a diagram for explaining the reason why the wheel acceleration recovery strength is determined by executing the program shown in the flowchart of FIG. 10. FIGS. 12(a) and 12(b) and FIGS. 13(a) and 13(b) are graphs showing the experimental results of the example of FIG. 10. 12: Mask cylinder 14: Wheel 16: Brake cylinder 18: Main liquid passage 20: Open/close valve 26: Increased pressure switching valve 32: Accumulator 34: Pump 37: Control device 38: Rotation sensor 5 6

Claims (3)

[Claims] (1) A hydraulic pressure control valve device that is provided between a brake cylinder of a brake that suppresses rotation of a wheel and a hydraulic pressure source and that increases or decreases the hydraulic pressure of the brake cylinder, and a slip detection means that detects slip of the wheel. and a control means for controlling the hydraulic pressure control valve apparatus based on the detection result of the slip detection means to prevent excessive slip of the wheels, the hydraulic pressure control valve apparatus comprising: is a two-position pressure increase/decrease switching valve that can take a pressure increase position that increases the hydraulic pressure of the brake cylinder and a pressure decrease position that decreases it, and until the slip detected by the slip detection means increases to a reference state. acceleration average value detection means for determining an average value of wheel accelerations; and when the slip detected by the slip detection means increases to the reference state, the average value of the wheel accelerations detected by the acceleration average value detection means is approximately equal to An anti-skid control device comprising: a pressure reduction time setting means for setting a pressure reduction time having a length that is inversely proportional to the length and supplying the pressure reduction time setting means to the control means. (2) A hydraulic pressure control valve device that is provided between a brake cylinder of a brake that suppresses rotation of a wheel and a hydraulic pressure source and that increases or decreases the hydraulic pressure of the brake cylinder, and a slip detection means that detects slip of the wheel. and a control means for controlling the hydraulic pressure control valve apparatus based on the detection result of the slip detection means to prevent excessive slip of the wheels, the hydraulic pressure control valve apparatus comprising: is a two-position pressure increase/decrease switching valve that can take a pressure increase position where the hydraulic pressure of the brake cylinder is increased and a pressure decrease position where it is decreased, and the slip detected by the slip detection means is increased to a first reference state. an acceleration average value detection means for calculating the average value of the wheel acceleration until the slip is increased to the first reference state; The first decompression time T0 is approximately inversely proportional to the average value.
and a first depressurization time setting means for setting and supplying to the control means; when the slip detected by the slip detection means decreases to a second reference state, the slip increases to the first reference state and then the When the time T1 until the time T1 decreases to the second reference state is longer than the reference time C3, the second decompression time T2 is set to be longer as the difference between the time T1 and the reference time C3 becomes larger, and 1. An anti-skid control device comprising: second depressurization time setting means for supplying the second pressure reduction time to the second depressurization time setting means. (3) A hydraulic pressure control valve device that is provided between a brake cylinder of a brake that suppresses rotation of a wheel and a hydraulic pressure source and that increases or decreases the hydraulic pressure of the brake cylinder, and a slip detection means that detects slip of the wheel. and a control means for controlling the hydraulic pressure control valve apparatus based on the detection result of the slip detection means to prevent excessive slip of the wheels, the hydraulic pressure control valve apparatus comprising: is a two-position pressure increase/decrease switching valve that can take a pressure increase position where the hydraulic pressure of the brake cylinder is increased and a pressure decrease position where it is decreased, and the slip detected by the slip detection means is increased to a first reference state. an acceleration average value detection means for calculating the average value of the wheel acceleration until the slip is increased to the first reference state; The first decompression time T0 is approximately inversely proportional to the average value.
a first depressurization time setting means for setting and supplying the first depressurization time to the control means; and determining the recovery strength of the wheel acceleration when a predetermined set time Tcheck has elapsed from the time when the first depressurization time was supplied to the control means. wheel acceleration recovery strength detection means; and a second decompression time setting that sets a second decompression time T2 that is longer as the difference between the two intensities is larger, when the wheel acceleration recovery strength is smaller than the reference recovery strength, and supplies the second decompression time T2 to the control means. An anti-skid control device comprising: means.