JPS60261767A - Antiskid controller - Google Patents

Abstract

PURPOSE:To shorten the stop distance of a car by prohibiting decompression control during the state where the wheel speed value is relatively large immediately after the sharp rise of the wheel speed. CONSTITUTION:An antiskid control circuit 100 controls the switching between an inflow valve 14 and an effluence valve 15 on the basis of the signal outputted from a wheel-speed sensor 1 on brake application. In other words, the control circuit 100 generates a pseudo-chassis-speed having a prescribed inclination on the basis of the detected wheel speed value in the case when a prescribed wheel deceleration speed is obtained, and the decompression control for the brake hydraulic pressure is performed when the slip rate determined by the pseudo- chassis-speed and the detected wheel speed reaches a preset value. During a prescribed time after a predetermined certain wheel acceleration speed is detected, the car speed value which forms the generation point for the pseudo-chassis- speed is corrected to a value smaller than the detected wheel speed value.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention generates a pseudo vehicle speed having a predetermined slope from a detected wheel speed value when a predetermined wheel deceleration is reached, and The present invention relates to an improvement in an anti-skid control device that performs pressure reduction control on brake fluid pressure when a slip ratio determined by a vehicle speed and a detected wheel speed reaches a predetermined set value.

[Technology background]

The coefficient of friction μ between the wheels of a vehicle and the road surface is generally the 10th
As shown in the figure, a predetermined slip rate λ.

(approximately 15%), the maximum μ (max) is reached, and at this time, the braking efficiency in the vehicle becomes maximum. Therefore, in normal anti-skid control, when the vehicle is braked, the slip rate λ of the wheels is always the same as the slip rate λ. The braking fluid pressure is controlled by switching to increase, decrease, or maintain the pressure so that the pressure becomes around the same value. As a result, it is possible to shorten the stopping distance during braking, and to ensure steering stability.

By the way, in the actual anti-skid control device,
The above slip ratio λ is determined by detecting the vehicle body speed vc1 wheel speed Vw from the relationship λ=I Vw /Vc, but the vehicle body speed Vc at the time of braking
Since it is technically difficult to directly detect the wheel speed, the present inventors proposed to create a pseudo vehicle speed (hereinafter referred to as pseudo vehicle speed 'Vi) based on the detected wheel speed during braking. are doing.

[Conventional technology and problems]

Conventionally, in this type of anti-skid control device, for example, the first
Braking control as shown in Figure 1 was carried out (for example, Japanese Patent Publication No. 53-137'51, Japanese Patent Publication No. 50-34185, etc.).

This is the pseudo vehicle speed V that decreases at a predetermined slope from the detected wheel speed Vb at that time when the wheel deceleration increases and reaches a predetermined value as the wheel speed Vw decreases during braking.
generate i. Is the slope of this pseudo vehicle speed M a general deceleration tendency during sudden braking? Experimentally, the experimental value, for example 0.
It may be fixed such as 4G, or it may be made variable sequentially based on the tendency of a plurality of detected wheel speeds to decrease each time the predetermined wheel deceleration is reached during braking. good.

Then, the detected wheel speed Vw is the slip ratio λ at which the braking efficiency is maximum.

When the brake fluid pressure P falls below the target wheel speed Vwo corresponding to λo = I Vwo /Vt = 15%, pressure reduction control of the brake fluid pressure P is performed to prevent the wheel speed Vw from decreasing excessively from the target wheel speed VWO.

In this example, the brake fluid pressure is further controlled based on the wheel acceleration/deceleration, and until the detected wheel speed Vw falls below the target wheel speed Vwo, the wheel acceleration/deceleration remains at the predetermined value bl.
Pressure increase control is carried out in the range from al (acceleration) to al (acceleration), and holding control is carried out until the wheel deceleration reaches 0.Furthermore, when the wheel acceleration exceeds a predetermined value of 31, braking hydraulic pressure holding control 2 is carried out. ing. (In addition, Vc in FIG. 11 is the true vehicle speed.) In such an anti-skid control device, when the wheel deceleration reaches a predetermined value b1, based on the detected wheel speed Vb at that time, Pseudo vehicle speed Vi f is generated and wheel speed Vw
is the 85% value of the pseudo vehicle speed V+ (target wheel speed V
Every time WO is reached (every time the slip ratio λ reaches the predetermined value λ), the brake fluid pressure 2 is increased until the wheel acceleration reaches the predetermined value a1.
Since pressure reduction control is performed, the wheel speed Vw does not decrease excessively from the target wheel speed Vwo, and efficient braking that prevents wheel locking is possible.

However, for example, when the vehicle approaches a high μ road surface with a large friction coefficient μ while braking, the wheel speed Vw becomes temporarily higher than the actual vehicle speed Vc due to the pressure reduction control of the braking obstacle pressure. Therefore, this high level wheel speed Vw is
The pseudo vehicle speed vI, which is generated when the wheel deceleration reaches the predetermined value b1 after being reduced by the pressure increase control of the brake fluid pressure, etc., is also at a high level as a whole because the detected wheel speed Vb at that time becomes a large value. Becomes the property of Therefore, the target wheel speed V
wo is also at a high level, and although it is originally desired to further reduce the wheel speed Vw, the wheel speed V is relatively large.
Since the brake fluid pressure is lower than the target wheel speed Vwo f even when the wheel speed is W, the brake fluid pressure is controlled to be reduced, and the stopping distance of the vehicle becomes longer.

Further, when wheel spin occurs when the vehicle starts, a situation similar to the above occurs, and there is a risk that the brake pedal will not be applied even if the brake pedal is pressed immediately after the vehicle starts due to the pressure reduction control.

[Purpose of the invention]

A pseudo vehicle speed with a predetermined slope is generated from the detected wheel speed value when a predetermined wheel deceleration is reached, and a slip rate determined by this pseudo vehicle speed and the detected wheel speed is set in advance. In an anti-skid control device that performs pressure reduction control of the brake fluid pressure when a certain value is reached, if the wheel speed suddenly increases due to the pressure reduction control of the brake fluid pressure mentioned above on a high μ road surface, this problem occurs immediately after the wheel speed increases. It is an object of the present invention to provide an anti-skid control device which prevents brake fluid pressure from being controlled to be reduced when the wheel speed is relatively large due to a high-level pseudo-vehicle speed.

[Structure of the invention]

In order to achieve the above object, the present invention provides, in the anti-skid control device, for a predetermined period of time after detecting a predetermined constant wheel acceleration, a vehicle speed value at which the pseudo vehicle speed occurs and the detected wheel speed The value is corrected by subtracting a predetermined value from the value.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 111 is a block diagram showing the basic configuration of an anti-skid control device according to the 111th invention. FIfJ, basically this anti-skid control device (anti-skid control circuit 1
00) is an inflow provided in a path from the master cylinder 101 of the brake hydraulic pressure system to the wheel cylinder 103 based on a detection signal with a frequency proportional to the rotational speed of the wheel 102 output from the wheel speed sensor 1 during braking. Valve 14 (hereinafter referred to as EV
switching control of valve 14 and one) and foil cylinder "da 1"
03 to reservoir tank 104, pump 1 for hydraulic pressure recovery
This control is performed in conjunction with switching control of the outflow valve 15 (hereinafter referred to as AV valve 15) provided at the first stage before the reservoir tank 104 and the pump 17 in the hydraulic pressure recovery path leading to the master cylinder 101 via the valve 7. Then, the hydraulic pressure in the wheel cylinder 03, that is, the braking hydraulic pressure, is determined as shown in the following table by the switching signal of the IflV valve 14 (hereinafter referred to as the EV double signal) and the switching signal of the AV valve 15 (hereinafter referred to as the AV double signal). It will be controlled.

Table Here, the specific configuration of the anti-skid control circuit 100 is shown in FIG. 5 in the same figure, a wheel speed detection circuit calculates the wheel speed Vw based on the output signal from the two-digit wheel speed sensor, and a wheel speed detection circuit that calculates the wheel speed Vw based on the output signal from the two-digit wheel speed sensor, for example, performs differential processing on the detected wheel speed signal from the three-digit wheel speed detection circuit 2. This is an acceleration/deceleration detection circuit that detects acceleration and deceleration (negative acceleration). 4 is a pseudo vehicle speed generating circuit that generates the pseudo vehicle speed Vi (pseudo vehicle speed) necessary for detecting the slip ratio λ, and 5 is a pseudo vehicle speed generation circuit that generates the detected deceleration from the acceleration/deceleration detection circuit 3 as the reference deceleration b1. or more, the H level signal (hereinafter referred to as b
This is a comparator circuit that outputs a signal (referred to as a signal), and has a configuration as shown in FIG. 3, as will be described later.
At that time, based on the detected wheel speed output from the wheel speed detection circuit 2, a new pseudo vehicle speed vi? It is designed to output . 6 is a target wheel speed generation circuit, and this target wheel speed generation circuit 6 is based on the pseudo vehicle speed Vi from the pseudo vehicle speed generation circuit 5 to determine the slip ratio λ at which the braking efficiency is near the maximum.

It outputs the target wheel MVwo which is the control target corresponding to λo = 1 (Vwo/Vt). Specifically, since the bow is approximately 0.15 (15%), Vwo = VIX O, 85. It performs calculations and outputs the calculated values.

7 is the target wheel speed VWO from the target wheel speed generation circuit 6 and the detected wheel speed Vw from the wheel speed detection circuit 2? 8 is a comparison circuit that outputs a KH level signal (hereinafter referred to as a slip signal) when the detected wheel speed Vw falls below the target wheel speed Vw o, and 8 is a comparison circuit that outputs a KH level signal (hereinafter referred to as a slip signal) when the detected acceleration from the acceleration/deceleration detection circuit 3 is equal to or higher than the reference acceleration 81 A comparison circuit 9 outputs an H level signal (hereinafter referred to as a - signal) when
This is a comparator circuit that outputs an H level signal (b1 signal) when the above conditions occur. Then, an AND signal (AV multiplied signal is input to the AY valve 15 via the driver 13, and an AND signal (AV multiplied signal) is input to the AY valve 15 via the driver 13, and the inverted signal of the 31 signal from the comparison circuit 8 and the slip signal from the comparison circuit 7 is from a
□The b1 signal from the double signal comparison circuit 9 and the AND gate are manually input.

H level signal (hereinafter referred to as M
R times signal) f! : This is a retriggerable timer that outputs, and the MR multiplication signal from this retriggerable timer 16 causes the hydraulic pressure recovery pump 17 to operate.
The pseudo vehicle speed generating circuit 4 is further controlled by this MR multiplied signal.

Here, a specific configuration of the pseudo vehicle speed generating circuit 4 will be explained. In FIG. 3, there is a correction circuit 400 which is a main part of the anti-skid control device according to the present invention, and this correction circuit 400 receives the detected wheel speed from the wheel speed detection circuit 2, as will be described later in FIG. Vw is corrected and output based on the wheel acceleration αW from the acceleration/deceleration detection circuit 3. 40a is the inverted signal from the retriggerable timer 16 via the MR double signal inverter G2 in FIG. A sample hold circuit 40b extracts and holds the wheel speed from the circuit 1400, a sample hold circuit 40b extracts and holds the same wheel speed in synchronization with the b1 signal, and a timer counter 41 increments at a predetermined cycle, 40C. 40d is a sample hold circuit that extracts and holds the value of the timer counter 41 in synchronization with the output signal from the AND gate G, and 40d is a sample hold circuit that extracts and holds the value of the timer counter 41 in synchronization with the signal. Aya.

42 is a subtraction circuit that subtracts the sampling value yb of the sample and hold circuit 40b from the sampled wheel speed value island of the sample and hold circuit 40a, and 43 is a subtraction circuit that subtracts the sampled value Tb of the sample and hold circuit 40d from the sampled value TO of the sample and hold circuit 4Qc. 44 is a subtraction value from the subtraction circuit 42 (To −vb
) by the subtraction value (To - Tb) from the subtraction circuit 43. Also, 45 is a predetermined wheel speed slope signal, for example, a slope signal corresponding to 0.4G? 46 is a changeover switch that switches between the slope signal from the slope generation circuit 45 and the calculation output (Vavb) / (To - Tb) from the division circuit 44, and 47 is a sample hold switch. A subtraction circuit 48 subtracts the output value from the timer counter 41 from the sampling value Tb(n) held in the circuit 40b, and 48 is a slope generation circuit 45 that connects the subtraction value from the subtraction circuit 41 and the division value or changeover switch 46. 49 is a subtraction circuit that subtracts the calculation output from the multiplication circuit 48 from the detected wheel speed values sequentially sampled by the sample and hold circuit 40b. 50 is set at the rising edge of the AND signal by the b1 signal and the MR multiplied signal AND gate G, and is reset at the falling edge of the MR multiplied signal.
), and the changeover switch 46 is
l? When the output Q of 5Q is at L level, it is switched to the slope generation circuit 45 side, and when the output Q is at H level, it is switched to the division circuit 44 side.

Here, the correction circuit 400 is configured as shown in FIG. 4, for example. In the same figure, 4 o 1 digit detected wheel speed V
A subtraction circuit 402 that subtracts a predetermined value δ from w,
A changeover switch that switches the output of the correction circuit 400 to the detected wheel speed Vw of the wheel speed detection circuit 2 or the output of the subtraction circuit 401, and the wheel acceleration output from the acceleration/deceleration detection circuit 3 and a predetermined reference value. Compare the value corresponding to a2, for example 10G, and calculate the wheel acceleration αW
A comparator circuit 404 outputs a full H level signal when the reference value 82 or higher is reached, and 404 is a comparator circuit that outputs a full H level signal when the output from the comparator circuit 403 falls from H level to L level for a predetermined time
The changeover switch 402 is controlled by the output signal Q from the timer 404, and when the output signal Q is at the L level, the switch 402 is connected directly to the wheel speed detection circuit 2. , and are switched to the subtraction circuit 401 side when the output signal Q is at U level.

Next, the operation of this device will be explained.

When the driver depresses the brake pedal and the braking fluid pressure (hydraulic pressure in the foil cylinder 103) increases, the wheel speed decreases and the wheel deceleration (negative acceleration) increases. The speed further increases to the predetermined value b1
When the EV valve 14 is actuated by the signal (BY signal) via the OR gate 11, the brake fluid pressure is maintained at that point. When the wheel deceleration reaches a predetermined value b1, the pseudo vehicle speed generating circuit 4 outputs a pseudo vehicle speed vI having a predetermined slope from the detected wheel speed at that point, and at the same time, the target wheel speed generating circuit 6 to the target wheel speed Vw corresponding to the slip rate λ.

(= Vi X 0.85) are output sequentially. Then, when the wheel speed further decreases and falls below the target wheel speed Vwo by maintaining the brake fluid pressure at a high hydraulic pressure as described above,
A slip signal is output from comparison circuit 7, and AND gate 1
AV by the slip signal (AV signal) via 0
Valve 15 is activated and (or game)-911! The rv valve 14 is activated by the same slip signal (EV signal) via the
The operating state is maintained and the brake fluid pressure is reduced. When the brake fluid pressure is reduced in this way, the wheel speed and wheel acceleration return accordingly, and when the wheel acceleration reaches the predetermined value a1, the a1 signal is output from the comparison circuit 8, and the OR gate
The a1 signal (EV
While the operation of the valve 14 continues, the AND gate 10 becomes inhibited by the same a□ signal, so the AV valve 15
returns to its initial state and brake fluid pressure is maintained. In this way, when the brake fluid pressure is maintained even though it is relatively low, when the wheel speed exceeds the target wheel speed (at this point the slip signal disappears) and increases to a certain extent, it starts to decrease again. , the wheel acceleration also decreases from the predetermined value 31 or above. Here, this wheel acceleration is a predetermined value a11! −, the a1 signal from the comparator circuit 8 falls, and together with the fact that the outputs from the comparator circuits 7 and 9 at that point are at the L level, the EV multiplied signal AV signal goes to the L level, The brake fluid pressure is increased again. Then, the wheel speed and wheel acceleration further decrease, and thereafter, the control of the brake fluid pressure similar to that described above is repeated one after another.

That is, the braking hydraulic pressure switching control during braking is performed according to a control mode determined based on the wheel acceleration/deceleration αW and the slip ratio λ (actually Vw/Vi) as shown in FIG.

The more specific operation of the pseudo vehicle speed generating circuit 40 in the overall operation process of the device as described above will be explained based on the timing chart shown in FIG.

When braking is started and the wheel deceleration reaches a predetermined deceleration S for the first time at time t0, a signal is output from the comparator circuit 5.

The sample and hold circuit 40 synchronizes with the rising edge of the signal.
The detected wheel speed from the wheel speed detection circuit 2 is sampled as the value Vb(0)=Vo at the a1 40b, and the signal from the time counter 41 is sent to the sample hold circuit 4001 and 40d in synchronization with the rise of the signal 1. A count value T(0)=To is sampled. Furthermore, since the AV signal in the control device is at the L level at this point, the FF 50 is not set, and the output Q of the FF 50 is held at the L level and the changeover switch 46 is switched to the slope generating circuit. It is on the 45 side. Then, as time elapses until the wheel deceleration reaches the predetermined value - again, the subtraction circuit 47 outputs a count value Tc corresponding to the elapsed time. At the same time, based on this count value Tc and the slope value Ao (0,4G) from the slope generation circuit 45, the multiplier circuit 48 sequentially outputs a value Ao XTc corresponding to the speed reduction value. Further, the subtraction circuit 49 outputs vb (o) - Ao X'I'c to the target wheel speed generation circuit 6 as the pseudo vehicle speed Vi.

That is, in the first skid cycle from when the wheel deceleration reaches the predetermined value b1 at time t0 to when the wheel deceleration reaches the predetermined value b1 again, the detected wheel speed value V (0) at time to has a gradient AO. A pseudo vehicle speed Vi having a decreasing characteristic is output.

Next, when the wheel deceleration reaches the predetermined value S again at time t, the detected wheel speed value Vb (11) at that time is newly sampled in the sample and hold circuit 40b in synchronization with the b1 signal, and , time counter 41 at the same time
The count value Tb(1) from sample and hold circuit 40d4C is newly sampled in synchronization with the same signal. Also, at this time, the MR from the retriggerable timer 16
The signal is at the 1 dH level, and the AND gate G is disabled and the sample and hold circuits 40a and 4 are disabled.
The values Vb(0) and Tb(0) within 0C are further held, and Fr2O is set, and the changeover switch 46 is switched to the division circuit 44 side and held (this state continues thereafter). . Here, from the subtraction circuit 42, the above time t
. The detected wheel speed value Vb(0) at time t, and the match at time t,
. tB JK M″p * Vb(”) & □tE(m
AVo('')ΔVMI)=Vb(0)-vb(1) is output, and the subtraction circuit 43 outputs the above-mentioned time t.

Counter value Tb(0) at time 1. Counter value T at
The difference value ΔTb (1) with b(1) ΔTb (1) = Tb (0) −Tb (1) is output, and these difference values ΔVb(1), Δ'I'1(1)
Based on K, the division circuit 44 calculates △Vb(1)/Δ'I'b(1), and converts this calculated value A1 from Vb(0) to Vb
It is output as slope information leading to (1). Then, as time elapses until the wheel deceleration further reaches a predetermined value b□, a count value T corresponding to the elapsed time is output from the subtraction circuit 47
c Tc=T Tb(11 Personnel [(i-th output, and this count value Tc and slope information A from the division circuit 44.

Based on (At-ΔVb(1)/Tb(1)), the multiplier circuit 48 sequentially outputs values A and X Tc corresponding to the speed reduction value. Furthermore, the subtraction circuit 49 outputs 1 vb(1) AI X TC as a pseudo vehicle speed.

That is, in the second skid cycle from when the wheel deceleration reaches the predetermined value b1 at time t1 until the wheel deceleration reaches the predetermined value b1 again, the detected wheel speed value Vb (
Pseudo vehicle speed with characteristics that decreases from 1) with slope A ■1
will be output.

Similarly, each time the wheel deceleration reaches a predetermined value in each skid cycle, the difference between the detected wheel speed value at that time and the first detected wheel speed value Vb(0) under the same conditions and the time interval are calculated. (count value), and then, until the wheel deceleration reaches a predetermined value, a pseudo vehicle speed Vi that decreases with the above-mentioned inclination is output from the detected wheel speed value at that time. It turns out.

Along with the generation of the pseudo vehicle speed v1 as described above, in the process of sequentially switching and controlling the braking fluid pressure P based on the slip rate determined by the pseudo vehicle speed V1 and the detected wheel speed VW and the wheel acceleration/deceleration αW, for example, the seventh As shown in the figure, the wheel speed Vw changes from time t1 to time t.

(When the wheel deceleration reaches ), the detected wheel speed Vb (
The target wheel speed Vwo (=Vi
X O, 85) and the brake fluid pressure P is under pressure reduction control.Afterwards, at time t2, the wheel acceleration/deceleration reaches a and the brake fluid pressure P is maintained at a relatively low fluid pressure. When the wheel speed suddenly increases due to such reasons and the wheel acceleration reaches a predetermined constant reference value a2 (time 's), the comparator circuit 40
The output of No. 3 becomes H level. Then, after the wheel acceleration reaches its peak, it decreases and falls below the reference value a2 at time t4, the output signal from the comparator circuit 403 falls to the L level, and accordingly, the output Q of the timer 404 goes to the H level. Then, the changeover switch 402 is switched to the subtraction circuit 401 side. Then, the wheel speed value output from the correction circuit 400 in the pseudo vehicle speed generation circuit 4 becomes a value obtained by subtracting the predetermined value δ from the detected wheel speed value Vw, and the wheel speed value sampled by the sample hold circuit 40b is thereafter (VW- δ
).

Thereafter, the wheel acceleration further decreases to below the predetermined value a, the brake fluid pressure is increased, and after the wheel speed Vw reaches its peak, it begins to decrease again, and the wheel deceleration reaches the predetermined value at time t. When the vehicle speed reaches VN, a new pseudo vehicle speed VN is generated. This new pseudo vehicle speed VI is obtained by subtracting the predetermined value δ from the detected vehicle M speed value VW in the sample hold circuit 40b (VW-δ
) is sampled, its generation point becomes V-〇)-4Vb(n))-δ, which is lower by a predetermined value δ than the conventional generation point (Vb(n)'II (detected wheel speed value at that time)). , the detected wheel speed value Vb when the inclination An reaches the corresponding Vb(n) and the wheel deceleration reaches a predetermined value at the initial stage of braking.
(0) is the slope of the velocity straight line connecting it to (0). When the wheel deceleration reaches a predetermined value (t) and a new pseudo vehicle speed V'i is generated, the brake fluid pressure P is maintained, and by holding the brake fluid pressure P, the wheel deceleration is reduced. Although the wheel speed w continues to decrease after reaching its peak, the target wheel speed (Vwo) - ((Vi) Even if the wheel speed Vw is lower, the target wheel speed V''°, which is actually output from circuit 6 or 6 to generate the target wheel speed t''''C'', is a value that is further lower by δX0.85.
No slip signal is output from the comparator circuit 7, and the brake fluid pressure P
maintains the holding liquid pressure.

When the wheel deceleration returns to normal at time t6 by maintaining this hydraulic pressure, the braking hydraulic pressure is increased and the wheel deceleration decreases to reach the predetermined value b1 again, and the new pseudo vehicle speed v1
occurs, and the braking hydraulic pressure P is maintained at a relatively high hydraulic pressure. The new pseudo vehicle speed vI generated at this time is determined by the fact that the output of the timer 404 in the correction circuit 400 falls to the L level before the b1 signal is output from the comparison circuit 5 at time t, and the output of the correction circuit 400 The detected wheel speed 'Vw' from the wheel speed detection circuit 2 is itself, and the sample hold circuit M40b, which operates in synchronization with the signal,
Since the detected wheel speed value Vb(n+1) at that time is sampled, the detected wheel speed value Vb(n+1) is sampled as described above.
1) to slope An+I CVb(n+1) and Vb(0)
It becomes a velocity straight line with a slope of the straight line connecting the . Thereafter, normal brake fluid pressure control is performed.1 As described above, according to this embodiment, when the wheel acceleration is, for example, L
For a predetermined period of time from the time when the vehicle returns after exceeding "OG't", the vehicle speed value at which the pseudo vehicle speed is generated is determined by the wheel deceleration.
Since the detected wheel speed Vb is corrected to a value obtained by subtracting a constant value δ when the wheel speed reaches Vb, it is possible to prohibit hydraulic pressure control in a state where the wheel speed is relatively high immediately after the wheel speed has suddenly increased. become able to.

FIG. 8 is a block diagram showing another example of the configuration of the correction circuit 400 in the pseudo vehicle speed generation circuit 4.

In this example, the subtraction value δ is made variable depending on the degree of increase in the wheel speed Vw, that is, the magnitude of the wheel acceleration.

To explain its configuration, when the wheel acceleration exceeds a predetermined value of 33, which is 5G, for example, the comparator circuit 403 becomes H level, and the timer 404 outputs an H level signal for a predetermined time from the fall of the comparator circuit 403. It has become. When the OR signal from the OR gate G of the output of the comparison circuit 403 and the output Q from the timer 404 is at H level, the peak hold circuit 405 calculates the wheel acceleration during that period (the period in which the output of the OR gate G3 is at the H level). The peak value αW (ma The subtraction value δ to be subtracted from the detected wheel speed Vw by the subtraction circuit 407 is determined according to the relationship between the peak value αw (max) and the subtraction value δ as shown in the figure.

According to the correction circuit 400 shown in FIG. 8, the greater the degree of increase in wheel speed (the degree of increase in wheel acceleration), the more
Target wheel speed Vwo output from target wheel speed generation circuit 6
(= Vi
It becomes possible to reduce the wheel speed faster.

Note that the correction circuit 400 described so far subtracts a constant value δ from the detected wheel speed Vw during correction, but by multiplying the detected wheel speed value Vw by a positive value less than 1,
It may be corrected to a value smaller than the detected wheel speed value Vw.

〔Effect of the invention〕

As explained above, according to the present invention, a pseudo vehicle speed having a predetermined slope is generated from the detected wheel speed value when a predetermined wheel deceleration is reached, and this Sakai-like vehicle speed is generated. In an anti-skid control device that performs depressurization control of braking fluid pressure when the slip rate determined by the wheel speed and the detected wheel speed reaches a predetermined set value, The time is corrected to a value smaller than the vehicle speed value at which the pseudo vehicle speed occurs and the detected wheel speed value described above, so that the time value is corrected to a value smaller than the vehicle speed value at which the pseudo vehicle speed occurs and the detected wheel speed value described above. Preventing pressure reduction control2
This can prevent the vehicle's stopping distance from becoming unnecessarily long.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an example of a brake hydraulic system in an anti-skid control device according to the present invention, 1 Fig. 2 is a block diagram showing the basic configuration of an example of an anti-skid control device according to the present invention, and Fig. 3 is a block diagram showing an example of a specific configuration of the pseudo vehicle speed generation circuit in FIG. 2, and FIG.
FIG. 5 is an explanatory diagram showing a control mode of brake fluid pressure by the device shown in FIG. 2, and FIG. 6 is a block diagram showing an example of the specific configuration of the correction circuit shown in FIG. FIG. 7 is a timing chart showing the state of the pseudo vehicle speed generated from the pseudo vehicle speed generation circuit, FIG. 7 is a timing chart showing the operation of the device shown in FIGS. 2 to 4, and FIG. FIG. 9 is an explanatory diagram showing the subtraction value determination pattern in the subtraction value determination circuit in FIG. FIG. 11, a graph diagram showing the relationship, is an explanatory diagram showing the states of wheel speed, brake fluid pressure, and wheel acceleration/deceleration during braking by a conventional anti-skid control device. 1... Wheel speed sensor 2... Wheel speed detection circuit) 3... Acceleration/deceleration detection circuit 4... Pseudo vehicle speed generation circuit 5.7, 8.9... Comparison circuit 6... Target wheel speed generation circuit 12, 13... Driver 14... Drift valve (E'V valve) 15... Outflow valve (AV valve) 16... Retriggerable timer 17... Pump 40a, 4 (lb, 40C, 40d - Sample hold circuit 41... Time counter 42, 43, 47, 49... Subtraction circuit 44...
・Division circuit 45...Slope generation circuit 46...Switch switch Tsukuda...Multiplication circuit 50...RS flip 70 tube (FF) 400...
・Correction circuit 401... Subtraction circuit 402... Changeover switch 403... Comparison circuit 404... Timer patent applicant Nissan Automatic Co., Ltd. Figure 8 λ0 person Figure 1 C

Claims (1)

[Claims] An fc pseudo vehicle speed with a predetermined slope is generated from the detected wheel speed value when a predetermined wheel deceleration is reached, and a slip rate determined by this pseudo vehicle speed and the detected wheel speed is set in advance. In an anti-skid control device that performs brake fluid pressure reduction control when a predetermined constant wheel acceleration is detected, a predetermined period of time after a predetermined constant wheel acceleration is detected is the vehicle speed value at which the above-mentioned pseudo vehicle speed occurs. An anti-skid control device comprising means for correcting the detected wheel speed value to a value smaller than the detected wheel speed value.