JPH02303963A - Antiskid control device - Google Patents

Abstract

PURPOSE:To improve braking performance by utilizing a speed of non-drive wheel as an arithmetic data of a simulated car speed when a drive wheel is detected for its acceleration slip at the time of antiskid starting in which a pressure of brake fluid is reduced when the wheel speed is placed in a slip condition of not less than a predetermined degree for the simulated car speed. CONSTITUTION:In the captioned control device, a braking slip is prevented by reducing a pressure of brake fluid of a wheel in which a wheel speed is placed in a slip condition of no less than a predetermined degree for a simulated car speed obtained being based on speeds of non-drive and drive wheels in a simulated car speed generating circuit 27. Here the simulated car speed generating circuit 27 is provided with a simulated car speed arithmetic circuit 47, which calculates a simulated car speed being based on the wheel speed selected in a select switch 46, and a wheel spin discrimination value arithmetic circuit 48 which obtains a discrimination value for judging an acceleration slip of the drive wheel. While a comparator 49, which discriminates a wheel spin of the drive wheel from the discrimination value and the wheel speed, is provided, and the select switch 46 is switched for using the speed of the non-drive wheel as an arithmetic data of the simulation car speed when the wheel spin in generated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anti-skid control device that controls brake fluid pressure to prevent brake slippage of wheels.

(Prior art) An anti-skid control device is designed to control when the wheel speed during braking has a predetermined slip relationship with respect to the vehicle body speed (for example, the road surface of the wheels [state B exceeding the ideal slip ratio where the friction coefficient is maximum]). It is designed to reduce brake fluid pressure to prevent wheel slipping (locking).

By the way, direct detection of vehicle speed (actual vehicle speed) requires expensive Doppler radar, etc., and is not practical. Therefore, it is possible to detect pseudo vehicle speed from wheel speed using the technology disclosed in Japanese Patent Application Laid-Open No. 60-285163. and use this as the vehicle speed. This technology determines the wheel speed of the right front wheel (non-driving wheel) ■1 and the wheel speed of the left front wheel (non-driving wheel) ■. 2, and the average wheel speed of the two rear wheels (drive wheels)■. 6(a) (where Vc is the actual vehicle speed shown for reference), the pseudo vehicle speed is calculated as follows. That is, wheel speed vWI+ ``'A2+ ■1-13
Since the highest one among them is closest to the actual vehicle speed, it is selected high as shown by ■- in the same figure (b), and the acceleration αL4 of this selected high wheel speed v, J (negative is deceleration) is calculated as shown in (c) of the same figure.

And the deceleration α. t0 to t2 when is equal to or greater than the reference value b2
At the time, select high wheel speed ■actual vehicle speed■.

Select high wheel speed at this time, as it will not be imitated. Calculated vehicle speed of a predetermined decreasing gradient based on
seek. The slope is point ■1° for the first time.

The second time, we set the slope to a predetermined slope.

, and the point ■1°, and from the third time onward, the gradient obtained from the point Vb(.) is the same as the second time. Note that vI is a gradient obtained by connecting the point Vb(. When ΔT has elapsed, the wheel speed is made to match the select high wheel speed V.

Then, between the calculated vehicle speed ■ 〼 and the selected high wheel speed V- obtained in this way, the higher one is closer to the actual vehicle speed VC, so this is selected as shown in Viw in Fig. 6(d). Let it be pseudo-vehicle speed Vow.

(Problem to be Solved by the Invention) However, if the pseudo vehicle speed is created unconditionally based on the highest wheel speed in this way, as shown in Fig. The drive wheels generate acceleration slip (wheel spin) and the wheel speed VW3 exceeds the actual vehicle speed, and then instantly! The wheel speed increases by braking by subsequently pressing the brake pedal■. is the non-driven wheel speed VWI
+ 2 with VH2. From the moment t3 when the vehicle speed decreases, the pseudo vehicle speed y iw becomes as shown in FIG.

Therefore, the pseudo vehicle speed Viw is the actual vehicle speed■. This causes the braking slip to be judged by comparing this with the wheel speed, resulting in a erroneous judgment that the brake slip has occurred when there is no slip, and the braking distance becomes longer due to an unnecessary decrease in brake fluid pressure. Or, in the worst case scenario, you will be unable to brake.

In order to solve this problem, it is conceivable to create a pseudo vehicle speed from only the wheel speed of the non-driving wheels that do not cause drive slip, but in this case, the following problem occurs. In other words, when the wheels are recovering their rotation by reducing the brake fluid pressure due to anti-skid control, it is unavoidable that the timing of re-increasing the pressure will be earlier due to fluctuations in wheel speed due to unevenness of the road surface, and therefore the timing will be lower than the own wheel speed. The wheels subjected to anti-skid control based on the created pseudo-vehicle speed gradually reduce the pseudo-vehicle speed and wheel speed. Fluctuations in wheel speed due to unevenness of the road surface occur almost synchronously between non-driving wheels and driving wheels. In both cases, the wheel speed gradually decreases, and as a result, the pseudo vehicle speed decreases, making it difficult to achieve anti-skid control with a positive value.

For this reason, as mentioned above, the pseudo vehicle speed is usually created based on the wheel speed of the driving wheels as well as the wheel speed of the non-driving wheels. Another reason is that the front wheels, which are the non-driving wheels, This is also because the front wheels support a larger load than the wheels, so the front wheels have a larger share of braking than the rear wheels, and the depressurization of the front wheels should be slightly suppressed.

An object of the present invention is to solve the above-mentioned problem by creating a pseudo vehicle speed based on the acceleration speed of the driving wheels and the wheel speed of the non-driving wheels at the time of lip order.

(Means for Solving the Problem) For this purpose, the present invention obtains a pseudo vehicle speed based on the wheel speed of the non-driving wheels or the driving wheels, and when the wheel speed is in a braking slip state higher than a predetermined value with respect to the pseudo vehicle speed. An anti-skid control device that prevents braking slip by reducing the brake fluid pressure of a non-driving wheel includes an acceleration slip detecting means for detecting acceleration slip of a driving wheel at the time of anti-skid initiation, and an acceleration slip detecting means for detecting an acceleration slip of a driving wheel at the time of anti-skid initiation, and a non-driving wheel and wheel speed selection means that uses the speed as calculation data for the pseudo vehicle speed.

(Function) ´ The anti-skid control device detects during braking when brake fluid pressure is generated that the wheel speed is higher than a predetermined value and enters a braking slip state with respect to the pseudo vehicle speed determined based on the wheel speed of the non-driving wheel or the driving wheel. This reduces the brake fluid pressure of the wheel that has been braked to prevent the brake slip of that wheel.

By the way, if the driving wheels are experiencing acceleration slip at the start of anti-skid, the wheel speed selection means receives a signal from the acceleration slip detection means that detects this and uses the wheel speed of the non-driving wheels as the data for calculating the pseudo vehicle speed. . Therefore, it is no longer possible to create a pseudo vehicle speed based on the wheel speed of the drive wheel that is experiencing acceleration slip, and this pseudo vehicle speed may become higher than the actual vehicle speed, resulting in a longer braking distance due to unnecessary brake fluid pressure reduction. , it is possible to prevent the vehicle from becoming unable to brake.

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

FIG. 1 is an overall system diagram showing an embodiment of the anti-skid control device of the present invention, in which 1 is the right front wheel (non-driving wheel);
a is the wheel cylinder, 2 is the left front wheel (non-driving wheel),
2a is the wheel cylinder, 3 is the right rear wheel (drive wheel),
3a is the wheel cylinder, 4 is the left rear wheel (drive wheel),
4a indicates the respective wheel cylinders. Also, 5 is the engine, 6 is the transmission, 7 is the propeller shaft 1.8 is de,
Differential gears 9 and 10 are rear axles, which drive the two rear wheels 3 and 4 to make the vehicle run.

In the brake system, one system 11a of the two-system master cylinder 11 is connected to the right front wheel cylinder 1a through a pipe 12, and the other system 11b is connected to the right front wheel cylinder 1a through a pipe 13, and the other system 11b is connected to the right front wheel cylinder 1a through a pipe 14. It is a so-called front-rear split type hydraulic brake device which is connected to the rear wheel 3a and to the left rear wheel cylinder 4a through conduits 14 and 15. This brake device is actuated by master cylinder hydraulic pressure generated by depression of the brake pedal 16 and output from two systems 11a and 11b of the master cylinder 11, and can decelerate the vehicle.

A total of three unskid control means for the front right wheel 1, the front left wheel 2, and the two rear wheels 3 and 4 are provided, and these control means are connected to the conduit 12.
13. Actuators 17a inserted into 14, respectively;
17b, 17c, and an anti-skid control circuit 18 that controls their operation.

Since the actuators 17a+ 17J and 17c are similar, corresponding parts are designated by suffixes a and b.

Only the right front wheel actuator 17a, which is indicated by the same reference numerals with different C, will be described in detail below. The actuator 17a includes an inflow valve (EV valve) 19a, an exhaust valve (AV valve) 20a, a pump 21a, and an accumulator 22a.
and a check valve 23a are connected as shown in the figure. The EV valve 19a and the AV valve 20a are individually controlled by the HVI signal and AVI signal from the anti-skid control circuit 18, and the pump 21a is controlled by the other actuator 1.
It is suitably driven by a common motor 24 together with the pumps 21b and 21c in the pumps 7b and 17c, and this drive is controlled by the MR multiplication signal from the anti-skid control circuit 18. When the EVI signal is at L level, the EV valve 19a is opened and the AVI
With the signal at L level and the AV valve 20a closed, the brake fluid pressure to the wheel cylinder la is increased to the same value as the master cylinder fluid pressure.

Also, in this state, the EVI signal changes to H level and EV valve 1
When 9a is also closed, the brake fluid pressure to the wheel cylinder 1a is maintained. Next, in this state, the AVI signal changes to H level and goes to the ν valve? Open oa, plus H level M
When the transistor 25 is made conductive by the R times signal and the motor 24 is energized by the power supply element E to drive the bore 7'' 21a,
The brake fluid pressure in the wheel cylinder 1a is returned to the master cylinder 11 and reduced therein.

The above operations are summarized in the table below.

The anti-skid control circuit 18 controls the EV based on a signal from a wheel speed sensor 26a that detects the rotational speed of the right front wheel l.
The EV2 for the left front wheel actuator 17b is based on the signals from the circuit section 18a that generates the I signal and the AVI signal, and the wheel speed sensor 26b that detects the rotational speed of the left front wheel 2.
Based on the signals from the circuit portion 18b that generates the signal and the AV2 signal, and the wheel speed sensor 26c that detects the rotational speed of the propeller shaft 7, which is the average rotational speed of the two rear wheels 3 and 4, EV3 signal and AV
A circuit portion 18c that emits three signals and these circuit portions 18
Pseudo vehicle speed generation circuit 27 common to a, 18b, and 18c
, target wheel speed generation circuit 28, AVI.

^V2. OR to take the logical sum of the AV3 signal (H level)
It consists of a gate 29 and a lid couple timer 30 which is triggered every time the output of the OR gate rises and generates a signal MR times the level 1 (level MR) for a predetermined period of time.

Since the circuit portions 18a, 18b, and 18c have similar configurations, corresponding portions are designated by the same reference numerals with different suffixes a, b, and c, and only the circuit portion 18a will be described in detail. A wheel speed detection circuit 31a calculates the circumferential speed (wheel speed) 1 from the right front wheel rotation speed (pulse) signal from the wheel speed sensor 26a and the right front wheel rotation radius. This wheel speed is input to the wheel acceleration detection circuit 32a, and the wheel acceleration α, 1. (The negative value is deceleration).

The wheel acceleration α, , is compared with the deceleration reference value and the acceleration reference value a1 by the comparators 33a and 34a.
a, outputs an H level signal when the wheel deceleration α□ becomes a larger deceleration than the reference value, and the comparator 34a outputs an H level signal when the wheel acceleration α becomes larger than the reference value a1. do. The comparator 35a converts the wheel speed VW+ into a target wheel speed (V, , x
0,85), wheel speed■. 1 is below this target wheel speed, the comparator 35a outputs an H level signal. The OR game 36a takes the logical sum of the H level outputs of the comparators 33a to 35a, generates an EVI signal at [■ level, and supplies this signal to the EV valve 19a via the amplifier 37a.

AND gate 38a connects the H level output of comparator 35a and
The logical product with the L level signal from the comparator 34a is taken and the H level signal is
A level AVI signal is generated, and this signal is supplied to the AV valve 20a via an amplifier 39a.

The pseudo vehicle speed generation circuit 27 has the configuration shown in FIG.
~V, . . . The MR signal and the AV3 signal for the drive wheels are respectively input, and the revealed pseudo vehicle speeds V and W are calculated from these as described below. Therefore, circuit 27 is front wheel speed VWI+
Select high switch 4 to select the higher vwz
1 and a select low switch 42 for selecting the lower one. Select high front wheel speed from switch 41, MR
During the anti-skid control when the double signal is at H level, the inner race difference is corrected by the inner race difference correction circuit 43, and when the anti-skid control is not executed when the MR double signal is at the 15 level, it is directly input to the select high switch 44. This select high switch 44 selects the higher of the select high front wheel speed via the inner wheel difference correction circuit 43 and the select low front wheel speed from the switch 42 as the non-driving wheel speed VWF because it is close to the actual vehicle speed. switch 46
Enter. Select high switch 45 is the non-driving wheel speed ■
1 and drive wheel speed vw3 is input to the select switch 46 as the select high wheel speed VWH because it is closer to the actual vehicle speed. This select switch sets the contact point to the normal solid line position and uses the select high wheel speed V- from the switch 45 to calculate the pseudo vehicle speed Viw, and sets the contact point to the dotted line position while the control signal S1 is at H level to calculate the non-driving wheel speed ■. F should be used to calculate the pseudo vehicle speed y iw (input to the pseudo vehicle speed calculation circuit 47).

The pseudo vehicle speed calculation circuit 47 calculates the speeds shown in FIGS. 6(b), (c), based on the wheel speed selected by the left switch 46.
It is assumed that the pseudo vehicle speed 1 is calculated as shown in (d), and this pseudo vehicle speed is calculated by the wheel spin discrimination value calculation circuit 4.
8 and also to the target wheel speed generation circuit 28 shown in FIG. The circuit 48 determines the set value for determining the acceleration slip (wheel spin) of the driving wheels 3 and 4 from experiments as V i, .
X1.05+4 is calculated by m/h, and this is input to the comparator 49. Comparison 2S49 is driving wheel speed■. □
is supplied to the extraction input, and this is the wheel spin judgment value V=
, when the speed exceeds X1.05+4Km/h, the driving wheel is 3°4
It is determined that this is wheel spin and the output is set to H level. This H level output is supplied to one input of the OR gate 50 on the one hand, and to the extraction input of the OR gate via the NOT gate 51 and the retriggerable timer 52 on the other hand.

The retriggerable timer 52 keeps the output at H level for a set time TI from when the output of the NOT gate 51 rises, that is, when the output of the comparator 49 falls as shown in FIG. 3 corresponding to FIG. shall be made. Therefore, the OR gate 50 sets the output to H level during the wheel spin of the drive wheels 3 and 4 and during the subsequent set time T, and performs the AN
Supply to D gate 53 by one person.

The other person operating the AND gate 53 has the MR multiplication signal rising, that is, the instant t when any one wheel starts anti-skid.
, and supplies the output from the retriggerable timer 54 which outputs a 14-level signal during the set time T2 as shown in FIG.

Then, the output of the flip-flop circuit 55 is supplied to the remaining one input of the AND gate 53, and this flip-flop circuit is set at the rising edge of the AV3 signal, that is, at the instant t4 when the anti-skid of the drive wheels starts, and outputs L. At the rise of the NOTOR gate 50 force to which the MR multiplied signal is input, that is, when the anti-skid of all wheels is completed, the output is set to H level. The output of the three-man power AND gate 53 is supplied to the one-man power of the OR gate 57, and is input to the extraction input of the OR gate 57. Provides the output of NQT gate 59 which inverts the IR signal. The output of the OR gate 57 is used as a control signal S for the select switch 46.

In the target wheel continuous generation circuit in Figure 1, on the 2nd day of the road, the pseudo vehicle speed is V! , the target wheel speeds vi, xo, 85 for obtaining an ideal slip ratio of 0.15 at which the road surface friction coefficient of the wheels is maximized (the braking distance is the shortest) are determined, and these are determined by the comparators 35a to 35.
c to determine whether the wheels are locked.

The operation of the above embodiment will be explained next.

First, as shown in FIG. 3, the action of the pseudo double series generation circuit 27 is as shown in FIG.
An example will be explained in which Z is locked instantaneously and anti-skid control begins (the MR multiplier signal rises). instant t
Up to 3, the anti-skid control of the MR multiplied signal L level is not being executed, so the H level output from the NOT gate 59 is supplied to the select switch 46 via the OR gate 57, and this select switch 46 controls the non-driving wheel speed VWF. is supplied to the circuit 47 to contribute to the calculation of the pseudo vehicle speed Viw.

When the MR double signal rises at instant t3 and anti-skid control is started for one of the front two wheels, the output of the NOT gate 59 goes to L level, and the control signal S of the select switch 46 is set to the level S by the AND gate 53. It is determined.

Even momentarily, when the l signal rises, the set time T2 starts.
The middle retriggerable timer 54 sets the corresponding input of the AND gate 53 to H level. Further, the flip-flop circuit 55 is reset when the previous anti-skid is completed, and in order to keep the output at the H level, the corresponding input of the AND gate 53 is set at the H level.

On the other hand, the OR gate 50 sets the corresponding input of the AND gate 53 to the H level during and after the wheel spin of the driving wheels for a set time T. Therefore, from the moment when the anti-skid control starts, until the moment t, the AND gate 53 sets the control signal SI of the select switch 46 to the H level due to wheel spin detection, and the non-driven wheel speed ■. F contributes to the calculation of the pseudo vehicle speed ■i. Therefore, the driving wheel speed V when wheel spin occurs. , is the pseudo vehicle speed v! .

The circuit 47 can obtain this pseudo vehicle speed as shown by the two-dot chain line in FIG. It can be resolved.

Note that even under the same anti-skid control, no wheel spin occurs and the OR gate 50. If the output of the select switch 46 is at the L level, the control signal S is at the L level and the contact of the select switch 46 is set to the solid line position. As a result, the highest wheel speed of all wheels will be used to calculate the pseudo vehicle speed ■1 as before, but since no wheel spin has occurred,
The pseudo vehicle speed V iw never becomes higher than the actual vehicle speed.

Also, after the instant L4 when the anti-skid control of the drive wheels 3 and 4 is started, or even at that instant, the set time T! After the elapse of , the corresponding two-manpower of the AND gate 53 becomes L level, and in these cases as well, the highest of all wheel speeds is used for calculating the pseudo vehicle speed. Therefore, it is possible to prevent the above-mentioned problem caused by calculating a pseudo vehicle speed based only on the non-driven wheel speed vwF at any time.

Next, anti-skid control related to the right front wheel 1 of the device shown in FIG. 17 will be explained based on the operation example shown in FIG. 4.

When brake fluid pressure is generated by depressing the brake pedal 16 at instant L0, wheel speed V W + decreases and wheel deceleration α1 occurs. Wheel deceleration α□ is the reference value.

At the instant t1 exceeding the 1-level output of the comparator 33a, the EVI signal is raised and the EV valve 19a is closed. As a result, the brake fluid pressure P- is maintained at the current value despite the increase in the brake pedal depression force, and the first skid cycle is started.

The wheel speed 1 also decreases due to this pressure holding, and the comparator 3
The output of the comparator 5a also rises, and together with the L level output of the comparator 34a, the AVI signal also rises, opening the AV valve 20a.

Therefore, after the moment t2, the brake fluid pressure is reduced, and the rotation of the front wheel 1 can be restored.

At this time, the MR multiplier signal rises and the retriggerable timer 30 continues the H level during the anti-skid control, thereby driving the motor 24 and making the above pressure reduction possible.

When the rotation of the front wheel I is restored and its wheel speed Vwl increases, a wheel acceleration α1 occurs. Between the instants L3 and t4 when α1≧a, the comparator 34a sets the output to the ■I level, and closes the AV valve 20a at the ■7 level of the Aν1 signal.

Therefore, brake fluid pressure P. is maintained, and even at the moment when αkl<a+, the fall of the output of the comparator 34a (E
V1. When the signal rises, the EV valve 19a is opened and the brake fluid pressure P is increased. to rise.

Brake fluid pressure P. As the wheel speed Vl+11 increases, the wheel speed Vl+11 decreases again, and at the instant t when the deceleration α1 exceeds the reference value , the next skid cycle begins, and the above-mentioned anti-skid control is repeated for each skid cycle.

Therefore, the brake fluid pressure P is maintained at a value near the lock fluid pressure PL that maximizes braking efficiency, and anti-skid control is performed on the front wheels 1 in a manner that minimizes the braking distance. .

Similar anti-skid control is performed for the other front wheels 2 and the two rear wheels 3 and 4, but in determining the common pseudo vehicle speed Viw, when wheel spin occurs in the driving wheels 3 and 4, the wheel speed v1 is not used. Wheel speed of non-driven wheels 1 and 2 ■. 1.
Since Vwg (non-driven wheel speed V, IF) is used, it is possible to prevent the pseudo vehicle speed V iw from becoming larger than the actual vehicle speed, thereby preventing the braking distance from increasing due to unnecessary pressure reduction, or from making braking impossible.

Incidentally, the pseudo vehicle speed generating circuit 27 may be constructed as shown in FIG. 5 instead of that shown in FIG. 2, and a flip-flop circuit 55 may be set therein. That is, in this example, the AND gate 61 is connected to the set input of the flip-flop circuit 55, and the
Retriggerable timer 62 to NDN-gate 610,
Also, a NOR gate 63 is connected to other inputs. The retriggerable timer 62 detects the rising edge of the AV signal, that is, the driving wheels 3 and 4.
Outputs an H level signal for the set time from the start of depressurization, and NO
It is assumed that the R gate 63 outputs an H level signal when the pressure increase of the driving wheels 3.4 starts when the EV, signal, and ^v3 signal are all at the L level.

Therefore, the AND gate 61 sets the i7 flip-flop circuit 55 when the pressure of the drive wheel 3.4 increases after the initial pressure decrease.

(Effects of the Invention) Thus, the anti-skid control device of the present invention has the following effects as described above.
Since the pseudo vehicle speed is determined based on the wheel speed of the non-drive wheels during acceleration slip of the driving wheels, it is no longer necessary to obtain a pseudo vehicle speed higher than the actual vehicle speed based on the drive wheel speed during acceleration slip. Anti-skid control based on a simulated vehicle speed can prevent unnecessary pressure reduction, extending braking distance, and preventing braking from becoming impossible.

Further, according to the structure of claim 2, after the anti-skid of the driving wheel starts, it is clear that the driving wheel is not experiencing acceleration slip, so the calculation is performed based on the higher of the non-driving wheel speed and the driving wheel speed as usual. Since the pseudo vehicle speed is determined, it is possible to avoid the above-mentioned disadvantage of forever obtaining the pseudo vehicle speed based on the non-driven wheel speed.

[Brief explanation of drawings]

Fig. 1 is an overall system diagram showing one embodiment of the anti-skid control device of the present invention, Fig. 2 is an electronic circuit diagram of a pseudo vehicle speed generation circuit on the same side, Fig. 3 is an operating waveform diagram of the circuit, and Fig. 4 is an operation waveform diagram showing the anti-skid control effect on the right front wheel of the device shown in FIG. 1, FIG. 5 is an electronic circuit diagram showing another example of the pseudo vehicle speed generation circuit, and FIGS. 6 and 7 are respectively conventional FIG. 3 is a waveform diagram of pseudo vehicle speed calculation operation. 1... Right front wheel (non-driving wheel) 2... Left front wheel (non-driving wheel) 3.4... Rear wheel (driving wheel) la~4a... Wheel cylinder 7... Propeller shaft 8. ... Differential gear 11 ... Two-system master cylinder 16 ... Brake pedals 17a, 17b, 17c =-actuator 18
...Anti-skid control circuits 19a, 19b, 19c -EV valves 20a, 20
b, 20c - AV valve 21a, 21b, 21c
---Pumps 22a, 22b, 22c...Accumulator 24...Pump drive motors 26a, 26b, 26c -Wheel speed sensor 27...
- Pseudo vehicle speed generation circuit 28...Target wheel speed generation circuit 30...Retriggerable timer 31a, 31b, 31c -Wheel speed detection circuit 32a
, 32b, 32c...wheel acceleration detection circuit 41,
44.45...Select high off switch 42...Select low switch 43...Inner wheel difference correction circuit 46...Select switch 47...1 pseudo vehicle speed calculation circuit 48...Wheel spin discrimination value calculation circuit 49...Comparators 52, 54.65...Retriggerable timer 55...
Flip-flop circuit Figure 3 Figure 7

Claims (1)

[Claims] 1. A pseudo vehicle speed is determined based on the wheel speed of a non-driving wheel or a driving wheel, and braking is performed by reducing the brake fluid pressure of a wheel whose wheel speed is in a braking slip state with respect to this pseudo vehicle speed. In an anti-skid control device that prevents slipping, an acceleration slip detection means detects acceleration slip of the driving wheels at the time of starting anti-skid, and when the acceleration slip is detected, the wheel speed of the non-driving wheels is used as calculation data for the pseudo vehicle speed. An anti-skid control device comprising wheel speed selection means. 2. The anti-skid control according to claim 1, wherein the wheel speed selection means uses the higher of the wheel speeds of the non-driving wheels and the wheel speeds of the driving wheels as the calculation data for the pseudo vehicle speed after the anti-skid of the driving wheels starts. Device.