JPH01249561A - Antiskid control device - Google Patents

Abstract

PURPOSE:To contrive the improvement of estimating accuracy of a car body speed by setting the initial value of an estimated car body speed to a wheel speed in that time, when wheel acceleration and deceleration exceed a preset value thereafter decrease less than a predetermined set value, in case of calculating the estimated car body speed integrating longitudinal acceleration. CONSTITUTION:An estimated car body speed arithmetic means C, which calculates an estimated car body speed integrating longitudinal acceleration by a longitudinal acceleration sensor A, detecting acceleration of a vehicle in its longitudinal direction, with a wheel speed by a wheel speed detecting means B as the initial value, is provided. Being based on the wheel speed, wheel acceleration and deceleration by an acceleration and deceleration detecting means D and the above described estimated car body speed, a fluid pressure control means E controls a fluid pressure in a braking cylinder F. Now when the wheel acceleration and deceleration decrease not more than a predetermined set value after exceeding it, an integration reset means G sets the initial value of the above described arithmetic means C to the wheel speed in that time while resetting integral calculation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an anti-skid control device that controls the hydraulic pressure of a wheel cylinder during braking to obtain an optimal braking condition, and particularly relates to an anti-skid control device that controls the hydraulic pressure of a wheel cylinder during braking to obtain an optimal braking condition. The present invention relates to an anti-skid control device that can accurately calculate.

[Conventional technology]

As a conventional anti-skid control device, there is one described, for example, in Japanese Patent Application Laid-open No. 11149/1983.

This conventional example consists of a rotation detector that detects the wheel rotation speed proportional to the wheel speed and sends out a wheel speed signal, an acceleration detector that detects acceleration in the longitudinal direction of the vehicle and sends out an acceleration signal, and a brake. and a ground vehicle speed calculation device that integrates the acceleration signal from when the brake pedal is depressed and subtracts the integral value of the acceleration signal from the wheel speed signal when the brake pedal is depressed to send a ground vehicle speed signal. A control device for generating a loosening signal for loosening the brake pressure when the wheel speed signal becomes smaller than the ground vehicle speed signal.

(Problem to be Solved by the Invention) However, in the conventional anti-skid control device described above, when the wheel speed is about to change in the locking direction, the vehicle body speed is calculated by integrating the detected value of the longitudinal acceleration sensor. Therefore, when performing continuous integral calculations over a long period of time, it is important to avoid the possibility of errors caused by changes in the gain of the longitudinal acceleration sensor itself, changes over time due to the occurrence of DC offset, or detection errors due to inclinations such as slopes. In addition, because the deceleration immediately after braking was kept constant, there was an inconvenience that the actual vehicle speed and estimated vehicle speed did not match. was. In this case, especially if the estimated vehicle speed is calculated to be lower than the actual vehicle speed, the anti-skid control device incorrectly determines that the wheel slip rate is small and advances the timing to start gradual pressure increase after pressure reduction. As a result, anti-skid control is continued with a high wheel slip rate, resulting in an unresolved problem that the running stability of the vehicle cannot be ensured.

Therefore, this invention was made by focusing on the unresolved problems of the conventional example, and uses an acceleration integral type vehicle speed estimating means, and sets and resets the initial value of the integral calculation based on the wheel acceleration/deceleration. It is an object of the present invention to provide an anti-skid control device that can estimate a vehicle speed with less error by performing monitoring while performing an integral calculation for a long time.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an anti-skid system that controls the fluid pressure of a braking cylinder disposed on each wheel based on the wheel speed of each wheel, as shown in the basic configuration diagram of FIG. In the control device, wheel speed detection means detects the speed of each wheel, wheel acceleration/deceleration calculation means calculates wheel acceleration/deceleration based on the wheel speed detection value of the wheel speed detection means, and acceleration/deceleration in the longitudinal direction of the vehicle. a longitudinal acceleration sensor that detects the longitudinal acceleration; an estimated vehicle speed calculation means that calculates an estimated vehicle speed by integrating the acceleration detection value of the longitudinal acceleration sensor using the wheel speed detection value of the wheel speed detection means as an initial value; fluid pressure control means for controlling the fluid pressure of the braking cylinder based on the detected value, wheel acceleration/deceleration, and estimated vehicle body speed; The present invention includes an integral reset means for setting the initial value of the estimated vehicle speed calculating means to the wheel speed detection value at that time and resetting the integral calculation when the estimated vehicle speed is equal to or less than a set value.

[Effect]

In this invention, the integral reset means performs the integral calculation of the estimated vehicle speed by calculating the estimated vehicle speed by integrally calculating the detected vehicle acceleration value using the detected wheel speed value as an initial value. The differentiated wheel acceleration/deceleration is monitored, and the time when the wheel acceleration/deceleration goes from exceeding a preset value to below the predetermined value is detected, and at the time of this detection, the vehicle body estimates the wheel speed detection value at that time. By setting it as the initial value of the speed calculation means and resetting the integral calculation, the integral calculation can be made in a short time, and the error between the actual vehicle speed and the estimated vehicle speed can be reduced and used for braking by the fluid pressure control means. Improves cylinder fluid pressure control accuracy.

〔Example〕

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

FIG. 2 is a block diagram showing an embodiment of the present invention.

In the figure, reference numeral 1 is a brake switch that outputs a detection signal of, for example, a logical value of "1" when the brake pedal 22 is depressed, 2 is a longitudinal acceleration sensor as a friction coefficient detection means, and 3 is a brake switch that detects the rotational speed of each wheel. It is a wheel speed sensor that detects the wheel speed.Here, the wheel speed sensor may be one that outputs a pulse according to the rotation of the wheel, and it may be arranged opposite to a toothed disk that rotates according to the rotation of the wheel. A magnetic detection means consisting of a Hall element installed in the vehicle, and an optical device consisting of a light emitting/receiving element placed opposite a rotating disk having through holes or notches at equal angular intervals, which rotates in accordance with the rotation of the wheel. Any rotation sensor such as target detection means can be applied.

The output pulses of the wheel speed sensor 3 are supplied to a wheel speed calculation circuit 4, and the wheel speed calculation circuit 4 converts the output pulses into frequency and voltage to calculate the wheel speed, which is an analog voltage representing the wheel speed. , this is output as the wheel speed calculation value V.

This wheel speed calculation value ■ is supplied to a digital wheel speed filter 6 via an A/D converter 5, and the wheel speed filter 6 outputs a filter output after canting wheel speed fluctuations due to electrical noise and road surface irregularities. Output as wheel speed detection value ■ω.

The wheel speed detection value ■ω of the wheel speed filter 6 is input to the wheel acceleration/deceleration calculation circuit 7. This wheel acceleration/deceleration calculation circuit 7 is
The wheel acceleration/deceleration rate 9ω is calculated based on the wheel speed detection value ■ω, and the wheel speed detection (iVω) is sampled at relatively short intervals (for example, 5m5ec), and the wheel speed detection value ■ω7 is calculated from the wheel speed detection value ■ω7 at the time of reading. By subtracting the wheel speed detection value Vωn-1 at the time of the previous reading, the amount of change in wheel speed, that is, the wheel acceleration/deceleration 9ω is calculated sequentially.

Then, the switch signal BS of the brake switch 1, the detected acceleration value G of the acceleration sensor 2, the detected wheel speed value ■ω of the wheel speed filter 6, and the wheel acceleration/deceleration rate 9ω of the wheel acceleration/deceleration calculating circuit 7 are input to the controller 10.

The controller 10 includes, for example, an input interface circuit 1
0a, output interface circuit 10b, arithmetic processing unit 1
0c and a storage device 10d having ROM, RAM, etc., the switch signal BS of the brake switch 1, the detected acceleration value G,
Based on the wheel speed detection value Vω and the wheel acceleration/deceleration rate 9ω, predetermined estimated vehicle speed calculation estimation processing and anti-skid control processing are executed to determine the wheel cylinder 21 as a braking cylinder disposed on each wheel 20 and the brake. pedal 2
A control signal EV controls an actuator 24 that constitutes a part of a fluid pressure control means disposed between a master cylinder 23 connected to a master cylinder 2.

Outputs AV and MP.

As shown in FIG. 3, the actuator 24 is connected to an inflow side electromagnetic on-off valve 27 inserted between a hydraulic pipe 26 connected to the master cylinder 23 and the wheel cylinder 21, and between the hydraulic pipe 26 and the wheel cylinder 11. It is composed of a check valve 28, a motor pump 29, an outflow side electromagnetic on-off valve 30, and an accumulator 3I connected to a pipe between the motor pump 29 and the outflow side electromagnetic on-off valve 30.
The electromagnetic on-off valves 27 and 30 are driven and controlled by control signals EV and AV from the controller 16, and the motor pump 29 is driven by a control signal MP from the roller 17, respectively.

Next, the operation of the above embodiment will be explained with reference to the flowchart of FIG. 4 showing the procedure of estimated vehicle speed calculation processing in the controller 17 and the flowchart of FIG. 5 showing the procedure of anti-skid control processing.

First, the estimated vehicle speed calculation process is as shown in FIG.
For example, it is executed when the ignition switch is turned on, and in step ■ the switch signal BS of the brake switch l is read, then in step ■ the current detected wheel speed value ■ω is read, and then the process moves to step ■ and the switch signal BS is It is determined whether or not it is in the on state, and when the switch signal is in the on state, it is determined that the brake is in the braking state, and the process proceeds to step (2) a, where a variable F, which will be described later, is set to zero, and then the process proceeds to step (2).

In step (2), a predetermined set value T is set in the integral timer, and the detected wheel speed value (2) ω read in step (2) is set as an initial value of integration.

Next, the process moves to step (2), and it is determined whether the integral timer is zero. At this time, when T≠0,
It is determined that the integral calculation is in progress, and the process moves to step 2, reads the acceleration detection value G of the longitudinal acceleration sensor 2, and then proceeds to step 2.
Then, the estimated vehicle speed V raf is calculated by performing the integral calculation of the following equation (1).

V,,,=V ω −S IGld ・
...(1) Next, proceed to step (2) to determine whether the detected wheel speed value Vω is greater than or equal to the estimated vehicle speed V ref, and when ■ω<■rat, proceed to step (2). Transition.

In this step ■, the variable F described later is “I Q I+
.

+111ZI "2°" is determined, and when F=O, the process moves to step [phase] and the current wheel acceleration/deceleration 9ω from the wheel acceleration/deceleration calculation circuit 7 is determined.
8 is read, and then the process proceeds to step (3), where the current wheel acceleration/deceleration 9ω8 is subtracted from the wheel acceleration/deceleration 9ω8-7 at the time of the previous processing to calculate the wheel acceleration/deceleration change amount νω.

Next, the process moves to step @, and the wheel acceleration/deceleration change amount ν
It is determined whether ω has reversed from a positive state, that is, a state in which wheel acceleration is occurring, to a negative state, that is, a state in which wheel deceleration is occurring. At this time, when the wheel acceleration/deceleration change amount νω is reversed from a positive state to a negative state, the process moves to step @, sets the variable F to "1", and then moves to step 0.

In step (2), it is determined whether the wheel acceleration/deceleration tω read in step [phase] is equal to or greater than a predetermined value V3. At this time, when 9ω≧■, the process moves to step [phase], sets the variable F to ``2'', and then moves to step ■.

In this step ■, it is determined whether the absolute value of the wheel acceleration/deceleration Mω read in step [phase] is less than or equal to the predetermined setting value ■, and if 19ωl≦■, the process moves to step @. Set variable F to “0” and then step■
to move to.

In step (2), similarly to step (2), the integral timer is set to a predetermined value T, and the wheel speed detection value Vω read in step (2) or step O (described later) is set as the initial integral value, and then step (2) is performed. After decrementing the integral timer by "1", the process moves to step [phase] to determine whether the control flag As in the anti-skid control process shown in FIG. If the control flag AS is set to '1', it is determined whether a predetermined period of time, for example 20 m5ec, has elapsed or not. wait until
When a predetermined period of time has elapsed, the process moves to step @, reads the detected wheel speed value ■ω, and then returns to step ■. When the control flag AS has been reset to "0", the process moves to step [phase]. , determine whether or not to end the process. This determination is made, for example, by determining whether or not the ignition switch is in the off state. When the ignition switch is in the on state, the process returns to step (3), and when the ignition switch is in the off state, the process ends. .

On the other hand, if the judgment result in step ■ and step @ is that the switch signal BS of the brake switch 1 is in the OFF state, it is determined that the brake is not in the braking state, and the process moves to step ■, where the detected wheel speed value Vω read in step ■ is Estimated vehicle speed V r
After setting the value to ef, the process moves to step O to determine whether or not to end the process.

Further, when the determination result of step (■) is that the integral timer is zero and the determination result of step (■) is ■ω≧Vr・f, the process moves to step [phase], and similarly to step [phase], step (2) Alternatively, the detected wheel speed value ■ω read in step O is used as the estimated vehicle speed ■, . , and then proceeds to step [phase] to set a predetermined set value T in the integral timer, and also set the current detected wheel speed value ■ω8 as an initial value.

Furthermore, when the judgment result in step (2) is that the variable F is ``1'', the process directly proceeds to step 0, and the variable F is 2.
′°, the process proceeds directly to the step [phase].

Furthermore, if the determination result of step @ is that the wheel acceleration/deceleration change amount νω continues to be positive or negative, step [phase]
If the determination result in step (2) is ω<V, and if the determination result in step (2) is 1 summer ω1>vs, the process moves to step [phase] and the integral timer is decremented by 1″.

In the process shown in FIG. 5, the processes from step ① to step @ correspond to the estimated vehicle speed calculation means.

Next, anti-skid control processing by the controller 10 will be explained with reference to FIG.

The process shown in FIG. 5 is executed as a timer interrupt process every predetermined period of time, for example, every 20 m5ec. In this process, AS is a control flag and L is a depressurization timer. Moved to @ and cleared to zero.

Then, when the process shown in FIG. 5 is started, first step [
phase], the wheel acceleration/deceleration of the wheel acceleration/deceleration calculation circuit 7! ω is read, and then the process moves to step O, where the detected wheel speed value ■ω output from the wheel speed filter 6 is read, and then the process moves to step [phase], where calculation is performed in the estimated vehicle speed calculation process shown in FIG. The estimated vehicle body speed V raf thus obtained is read out, and then the process moves to step [phase] where the following equation (2) is calculated to calculate the slip ratio S.

raf Then, the oil pressure of the wheel cylinder 21 is controlled based on the wheel acceleration/deceleration 9ω read in step @ and the slip rate S calculated in step [phase].

That is, the slip rate S is a preset predetermined value S0.
(for example, 15%), and both the control flag As and the pressure reduction timer L are zero, and the wheel acceleration/deceleration 9ω is between the preset deceleration threshold α and the acceleration dark value 30, that is, α<
During non-braking and initial braking when Mω〈β, the transition goes through steps [phase] to [phase] to step 0, and the logic value “0” is reached.
A control signal EV of '° is output to the inflow side electromagnetic on-off valve 27 of the actuator 24 to open it, and the logic value is set to '0'.

The control signals AV and MP are outputted to the outflow side electromagnetic on-off valve 30 and the motor pump 29, respectively, to control these to the closed state and the stopped state, and the pressure in the wheel cylinder 21 disposed on each wheel 20 is adjusted to the mask cylinder. After setting the pressure to the pressure corresponding to the pressure of No. 23 and setting the pressure increase mode, the timer interrupt process is finished and the main program is returned. Therefore, the vehicle is in a non-braking state in which the brake pedal 22 is not depressed.

When the brake pedal 22 is depressed, the pressure in the master cylinder 23 is approximately zero, so the pressure in the wheel cylinder 21 is also maintained at approximately zero, maintaining the non-braking state, and at the initial stage of braking when the brake pedal 22 is depressed, the pressure in the master cylinder 23 is As the pressure rises, the pressure in the wheel cylinder 21 rapidly increases and enters a braking state.

Then, when the braking state is reached, the wheel speed ■ω gradually decreases, and the wheel decelerates accordingly! As ω increases, this wheel deceleration! When ω exceeds the deceleration threshold α, the transition is made from step [phase] to step 0, and the control signal EV is set to the logical value ``1''.
''', and the control signals AV and MP are set to a logical value of '0'. As a result, the inflow side electromagnetic on-off valve 27 and the discharge side electromagnetic on-off valve 3
0 are both closed, and the motor pump 29 is also maintained in a stopped state, so pressure oil is trapped in the wheel cylinder 21, and the cylinder pressure becomes a constant value, resulting in a high pressure side holding mode.

However, even in this holding mode, since braking force is acting on the wheels, the wheel deceleration Vω increases and the slip ratio S also increases.

When the slip rate S exceeds the predetermined value S0 and the wheel deceleration 9ω remains below the acceleration value β,
Transitioning from step [phase] to step @ via step [phase], the pressure reduction timer L is set to a preset predetermined value L0, and the control flag AS is set to "1°".For this reason, step [ phase], passes through steps @ and @ to step ■, and the control signal A with the logical value “°1°°
V and MP are output to open the outflow side electromagnetic on-off valve 30 and the motor pump 29 is activated, and a control signal EV with a logical value of +1111 is outputted to close the inflow side electromagnetic on-off valve 27. to be maintained. Therefore, the pressure oil in the wheel cylinder 21 is discharged through the electromagnetic on-off valve 30, the motor pump 29, and the check valve 28, and the cylinder pressure is reduced to enter the pressure reduction mode.

In this depressurization mode, the braking force on the wheels is relaxed, but the wheel speed ■ω remains in a decreasing state for a while, and therefore the wheel deceleration Mω and the slip ratio S continue to increase, but after that the wheel speed The rate of decrease of the detected value Vω decreases and the state shifts to an acceleration state.

Correspondingly, wheel acceleration/deceleration 9ω increases in the positive direction, and when wheel acceleration/deceleration Mω exceeds acceleration dark value β, step Φ
The process moves from step 0 to step @.

In this step @, the pressure reduction timer L is cleared to "0'°, and then the process moves to the step @.

Therefore, in the judgment at step @, L=O, so the process moves to step @, and since 9ω≧β, the process moves to step 2, and since the control flag As is set to "1'," Move to step [phase] and move to holding mode.

In this way, when it comes to the holding mode, the wheel cylinder 2
The cylinder pressure of No. 1 becomes a constant value on the low pressure side, and the detected wheel speed value ■ω continues to increase in speed. For this reason, wheel acceleration/deceleration M
Regarding ω and the slip rate S, the wheel acceleration/deceleration Mω increases in the positive direction, and the slip rate S decreases.

Then, when the slip rate S becomes less than the set slip rate S0, the step [phase] shifts to step 0, and since the pressure reduction timer L was cleared to "0" in the previous low pressure side holding mode, it directly goes to step @. and continues the high pressure side holding mode.

Even in this high pressure side holding mode, for the wheels,
Since the braking force is acting, the rate of increase in the detected wheel speed value ■ω gradually decreases, and when the wheel acceleration/deceleration rate 9ω becomes less than the acceleration dark value β, the transition from step [phase] to step @ occurs.
Since ω>α, the process moves to step [phase], and since the control flag AS is 1°, the process moves to step @.

In this step @, the logical value PA1°° and the logical value '“0
It outputs a control signal EV that alternately repeats "" at a predetermined period, and maintains the control signals AV and MP at the logical value "0".For this reason, pressure oil from the master cylinder 23 is intermittently supplied to the wheel cylinder 21. will be
The cylinder pressure of the wheel cylinder 21 is increased stepwise to enter a slow pressure increase mode.

In this slow pressure increase mode, the pressure in the wheel cylinder 21 increases gradually, so the braking force on the wheels 20 gradually increases, the wheel speed detection value Vω decreases, and the wheels 20 enter a deceleration state.

After that, when the wheel acceleration/deceleration rate 9ω becomes less than the deceleration threshold α, the process moves from step @ to step [phase], and the mode becomes a high-pressure side holding mode. After that, when the slip rate S becomes the set slip rate 30 or more, step [phase] is entered. ], passes through step 0, moves to step [phase], then moves through step @, and then moves to step ■, so it becomes pressure reduction mode, and then low pressure holding mode, slow pressure increase mode, high pressure side holding mode,
The decompression mode is repeated and the anti-skid effect can be achieved.

Note that when the speed of the vehicle decreases to a certain extent, the slip ratio S may recover to less than the set slip ratio of 80 in the depressurization mode, and in this case, the step [phase] shifts to step 0, and the depressurization mode is activated as described above. In the step [phase] of setting the decompression timer L, the predetermined setting value L0
Since it is set to step 0, the predetermined setting value of the decompression timer L is subtracted by °゛1''' before moving to step @.Therefore, from step 0 to step When the pressure reduction timer L reaches "0" after repeating the transition process, the process moves from step [phase] to step [phase] to step @, shifts to the slow pressure increase mode, and then shifts to the high pressure side holding mode. After that, the mode will shift to the slow pressure increase mode.

Then, when the vehicle reaches a speed close to stopping, or when the brake pedal 22 is released and the switch signal BS of the brake switch 1 is turned off, it is determined that the control ends in step @. Step @
Then, the process moves to step 2, where the pressure reduction timer L and control flag AS are cleared to "0", and then the process moves to step (2), where the rapid pressure increase mode is set, and then the anti-skid process is ended.

Therefore, when the vehicle stops with the brake pedal depressed, the hydraulic pressure of the mask cylinder 23 is directly applied to the wheel cylinder 21, making it possible to maintain the stopped state of the vehicle, and when the brake pedal 22 is released, Since the oil pressure in the master cylinder 23 becomes zero, the cylinder pressure in the wheel cylinder 21 is maintained at zero, and no braking force is applied to the wheels 20.

Also, for example, high Fg! When the state of driving on a friction coefficient road changes to the state of driving on a low friction coefficient road such as a snowy road or a rainy road, and in this state, when the brake pedal 22 is depressed to enter the braking state, the state of driving on the low friction coefficient road is changed. Therefore, slip may occur in the driving wheels, and the wheel speed ■ω detected by the wheel speed sensor 3 may increase, and the wheel acceleration/deceleration 9ω may exceed the acceleration threshold β. for,
In the process shown in Fig. 5, the process moves to step O through steps [phase] to step [phase], and since the anti-skid control has not yet started, the control flag AS is 0'', and the process moves to step 0, where the rapid pressure increase The anti-skid control is executed after the vehicle enters the anti-skid mode and reduces the wheel speed Vω.

Next, the overall operation will be outlined over time based on FIG.

That is, if it is assumed that the vehicle is running at a constant speed without braking at time t0, the switch signal BS in the off state is output from the brake switch 1, as shown in FIG. 7(e), and in response to this, The wheel speed detection value ■ω of a constant value is outputted from the wheel speed filter 6 as shown in FIG. It is zero. Therefore, the fourth
In the estimated vehicle speed calculation process shown in the figure, since the switch signal of the brake switch 1 is in the OFF state, the process moves from step ■ to step @, where the estimated vehicle speed ■raf is matched with the detected wheel speed value Vω, and then step Return to ■. Therefore, the integral timer continues to be zero as shown in FIG. 7(d).

On the other hand, in the anti-skid control process shown in FIG. 5, since the detected wheel speed value ■ω and the estimated vehicle speed V Paf are equal, the slip rate S calculated in step [phase] becomes zero, and from step ■ to step [phase] After that, the process moves to step 0 and the actuator 24 is set to the rapid pressure mode.
In this state, the brake pedal 22 is not depressed, so the pressure in the master cylinder 23 is approximately zero, and the pressure in the wheel cylinder 2 maintains approximately zero as shown in Figure 7(C) to maintain a non-braking state. continue.

From this state, point 1. When the brake pedal 22 is depressed (depressed), the pressure in the master cylinder 23 increases rapidly, and in response, the pressure in the wheel cylinder 21 increases rapidly as shown in FIG. Correspondingly, the wheel speed detection value Vω begins to decrease as shown by the solid line in FIG. 7(b), and along with this, the wheel acceleration/deceleration 9ω increases in the negative direction as shown in FIG. 7(a).

On the other hand, as the switch signal BS of the brake switch l is turned on as shown in FIG. 7(e), in the estimated vehicle speed calculation process of FIG. At the same time, the process moves to step ■, where the integral timer is set to a predetermined setting value T, and the wheel speed detected value at that time ■ω1 is set as the initial value.
is set, and then the process proceeds to step (2) via steps (2) and (2), and the estimated vehicle speed V Paf is calculated in accordance with equation (1).

When the wheel speed detection value Vω becomes lower than this estimated vehicle speed V rat, the process moves from step ■ to step @ through steps ■ to step ■, and since the wheel acceleration/deceleration 9ω continues to increase in the negative direction, it is directly Go to step ■, decrement the integral timer by 1°, then go through steps [phase] to step @, go to step 0, read the detected wheel speed value ■ω, then return to step ■, and calculate this integral. The processing state continues until the wheel acceleration/deceleration change amount νω is reversed from positive to negative.

Then, at time 1t, when the wheel acceleration/deceleration 9ω becomes smaller than the preset deceleration threshold α, the actuator 24 is set to the holding mode (step O), the pressure increase in the wheel cylinder 21 is stopped, and then at time t3 When the slip rate S becomes equal to or higher than the set slip rate 30, the actuator 24 is set to the pressure reduction mode (step 2), and the pressure in the wheel cylinder 2 is reduced. therefore,
At time L4 in the middle of the decompression mode, the wheel speed detection value ■ω takes a minimum value as shown by the solid line in FIG. (a)
As shown in the figure, it becomes zero at time L4, and increases in the positive direction thereafter.

Then, at the time point, when the wheel acceleration/deceleration Mω becomes equal to or higher than the acceleration dark value β, the decompression timer is cleared to zero (step 0).
), the actuator 24 is set to holding mode (step 0), and the pressure in the wheel cylinder 21 is held at a relatively small value.

In this manner, when the pressure reduction side holding mode is entered, the wheel acceleration/deceleration 9ω takes a maximum value in the positive direction at time t6, and thereafter tends to decrease. Therefore, time t.

The wheel acceleration/deceleration change tVω is reversed from positive to negative.

Therefore, in the estimated vehicle speed calculation process shown in FIG. 4, the process moves from step @ to step 0 and the variable F is set to 1.

At the same time, the process moves to Step ■ and determines whether the wheel acceleration/deceleration Mω is equal to or higher than the preset value 73. Since 9ω>vS, the process moves to Step ■ and sets the variable F.
is set to ``2'', and then the process proceeds to step (2), where it is determined whether the absolute value 19ω1 of the wheel acceleration/deceleration is less than or equal to the set value V, and 19ω1>■.

Therefore, the process moves to step (2) to continue decrementing the integral timer.

Thereafter, when the absolute value 19ωl of the wheel acceleration/deceleration becomes equal to or less than the set value vs at time t, the process moves from step ■ to step @, where the variable F is set to zero, and then the process moves to step [phase], where the integral timer is set. is set to a predetermined setting value T as shown in FIG. 7(d), and the time t is set as the initial integral value.
By setting the detected wheel speed value ■ω7 at step 7, the integral processing is reset, and then the integral timer is decremented in step [phase], and then the process returns to step ■ through steps [phase] to step [phase]. Therefore, at this point in time, a new integration process is executed based on the initial integration value ■ω6.

Thereafter, when the wheel acceleration/deceleration 9ω becomes equal to or less than the acceleration value β at time t3, in the anti-skid control process shown in FIG. The mode is set to slow pressure increase mode, and the pressure in the wheel cylinder 21 is gradually increased in steps. This slow pressure increase mode allows the wheel speed detection value to
ω decreases, and wheel acceleration/deceleration Mω also increases in the negative direction.

Thereafter, when the wheel acceleration/deceleration 9ω becomes equal to or less than the deceleration value α at a certain point in time, the anti-skid control process shown in FIG. However, when the slip rate S exceeds the set slip rate S0 at time too, step [phase], o, o, @,.

After that, the actuator 24 is set to the pressure reduction mode by proceeding to step [Yes], and then the low pressure side holding mode, the slow pressure increase mode, and the high pressure side holding mode are sequentially repeated. Repeat control modes sequentially.

On the other hand, in the estimated vehicle speed calculation process of FIG. 4, after the wheel acceleration/deceleration exceeds the predetermined set value ■8
When the value becomes less than the predetermined value T, the integral timer is set to a predetermined value T, and the detected wheel speed value ■ω at that time is set as the initial integral value.

Then, when the detected wheel speed value ■ω becomes close to zero or the switch signal BS of the brake switch 1 turns off,
In the anti-skid control process shown in FIG. 5, the process moves from step [phase] to step @, the pressure reduction timer L is set to zero, and the control flag As is set to zero, and then the process moves to step 0, where the actuator 24 is set to 2 and pressure increase mode. Set to .

In addition, in the estimated vehicle speed calculation process shown in FIG. 4, when the integral timer becomes zero or the switch signal BS of the brake switch 1 becomes OFF, the process moves from step ■ to step @ or from step @ to step @. [phase]
Then, the detected wheel speed value ■ω is set to the estimated vehicle speed v1°.

For example, when the wheel speed detection value approaches the stopped state while the vehicle is braking and the maximum value of the wheel acceleration/deceleration 9ω in the positive direction does not exceed the predetermined set value V, as shown by the solid line in FIG. In the estimated vehicle speed calculation process shown in Figure 4, step 0
The process moves directly from step ■ to step ■, continues decrementing the integral timer, and does not reset the integral process, so when the integral timer reaches zero, it moves from step ■ to step @.
Then, the wheel speed detection value ■ω at that time is set as the estimated vehicle speed V, .

At this time, in the next process, as shown in FIG. 9, at time tz+ when the detected wheel speed value ■ω is equal to or higher than the estimated vehicle body speed V rat calculated in step ■, the process moves from step ■ to step @ and the wheel speed is Since the speed detection value ■ω is set as the estimated vehicle speed V raf and then the process moves to step [phase] to reset the integral processing, the wheel speed detection value Vω becomes less than the estimated vehicle speed V rmf from this time tz+. t
The integral process continues to be reset until 2□, so
The integral timer maintains a predetermined set value T as shown in FIG. 9(b), and the integral process is executed from time tzz onwards. Therefore, as shown by the chain line in FIG. 9(b), the estimated vehicle speed V
It is possible to prevent raf from deviating significantly from the actual vehicle speed (a).

In this way, according to the above embodiment, the wheel acceleration/deceleration 9ω is monitored, and this wheel acceleration/deceleration! When ω exceeds the predetermined set value V and becomes less than the predetermined set value ■3, the wheel speed detection value at that time ■ω is set as the initial value for integration, and the integration timer is set to the predetermined set value T, and the integration is performed. Since the process is reset, the estimated vehicle speed V is increased while reducing the integration time.
It is possible to reliably prevent ra'f from deviating significantly from the actual vehicle speed V7, and this estimated vehicle speed V r
Control accuracy when performing actuator control using ar can be significantly improved.

In the above embodiment, a case has been described in which the integral timer has a subtraction counter configuration, but the present invention is not limited to this, and an addition counter configuration that resets to zero when a predetermined set value T is reached is used. You may also do so.

In the above embodiment, when monitoring the wheel acceleration/deceleration rate ω, it is determined whether the wheel acceleration/deceleration rate ω is equal to or greater than the predetermined set value 73 at the time when the wheel acceleration/deceleration change amount νω is reversed from positive to negative. Although the above description is not limited to this, it is determined whether the wheel acceleration/deceleration tω exceeds the predetermined set value V, and after the wheel acceleration/deceleration tω exceeds the predetermined set value ■3, the predetermined set value ■8 is determined.
The integration process may be reset when the value becomes less than .

Further, in the above embodiment, a case has been described in which the estimated vehicle speed calculation process and the anti-skid control process are executed by one cositroller 10. The speed calculation means and the fluid pressure control means are not limited to microcomputers, but can also be configured by combining electronic circuits such as comparison circuits and arithmetic circuits.

Further, in the above embodiments, the case where the present invention is applied to a drum type brake has been described, but the present invention can be similarly applied to a disc type brake.

Further, in the above embodiments, the case where the wheel cylinders are controlled by hydraulic pressure has been described, but it goes without saying that the control is not limited to this, and other liquids such as water or gases such as air can be applied.

〔Effect of the invention〕

As explained above, according to the present invention, when calculating the estimated vehicle speed by integrating the acceleration detection values of the longitudinal acceleration sensor, wheel acceleration/deceleration is monitored, and after the wheel acceleration/deceleration exceeds a predetermined set value, , when the wheel speed is less than a predetermined set value, the current detected wheel speed value is used as the initial value for integration, and an integration timer is set. , it is possible to improve the accuracy of determining the vehicle speed by reducing the amount of deviation between the estimated vehicle speed and the actual vehicle speed, and the control accuracy when performing anti-skid control using this estimated vehicle speed is also significantly improved. The effect that can be obtained is obtained.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram showing the basic structure of this invention, Fig. 2 is a block diagram showing an embodiment of this invention, Fig. 3 is a block diagram showing an example of an actuator, and Fig. 4 is applied to this invention. FIG. 5 is a flowchart showing an example of an anti-skid control process of a controller that can be applied to the present invention, and FIG. 6 is a control map of the anti-skid control process. 7 to 9 are signal waveform diagrams for explaining the operation of the present invention. In the figure, l is the brake switch, 2 is the longitudinal acceleration sensor,
3 is a wheel speed sensor, 4 is a wheel speed calculation circuit, 6 is a wheel speed filter, 7 is a wheel acceleration/deceleration calculation circuit, 10 is a controller, 20 is a wheel, 21 is a wheel cylinder (braking cylinder), 22 is a brake pedal, 23 is a master cylinder, and 24 is an actuator.

Claims (1)

[Claims] (1) In an anti-skid control device that controls fluid pressure of a braking cylinder disposed on each wheel based on the wheel speed of each wheel, a wheel speed detecting means for detecting the speed of each wheel; A wheel acceleration/deceleration calculation means that calculates wheel acceleration/deceleration based on the wheel speed detection value of the detection means, a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, and a longitudinal acceleration sensor that detects the acceleration detection value of the longitudinal acceleration sensor. estimated vehicle speed calculation means for calculating an estimated vehicle speed by integrating the wheel speed detection value of the means as an initial value; A fluid pressure control means to control and monitors the wheel acceleration/deceleration, and when the wheel acceleration/deceleration exceeds a predetermined set value and becomes below a predetermined set value, the initial value of the estimated vehicle body speed calculation means is set to the wheel speed at that time. An anti-skid control device comprising an integral reset means for setting a detected value and resetting an integral calculation.