JPH10114264A - Anti-lock brake controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a shortage of pressure increase and prevent the fluctuation of deceleration of a car body surely so as to enable good anti-lock brake control by providing an upper limit value compensation means which compensates an upper limit value of cylinder pressure for braking and compensating the upper limit value of cylinder pressure for braking in accordance with a pressure increase time stored value in one braking cycle. SOLUTION: In a controller CR which inputs output signals of wheel speed sensors 3FL to 3R when a vehicle is driven, car body speed gradient is calculated based on wheel speed detected values by wheel speed computing circuits 15FL to 15R, and car body speed is estimated based on the wheel speed detected values. Furthermore, pressure of cylinders for braking 2FL to 2R is estimated based on master cylinder pressure obtained by pressure sensors 13A, 13B which detect master cylinder pressure and control signals for actuators 6FL to 6R. An upper limit value of cylinder pressure for braking is set based on car body speed gradient, and the upper limit value of cylinder pressure for braking is compensated in accordance with the number of times of pressure increase signals in one braking cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-lock brake control device for preventing wheel lock during braking of a vehicle.

[0002]

2. Description of the Related Art A conventional anti-lock brake control device is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-3564 (hereinafter referred to as a first conventional example) and Japanese Patent Application Laid-Open No. Hei 8
The one described in US Pat. No. 133060 (hereinafter referred to as a second conventional example) is known.

[0003] A first conventional example is a wheel speed sensor for detecting a wheel speed, a pressure control means provided between a master cylinder and a wheel cylinder of the wheel for controlling a brake pressure of the wheel cylinder, Pressure detecting means for detecting only the cylinder brake pressure, and determining that a slip has occurred on the wheel, and instructing the pressure control means to control the brake pressure of the wheel cylinder upon determining that the wheel has slipped. A slip control means for controlling the brake pressure of the wheel cylinder when the pressure control means controls the brake pressure of the wheel cylinder. Pressure estimating means for estimating the brake pressure of the wheel cylinder from Comparing means for comparing the brake pressure of the wheel cylinder estimated by the estimating means with the brake pressure of the master cylinder detected by the pressure detecting means; and the result of the comparison performed by the comparing means, A simple anti-skid control device comprising: end means for terminating control of the brake pressure of the wheel cylinder by the pressure control means when the pressure becomes lower than the brake pressure of the wheel cylinder. Thus, the anti-skid control is performed with the minimum number of pressure sensors.

[0004] A second conventional example is an actuator for controlling the fluid pressure of a braking cylinder provided in a vehicle to be controlled based on the master cylinder pressure from the master cylinder, and a control signal and a master cylinder pressure for the actuator. Braking cylinder pressure estimating means for estimating the pressure of the braking cylinder based on the vehicle speed gradient calculating means for calculating a vehicle speed gradient based on the wheel speed detection value of the wheel speed detecting means; By providing a vehicle speed gradient restricting device that restricts the braking cylinder pressure of the estimating device based on the vehicle speed gradient, good antilock brake control is performed while minimizing the pressure detecting device.

[0005]

However, in the anti-skid control device of the first prior art, the number of pressure sensors can be kept to a minimum and the whole anti-skid control system can be simplified and miniaturized. Since the wheel cylinder pressure is estimated by using the drive signal after the start of the actuator operation and the preset pressure increasing / decreasing characteristic function, the pressure increasing / decreasing characteristic fluctuates due to fluctuations in the temperature, viscosity, battery voltage, etc. of the brake fluid. The wheel cylinder pressure estimation value may deviate from the actual wheel cylinder pressure. In particular, if the actual pressure increase amount is smaller than the pressure increase function, Anti-skid control ends when the estimated cylinder pressure exceeds the master cylinder pressure detection value, and good anti-skid control is performed. There is an unsolved problem that can not be.

In the second prior art anti-skid control device, it is possible to improve the accuracy of estimating the brake cylinder pressure while minimizing the number of pressure detecting means, thereby performing good anti-lock brake control. However, since the vehicle speed gradient calculated by the vehicle speed gradient detecting means is calculated later than the actual vehicle speed change, a low friction coefficient such as a snowy road or a frozen road causes a high friction on a dry pavement road or the like. When the coefficient of friction, which results in the running state on the coefficient road surface, jumps suddenly from a low state to a high state, the braking cylinder pressure estimated value remains limited to a low value, and immediately after switching to the high friction coefficient road surface. There is an unsolved problem that the amount of pressure increase is reduced to cause a delay in the rise of deceleration.

Further, in the second conventional example, since the estimated value of the cylinder pressure for braking is always regulated by the vehicle body speed gradient, the road surface friction coefficient becomes 0.4 to 0.4 as in the case of running on a rough road.
When it is about 0.6, the vehicle body speed gradient also becomes a small value, so the upper limit value is set small, and the actuator tends to over-pressure-decrease, giving a feeling of insufficient braking force when traveling on a rough road. There are also issues to be solved.

Accordingly, the present invention has been made in view of the above-mentioned unsolved problems of the prior art. When regulating the estimated value of the braking cylinder pressure at the upper limit, the traveling road surface has low friction during braking. It is an object of the present invention to provide an anti-lock brake control device that can continue good anti-lock brake control even when the road surface suddenly changes from a coefficient road surface to a high friction coefficient road surface or when traveling on a rough road.

[0009]

In order to achieve the above object, an antilock brake control device according to claim 1 is provided.
An actuator for controlling a fluid pressure of a braking cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder, a wheel speed detecting means for detecting a wheel speed of the wheel to be controlled, and at least the wheel A vehicle speed gradient calculating means for calculating a vehicle speed gradient based on a wheel speed detection value of the speed detecting means; a vehicle speed estimating means for estimating a vehicle speed based on a wheel speed detected value of the wheel speed detecting means; Master cylinder pressure detecting means for estimating or detecting cylinder pressure; braking cylinder pressure detecting means for estimating the pressure of the braking cylinder based on a master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. An upper limit value of the braking cylinder pressure detected by the braking cylinder pressure detecting means based on the vehicle body speed gradient. A brake cylinder pressure upper limit value setting means for setting the brake cylinder pressure upper limit value setting means, wherein the brake cylinder pressure upper limit value setting means stores the number of pressure increase signals during one braking cycle. And an upper limit value correcting means for correcting the upper limit value of the braking cylinder pressure in accordance with the pressure increasing number storage value of the pressure increasing number storing means.

According to a second aspect of the present invention, in the anti-lock brake control device according to the first aspect of the present invention, the upper limit value correcting means determines that the brake cylinder pressure is lower when the pressure increase number storage value exceeds a predetermined value. The configuration is such that the setting of the upper limit is canceled.

Further, in the antilock brake control device according to a third aspect of the present invention, in the first aspect of the invention, the upper limit value correcting means sets the upper limit value of the braking cylinder pressure in accordance with the pressure increase number storage value. The correction is performed by adding a predetermined value to

Further, in the antilock brake control device according to a fourth aspect, in the first aspect of the invention, the upper limit value changing means calculates an upper limit value of the braking cylinder pressure according to the pressure increase number storage value. The upper limit value is corrected by changing the calculation coefficient.

Still further, according to a fifth aspect of the present invention, there is provided an anti-lock brake control device, comprising: an actuator for controlling a fluid pressure of a braking cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder; Wheel speed detecting means for detecting a wheel speed of a wheel to be controlled, vehicle speed gradient calculating means for calculating a vehicle speed gradient based on at least a wheel speed detected value of the wheel speed detecting means, and a wheel speed of the wheel speed detecting means A vehicle speed estimating means for estimating a vehicle speed based on the detected value; a master cylinder pressure detecting means for estimating or detecting the master cylinder pressure; and a master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. Braking cylinder pressure detecting means for estimating the pressure of the braking cylinder based on the
An anti-lock brake control device comprising: braking cylinder pressure upper limit value setting means for setting an upper limit value of the braking cylinder pressure detected by the braking cylinder pressure detecting means based on the vehicle body speed gradient. Pressure upper limit value setting means for determining whether or not the vehicle is traveling on a rough road, and an upper limit of the cylinder pressure for braking when the rough road determination means determines that the vehicle is traveling on a rough road. And an upper limit setting canceling means for canceling the setting of the value.

An anti-lock brake control device according to a sixth aspect of the present invention is an actuator for controlling a fluid pressure of a braking cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder; Wheel speed detecting means for detecting a wheel speed of a target wheel, vehicle speed gradient calculating means for calculating a vehicle speed gradient based on at least a wheel speed detected value of the wheel speed detecting means, and wheel speed detecting means for the wheel speed detecting means Vehicle speed estimating means for estimating the vehicle speed based on the value, master cylinder pressure detecting means for estimating or detecting the master cylinder pressure, and a master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. Braking cylinder pressure detecting means for estimating the pressure of the braking cylinder, and detecting the braking cylinder pressure. A braking cylinder pressure upper limit value setting means for setting an upper limit value of the braking cylinder pressure detected in the step based on the vehicle body speed gradient, wherein the braking cylinder pressure upper value setting means comprises: Pressure increase number storage means for storing the number of pressure increase signals during one braking cycle; and upper limit value correction for correcting the upper limit value of the brake cylinder pressure according to the pressure increase number storage value of the pressure increase number storage means. Means, a rough road determining means for determining whether or not the vehicle is traveling on a rough road, and setting the upper limit value of the brake cylinder pressure when the rough road determining means determines that the vehicle is traveling on a rough road. And an upper limit setting canceling means for canceling.

[0015]

According to the antilock brake control device of the first aspect, the upper limit value correcting means of the brake cylinder pressure upper limit value setting means sets the braking pressure in accordance with the stored pressure increase number during one braking cycle. Since the upper limit of the cylinder pressure is corrected,
The upper limit value can be increased in accordance with the increase in the number of times of pressure increase, and when the road surface friction coefficient suddenly rises after traveling from a low friction coefficient road surface to a high friction coefficient road surface, the braking force is accordingly increased By increasing the upper limit of cylinder pressure,
Eliminates insufficiency of pressure boost to reliably prevent fluctuations in vehicle deceleration,
The effect that good antilock brake control can be performed is obtained.

According to the antilock brake control device of the second aspect, in addition to the effect of the first aspect,
The upper limit value correcting means cancels the setting of the upper limit value of the braking cylinder pressure when the pressure increase number storage value exceeds a predetermined value. An effect is obtained that the insufficient pressure increase due to the regulation of the cylinder pressure is reliably eliminated, and good antilock brake control can be performed.

Further, according to the antilock brake control device according to the third aspect, in addition to the effect of the first aspect, the upper limit value correcting means can control the brake cylinder pressure in accordance with the pressure increase number storage value. Is corrected by adding a predetermined value to the upper limit value, so that the upper limit value can be finely corrected, and an effect that better antilock brake control can be performed can be obtained.

Further, according to the antilock brake control device according to the fourth aspect, in addition to the effect of the first aspect, the upper limit value changing means may control the brake cylinder pressure in accordance with the pressure increase number storage value. Since the upper limit value is corrected by changing the calculation coefficient for calculating the upper limit value, the upper limit value can be finely corrected, and an effect that better antilock brake control can be performed can be obtained.

Further, according to the antilock brake control device according to the fifth aspect, when the upper limit setting release means determines that the vehicle is traveling on a rough road by the rough road determination means, the upper limit of the braking cylinder pressure is increased. Since the setting of the value is canceled, it becomes equivalent to the upper limit value being set to infinity. Thus, the effect that the anti-lock brake control can be performed satisfactorily can be obtained.

Further, according to the antilock brake control device of the sixth aspect, since the configuration of the first and fifth aspects of the invention is provided, the effects of both the inventions can be simultaneously exhibited.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention.

In the figure, 1FL, 1FR are front wheels, 1RL, 1
RR is a rear wheel, and an engine E is provided on the rear wheels 1RL and 1RR.
The rotational driving force from G is transmission T, propeller shaft PS
And differential gears DG. Wheel cylinders 2FL to 2RR as braking cylinders are attached to the wheels 1FL to 1RR, respectively, and pulse signals P corresponding to the wheel rotation speeds are applied to the front wheels 1FL and 1FR. _FL, the wheel speed sensors 3FL as wheel speed detecting means for outputting a P _FR, 3FR is attached, the wheel of the wheel speed detecting means for outputting a pulse signal P _R corresponding to the average rotational speed of the rear wheel propeller shaft PS The speed sensor 3R is attached.

Each front wheel wheel cylinder 2FL, 2FR
, The master cylinder pressure from the master cylinder 5, which generates two systems of master cylinder pressures on the front wheel side and the rear wheel side in response to depression of the brake pedal 4, is individually supplied via front wheel actuators 6FL, 6FR. At the same time, the master cylinder pressure from the master cylinder 5 is supplied to the rear wheel wheel cylinders 2RL and 2RR via a common rear wheel actuator 6R, so that a three-sensor three-channel system is configured as a whole.

As shown in FIG. 2, each of the actuators 6FL to 6R has an electromagnetic inflow valve 8 interposed between a hydraulic pipe 7 connected to the master cylinder 5 and the wheel cylinders 2FL to 2RR. Electromagnetic outflow valve 9, hydraulic pump 10 and check valve 1 connected in parallel with inflow valve 8
1 and a accumulator 12 connected to a hydraulic line between the outflow valve 9 and the hydraulic pump 10.

The electromagnetic inflow valve 8, the electromagnetic outflow valve 9 and the hydraulic pump 10 of each of the actuators 6FL to 6R are connected to the wheel speed pulse signals P _FL to P _FL from the wheel speed sensors 3FL to 3R.
Brake from P and _R, and the master cylinder pressure detection value P _MCF and P _MCR pressure sensors 13F and 13R as the master cylinder pressure detecting means for detecting the respective master cylinder pressure, a brake switch 14 for detecting the depression of the brake pedal 4 It is controlled by hydraulic pressure control signals EV, AV, and MR from the controller CR to which a brake switch signal BS that is turned on when the pedal is depressed is input.

The controller CR has a wheel speed sensor 3FL.
Wheel speed pulse signal P from ~ 3R_FL~ P_RIs entered,
From these and the turning radius of each wheel 1FL-1RR,
Wheel speed Vw consisting of peripheral speed_FL~ Vw_RTo calculate the wheel speed
Calculation circuits 15FL to 15R and these wheel speed calculation circuits 1
Wheel speed Vw of 5FL to 15R_FL~ Vw_RHighest among
Select high switch 16 for selecting the correct wheel speed,
Select high selected by the select high switch 16
Wheel speed Vw_HAnd longitudinal acceleration sensor 1 provided on vehicle body
7 longitudinal acceleration detection value X_GVehicle speed V based on
_XAnd a wheel speed calculation
Wheel speed Vw of circuits 15FL to 15R_FL~ Vw_R, Estimated
The estimated vehicle speed V of the vehicle speed calculation circuit 18_X, Longitudinal acceleration
Longitudinal acceleration detection value X of sensor 17_G, Pressure sensor 13
A, 13B Master cylinder pressure detection value P_MCF,P_MCRas well as
Bad road detection signal of a bad road detection circuit 19 as a bad road determination means
OR is input and the target pressure increase / decrease amount ΔP^* _FL~ ΔP^* _RIs calculated
And the estimated wheel cylinder pressure P_FL~ P_RIs calculated
To the actuators 6FL to 6R based on these
Microcontroller that outputs control signals EV, AV, and MR
Computer 20 and a microcomputer
The control signal output from the driving circuit 22a _FL~ 22
a_R, 22b_FL~ 22b_R, 22c_FL~ 22c_RThrough
To the actuators 6FL to 6R.

Here, the estimated vehicle speed calculation circuit 18 is shown in FIG.
As shown in FIG.
Select high wheel speed Vw_HIs the wheel speed sampling value V
_SSample and hold circuit 181 that holds
The longitudinal acceleration detection value X of the acceleration sensor 17_GThe absolute value circuit
In step 182, the absolute value is converted to an absolute value,
3 and an offset value corresponding to, for example, 0.3G.
The longitudinal acceleration correction value X added by the arithmetic circuit 184_GCOutput
Sensor output correction circuit 185 and an operational amplifier.
An integrating circuit 186 for integrating the input voltage E;
186 integral output V_eAnd the sample and hold circuit 181
Wheel speed sampling value V_SAnd the filter output V
f_iCircuit 187 for calculating the high wheel speed
Degree Vw_HIs the estimated vehicle speed V_XPredetermined for
Within the dead band width, ie, V_X-1km / h <Vw_H<V_X+ 1km / h
Is detected, and V_X-1km / h <Vw_H<V_X+
Output C at 1 km / h₁And C_TwoTogether with low level
Then Vw_H≧ V_X+1 km / h, output C₁The high
Level and Vw_H≤V_XOutput C at -1km / h
_TwoDead zone detection circuit 188 that sets
Select high wheel speed Vw by band detection circuit 188_HIs insensitive
When it is in the band and when the ignition switch
When the signal IG is input, the sample and hold circuit
181 selects high wheel speed Vw_HHold
And a reset signal SR for resetting the integration circuit 186.
A reset circuit 189 to output the vehicle speed Vw_iIs insensitive
Off-delay when within the band width or outside the dead band width
The predetermined time T set by the race timer 190_ThreeDuring integration
A zero voltage is supplied to the integrating circuit 186 as the force voltage E, and Vw
_H> V_XSpecified time T after + 1km / h_ThreeNon-after
Negative corresponding to + 0.4G during antilock brake control
Voltage to + 10G during anti-lock brake control.
The corresponding negative voltages are used as integration input voltages E, respectively.
Route 186, and_H<V_X-1km / h
Predetermined time T after_ThreeAfter the passage, a positive value corresponding to -1.2G
The voltage is supplied to the integration circuit 186 as the integration input voltage E.
And a selection circuit 191.

The bad road detecting circuit 19 has a road surface state detector constituted by an ultrasonic distance measuring device for measuring a distance from a road surface mounted on the lower surface of the vehicle body, for example. For example, a band-pass filter extracts a unsprung resonance frequency component of about 10 Hz corresponding to the road surface input from a signal, and averages the unsprung resonance frequency component by averaging processing. The average value is larger than a predetermined set value. Sometimes it is determined that the road is bad, and the bad road detection signal OR
Is turned on, and when the average value is equal to or less than a predetermined value, it is determined that the road is good and the bad road detection signal OR is turned off.

Furthermore, the microcomputer 20
As shown in FIG. 1, for example, an input port having an A / D conversion function is provided.
Interface circuit 20a, output interface circuit 20
d, at least the arithmetic processing unit 20b and the storage device 20c
And the estimated vehicle speed V_XBased on
Target wheel speed Vw^*And the wheel speed Vw
_FL~ Vw_RAnd the wheel acceleration Vw_FL'~ Vw_R′
Calculated and the wheel speed Vw _FL~ Vw_R, Wheel acceleration Vw_FL′
~ Vw_R'And the target wheel speed Vw^*Target increase / decrease based on
Pressure ΔP^* _FL~ ΔP^* _RAnd the master cylinder
Pressure detection value P_MCF,P_MCR, Body speed gradient V_Xk, Road surface inspection
Control for output signal OR and actuators 6FL-6R
Estimated wheel cylinder pressure P based on control signals AV and EV_FL
~ P_RAnd calculate these estimated wheel cylinder pressures P_FL~
P_RAnd target cylinder pressure P^* _FL~ P ^* _RAnd match
Control signals AV for the actuators 6FL to 6R_FL
~ AV_R, EV_FL~ EV_R, MR_FL~ MR_ROutput
You.

Next, the operation of the above embodiment will be described with reference to FIGS. The control process of FIG. 4 is executed as a timer interrupt process for the main program every predetermined time (for example, 10 msec). First, in step S1, the pressure sensors 13F and 13F are set.
R master cylinder pressure (M / C pressure) detection values P _MCF and P
_MCR , wheel speeds Vw _{FL to} Vw _{R of the} wheel speed calculation circuits 15FL to 15R, and wheel speed filters 18FL to 18R
And a filter output Vf _FL ~Vf _R with read free of the wheel acceleration Vw _FL differentiates the wheel speed Vw _FL ~Vw _R '~V
w _R ′ are calculated, and these are updated and stored in a predetermined storage area of the storage device 20c.

[0031] Then, the process proceeds to step S2, and executes the vehicle speed calculating process for calculating a vehicle velocity gradient V _Xk and estimated vehicle speed V _X based on the filter output Vf _FL ~Vf _R,
At a step S3, the master cylinder pressure detection value P _MCF, the control signal EV _FL ~EV _E, each wheel cylinder 2FL~2RR based on the AV _FL ~AV _R for P _MCR and the previous actuator 6FL~6R executing the current estimated wheel cylinder pressure calculating process of calculating the estimated wheel cylinder pressure P _FL to P _R for estimating the wheel cylinder pressure (W / C pressure).

Next, the process proceeds to step S4, where the target pressure increase / decrease amount ΔP _i for each of the wheel cylinders 2FL-2R is set.
Is executed. Then
The process proceeds to step S5 to execute an actuator control process for controlling the actuators 6FL to 6R based on the target pressure increase / decrease amount ΔP _i , then terminate the timer interrupt process, and return to the predetermined main program.

Here, the vehicle speed calculation processing in step S2
As shown in FIG. 5, first, in step S7,
The brake switch signal BS of the key switch 14 is off.
Is determined, and when this is in the off state,
It is determined that the vehicle is in the non-braking state, and the process proceeds to step S8.
As shown in equation (1), the filter output Vf_FL,Vf _FR
And Vf_RSelect the lowest value among the low wheel speeds
Vw_LAnd then the process proceeds to step S9.
Calculated select low wheel speed Vw_LIs estimated vehicle speed V
_XAnd the estimated vehicle formed in the storage device 20c
Update and store in the body speed storage area, then go to step S10
The vehicle speed gradient V_XKSet later as
Limit system for calculating estimated wheel cylinder pressure
Set slope V of your map_XK2Set value V consisting of the above values_XK0
Is set in the storage device 20c.
Subroutine processing after updating and storing in the allocation storage area
Is completed, and the estimation wheel of step S3 in FIG.
The process proceeds to cylinder pressure calculation processing.

V _X = MIN (Vf _FL, Vf _FR , Vf _R ) (1) On the other hand, when the result of the determination in step S7 is that the brake switch signal BS is in the on state, it is determined that the vehicle is in the braking state. and the process proceeds to step S11, as shown in the following equation (2), selects a filter output Vf _FL, any larger value of Vf _FR and Vf _R as a select high wheel speed Vw _H,
This is updated and stored in the select high wheel speed storage area formed in the storage device 20c.

V _X = MAX (Vf _FL, Vf _FR , Vf _R ) (2) Next, the process proceeds to step S12, in which the select high wheel speed Vw _H is differentiated to obtain the select high wheel speed Vw _H. The acceleration / deceleration Vw _H ′ is calculated.

[0036] Then, the processing proceeds to step S13, the select high wheel deceleration Vw _H 'braking state flag F1 indicating whether or not a braking state reaches the set deceleration -D _S a preset is "1" It is determined whether or not there is, and when this is reset to "0", it is determined that the vehicle is in the non-braking state, and the process proceeds to step S14.

[0037] In the step S14, it is determined whether the select high wheel acceleration Vw or _H 'is less than or equal to a set deceleration -D _S, determines that when a larger set deceleration -D _S is braked initial state And proceed to S15 as it is,
Moves to the estimated wheel cylinder pressure calculating process of step S3 after updating stored in a predetermined storage area of the storage device 20c the select high wheel speed Vw _H as the estimated vehicle speed V _X Exit vehicle speed calculation processing, setting deceleration proceeds to step S16 when it is less -D _S.

In step S16, the current select high wheel speed Vw _{H is changed} to the current sampling wheel speed Vs.
(n) is updated and stored in the current value storage area formed in the storage device 20c. Then, the process proceeds to step S17 to clear the timer T for counting the elapsed time to "0", and then proceeds to step S18 to perform the braking state. After the flag F is set to "1", the process proceeds to the step S15.

On the other hand, the result of the determination in step S13 is
When the braking state flag F is set to "1", the process proceeds to step S19, and the brake control state flag AS indicating that the antilock brake control is being performed is set to "1" in the actuator control processing described later. It is determined whether or not this is the case, and if this is set to “1”, the flow proceeds to step S20.

In step S20, a control flag F2 representing the processing state after the start of the anti-skid control processing
Is set to "1", and then the process proceeds to step S21, where it is determined whether or not the control flag F3 indicating the deceleration start state is set to "1", and the control flag F3 is set to "0".
When the flag has been reset to step S21a, the process proceeds to step S21a to determine whether or not the control flag F4 has been set to "1". When F4 = 1, the process directly proceeds to step S22, and F4 = 0. Sometimes step S
21b, it is determined whether the acceleration / deceleration Vw _H ′ of the select high wheel speed Vw _H is positive, and Vw _H ′ ≦ 0
If Vw _H ′> 0, the process directly proceeds to step S28, and if it is Vw _H ′> 0, the process proceeds to step S21c to set the control flag F4 to “1”, and then proceeds to step S28, which will be described later.

In step S22, the aforementioned step S
14 similarly to 'determine whether is equal to or smaller than the set deceleration -D _S, Vw H' select wheel deceleration Vw _H> when a -D _S proceeds to step S28 to be described later as, Vw _H ' when a ≦ -D _S is step S23
Then, the previous sampling wheel speed stored in the current value storage area of the storage device 20c is updated and stored in the previous value storage area as the previous sampling wheel speed Vs (n-1). The speed Vw _H is updated and stored in the current value storage area as the current sampling wheel speed Vs (n).

Next, the process proceeds to step S24, where the following equation (3) is calculated based on the current sampling wheel speed Vs (n) and the previous sampling wheel speed Vs (n-1) to calculate the vehicle body speed gradient V _Xk . calculate.

V _Xk = (Vs (n−1) −Vs (n)) / T + V _XOF (3) where T is the elapsed time from the previous sampling, V
_XOF is an offset value for compensating for a deviation in estimated vehicle speed due to insufficient vehicle speed gradient.

Then, the process proceeds to step S25 to clear the timer for counting the elapsed time T to "0", and then to step S26 to set the control flag F3 indicating the deceleration start state to "1". After resetting the control flag F4 to "0", the process proceeds to step S15 described above.

On the other hand, if it is determined in step S19 that the brake control state flag AS has been reset to "0", the process proceeds to step S27 to determine whether the control flag F2 has been set to "1". judge. This determination is for determining whether or not the anti-skid control has been started. When the control flag F2 has been reset to “0”, it is determined that it is immediately before the anti-skid control is started. The process proceeds to step S28, where the count value T of the timer for counting the elapsed time for calculating the vehicle speed gradient is incremented by "1", and then the process proceeds to step S29.
Move to

[0046] In step S29, it is determined whether the select high wheel speed Vw _H is the estimated vehicle speed V _X is less than or, Vw _H <V when _X is the current estimated vehicle speed V and proceeds to step S30 _The value obtained by subtracting the vehicle speed gradient V _Xk updated and stored in the predetermined storage area of the storage device 20c from _X is used as a new estimated vehicle speed V _X in the storage device 2.
Moves to the estimated wheel cylinder pressure calculating process in step S3 in FIG. 4 terminates the subroutine processing after updated and stored in a predetermined storage area of 0c, when a Vw _H ≧ V _X proceeds to step S31, the control flag After resetting F3 to "0", the process proceeds to step S15.

When the result of the determination in step S21 is that the control flag F3 is set to "1", the flow proceeds to step S28, and in the result of the determination in step S27, the control flag F2 is set to "1". If so, the process proceeds to step S33, where each control flag F
1, F2, and F3 and F4 are reset to respectively "0", then the processing proceeds to step S34, the current select-high wheel speed Vw _H set to exit the vehicle speed calculation processing from the estimated vehicle speed V _X Then, the process proceeds to the estimated wheel cylinder pressure calculation processing in step S3.

The result of the determination in step S29 is V
It proceeds to the step S34 when a w _H ≧ V _X -1. In the process of FIG. 5, steps S15 and S15
30 and S34 correspond to the estimated vehicle speed calculation means,
Steps S14 and S16 to S28 correspond to the vehicle speed gradient calculating means.

Further, as shown in FIG. 6, the wheel cylinder pressure estimated value calculation processing in step S3 in FIG. 4 first reads the previous actuator control signal in the actuator control processing described later in step S41 for the front wheel side, as shown in FIG. Next, in step S42, it is determined from the state of the read actuator control signal whether the wheel cylinder 2j (j = FL, FR, RL, RR) is in a pressure increasing state, a pressure decreasing state, or a holding state. If it is in the pressure increasing state, the process proceeds to step S43, and the storage device 20
previously estimated wheel cylinder pressure stored in the estimated wheel cylinder pressure storage regions formed in c P _i (n-1) read out, this and the current master cylinder pressure P _MC and based on pre-stored in the storage device 20c of The estimated pressure increase amount ΔP _iZ is calculated with reference to the estimated pressure increase amount calculation control map shown in step S43. Here, the estimated pressure increase amount calculation control map, the estimated pressure increase amount Δ by the increase in the last wheel cylinder pressure P _i (n-1) when the master cylinder pressure P _MC is constant
P _iZ is increased, and the maximum value of the estimated increase [Delta] P _iZ by an increase in the master cylinder pressure P _MC is set to increase.

Next, the routine proceeds to step S44, where the previous estimated wheel cylinder pressure P _i (n) stored in the estimated wheel cylinder pressure storage area is expressed by the following equation (4).
-1) and the estimated pressure increase amount ΔP _iZ are added to calculate the current estimated wheel cylinder pressure P _i (n), and this is updated and stored in the current wheel cylinder pressure storage area.

P _i (n) = P _i (n−1) + ΔP _iZ (4) Then, the _{process proceeds to} step S45, where the rough road detection circuit 19 is set.
Is read, and it is determined whether or not the vehicle is traveling on a bad road that is on. If the bad road detection signal OR is off, it is determined that the vehicle is traveling on a good road. The process moves to S46.

In step S46, the vehicle speed gradient V _Xk calculated in the vehicle speed calculation process of FIG. 5 is read, and based on this, the vehicle speed shown in FIG. with reference to the front-wheel-side upper limit calculating control map showing the relation between the gradient V _Xk and the estimated wheel cylinder pressure upper limit value P _MAX to calculate the estimated wheel cylinder pressure upper limit value P _MAX.

Here, the front wheel upper limit value calculation control map is:
Body speed gradient V_XkIs relatively small when is zero
Cylinder pressure upper limit P_LTo the vehicle speed gradient
Distribution V _XkIs the set value V_Xk1Until the vehicle speed gradient
V_XKThe upper limit value P according to the increase of _MAXHas a relatively gentle gradient
And the vehicle speed gradient V_XkIs the set value V_Xk1And this
Set value V_Xk2Up to a relatively steep slope
And the set value V_Xk2Above, the maximum value P_HFFixed to
It is set as follows.

Step S46 is performed for the rear wheel side.
The rear wheel upper limit value calculation control map referred to in FIG. 9 is shown in FIG.
In consideration of the braking force distribution in the actual vehicle,
Limit value P_MAXIs the vehicle speed gradient V_XKIs the set value V_XK1Reach
Until the vehicle speed gradient V _XKOn the front wheel side as the increase
Set value V of limit value calculation control map_XK1Slightly higher than the gradient
Increased at a gentle slope, the vehicle speed gradient V_XKIs the set value V_XK1Passing
And V_XK2Vehicle speed gradient V_XKRespond to the increase
Set value V_XK1Steeper than the slope up to the front wheel
Value V of the side upper limit calculation control map_Xk1And V_XK2Among
It increases at a gentler slope than the slope,
V_XKIs the set value V_XK2In the above, the front wheel upper limit value calculation control
Maximum value P_HFMaximum value P about half of_HRFixed to
It is set to be.

Next, the process proceeds to step S47 to be described later.
Count up during slow pressure increase
Number of slow pressure increase N_ZIs stored in the storage device 20c.
With reference to the formed slow pressure increase number storage area, the slow pressure increase number N
_ZIs the set value N_S(For example, “8”)
And the number of slow pressure increase N_ZIs the set value N_SWhen less than
Goes to step S48 and is expressed by the following equation (5).
In this way, the updated estimated wheel cylinder pressure storage area is stored.
Estimated wheel cylinder pressure P_i(n) and
Estimated wheel cylinder pressure upper limit value P calculated in step S46
_MAX, Whichever is smaller,
Cylinder pressure P_i(n).
Updated in the cylinder pressure storage area, and then
Proceeding to S49, as shown in the following equation (6),
The current estimate stored in the constant wheel cylinder pressure storage area
Constant wheel cylinder pressure P_i(n) and read this and the current
Master cylinder pressure P_MCAnd compare any smaller value now.
Times estimated wheel cylinder pressure P _i(n) estimated wheel
Subroutine processing after updating and storing in the cylinder pressure storage area
And the process proceeds to the actuator control process of step S6.
Transition.

P _i (n) = min ｛P _i (n), P _MAX ｝ (5) P _i (n) = min ｛P _i (n), P _MC ｝ (6) If the result of the determination in step S45 is that the rough road detection signal OR is on and it is determined that the vehicle is running on a rough road, the process directly jumps to step S49, and similarly, step S47.
Also it jumps to step S49 when the determination result is gradual increase pressure circuit number N _Z is the set value N _S more.

Further, if the result of the determination in step S42 is that the wheel cylinder 2j (j = FL, FR, RL, RR) is in the holding state, the flow directly goes to step S45, and if it is in the depressurized state, the flow goes to step S50. The previous estimated wheel cylinder pressure P _i (n-1) stored in the estimated wheel cylinder pressure storage area is read out, and the previously estimated wheel cylinder pressure P _i (n- The estimated pressure reduction amount ΔP _iG is calculated by referring to the control map shown in step S50 of FIG. 6 _showing the relationship between 1) and the estimated pressure reduction amount ΔP _iG, and then the process proceeds to step S51. Here, the estimated pressure reduction amount calculation control map is set so that the estimated pressure reduction amount ΔP _iG increases in proportion to the increase in the previous estimated wheel cylinder pressure P _i (n−1).

In step S51, the estimated pressure reduction amount ΔP _iG is subtracted from the previous estimated wheel cylinder pressure P _i (n-1) stored in the estimated wheel cylinder pressure storage area, as shown in the following equation (7). Current estimated wheel cylinder pressure P
Calculate _i (n).

P _i (n) = P _i (n−1) −ΔP _iG (7) Then, the process proceeds to step S52 to calculate the currently estimated wheel calculated as shown in the following equation (8). Cylinder pressure P
_i (n) is compared with "0", and a larger value is updated and stored in the current wheel cylinder pressure storage area as the current estimated wheel cylinder pressure P _i (n), and then the step S4 is performed.
Move to 5.

P _i (n) = max {P _i (n), 0} (8) In the processing of FIG. 6, the processing of steps S 41 to S 44 and steps S 50 to S 52 is performed by estimating the braking cylinder pressure. The processing of steps S46 to S48 corresponds to the vehicle speed gradient regulating means, the processing of step S47 corresponds to the upper limit value correcting means, and the processing of step S45 corresponds to the upper limit value canceling means. I have.

Further, as shown in FIG. 7, the target pressure increasing / decreasing amount calculating process in step S4 first includes step S61.
The target wheel speed Vw ^* is calculated by performing the calculation of the following equation (9), and this is updated and stored in the target wheel speed storage area formed in the storage device 20c.

Vw ^* = 0.8V _X (9) Next, the routine proceeds to step S62, where the target wheel speed Vw is set.
^* It is determined whether or not larger than the wheel speed Vw _i, Vw ^*
> When a Vw _i, the process proceeds to the target wheel deceleration Vw ^* '"0" is set to the storage device 20c to update stored in the target wheel deceleration storage region formed by the step S63, Vw ^* ≦ Vw when _i is, it proceeds to step S64 to calculate the following (10) the target wheel deceleration Vw ^* 'by performing the calculation of the equation.

Vw^*'= -Vw₀′ ... (10) where Vw₀'Is a preset value. Next
Then, the process shifts to step S65 and the wheel speed Vw_i, Target car
Wheel speed Vw^*, Wheel acceleration / deceleration Vw_i′ And target wheel adjustment
Speed Vw^*'Based on the following formula (11).
The target increase / decrease by proportional / differential control (PD control)
Pressure ΔP^* _iIs calculated, and this is added to the target increase of the storage device 20c.
The data is updated and stored in the reduced pressure storage area.

[0064] ^{_{ΔP * i = K 1 (Vw}} i -Vw *) + K 2 (Vw i '-Vw *') ...... (11) In this equation (11), a proportional control term first term, right side is a second term derivative control term, K ₁ is a proportional gain, K ₂ is the derivative gain.

[0065] Then, the processing proceeds to step S66, the target wheel speed Vw ^* is determined whether large and the target pressure increase amount [Delta] P ^* _i from the wheel speed Vw _i is positive, Vw ^*> V
when it is w _i and ΔP ^* _i> 0, the step S67
Then, the target pressure increase / decrease amount ΔP ^* _{i is set} to “0”, updated and stored in the target pressure increase / decrease amount storage area, the processing is terminated, and the flow proceeds to step S5 in FIG. I do.

In step S68, the target wheel speed V
w ^* is and the target pressure increase amount ΔP in the following wheel speed Vw _i ^* _i
There it is determined whether the negative, Vw ^* ≦ Vw _i and [Delta] P ^*
_{If i} <0, the process proceeds to step S67. If not, the process ends and the process proceeds to step S5 in FIG.

As shown in FIG. 8, the actuator control process of step S5 in FIG.
1, when the vehicle speed V _X becomes stopped near the speed, it is determined whether the switch signal of the brake switch 14 satisfies a predetermined control termination conditions such as when the OFF state, the control end condition Is satisfied, the flow proceeds to step S72 to set a brake control state flag AS indicating whether or not an antilock brake control process described later is being performed to “0”.
After that, the process goes to step S73, where the control signals EV _i , AV _i and MR _i for the actuator 6i are controlled.
All and ends the processing by controlling the actuator 6i is turned off in the surge pressure state the master cylinder pressure P _MC is directly supplied to the wheel cylinders 2i returns to the predetermined main program.

If the result of the determination in step S71 does not satisfy the control end condition, the flow advances to step S71.
The process proceeds to 74, where the target pressure increasing / decreasing amount ΔP ^* _i updated and stored in the above-described target pressure increasing / decreasing amount calculation processing is read from the target pressure increasing / decreasing amount storage area. Mode or the slowly increasing mode.

This determination is based on the target pressure increase / decrease amount calculation processing of FIG.
Target pressure increase / decrease amount ΔP calculated in^* _iTo determine the sign of
And the target pressure increase / decrease amount ΔP^* _iIs negative
(ΔP ^* _iIn <0), it is determined that the mode is the pressure reduction mode, and the target
Increase / decrease amount ΔP^* _iIs “0” (ΔP^* _i= 0)
Is determined to be the hold mode, and the target pressure increase / decrease amount ΔP^* _i
Is positive (ΔP^* _i> 0) is the pressure increase mode
Is determined.

If the result of the determination in step S75 is the pressure reduction mode, the flow shifts to step S76, where the brake control state flag AS is set to "1".
Next, the routine proceeds to step S77, the when the pressure reduction mode status flag F _G represents a reduced pressure mode state is judged whether it is set to "1", which is reset to "0", the start of the pressure decrease mode in it shifts to the step S78 determines that stores the estimated wheel cylinder pressure P _i stored in the estimated wheel cylinder pressure storage region at that time as a pressure reducing start wheel cylinder pressure PG _Ii.

[0071] Then, the processing proceeds to step S79, the pressure reduction mode state flag F _G is set to "1" indicating that the reduced pressure mode, then the process proceeds to step S80, the preset down representing a gradual increase圧周life Count value T _Z
Is cleared to "0", and these are updated and stored in the slow pressure increase count storage area and the count value storage area formed in the storage device 20c, and then the process proceeds to step S81.

In step S81, the target increase
The target pressure increase / decrease amount ΔP updated and stored in the pressure decrease amount calculation process^* _i
Is read from the target pressure increase / decrease amount storage area,
ΔP ^* _iAnd the preset pressure reduction upper limit value ΔP_G0Based on
Calculate the following equation (12) and select the smaller one.
And the target pressure reduction amount ΔPG_iAs decompression amount storage area
And store the updated information.

[0073]? Pg _i = min then [[Delta] P ^* _i, [Delta] P _G0] ............ (12), the process proceeds to step S82, the vacuum in accordance with the target pressure decrease amount? Pg _i stored in the pressure reduction amount storage area as performed, only the control signal AV _i only decompression time corresponding to the target pressure decrease amount? Pg _i is turned on, the actuator 6i and ends the processing under vacuum control, returns to the predetermined main program.

The result of the determination in step S75 is
If a holding mode, the process proceeds to step S83, the is reset to "0" vacuum mode state flag F _G, migrated to clear the preset down-count value T _Z to "0" in step S84 , only the control signal EV _i for actuators 6i is turned on, thereby, the inlet valve 8 of the actuator 6i are closed, outlet valve 9 so to maintain the closed state, the wheel cylinders 2i and the master cylinder 5 The interval is cut off,
After setting the holding mode in which the cylinder pressure of the wheel cylinder 2i is maintained at a constant value, the process is terminated as it is, and the process returns to the predetermined main program.

Further, when the result of the determination in step S75 is the pressure increase mode, the flow shifts to step S85 to determine whether or not the brake control state flag AS is set to "1". when it is reset to ", the control signal EV _i for similarly actuator 6i and step S73 described above proceeds to the step S86, after controlling the actuator 6i to rapid pressure increase state as all the AV _i and MR _i turned off When the process ends and returns to the predetermined main program, and the brake control state flag AS is set to "1",
The process moves to step S87a.

In step S87a, it is determined whether the previous mode was any of the holding mode and the pressure reducing mode other than the pressure increasing mode. If the previous mode was the mode other than the pressure increasing mode, the initial state of the slow pressure increasing mode is determined. Then, the process proceeds to step S87b, resets the number of times of gradual pressure increase _NZ to "0", and then proceeds to step S87c. If the pressure increase mode was also the previous time, the gradual pressure increase mode continues. Then, the process directly proceeds to step S87c.

[0077] In step S87c, reset to "0" vacuum mode state flag F _G, then step S
88 proceeds to preset down-count value T _Z that determines the gradual increase圧周life it is determined whether or not "0", T _Z
If> 0, the process proceeds to step S89 to decrement the count value T _Z , to count down, to end the process, and to return to the predetermined main program, and to return to step S90 when T _Z = 0. .

In step S90, the storage device 20c
Slow pressure increase the gradual increase pressure circuit number N _Z stored in the slow increase of pressure circuit number storage area formed in a predetermined memory area read out, the value obtained by adding "1" as a new Yuruzo pressure circuit number N _Z to the After the number of times is updated and stored in the number storage area, the process proceeds to step S91.

In step S91, the number N of times of gradual pressure increase is_Z
Is determined to be “1”, and N _Z= 1
Determines that the mode is the first slow pressure increasing mode, and determines in step S9
The process proceeds to step S2, and the pressure reduction stored in step S78 is started.
Hour wheel cylinder pressure PG_IiAnd read the current
Constant wheel cylinder pressure P_iAnd read
Calculate the expression (13) to calculate the total pressure reduction amount Δ in the pressure reduction mode.
PG_TiIs calculated.

ΔPG _Ti = PG _Ii −P _i (13) Next, the routine proceeds to step S93, where the total pressure reduction amount ΔPG _Ti
The initial pressure increase amount ΔP is calculated based on the following equation (14).
Calculating the Z _0i, which proceeds from the updated and stored in the pressure increase amount storage area as a pressure increase amount DerutaPZ _i in step S94.

ΔPZ _0i = K · ΔPG _Ti (14) Here, K is an initial pressure increase coefficient, and is selected to be, for example, about 0.5. In step S94, sets the preset value T _P corresponding to the preset down-count value T _Z and to e.g. 60msec representing a gradual increase圧周life determines in step S87 described above, which after updating stored in the count value memory region the process proceeds to step S95, only the pressure increase amount DerutaPZ _i only pressure increasing time corresponding control signal EV _i stored in the pressure increase amount storage area is turned on, the actuator 6i after your Yuruzo pressure The process ends, and the process returns to the predetermined main program.

On the other hand, if the result of determination in step S91 is that the number of times of gradual pressure increase _NZ is "2" or more, step S9
The process proceeds to 6 to determine whether the vehicle is traveling on a low friction coefficient road surface such as a snowy road, a frozen road, or a rainy road. This determination is based on the vehicle speed gradient V calculated in the estimated vehicle speed calculation process.
_XKP is read, and it is determined whether or not the vehicle body speed gradient V _XKP is equal to or less than a preset gradient V _XKS representing a predetermined road surface friction coefficient μ of about _{0.1 to 0.2} , and V _XKP ≦ V _XKS On certain occasions, it is determined that the traveling road surface is a low friction coefficient road surface,
When V _XK > V _XKS, it is _determined that the traveling road surface is a high friction coefficient road surface such as a dry pavement road.

If the result of determination in step S96 is that the traveling road surface is a low friction coefficient road surface, step S97
Then, the following equation (15) is calculated and the larger one of the target pressure increase / decrease amount ΔP ^* _i and a relatively small low friction coefficient road surface upper limit value ΔP _Z0L is determined to be the larger pressure increase amount ΔPZ.
_i , which is updated and stored in the pressure increase amount storage area, and then proceeds to step S94.

ΔPZ _i = max [ΔP ^* _i , ΔP _Z0L ] (15) If the result of determination in step S96 is a road surface with a high friction coefficient, the _flow shifts to step S98, and the following (16)
Whichever is greater increase to the high friction coefficient road surface for the upper limit value [Delta] P _Z0H preset the value greater than the upper limit value [Delta] P _Z0L for low friction coefficient road surface and the target pressure increase amount [Delta] P ^* _i by performing the calculation of the formula calculated as pressure amount ΔPZ _i, shifts which after updating stored in the pressure increase amount storage area to the step S94.

ΔPZ _i = max [ΔP ^* _i , ΔP _Z0H ] (16) In the processing of FIG. 8, the processing of step S90 and the storage device 20c correspond to the _pressure increase frequency storage means.

Therefore, when the vehicle is traveling on a flat good road and traveling at a constant speed in a non-braking state on a low friction coefficient road such as a snowy road or a frozen road, the brake switch 14 is off and the brake switch 14 is off. The control state flag AS has been reset to "0".

In the constant-speed running state in the non-braking state, when the vehicle speed calculation processing of FIG.
By moving from 7 to step S8 to S10, and selects the smallest value among the filter output Vf _FL ~Vf _R of the wheel speed Vw _FL ~Vw _R as select low wheel speed Vw _L, select low wheel which is selected speed Vw _L and updates the estimated vehicle speed storage area stored as the estimated vehicle speed V _X, sets the set values V _XK0 as vehicle velocity gradient V _XK, updates and stores it in the vehicle velocity gradient storage area. Thus, by setting the select-low wheel speed Vw _L as the estimated vehicle speed V _X, wheels 1R After the drive wheel
Even when the wheel speed Vw _R increases caused slip at L and 1RR, it is selected either of the wheel speed Vw _FL and Vw _FR of the front wheels 1FL and 1FR that the non-driven wheels correspond to the vehicle speed smaller , it is possible to calculate an accurate estimated vehicle speed V _X which is not affected by the slip in the drive wheels. At this time, a relatively large initial value V _XK0 corresponding to a road surface with a high friction coefficient is set as the vehicle body speed gradient V _XK .

Next, when the estimated wheel cylinder pressure calculation processing of FIG. 6 is executed, the vehicle is in the non-braking state.
The actuator 6i will be described later in the actuator control processing
Are output with the control signals EV _i, AV _i, MR _{i corresponding} to the logical value “0”, and a step S42 is executed.
From step S43 to continue the constant-speed running state, so that the previous estimated wheel cylinder pressure P _i (n
-1) is zero, because it does not depress the brake pedal 4, the current master cylinder pressure P _MCF, since P _MCR is also at zero, also becomes zero estimated pressure increase amount [Delta] P _iZ. On the other hand, step S4
The estimated wheel cylinder pressure upper limit value P _MAX calculated in step 6 is substantially the maximum values P _FH and P _RH because the relatively large initial value V _XK0 is set as the vehicle body speed gradient V _XK. S48, S49 in the estimated wheel cylinder pressure of each "0" P _i (n) by the smaller upper limit value P _MAX and the master cylinder pressure P _MC is selected, the estimated wheel cylinder pressure P _i (n) is It is set to “0”.

[0089] Further, since the target wheel speed Vw ^* is calculated in step S61 in FIG. 7 is 80% of the estimated vehicle speed V _X as shown in FIG. 10 (a), lower than the select low wheel speed Vw _S And therefore the actual wheel speed V
Since the value is lower than w _i , the process proceeds from step S62 to step S64, and the target wheel deceleration Vw ^* ′ is set as shown in FIG.
The value is set to a predetermined value -Vw ₀ 'as shown in FIG.

As a result, as shown in FIG. 10 (c), the target pressure increase / decrease amount ΔP ^* _i calculated in step S65 becomes V
a w ^* ≦ Vw _i, the wheel deceleration Vw _i 'is zero, the target wheel deceleration Vw ^*' by is a negative predetermined value -Vw ₀ ', a positive value.

However, when the actuator control process of FIG. 8 is executed, the brake is not being braked and the brake control end condition is satisfied, so that the process shifts from step S71 to step S72 to set the brake control state flag AS to “ 0 ", and the process shifts to step S73 to control signals EV _i and AV for the actuator 6i.
_i and MR _i are all turned off, so that only the inflow valve 8 of the actuator 6i is opened, and the wheel cylinders 2FL, 2FR and 2RL, 2RL, 2RL,
2RR is in communication with the master cylinder 5.
At this time, since the brake pedal 4 is not depressed, the cylinder pressure output from the master cylinder 5 is zero, so the cylinder pressure of each of the wheel cylinders 2FL to 2RR is also zero, and a braking force is generated. The non-braking state is continued.

[0092] The low friction coefficient road of the good road from a state in which the constant speed running, if the braking state depress the brake pedal 4 at time t _1, when the vehicle speed calculating process of FIG. 5 is executed, By shifting from step S7 to step S11, the select high wheel speed Vw _H is calculated, and based on this, the vehicle speed gradient V _XK and the estimated vehicle speed V _X are calculated. Gradient V _XK
And it is possible to accurately calculate the estimated vehicle speed V _X.

That is, immediately after braking, the control flag F1
Since it has been reset to "0", step S1
3 to step S14 to select high wheel speed.
Vw _HDeceleration Vw_H'Is the set deceleration -D_SHas reached
No, go to step S15 and select high wheels
Speed Vw_HIs the estimated vehicle speed V_XSet as
This is updated and stored in the estimated vehicle speed storage area.

On the other hand, in the estimated wheel cylinder pressure calculation process of FIG. 6, the master cylinder pressures _{PMCF and PMCR} are rapidly increased, and this and the previous estimated wheel cylinder pressure P
Although the estimated pressure increase amount [Delta] P _iZ is determined by a _i, since the previous estimation wheel cylinder pressure P _i is zero, the estimated pressure increase amount [Delta] P _iZ is a value dependent master cylinder pressure P _MCF, only P _MCR together it becomes, since the vehicle velocity gradient V _XK is set to the set value V _XK0 of relatively large value, because the estimated wheel cylinder pressure upper limit value P _MAX is not limited by this set to the maximum value P _H, the current Estimated wheel cylinder pressure P
_i (n) becomes equal to the master cylinder pressures _{PMCF and PMCR} .

[0095] Therefore, when the target pressure increase amount calculation process in FIG. 7 is executed, but the wheel deceleration Vw _i 'is increased in the negative direction, the target pressure increase amount [Delta] P ^* _i in FIG. 10 (c) Still continue positive value as shown.

Therefore, when the actuator control process shown in FIG. 8 is executed, the control end condition is not satisfied, so that the process shifts from step S71 to step S74, where the target pressure increase / decrease amount ΔP ^* _i is read. Therefore, it is determined that the mode is the pressure increase mode, and the process shifts from step S75 to step S84 to set the brake control state flag AS.
Is still reset to "0", so that step S
85 proceeds to, keeping the actuator 6i to rapid pressure increase state, the master cylinder pressure P _MCF, the braking state by increasing the wheel cylinder pressure in accordance with an increase in the P _MCR.

For this reason, the wheel speed Vw of each wheel 1i_iBut
As shown in FIG. ₁Begins to decrease from
You. In FIG. 10, for simplicity of explanation, each vehicle
The wheels 1i simultaneously start to decelerate and their wheel speeds Vw_i
Are equal to each other and therefore the select high wheel speed Vw
_HAnd wheel speed Vw_FL,Vw_FRAnd Vw_RMatches
Is represented as

[0098] Thereafter, when the deceleration Vw _H of select-high wheel speed Vw _H at t ₂ 'reaches the set deceleration -D _S, when vehicle speed arithmetic processing of Fig. 5 is performed, step from step S14 S16~S18 proceeds to, together with the select high wheel speed Vw _H at the time is now updated and stored in the current value storage area as a sampling wheel speed Vs (n), is and cleared the elapsed time T is "0" ,
Control flag F1 is set to "1", then the processing proceeds to step S15, to keep the estimated vehicle speed V _X in select-high wheel speed Vw _H.

For this reason, the control flag F1 is set to "1" when the vehicle speed calculation processing shown in FIG.
9, since the state in which the brake control state flag AS has been reset to “0” is maintained in the actuator control process of FIG. 8, the process proceeds to step S27, and the control flag F2 is reset to “0”. since it has, the process proceeds to step S28, the elapsed time T "1" transition from incremented by the step S29, the select-high wheel speed Vw _H is the estimated vehicle speed V _X "1"
Is smaller than the value obtained by subtracting the set value V from the current estimated vehicle speed V _X (= Vw _H ).
The vehicle velocity gradient V _XK set in _XK0 updates and stores the subtracted value as a new estimated vehicle speed V _X. Therefore,
Estimated vehicle velocity V _X is as shown by a broken line shown in FIG. 10 (a), the
Will be sequentially reduced in gradient setting V _XK0, which decreases the target wheel speed Vw ^* may in accordance with the further wheel deceleration Vw _i 'also increases in the negative direction as shown in Figure 10 (b).

Therefore, when the target pressure increasing / decreasing operation shown in FIG. 7 is executed, the target pressure increasing / decreasing amount ΔP ^* _i calculated in step S65 starts to decrease as shown in FIG. 10 (c). t ₃ in becomes zero, then increases in the negative direction.

[0102] During this time, every time the vehicle speed calculating process of FIG. 5 is executed, step S13, S19, since the processing of S27 to S31, the estimated vehicle speed V _X is the vehicle velocity gradient V
_Continue to be reduced by _XK0 minutes.

Then, at time t ₃ , when the target wheel cylinder pressure calculation processing of FIG. 7 is executed, the target pressure increase / decrease amount ΔP ^* _i becomes zero, so that the actuator control processing of FIG. 8 is executed. Occasionally, with been determined to be holding mode in step S75 proceeds to step S83, the reset to "0" vacuum mode state flag F _G,
The slow increase pressure circuit number N _Z and preset down-counter value T _Z is cleared to both "0" the process proceeds to step S84, the only control signal EV _i for actuators 6i is turned on, whereby, the actuator 6i Since the inflow valve 8 is closed and the outflow valve 9 is kept closed, the wheel cylinder 2i and the master cylinder 5 are closed.
Is cut off, and the mode is switched to the holding mode in which the cylinder pressure of the wheel cylinder 2i is maintained at a constant value.

As described above, in the holding mode in which the cylinder pressure of the wheel cylinder 2i is held at a constant value, FIG.
When the estimated wheel cylinder pressure calculation process is performed, the process directly proceeds from step S42 to step S45, and the entire estimated wheel cylinder pressure _Pi is held. On the other hand, when the target pressure increase / decrease amount calculation process of FIG. 7 is executed, the target pressure increase / decrease amount ΔP ^* _i calculated in step S65 increases in the negative direction as shown in FIG. 10 (c). However, the target wheel speed Vw ^* is equal to the wheel speed Vw.
_Since the state of _i or less is continued, the process proceeds from step S68 to step S67, and the target pressure increase / decrease amount ΔP ^* _i is limited to “0” as shown in FIG.

For this reason, in the actuator control process of FIG. 8, the holding mode is determined in step S75, and the process shifts to step S84 to maintain the actuator 6i in the holding state.

[0105] Then, decreasing the wheel speed Vw _i is the at t ₄ becomes the target wheel speed Vw ^* value less than 7
Is executed, the process proceeds from step S62 to step S63, and the target wheel deceleration Vw ^* 'is set to "0". At this time, the target pressure increase / decrease amount ΔP ^* _i calculated in step S65 is as shown in FIG.
As shown in (c), it continues to increase in the negative direction,
Since the target wheel speed Vw ^* is greater than the wheel speed Vw _i, by the processing is ended after steps S66, S68, the target pressure increase amount [Delta] P ^* _i restriction is released, is updated and stored in the target pressure decrease amount storage area Target pressure increase / decrease amount ΔP ^* _i
Is a negative value as shown in FIG.

For this reason, when the actuator control process of FIG. 8 is executed, it is determined in step S75 that the mode is the pressure reduction mode, and the flow shifts to step S76 to set the brake control state flag AS to "1". Step S
77 proceeds, since a reduced pressure mode state flag F _G is reset to "0" in the previous hold mode, the process proceeds to step S78 it is determined that the pressure-decrease start state, the estimated wheel cylinder pressure at this time the P _i stored as reduced pressure immediately before the estimated wheel cylinder pressure PG _Ii, then set to "1" vacuum mode state flag F _G (step S79),
Then clearing the slow increase pressure circuit number N _Z and preset down-counter value T _Z are both "0" (step S80).

Next, the target pressure increase / decrease amount ΔP ^* _i (ΔP ^* _i
<0), whichever is smaller negative limit [Delta] P _G0 previously set and selected as the target pressure decrease amount? Pg _i it was updated and stored in the pressure reduction amount storage area (step S81), to the target pressure decrease amount? Pg _i The target pressure reduction amount ΔP
Decompression time only the control signal AV _i only with the on-state corresponding to the G _i, the control signal EV _i and MR _i and a predetermined time on-state (step S82). Therefore, the inflow valve 8 of the actuator 6i is maintained in the closed state, the outlet valve 9 is only opened time corresponding to the target pressure decrease amount? Pg _i, pump 10 is driven to rotate, in the wheel cylinder 2i The hydraulic oil is discharged to the master cylinder 5 side, whereby the cylinder pressure of the wheel cylinder 2i is reduced as shown in FIG.
Decompression is started as shown in (f).

When the depressurized state is reached, when the wheel cylinder pressure estimating process of FIG. 6 is executed, the process shifts from step S42 to step S50, where the previous estimated wheel cylinder pressure P _i (n-1) is reduced. Estimated pressure reduction amount ΔP _iG
Then, in step S51, a value obtained by subtracting the estimated pressure reduction amount ΔP _iG from the previous estimated wheel cylinder pressure P _i (n-1) is set as the current estimated wheel cylinder pressure P _i (n), and is updated and stored. .

On the other hand, when the vehicle speed calculation processing shown in FIG. 5 is executed by setting the brake control state flag AS to "1", the process shifts from step S19 to step S20 to set the control flag F2 to "1". ", And then the process proceeds to step S21 where the control flag F3
Is reset to “0”, the step S
Proceeds to 21a, the control flag F4 is reset to "0", the process proceeds to step S21b, the procedure proceeds to step S28 since acceleration Vw _H of the select high wheel speed Vw _H 'is negative, lapse continues incrementing the time T, then the process proceeds to step S29, since the select high wheel speed Vw _H is smaller than the estimated vehicle speed V _X, the process proceeds to step S30, the vehicle speed gradient V _XK from the estimated vehicle speed V _X Is subtracted from the new estimated vehicle speed V
Update and store as _X.

By continuing this depressurized state, FIG.
0 (a), the result in the wheel speed Vw _i is restored at time t _5, when the target pressure increase amount calculation process in FIG. 7 is executed, the target pressure increase amount [Delta] P ^* _i Figure 10 (c)
As shown in FIG. 7, when the value becomes "0" again, and the actuator control process of FIG.
5 is judged to hold mode, the pressure reducing mode state flag F _G proceeds to step S83 "0" is reset, the gradual increase of pressure circuit number N _Z and preset down-counter value T _Z is cleared to "0" After that, the actuator 6i is controlled to the holding state, whereby the wheel cylinder 2i
Is maintained at a constant value as shown in FIG.

In the holding mode, the estimated wheel cylinder pressure P _i is held in the estimated wheel cylinder pressure calculation processing of FIG. 6 as described above, and the target pressure increase / decrease amount ΔP is calculated in the target pressure increase / decrease amount calculation processing of FIG. ^* _i increases in the positive direction as shown in FIG. 10C, but the target wheel speed Vw
Since ^* is greater than the wheel speed Vw _i, the process proceeds from step S66 to step S67, the target pressure increase amount [Delta] P ^* _i is limited to "0" as shown in FIG. 10 (d).

Then, at time t ₆ , the target wheel speed Vw ^*
Limiting the When the wheel speed Vw _i match by finishing the process from step S65 through steps S66, S68 when the target pressure increase amount calculation process in FIG. 7 is executed, the target pressure increase amount [Delta] P ^* _i Is released and the target pressure increase / decrease amount ΔP ^* _i updated and stored in the target pressure increase / decrease amount storage area becomes a large value in the positive direction in FIG.

Therefore, when the actuator control process of FIG. 8 is executed, it is determined in step S75 that the pressure increase mode is set, and the process proceeds to step S85, where the brake control state flag AS is set to "1". the process proceeds to step S87 it is determined that the slow increase mode, the transition from reset to "0" vacuum mode state flag F _G in step S88.

[0114] At this time, the preset down-count value T _Z in step S83 in the previous hold mode is "0"
Therefore, the process proceeds to step S90, and the number of gentle pressure increase _NZ , which is also cleared to “0”, is incremented to “1”.

Therefore, in step S91, the first gentle pressure increase is performed.
Is determined, the process proceeds to step S92, and the decompression mode is performed.
Estimated wheel cylinder pressure immediately before pressure reduction stored at the start of mode
PG _iAnd the current estimated wheel cylinder pressure P_iAnd based on
By performing the calculation of the above equation (13), the total pressure reduction amount ΔPG_TiCalculate
Then, the process proceeds to step S93, where the total pressure reduction amount ΔPG
_TiIs calculated based on the equation (14) to obtain the total pressure reduction amount ΔP
G_TiInitial slow pressure increase amount ΔPZ corresponding to half of_0iCalculate
You.

[0116] Then, the processing proceeds to step S94, the process moves after setting the preset down-count value T _Z the preset value T _P to determine the slow increase圧周period in step S95, initial slow pressure increase amount DerutaPZ _0i by only between increasing the corresponding pressure time and the control signal EV _i the oN state, the actuator 6i is controlled in the relaxed pressure increasing state, the wheel cylinder pressure is the total pressure reduction amount as a chain line shown in FIG. 10 (f) Increased to about half.

[0117] and, due to the recovery of the wheel speed Vw _i, filter output Vf _i that is output from the wheel speed filter 18i
By but when substantially coincident with the wheel speed Vw _i, in this state the control signal MR _i is a logic value "1", the selection circuit 1
87 the voltage corresponding to "+ 10 g" after the delay time set by the off-delay timer 186 has expired is selected, by which is supplied to the integrating circuit 182, a point filter output Vf _i in FIG. 10 (a) As shown by the dashed line, it increases sharply, and this is the select high wheel speed Vw _H
Therefore, when the vehicle speed calculation process of FIG. 5 is executed, the process proceeds from step S21b to step S2.
The process proceeds to 1c, where the control flag F4 is set to "1". Therefore, the next time the vehicle speed calculation processing of FIG. 5 is executed, the process proceeds from step S21a to step S22, a deceleration Vw _H of the select high wheel speed Vw _H 'is less than the set deceleration -D _S It is determined whether or not
because it is w _H '> -D _S, the process proceeds to step S28, and continues the subtraction of the estimated vehicle speed V _X as described above.

[0118] Thereafter, the select high wheel speed Vw _H is the estimated vehicle speed V _X or at time t _7, when the vehicle speed calculating process of FIG. 5 is executed, step S21a, S
The process proceeds to step S29 through steps S22 and S28, where Vw _H ≧
Since at V _X, the process proceeds to step S31, and proceeds from the reset control flag F3 to "0" in step S15, the select high wheel speed Vw _H at this time is set as the estimated vehicle speed V _X , whereby the estimated vehicle speed V _X is increased.

[0119] Thereafter, the target pressure increase amount ΔP is updated and stored in the target pressure increase amount storage area ^* _i continues a positive value, when the processing of FIG. 8 is executed, the preset down-count value T _Z is by being set to the preset value T _P, the process proceeds from step S88 to step S89,
Only the count value T _Z counting down is performed, step S8 in the count value T _Z is "0" and becomes the time t ₇ '
8 to step S90, and the number of gentle pressure increase _NZ becomes “2”.
Since the vehicle is traveling on a road surface with a low coefficient of friction,
Proceeding to step S97, the current target pressure increase / decrease amount ΔP ^*
_i or the upper limit value ΔP _Z0L for the low friction coefficient road surface, whichever is larger, is selected as the gentle pressure increase amount ΔPZ _i , and then step S
95 slow pressure-increasing control in accordance with the gradual pressure increase amount DerutaPZ _i selected is performed in the wheel cylinder pressure P _Ri is pressurized Yuruzo as shown FIG. 10 (f).

[0120] On the other hand, the wheel speed Vw _i by increasing pressure in the wheel cylinders 2i, as shown in FIG. 10 (a), started to decrease again, acceleration Vw _H of the select high wheel speed Vw _H at time t ₈ 'is when the following settings deceleration -D _S, when vehicle speed arithmetic processing of Fig. 5 is executed, the step S
Shifts from 22 to step S23, the select high wheel speed Vw at the time t ₂ stored in the current value storage area
_H , the previous sampling wheel speed Vs (n-1) is updated and stored in the previous value storage area as the previous sampling wheel speed Vs (n-1), and the current select high wheel speed Vw _H is stored in the subtraction value storage area as the current sampling wheel speed Vs (n). ) Is updated and stored. Then, in step S24, the calculation of equation (5) is performed to calculate the vehicle body speed gradient V _XK, which is updated and stored in step S25. Then, in step S26, the control flag F3 is set to "1" and the control flag F4
Is reset to “0”.

At this time, the vehicle body speed gradient V _XK calculated in step S24 is a value corresponding to the degree of decrease in the vehicle body speed during actual low friction coefficient road running as shown in FIG. 10 (e). , _Is smaller than the set value V _XK0 . For this reason, when the estimated wheel cylinder pressure calculation processing of FIG. 6 is executed, the estimated wheel cylinder pressure upper limit value P _MAX calculated in step S46 is changed to the vehicle body speed gradient V as shown by the broken line in FIG. It is changed to a small value according to _XK .

In this state, when the estimated wheel cylinder pressure calculation processing of FIG. 6 is executed, the previous control signal is in the pressure increasing state, and the previous estimated wheel cylinder pressure P
_i is a relatively large value and the master cylinder pressure P
_MCF, since P _MCR continues a large value, since the estimated pressure increase amount [Delta] P _iZ also a predetermined value, as shown by the solid line shown in FIG. 10 (f), the estimated wheel cylinder pressure P _i is holding and pressure increase Is repeated and the pressure is gradually increased.

[0123] Repeat this slow pressure increase state, when at time t ₉ estimated wheel cylinder pressure calculating process of FIG. 6 is executed, the estimated wheel estimated wheel cylinder pressure P _i to be calculated is calculated in step S46 Cylinder pressure upper limit value P
_When it exceeds _MAX , the estimated wheel cylinder pressure P
Since _i is limited by the upper limit value P _MAX, as shown by the solid line shown in FIG. 10 (f), an increase in the estimated wheel cylinder pressure P _i is held stopped at the upper limit value P _{MA X.}

[0124] Then, at time t _10, when the target pressure increase amount calculation process in FIG. 7 is executed by the target pressure increase amount [Delta] P ^* _i is calculated in step S65 becomes "0", the aforementioned becomes similar holding mode when t ₃ when the, by the target wheel speed Vw ^* from the wheel speed Vw _i is smaller at time t _11, the similarly reduced pressure and the time t ₄ when the aforementioned.

[0125] Subsequently, the holding state at time t _12, slow pressure increase state when t _13, which was updated and stored recalculate the vehicle speed gradient V _XK at time t _14, then the estimated wheel cylinder pressure at the time point t ₁₅ P _i is limited to the upper limit P _MAX , and then at time t
₁₆ holding state, successively repeating the reduced pressure state at time t _17,
The estimated vehicle speed V _X is reduced.

[0126] Thus, in the braking state of a low friction coefficient road surface limit, by estimating the wheel cylinder pressure P _i is limited by the upper limit value P _MAX, slow increase pressure circuit number N _Z is at most about 4 times In the estimated wheel cylinder pressure calculation processing of FIG. 6, the process proceeds from step S46 to step S48 via step S47, and the estimated wheel cylinder pressure _Pi is always limited by the upper limit value P _MAX ,
In (f), as shown by the solid line, the estimated wheel cylinder pressure P _i
Changes a value close to the actual wheel cylinder pressure P _Ri shown by the dashed line.

[0127] However, they continue to braking state of a low friction coefficient road surface as described above, for example, a slow pressure increase mode has become Yuruzo voltage dividing number N _Z is, for example, "5" as shown in FIG. 11 when traveling road surface at a time t ₂₁ which is continuously changed to the high friction coefficient road surface paved road such as a dry, although the friction coefficient of the road surface is increased, the solid line with the actual wheel cylinder pressure P _Ri FIG 11 (c) Since it is low as shown, the wheel speed Vw
_i hardly changes as shown by the solid line in FIG. For this reason, the estimated vehicle speed V _X shown by the dashed line in FIG.
Also, the vehicle speed gradient V _XK shown by the solid line in FIG. 11D hardly changes, and the gentle pressure increase state is continued.

Then, in the actuator control process of FIG. 8, the slow pressure increasing mode is continued,
When _Z is "8", after calculating the estimated wheel cylinder pressure upper limit value P _MAX then estimated wheel cylinder pressure when t ₂₂ the calculation process is performed in FIG. 6 at step S46, proceeds from step S47 to step S48 The process directly proceeds to step S49 without performing the process.

[0129] Therefore, limit processing for the estimated wheel cylinder pressure P _i (n) the smaller one of the current estimated wheel cylinder pressure P _i (n) and the upper limit value P _MAX is not performed in step S48, the The current estimated wheel cylinder pressure P _i (n) in step S49 and the master cylinder pressures P _{FMC and} P _RMC
Only the process of selecting the smaller of the two is performed. As a result, the estimated wheel cylinder pressure upper limit value P
_This is equivalent to selecting the current master cylinder pressures P _{FMC and} P _RMC as _MAX , and the upper limit of the estimated wheel cylinder pressure is released.

Accordingly, the estimated wheel cylinder pressure P _i
(n) increases as shown by the broken line in FIG. Thereafter, by performing actuator control process in FIG. 8 at time t _23, slow increase pressure circuit number N _Z is the control termination condition "1
0 ", the actuator 6i in step S95.
After the gradual pressure increase control is performed, the process proceeds from step S96 to step S97, and the brake control state flag AS is reset to “0”, followed by terminating the process.

For this reason, when the processing of FIG. 4 is executed next at time t ₂₄ , the brake control state flag AS is reset to “0” in the processing of FIG. 5 corresponding to step S2. The process proceeds from step S19 to step S33 via step S27, whereby the flag F
After all of F1, F2 and F3 have been reset to "0", the flow shifts to step S34 to select the current select high wheel speed Vw.
_H is set as the estimated vehicle speed V _X.

[0132] Thus, the estimated vehicle speed V _X is 11
(B) decreases as the chain line illustrated one point coincides with the select-high wheel speed Vw _H, and at the same time the target wheel speed Vw ^* is also reduced.

However, regarding the vehicle body speed gradient V _XK , since the processing of step S24 is not executed in the processing of FIG. 5, as shown in FIG. Maintain the gradient V _XK .

On the other hand, in the estimated wheel cylinder pressure calculation processing of FIG. 7, the target pressure increase / decrease amount Δ calculated in step S65.
Since P ^* _i maintains a positive state, in the actuator control process of FIG. 8, in the mode determination process of step S75, it is determined that the pressure increase mode is set, and the process proceeds to step S85.
Since the brake control state flag AS has been reset to "0", the flow shifts to step S86 to control the actuator 6i to the rapid pressure increase mode.

[0135] The steps of the reason, the wheel cylinder pressure P _Ri of the wheel cylinder 2i rapidly increases as indicated by a solid line shown in FIG. 11 (c), the master cylinder pressure P _MCF, approaches P _MCR, 7 thereafter time t ₂₅ The target pressure increase / decrease amount ΔP ^* _i calculated in S65 is negative and the target wheel speed Vw ^* is the wheel speed V
It becomes lower than the w _i, the target pressure increase amount ΔP ^* _i is limited to "0".

[0136] Therefore, when the actuator control process in FIG. 8 is executed, it is determined hold mode in step S75, the actuator 6i is set to the hold mode, the wheel cylinder pressure P _Ri of the wheel cylinder 2i is 11 In (c), it is held as shown by the solid line.

[0137] Thereafter, the target wheel speed Vw ^* is greater than the wheel speed Vw _i at time t _26, since the negative target pressure increase amount [Delta] P ^* _i at the wheel cylinder pressure calculating process of FIG. 7 is set as it is, FIG. 8 In step S75 of the actuator control process, the pressure reduction mode is determined and the brake control state flag AS is set to "1", and the estimated wheel cylinder pressure P _i (n) at that time is set as the estimated wheel cylinder pressure _PGIi immediately before pressure reduction. After the storage, the pressure of the actuator 6i is controlled to be reduced.
The pressure of i sharply decreases as shown by the solid line in FIG.

Here, in the rapid pressure increasing mode, the holding mode, and the pressure decreasing mode, the number of gentle pressure increasing _NZ is not cleared to “0” in the actuator control processing of FIG.
Be estimated wheel cylinder pressure calculating process of FIG. 7 during this period is performed, step since the slow increase pressure circuit number N _Z is maintained at the final value N _Z = 10 in the previous slow increase mode S4
7 directly proceeds to step S49, and the state in which the limitation of the estimated wheel cylinder pressure upper limit value _PMAX is released is maintained.

Thereafter, the mode is shifted to the holding mode at time t ₂₇ , and then at time t _{28 the} mode is shifted to the gradual pressure increasing mode because the brake control state flag AS is set to “1” in the pressure reducing mode.

In the gradual pressure increase mode, step S87a
Since the previous time is the hold mode, it is determined that the initial state of the gradual pressure increase is determined, and the process proceeds to step S87b, where the number of gradual pressure increase _NZ is cleared to "0", and the preset down count is performed in the pressure decrease mode. the value T _Z is cleared to "0", step S87c, S88, S90 and S91
Then, control goes to the step S92.

At this time, as described above, in the estimated wheel cylinder pressure calculation process of FIG. 6, when the number of times of gradual pressure increase _NZ exceeds a predetermined value N _S (= 8), the estimated wheel cylinder pressure upper limit value is increased. P _MAX restriction is released, by which the state is maintained, since the reduced pressure immediately before the estimated wheel cylinder pressure PG _Ii is increased according to the increase of the actual wheel cylinder pressure P _Ri, the total pressure reduction amount ΔPG _Ti becomes a value close to the actual pressure reduction amount.

As a result, the initial pressure increase amount ΔPZ ^* _0i calculated in step S93 becomes a large value, whereby the actuator 6i is subjected to the initial pressure increase process, so that the pressure of the wheel cylinder 2i is increased as shown in FIG. As shown by the solid line, the wheel cylinder pressure is greatly increased, and the pressure control of the wheel cylinder pressure immediately after the road friction has changed from a low friction coefficient road surface to a high friction coefficient road surface can be accurately performed, and the vehicle deceleration can be reduced. As shown in FIG. 11 (a), the vehicle smoothly shifts to the deceleration corresponding to the road surface with a high friction coefficient without large fluctuation.

[0143] After that, select-high wheel speed V at the time t ₂₉
By w _H is equal to or less than the predetermined value -D _S, the process proceeds to step S24 through step S23 from step S22 at a wheel speed calculation processing of FIG. 5, vehicle velocity gradient V _XK corresponding to the new high friction coefficient road surface Is calculated, which is shown in FIG.
It increases as shown in (d).

Subsequently, the estimated wheel cylinder pressure calculation processing of FIG. 6 is executed. At this time, since the vehicle speed gradient V _XK has a large value corresponding to the road surface with a high friction coefficient, it is calculated in step S46. The estimated wheel cylinder pressure upper limit value _PMAX is a value near the maximum values P _FH and P _RH .

When the process proceeds to step S47, since the number of times of gradual pressure increase _NZ is "1" in the previous actuator control process of FIG.
Then, the flow returns to step S8 to return to the state limited by the estimated wheel cylinder pressure upper limit value _PMAX .

[0146] Then, by continuing the gradual increase of pressure state, and the wheel speed Vw _i is restored, and the transition to a holding mode,
Thereafter, the pressure-reducing mode, the holding mode, and the gentle pressure-increasing mode are sequentially repeated to perform good antilock brake control on a road surface with a high friction coefficient.

[0147] Then, or become the brake switch 14 is turned off, by the wheel speed Vw _i is reduced to a speed in the vicinity of stop, to satisfy the control termination condition, step S7 from step S71 in the actuator control process in FIG. 8
2, the brake control state flag AS is reset to "0", and then, to step S73, the actuator 6i is controlled to a sudden pressure increase state, and returns to the initial non-braking state.

[0148] Incidentally, when the slow increase pressure circuit number N _Z reaches a predetermined value N _S, if not remove the restriction by the upper limit value P _MAX, as shown in FIG. 12, the vehicle velocity gradient V _XK Figure 12
(D), the so maintain the state of the low friction coefficient road surface, the low friction coefficient road surface as estimated wheel cylinder pressure P _i at start of evacuation of a chain line shown in FIG. 12 (c) of the time t ₂₆ Maintain the restricted state in.

[0149] Therefore, when the actuator control process in FIG. 8 is executed, vacuum just before the estimated wheel cylinder pressure PG _Ii becomes smaller than that in the case of FIG. 11, the result gradual pressure increase processing when t ₂₈ When executed, the total pressure reduction amount ΔPG _Ti calculated in step S92 of FIG. 8 becomes a value smaller than the actual total pressure reduction amount, and the initial pressure increase amount ΔPZ ^* _i similarly calculated in step S93 becomes a small value. As a result, the wheel cylinder pressure P _Ri in the initial state of the wheel cylinder 2i becomes a small value, causing insufficient pressure increase, and the deceleration of the vehicle fluctuates as shown in FIG. There is a problem of giving an occupant a sense of incompatibility.

On the other hand, when the vehicle is traveling on a rough road having a large unevenness, an unpaved road, an off-road road or the like from a state where the vehicle is traveling on a flat good road, the estimated wheel cylinder pressure calculation processing of FIG. When executed, the road is determined to be a bad road in step S45, and the process directly proceeds from step S45 to step S49 to release the restriction state by the estimated wheel cylinder pressure upper limit value _PMAX .

As described above, when the vehicle is running on a rough road
The estimated wheel cylinder pressure upper limit P _MAXLimited by
When the condition is released, the estimated wheel series is
Ensures over-decompression due to limited pressure
Can be prevented.

That is, when the vehicle is traveling on a rough road, the actual road surface friction coefficient is about 0.4 to 0.6, and the vehicle body speed gradient V _XK corresponding to the vehicle body deceleration changes in the vicinity thereof. In some cases, the wheel cylinder pressure upper limit value P _MAX is set to a small value. In this case, the estimated wheel cylinder pressure _Pi is limited to the set small value upper limit value P _MAX and becomes smaller than the actual wheel cylinder pressure. .

As described above, the estimated wheel cylinder pressure P _i
Is limited to a small value, the present embodiment uses a model of the pressure increasing / decreasing characteristic of the actuator in determining the valve driving time of the actuator 6i, so that the pressure tends to be excessively reduced and the braking force becomes insufficient. but by releasing the restriction by the upper limit value P _MAX at rough road running, it is possible to eliminate the above disadvantages.

In the first embodiment, the case where the set value N _S for judging the number of times of gradual pressure increase N _Z is set to “8” is described. However, the present invention is not limited to this. the value N _S can be arbitrarily changed in accordance with the specifications of the vehicle, similarly Yuruzo pressure circuit number N _Z is "10" returns the antilock brake control state release to rapid pressure increase mode when reaching the However, this value can be arbitrarily changed according to the specifications of the vehicle.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, instead of determining whether or not to release the restriction based on whether or not the number of gentle pressure increase _NZ in the first embodiment reaches a predetermined value, the number of gentle pressure increase N _The estimated wheel cylinder pressure upper limit value _PMAX is changed according to _Z.

In the second embodiment, as shown in FIG.
In addition, the estimation wheel of FIG.
Step S47 is omitted in the cylinder pressure calculation process.
Instead of this, after step S46, the number of gradual pressure increase
N_ZIs a predetermined value N_T(Eg N _T= 6) or specified
Value N_TLess than or even a predetermined value N_TIs over
Step S47a for determining
The determination result of S47a indicates that the number of times of the gradual pressure increase is N_ZIs a predetermined value N_TLess than
If so, the process directly proceeds to step S48.
The following formula (17) is used to calculate the estimated wheel cylinder pressure.
P_iSet (n).

P _i (n) = min ｛P _i (n), P _MAX (n)｝ (17) Also, the result of the determination in step S47a shows that the number of gentle pressure increases N _Z is equal to a predetermined value _NT . If they match, the process shifts to step S47b, and as shown in the following equation (18), step S4
6. The current estimated wheel cylinder pressure upper limit value P calculated in 6.
_MAX (n) to a preset set pressure P _S (e.g. 30kg / c
The value obtained by adding m ² ) is calculated as the correction upper limit PA _MAX (n).

PA _MAX (n) = P _MAX (n) + P _S (18) Then, the flow shifts to step S47c, where step S47c is performed.
The correction upper limit value PA _MAX (n) calculated in 47b is set as the current estimated wheel cylinder pressure upper limit value P _MAX (n), and this is updated and stored in a predetermined storage area of the storage device 20c, and then the process proceeds to step S48. I do.

[0159] Further, when the determination result is gradual increase pressure circuit number N _Z of the step S47a is one that exceeds the predetermined value N _T, the process proceeds to step S47d, the following (19)
As shown in the equation, the previous estimated wheel cylinder pressure upper limit value P _MAX stored in the predetermined storage area of the storage device 20c.
The value obtained by adding the set pressure P _S to (n-1) is the correction upper limit PA
Calculate as _MAX (n).

PA _MAX (n) = P _MAX (n-1) + P _S (19) Then, the flow shifts to step S47e, where the estimation calculated in step S46 is performed as shown in the following equation (19). The wheel cylinder pressure upper limit value P _MAX (n) is compared with the correction upper limit value PA _MAX (n) calculated in step S47d, and the larger one is set as the current estimated wheel cylinder pressure upper limit value P _MAX (n). This is updated and stored in a predetermined storage area of the storage device 20c, and the process proceeds to the step S48.

P _MAX (n) = max ｛P _MAX (n), PA _MAX (n)｝ (19) In the processing of FIG. 13, steps S 41 to S 41
44 and the processing of steps S50 to S52 correspond to the braking cylinder pressure estimating means, and the processing of steps S46 to S48 correspond to the vehicle body speed gradient restricting means.
The processing of 47a to S47e corresponds to the upper limit correction means, and the processing of step S45 corresponds to the upper limit setting canceling means.

According to the second embodiment, as described above, when the running state is changed from the low friction coefficient road surface to the high friction coefficient road surface, as shown in FIG. 8 in the first embodiment. When the slow pressure increase mode is continued in the actuator control process, the number of times of slow pressure increase _NZ is equal to the set value _NT.
(E.g. "6") to the time point t ₃₁ is less than in the first embodiment, and also step from step S46 S described above
The process directly proceeds to step S48 via the controller 47a, and the estimated wheel cylinder pressure upper limit P calculated in step S46.
_MAX (n) is executed to calculate the estimated wheel cylinder pressure according to the traveling state of the road surface with a low friction coefficient.

However, the slow pressure increase mode is continued.
Time t₃₂With gentle pressure increase N_ZIs the set value N_TWhen it reaches
Next, the estimated wheel cylinder pressure calculation processing of FIG. 13 is executed.
Time t₃₃Then, steps S47a to S4
7b, and the low friction engagement calculated in step S46.
Vehicle speed gradient V representing several road driving conditions_XKHoi based on
Cylinder pressure upper limit P_MAX(n) (Vehicle speed gradient V_XKBut
Since the value does not change as shown in FIG. 14 (d), the previous value is maintained.
To the set pressure P_SAnd the correction upper limit PA _MAX(n)
And calculate this as the upper limit of the estimated wheel cylinder pressure this time.
P_MAX(n) gives the estimated wheel cylinder pressure
Upper limit value P_MAX(n) is a dashed line in FIG.
Thus, the previous estimated wheel cylinder pressure upper limit value P_MAX(n-
Set pressure P compared to 1)_SIncrease by minutes and estimate accordingly
Wheel cylinder pressure P_i(n) also increases.

[0164] Then, the slow increase of voltage dividing number N _Z at time t ₃₄ exceeds the set value N _T, the estimated wheel time t ₃₅ to the cylinder pressure calculating process is performed in FIG. 13 to the next, step S4
7a, the process proceeds to step S47d, and the storage device 20c
By setting the value obtained by adding the set pressure P _S in the last time is stored in a predetermined storage area estimated wheel cylinder pressure upper limit value P _MAX (n) as the present estimated wheel cylinder pressure upper limit value P _MAX (n) , Estimated wheel cylinder pressure upper limit value P
_MAX (n) increases by the set pressure P _S , and the estimated wheel cylinder pressure P _i (n) increases accordingly.

Thereafter, each time the number of times of gradual pressure increase _NZ increases,
By estimating the wheel cylinder pressure upper limit value P _{MA X} (n) also increases, estimated wheel cylinder pressure P _i (n) also becomes to increase, as in the first embodiment described above, the road surface friction coefficient When the state is changed from a low state to a high state, the estimated wheel cylinder pressure P _i (n) is reliably prevented from continuing to be low, and the initial pressure increase in the first gentle pressure increase mode on the road surface with a high friction coefficient is performed. By setting the amount to a large value, an appropriate initial pressure increase amount can be secured, and good antilock brake control can be continued without fluctuation of the vehicle body deceleration.

In the second embodiment, the case where the set value _NT for judging the number of times of gradual pressure increase N _Z is set to “6” is described. However, the present invention is not limited to this. The value _NT can be set arbitrarily according to the specifications of the vehicle.

In the first and second embodiments, wheel speed filters 18FL to 18R are connected to the output sides of the wheel speed calculation circuits 15FL to 15R, and the vehicle speed gradient V _XK is determined based on these filter outputs. And estimated vehicle speed V
_Although the case of calculating _X has been described, the present invention is not limited to this, and the wheel speed filters 18FL to 18R are omitted, and the wheel speeds are calculated based on the wheel speeds Vw _{FL to} Vw _R output from the wheel speed calculation circuits 15FL to 15R. Body speed gradient V _XK
And may be calculated the estimated vehicle speed V _X, Further, for example, JP-place if the vehicle velocity gradient V _XK and estimated vehicle speed V _X is determined by the arithmetic processing 61-28
As described in Japanese Patent No. 5163, an electronic circuit such as a sample-and-hold circuit, a differentiation circuit, a subtraction circuit, a division circuit, a slope generation circuit, and a multiplication circuit may be combined.

Furthermore, in the first and second embodiments, the front-wheel and rear-wheel master cylinder pressures output from the master cylinder 5 are used as pressure sensors 13F, 13R.
However, the present invention is not limited to this, and the pressure sensors 13F and 13R may be omitted to estimate the master cylinder pressure from the vehicle deceleration at the start of braking. Can reduce the cost by omitting the pressure sensor.

Furthermore, in the first and second embodiments, the wheel speed on the rear wheel side is measured by the common wheel speed sensor 3.
The description has been given of the three-channel anti-skid control device configured to detect with the R. However, the present invention is not limited to this, and wheel speed sensors are separately provided for the left and right wheels on the rear wheel side. It is needless to say that the present invention can be applied to a so-called 4-channel anti-skid control device provided with the above actuator.

In the first and second embodiments, the microcomputer CR is used as the controller CR.
Although the case where 0 is applied has been described, the present invention is not limited to this, and electronic circuits such as a comparison circuit, an arithmetic circuit, a logic circuit, and a function generator can be combined.

Further, in the first and second embodiments, the case where the present invention is applied to a rear wheel drive vehicle has been described. However, the present invention is not limited to this, but is also applicable to a front wheel drive vehicle and a four wheel drive vehicle. be able to.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an antilock brake control device according to the present invention.
It is a block diagram showing an embodiment.

FIG. 2 is a configuration diagram illustrating an example of an actuator that can be applied to the antilock brake control device of FIG. 1;

FIG. 3 is a block diagram illustrating an example of a wheel speed filter applicable to the actuator control device of FIG. 1;

FIG. 4 is a flowchart illustrating an example of an anti-lock brake control process executed by the anti-skid control device illustrated in FIG. 1;

FIG. 5 is a flowchart showing a subroutine process of a vehicle speed calculation process of FIG. 4;

FIG. 6 is a flowchart showing a subroutine process of an estimated wheel cylinder pressure calculation process of FIG. 4;

FIG. 7 is a flowchart showing a subroutine process of a target pressure increase / decrease amount calculation process of FIG. 4;

FIG. 8 is a flowchart showing a subroutine process of the actuator control process of FIG. 4;

9 is an explanatory diagram showing a control map showing a relationship between a vehicle body speed gradient and an upper limit value when calculating an estimated wheel cylinder pressure upper limit value on the rear wheel side in FIG. 6;

FIG. 10 is a time chart for explaining an operation in the first embodiment;

FIG. 11 is a time chart for explaining an operation when a road surface friction coefficient changes from a low state to a high state.

FIG. 12 is a time chart for explaining a conventional example in which a road surface friction coefficient changes from a low state to a high state.

FIG. 13 is a flowchart illustrating a subroutine process of an estimated wheel cylinder pressure calculation process according to the second embodiment of the present invention.

FIG. 14 is a time chart for explaining an operation when a road surface friction coefficient changes from a low state to a high state in the second embodiment.

[Explanation of symbols]

 1FL-1RR Wheel 2FL-2RR Wheel cylinder 3FL-3R Wheel speed sensor 4 Brake pedal 5 Master cylinder 6FL-6R Actuator CR controller 13F, 13R Pressure sensor 18FL-18R Wheel speed filter 19 Bad road detection circuit 20 Microcomputer

Claims (6)

[Claims] 1. An actuator for controlling a fluid pressure of a brake cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder, and a wheel speed detecting means for detecting a wheel speed of the wheel to be controlled. A vehicle speed gradient calculating means for calculating a vehicle speed gradient based on at least a wheel speed detection value of the wheel speed detecting device, and a vehicle speed estimation for estimating a vehicle speed based on the wheel speed detected value of the wheel speed detecting device Means, a master cylinder pressure detecting means for estimating or detecting the master cylinder pressure, and a brake for estimating the pressure of the braking cylinder based on the master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. A cylinder pressure detecting means, and an upper limit value of the braking cylinder pressure detected by the braking cylinder pressure detecting means. An anti-lock brake control device comprising: a braking cylinder pressure upper limit value setting unit that sets based on a gradient. The braking cylinder pressure upper limit value setting unit stores the number of pressure increase signals during one braking cycle. Pressure count storage means;
An anti-lock brake control device comprising: an upper limit value correcting unit that corrects the upper limit value of the braking cylinder pressure according to the pressure increase number storage value of the pressure increase number storage unit. 2. The apparatus according to claim 1, wherein said upper limit value correcting means cancels the setting of the upper limit value of the braking cylinder pressure when the pressure increase number storage value exceeds a predetermined value. Item 2. An anti-lock brake control device according to item 1. 3. The apparatus according to claim 1, wherein said upper limit value changing means corrects an upper limit value of said braking cylinder pressure by adding a predetermined value to the upper limit value of said braking cylinder pressure in accordance with said pressure increase number storage value. The anti-lock brake control device according to item 1. 4. The apparatus according to claim 1, wherein the upper limit value changing means corrects the upper limit value by changing an operation coefficient for calculating an upper limit value of the braking cylinder pressure in accordance with the pressure increase number storage value. Item 2. An anti-lock brake control device according to item 1. 5. An actuator for controlling a fluid pressure of a braking cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder, and a wheel speed detecting means for detecting a wheel speed of the wheel to be controlled. A vehicle speed gradient calculating means for calculating a vehicle speed gradient based on at least a wheel speed detection value of the wheel speed detecting device, and a vehicle speed estimation for estimating a vehicle speed based on the wheel speed detected value of the wheel speed detecting device Means, a master cylinder pressure detecting means for estimating or detecting the master cylinder pressure, and a brake for estimating the pressure of the braking cylinder based on the master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. A cylinder pressure detecting means, and an upper limit value of the braking cylinder pressure detected by the braking cylinder pressure detecting means. An anti-lock brake control device comprising: a braking cylinder pressure upper limit value setting unit that sets based on a gradient; wherein the braking cylinder pressure upper limit value setting unit determines whether or not the vehicle is traveling on a rough road. Road determining means, and upper limit setting releasing means for releasing the setting of the upper limit value of the brake cylinder pressure when the rough road determining means determines that the vehicle is traveling on a rough road. Anti-lock brake control device. 6. An actuator for controlling a fluid pressure of a brake cylinder disposed on a wheel to be controlled based on a master cylinder pressure from a master cylinder, and wheel speed detecting means for detecting a wheel speed of the wheel to be controlled. A vehicle speed gradient calculating means for calculating a vehicle speed gradient based on at least a wheel speed detection value of the wheel speed detecting device, and a vehicle speed estimation for estimating a vehicle speed based on the wheel speed detected value of the wheel speed detecting device Means, a master cylinder pressure detecting means for estimating or detecting the master cylinder pressure, and a brake for estimating the pressure of the braking cylinder based on the master cylinder pressure of the master cylinder pressure detecting means and a control signal for the actuator. A cylinder pressure detecting means, and an upper limit value of the braking cylinder pressure detected by the braking cylinder pressure detecting means. An anti-lock brake control device comprising: a braking cylinder pressure upper limit value setting unit that sets based on a gradient. The braking cylinder pressure upper limit value setting unit stores the number of pressure increase signals during one braking cycle. Pressure count storage means;
Upper limit value correction means for correcting the upper limit value of the braking cylinder pressure according to the pressure increase number storage value of the pressure increase number storage means, and rough road determination means for determining whether or not the vehicle is traveling on a rough road. Anti-lock brake control, comprising: an upper limit setting canceling means for canceling the setting of the upper limit value of the braking cylinder pressure when the rough road judging means judges that the vehicle is traveling on a rough road. apparatus.