JP2775849B2 - Simulated vehicle speed generator for anti-skid control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an anti-skid control that controls the hydraulic pressure of a brake cylinder disposed on each wheel during braking to prevent the wheels from locking. It relates to improvement of the device.

[Conventional technology]

As a conventional pseudo vehicle speed generating device of the anti-skid control device, there is a device described in Japanese Patent Publication No. 41-17082, for example.

In this conventional example, since the highest wheel speed among the respective wheel speeds is closest to the vehicle speed, this select high wheel speed is selected as the pseudo vehicle speed. Even if this select high wheel speed is selected, since the wheel deceleration is large during rapid deceleration, the pseudo vehicle speed is actually too small than the actual vehicle speed. The set straight line is used as the pseudo vehicle speed.

[Problems to be solved by the invention]

However, in the above-described conventional anti-skid control device, when one wheel undergoes wheel spin during acceleration of the vehicle, the wheel speed is selected as the pseudo vehicle speed, so that the value of the pseudo vehicle speed becomes too high. In contrast to this, when determining the wheel lock to be performed, it is determined that the locked state is determined even though the other wheels are not actually locked, and unnecessary anti-skid control for setting the brake device of the other wheel to a reduced pressure state is performed. There were unresolved issues. Especially on rainy roads, snowy roads,
When traveling on a road surface with a low friction coefficient such as an icy road, wheel spin during acceleration is likely to occur, and malfunction of anti-skid control is likely to occur.

In order to solve this unsolved problem, it is conceivable to calculate a pseudo vehicle speed based on wheel speed detection values of non-driving wheels that do not cause wheel spin, but in this case, at the time of braking just below the lock hydraulic pressure, However, when the wheel speed detection value of the non-driving wheel gradually decelerates, the pseudo vehicle speed also decreases at the same time as the wheel speed value of the non-driving wheel. There is a new problem that cannot be performed.

In view of the above, the present invention has been made by focusing on the problems of the above-described conventional example, and it is intended to prevent the pseudo vehicle speed from being affected by the wheel spin of the drive wheels and to reduce the pseudo vehicle speed during the anti-skid control. It is an object of the present invention to provide a pseudo vehicle speed generating device of an anti-skid control device that can accurately correspond to the vehicle speed.

[Means for solving the problem]

To achieve the above object, the present invention provides a first wheel speed detecting means for detecting a wheel speed of a non-driving wheel of a vehicle, and a second wheel speed detecting means for detecting a wheel speed of a driving wheel of the vehicle. ,
A simulated vehicle speed generator for calculating a simulated vehicle speed that decelerates at a rate of change with respect to a predetermined time as a reference and a simulated vehicle speed detected by the first wheel speed detection means; A braking pressure control means for controlling a fluid pressure of a braking cylinder disposed on each wheel based on the wheel speed detection value of the means. And comparing the wheel speed detection value of the wheel speed detection means and the pseudo vehicle speed of the pseudo vehicle speed generator with a small first rate of change when the pseudo vehicle speed is intermediate between the two wheel speed detection values. A gradient setting means for setting a second rate of change larger than the first rate of change when the wheel speed is larger than the detected wheel speed is provided.

[Action]

According to the present invention, during non-braking, the pseudo vehicle speed is generated by the pseudo vehicle speed generator based on the wheel speed detection value of the non-driving wheel of the first wheel speed detecting means, so that the vehicle is accelerated during acceleration.
A pseudo vehicle speed that is not affected by the wheel spin of the drive wheels generated when traveling on a low friction coefficient road surface such as a rainy road, a snowy road, or a frozen road can be generated. The pseudo vehicle speed is compared with the wheel speed detection values of the speed detection means and the second wheel speed detection means, and the pseudo vehicle speed is an intermediate value between the wheel speed detection value of the non-drive wheel and the wheel speed detection of the drive wheel. In some cases, the pseudo vehicle speed is decelerated with a relatively small deceleration gradient of a first rate of change, and when the pseudo vehicle speed is larger than both wheel speed detection values, the pseudo vehicle speed is decelerated with a larger deceleration gradient of a second rate of change. Thus, a pseudo vehicle speed corresponding to the actual vehicle speed can be generated.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an overall system diagram showing an anti-skid control device provided with a pseudo vehicle speed generating device of the present invention, in which 1 is a right front wheel, 1a is its wheel cylinder, 2 is a left front wheel, 2a is its wheel cylinder, Reference numeral 3 denotes a right rear wheel, 3a denotes its wheel cylinder, 4 denotes a left rear wheel, and 4a denotes its wheel cylinder. Further, 5 is an engine, 6 is a transmission, 7 is a propeller shaft, 8 is a differential gear, and 9 and 10 are rear axles, respectively, which drive rear two wheels 3 and 4 to run the vehicle.

The brake system is one of the two-system master cylinder 11
11a is connected to the right front wheel cylinder 1a by a conduit 12, and the left front wheel cylinder 2a is connected by a conduit 13.The other system 11b is connected to the right rear wheel cylinder 3a by a conduit 14. The so-called front-rear split type hydraulic brake device connected to the left rear wheel cylinder 4a by 14,15. This brake device is a brake pedal 16
2 systems of master cylinder 11 generated by stepping on
The vehicle can be decelerated by being actuated by the master cylinder hydraulic pressure output from a and 11b.

A total of three anti-skid control means are provided for the right front wheel 1, the left front wheel 2, and the two rear wheels 3, 4, which are provided with conduits 12, 13,
Actuators 17a, 17b, 17c respectively inserted in 14
And an anti-skid control circuit 18 for controlling the operation thereof.

Since the actuators 17a, 17b, and 17c are the same, the corresponding portions are indicated by the same reference numerals with different suffixes ab and c, and only the right front wheel actuator 17a will be described in detail below. Actuator 17a has an inflow valve (E
A V valve 19a, a discharge valve (AV valve) 20a, a pump 21a, an accumulator 22a, and a check valve 23a are connected as shown in the figure. The EV valve 19a and the AV valve 20a are individually controlled by the EV ₁ signal and the AV ₁ signal from the accumulator control circuit 18, and the pump 21a is appropriately driven by a common motor 24 together with the pumps 21b and 21c in the other actuators 17b and 17c. This drive is controlled by the MR signal from the anti-skid control circuit 18. When EV ₁ signal is L level and EV valve 19a is opened, AV ₁ signal is also L level and AV valve 20a is closed and brake fluid pressure to wheel cylinder 1a rises until it becomes the same value as master cylinder fluid pressure. Is done. In this state, EV
_{When the 1} signal changes to the H level and the EV valve 19a is also closed, the brake fluid pressure to the wheel cylinder 1a is held. Next, open the AV valve 20a AV ₁ signal in this state is turned to H level, conducting the transistor 25 by the H level of the MR signal in addition,
When the motor 24 is energized by the power source + E to drive the pump 21a, the brake pressure of the wheel cylinder 1a is returned to the master cylinder 11 and reduced. The above operation is summarized in a table as shown in the following table.

The anti-skid control circuit 18 includes a circuit portion 18a that emits the EV ₁ signal and the AV ₁ signal for the right front wheel actuator 17a based on a signal from a wheel speed sensor 26a that detects the rotation speed of the right front wheel 1, A circuit portion 18b for generating an EV ₂ signal and an AV ₂ signal for the left front wheel actuator 17b based on a signal from a wheel speed sensor 26b for detecting a rotation speed of the front wheel 2
When, after EV ₃ signals and AV ₃ for the average rotational speed at which the propeller rear wheel actuator 17c based on a signal from the wheel speed sensor 26c for detecting the rotational speed of the shaft 7 of the two-wheeled 3,4
A circuit portion 18c for emitting a signal, the pseudo vehicle speed generator 27 of the present invention, the circuit 28a for generating a target wheel speed corresponding to the desired slip rate coefficient of friction becomes maximum between the wheel and the road surface from coming pseudo vehicle speed V _i , 28b, 28c _{and, AV 1, AV 2, AV} 3 signal (H
OR gate 29 which takes the logical sum of the (OR) level and an H level for a predetermined time triggered by the rising of the output of the OR gate.
It comprises a retriggerable timer 30 that issues an MR signal.

Since the circuit portions 18a, 18b, and 18c have the same configuration, the corresponding portions are indicated by the same reference numerals with different suffixes a, b, and c, and only the circuit portion 18a will be described in detail. 31a
In the wheel speed detecting circuit calculates the right front wheel rotational speed (pulse) signal and the peripheral speed of the right front wheel turning radius (wheel speed) Vw ₁ from the wheel speed sensor 26a. The wheel speed Vw ₁ is (negative deceleration) wheel acceleration alpha _w1 is subjected to calculation of the inputted vehicle speed acceleration detecting circuit 32a. The wheel acceleration α _w1 is determined by the comparator 33a,
34a in is compared with the deceleration reference value b ₁ and the acceleration reference value a _1,
The comparator 33a outputs an H level signal when the wheel deceleration α _w1 becomes larger than the reference value b ₁ , and the comparator 34a outputs an H level signal when the wheel acceleration α _w1 becomes larger than the reference value a _1. Is output. The comparator 35a compares the wheel speed V _w1 with a target wheel speed (V _i × 0.85) described later from the target wheel speed generating circuit 28a, and while the wheel speed V _w1 is equal to or lower than the target wheel speed, the comparator 35a
Outputs an H level signal. The OR gate 36a is a comparator 33a ~
A logical sum of the H level signal of 35a is taken to generate an H level signal, and this signal is supplied to the EV valve 19a after being amplified by the amplifier 37a as an EV ₁ signal via the OR gate 40a. AND gate 38a
Takes the logical product of the H level output of the comparator 35a and the L level signal from the comparator 34a to generate an H level AV ₁ signal,
This signal is supplied to the AV valve 20a via the amplifier 39a.

The remaining input of the OR gate 40a is connected to the output of the AND gate 41a. The variable timer 42a, the pulse generator (OSC) 43a for generating a rectangular pulse having a constant frequency, and the retrigger are connected to the three inputs of the AND gate 40a. The signal from the bull timer 30 is supplied. The variable timer 42a is triggered by the fall of the output of the comparator 34a, and the time T ₁ proportional to the peak value αmax of the wheel acceleration α _w1 detected by the peak value detection circuit 44a.
(7 see Figure) delayed is assumed that outputs a constant T ₂ hours H-level signal, the peak value detection value circuit 44a is a comparator 33a
The peak value αmax of the wheel acceleration α _w1 from the fall of the output from the vehicle to the next rise is detected.

As shown in FIG. 1, the pseudo vehicle speed generator 27
A wheel speed selection circuit 45 for selecting V _{w1 to} V _w3 , and a pseudo vehicle speed V based on the selected wheel speed V _ws selected by the wheel speed selection circuit 45
and a pseudo vehicle speed calculation circuit 46 for calculating _i .

Wheel speed selecting circuit 45, as shown in FIG. 3, a wheel V _w1
To V _w3 , a wheel speed filter 47A to 47C for performing a time limit filter process, a select high switch 48 for selecting a larger value of the filter outputs V _f1 and V _f2 of the wheel speed filters 47A and 47B, a filter output V _fR of the select output V _fF wheel speed filter 47C high switch 48 is input and a select switch 49 for selecting these, a select switch 49, through the anti-skid control of the pseudo vehicle speed calculating circuit 46 When the indicated MR signal is at the L level, that is, when the anti-skid control is not performed, the select output _VfF of the non-driving wheel is selected. When the MR signal is at the H level, that is, during the anti-skid control, the non-driving wheel is selected. of selecting one larger value of the filter output V _fR of the select output V _fF and the drive wheels, and outputs them to the pseudo vehicle speed computing circuit 46 as a selector wheel speed V _ws.

Here, each of the wheel speed filters 47A to 47C is
As shown, the comparator 47a of the wheel speed V _wi outputted from the wheel speed detection circuit 31a~31c (i = 1,2,3) is inputted, 47b
And an adder 47c and a subtractor 47d that set a dead zone of ± 1 km / h for the filter output V _fi and supply the other inputs to the comparators 47a and 47b.
And a NOR gate 47e to which the output signals C ₁ and C _{2 of} the comparators 47a and 47b are supplied. The comparator 47a outputs the output C ₁ of H level when the _{Vw i ≧ V fi + 1km /} h, the comparator 47b is Vw _i <
When V _fi -1 km / h, an H level output C ₂ is output. Accordingly, NOR gate 47e, the output C _1, C ₂ and outputs an output signal S ₅ of H level when the _{V fi -1km / h ≦ V wi} <V fi + 1km / h which both become L level. The output signal S ₅ of NOR gate 47e is
The signal is input to the off-delay timer 47f, the OR gate 47g, and the shot pulse generation circuit 47h. Off-delay timer 47f
It is started by the fall of the signal from the NOR gate 47e, and outputs an H-level signal by a predetermined time T _3, and supplies it to the OR gate 47 g.

The output of the OR gate 47g is supplied to the gate of the analog switch 47i as a select signal S _3, the AND gate 47k is inverted by an inverter 47j, it is supplied to one input side of 47l. The other input of the AND gate 47k, C ₁ signal, also C ₂ signal is supplied to the other input of the AND gate 47l, select AND gate 47k, the output of 47l signals S _2, S ₄ Are supplied to the gates of the analog switches 47m and 47n. Analog switch 47i is, the select signal S ₃ H
The supply voltage E to the integrator circuit 47o becomes level during the ON state to zero, the analog switch 47m is the select signal S ₂ H
It is turned on during the level, and the maximum value of a possible vehicle acceleration (rate of change in vehicle speed rise), for example, a negative voltage E corresponding to +0.4 g or a negative voltage E corresponding to +10 g is supplied to the integrating circuit 47o, switch 47n becomes the H level during the on state of the select signal S _4, for example, supplies a positive voltage E corresponding to -1.2g to the integration circuit 47o. The above + 0.4g, +10
g is selected by the changeover switch 47p.
p selects +0.4 g while the MR signal from the retrigable timer 30 is at the level, and selects +10 g during anti-skid control in which the MR signal is at the H level.

Integrator circuit 47o is an amplifier 47q, well known consisting capacitor 47r and an analog switch 47s, is reset when the analog switch 47s is turned on by the H level reset signals S ₁ to its gate, the reset signal S ₁
After disappearing, integration of the input voltage E is continued. Reset signal
S ₁ is to obtain by the shot pulse from the shot pulse generating circuit 47h, the shot pulse generating circuit 47h outputs the first one-shot pulse when the engine starts as a reset signals S ₁ by an ignition-on signal IG, then outputs a shot pulse each output signal S ₅ of NOR gate 47e rises as a reset signal S _1.

Reset signals S ₁ is other to the sample-and-hold circuit 47
This circuit is also used to reset the buffer amplifier 47.
u, 47v, and well known consisting capacitor 47w and an analog switch 47x, wheel speed V _wi is input. Sample-and-hold circuit 47t is the H-level reset signals S ₁ is reset when the analog switch 47x is turned on, continues to store the wheel speed V _wi at that time as wheel speed sampling value V _s, which in an adder circuit 47y input. The addition circuit 47y calculates the integration value of the integration circuit 47o. It was added to the wheel speed sampling value V _s, and outputs the addition value V _s + V _e as a filter output V _fi.

As shown in FIG. 2, the pseudo vehicle speed calculation circuit 46 includes a reference gradient determination unit 100, a pseudo vehicle speed calculation unit 200, and a re-pressure increase amount detection unit.
300 and a reference gradient changing unit 400.

In the reference gradient determining unit 100, 141a to 141d indicate sample and hold circuits, respectively, and the circuit 141a is a changeover switch.
The position of the solid line at 50 and the circuit 141b are always at the selected wheel speed V _ws
Is appropriately extracted and held, the circuit 141c extracts and holds the count value of the timer counter 142 that advances at a constant cycle, and the circuit 141d always extracts and holds the count value as appropriate. Appropriate extraction uncle of these sample-and-hold circuits, to perform the C ₂ signal of the pseudo vehicle speed calculating unit 200 and the MR signal from the retriggerable timer 30.

The sample-and-hold circuit 141a uses the retrigable timer 30
An inverted signal through the inverter G ₂ of the MR signals from the
The select wheel speed V _ws is extracted and held in synchronism with the output of the OR gate G ₄ from the H level signal from the AND gate G ₁ which takes the logical product with the C ₂ signal.
_The select wheel speed V _ws is extracted and held in synchronization with the _two signals. Further, the sample-and-hold circuit 141c extracts holds the count value of the timer counter 142 in synchronism with the H level output of the OR gate G _4, sample and hold circuit 141d is in synchronism with the C ₂ signal the count value of the timer counter 142 extracts Hold. 145 subtracting circuit for subtracting the sampled value V _b of the sample hold circuit 141b from the sampled value Vo of the sample and hold circuits 141a, 146 a sample hold circuit sampling values 141d from the sampling value T ₀ of the sample-hold circuit 141c
T _b is a subtraction circuit for subtracting, 147 subtraction value from the subtraction circuit 145 subtracts value from (V ₀ -V _b) a subtraction circuit 146 (T ₀ -
T _b ). 148a is a signal relating to the initial pseudo vehicle speed gradient (rate of change with respect to time), for example, a gradient generation circuit that generates a gradient signal having a positive voltage corresponding to -0.6G, 148b is a signal relating to the initial pseudo vehicle speed gradient,
For example, a slope generating circuit 149 for generating a slope signal having a positive voltage corresponding to -1.2 G, and a slope signal 149 from the slope generation circuits 148a and 148b and a calculation output (V ₀ −V _b ) / ( T
₀ -T _b) and switch the determining reference slope m of the pseudo vehicle speed. This reference gradient m is input to an adding circuit 151 as a pseudo vehicle speed correcting means, and contributes to the calculation of the corrected gradient m '. Further, a limiter 152 limits the correction gradient m 'output from the adding circuit 151 to a predetermined range.

Reference numeral 153 denotes a selection signal forming circuit for forming a selection signal for switching the changeover switch 149. As shown in FIG. 3, an AND gate G ₃ for obtaining a logical product of the C ₂ signal and the MR signal is provided. It is set at the rising edge of the signal from, RS flip-flop that is reset by the falling of the MR signal (hereinafter, simply referred to as FF154) and, from the select-high switch 48 of the wheel speed selecting circuit 45 and the pseudo vehicle speed V _i to be described later compares the select output V _fF output, a comparator 155 for outputting the comparison output of the H level when V _i> V _fF, the filter output V _f3 outputted as the pseudo vehicle speed V _i from the wheel speed filter 47C comparing, a comparator 156 for outputting the comparison output of the H level when V _i> V _f3, compares the pseudo vehicle speed V _i and the select output V _fF and filter output _{V f3, V f3 ≧ V i} > V fF Win output H level comparison output when Comparator 15
7, an AND gate 158 for calculating the logical product of the comparison outputs of the comparators 155 and 156, and the output of the AND gate 158 and the FF
An AND gate 160 that takes the logical product of the output of 154 and an inverted output obtained by inverting the output of the inverter 159, and a window comparator 157
A comparator output of the AND gate 161 for taking a logical product of the inverted output of the inverter 159, the selection signal SL ₁ and SL ₂ is output from the AND gate 160 and 161.

The changeover switch 149 is connected to the selection signal forming circuit 1.
When the selection signals SL ₁ and SL ₂ from 53 are both at L level, the division calculation power of the division circuit 147 is selected, and when the selection signal SL ₁ is at H level, the inclination signal of the inclination generation circuit 148b is selected. When the selection signal SL ₂ is at the H level, the slope generation circuit 1
The slope signal 48a is selected, and these are output to the addition circuit 151 as the reference slope m.

The simulated vehicle speed calculation unit 200 determines _whether the selected wheel speed V _ws of the wheel speed selection circuit 45 is the comparator 60a, 60b and the sample hold circuit 60.
t, and the limiter is connected to the analog switch 60n.
The correction gradient m output from 152 is supplied to the adder 60y.
Has a structure similar to that of the wheel speed filter 47A~47C described above except that the pseudo vehicle speed V _i is output to the target wheel speed generating circuit 28a~28c from the corresponding parts of Figure 4 reference numeral 47 Is replaced by reference numeral 60, and a detailed description thereof is omitted.

The re-pressure increase amount detecting section 300 is constituted by pressure increase counters 90a, 90b, 90c as re-pressure increase amount detection means. The booster counter 90a includes a circuit 91 that generates a shot pulse at the instant when the output of the comparator 34a falls, and an output of the OR gate 40a, that is, E.
A level converter 92 for level adjustment of the V ₁ signal, and more become the integrating circuit 92 for integrating the reset level converter output by the shot pulse, the EV ₁ signal in each skid cycle, as shown in FIG. 5 The number of disappearing pulses is integrated to determine the amount of pressure increase of the right front wheel. Similarly, the pressure increase counters 90b and 90c respectively obtain the re-pressure increase amount of the left front wheel and the re-pressure increase amount of the two rear wheels.

The signals relating to the re-pressure increase amounts of these three systems are added to an adder circuit 151.
Is added to the analog switch 60n as a correction gradient m '. At this time, the upper limit and the lower limit of the correction gradient m' are respectively set by the limiter 152. Limited to -1.2G and -0.1G.

Any one of the outputs of the pressure intensifier counters 90a to 90c is input to a comparator 94, which is a part of the reference gradient change unit 400, and in which the re-intensification amount of one system is high friction road. The H level signal is supplied to the shot pulse generation circuit 95 for a time equal to or more than the set value representing The shot pulse generation circuit 95 generates a shot pulse at the moment when the output of the comparator 94 falls and outputs a shot pulse to the AND gate 96.
To supply. The output of the comparator 97 is supplied to the other input of the AND gate 96, and this comparator outputs an H level signal when the absolute value | m | The remaining one input of the AND gate 96 is supplied with a signal from a lock time determination circuit 99 for determining the lock time of the wheel, and this circuit rises the output of the comparator 35a (which may be the comparator 35b or 35c). A circuit 105 for generating an hour shot pulse, a NOT gate 101 for inverting the output of the comparator 35a, and an integration for resetting by the shot pulse from the circuit 105 and integrating the inverted output from the NOT gate 101 as shown in FIG. A circuit 102;
A comparator 103 that outputs an H level signal while the integrated value is equal to or higher than a set value indicating a high friction road;
It comprises a NOT gate 104 for supplying to the ND gate 96.

AND gate 96 outputs a H level signal by a logical product of the three inputs, along with switching the changeover switch 50 and 51 the dotted line position, the sample and hold circuit 141a, 1 through the OR gate G ₄
By supplying an H level signal to 41c, the sample and hold values V ₀ and T ₀ of these circuits are changed to V _b and T _b , respectively, to change the reference gradient m.

 Next, the operation of the above embodiment will be described.

First, the anti-skid control operation of the entire system shown in FIG. However, in the following description, the wheel speed V _w1 of the front right wheel 1, the pseudo vehicle speed V _i which is asked as described below, the wheels and a target wheel for road surface friction coefficient to obtain a desired slip ratio of 15% of the wheel having the maximum Speed V _i × 0.
85, and the wheel acceleration α _w1 is as shown in FIG. 7 (V _c is the actual vehicle speed shown for reference).

In the depression of the brake pedal 16 (see FIG. 1), the brake fluid pressure P _w from Figure 7 in time t ₀ is generated, initially the braking wheel speed V _w1 is lowered as the FIG. 7, the wheel deceleration α _w1 is smaller than the reference value b _1, the output of the comparator 33a is L level,
Of course, since α _w1 <a ₁ , the output of the comparator 34a is also at the L level, and since the wheel speed V _w1 is not less than the target wheel speed V _i × 0.85 without causing wheel lock, the output of the comparator 35a is also at the L level. Level. Therefore, the output of the OR gate 36a is at L level and A
The output of the ND gate 38a (AV ₁ signal) is also at L level, AV ₁
The output of the OR gate 29 for ORing the signals ～AV ₃ signal keeps the MR signal from a retriggerable timer 30 maintains the L level to the L level, OR gate A output of AND gate 41a is also at the L level the output of 40a (EV ₁ signal) is also at the L level. EV
L-level ₁ signal opens the EV valve 19, the L level of the AV ₁ signal
Close the AV valve 20a, therefore the brake fluid pressure P _w to this period the wheel cylinder 1a is increased toward the pressure reduction from the master cylinder 11, normal braking can be obtained.

During the braking, when the wheel deceleration alpha _W1 exceeds the reference value b ₁
t ₁ ~t ₂ between the, t ₁ comparators 33a between '~t _2' outputs the H level, the time t ₃ when the wheel acceleration alpha _w1 exceeds the reference value a ₁
~t between _4, t ₃ 'comparator 34a outputs the H level in the subsequent, time t ₂ to the wheel speed V _w1 is less than the target wheel speed V _i × 0.85
~t between _6, comparators 35a between the t ₅ '~t _6' outputs the H level. Accordingly, EV ₁ signal H in the period from the time point t ₁ ~t ₄
Level, and to close the EV valve 19a, AV ₁ signal during this period time t ₂
Opening the AV valve 20a becomes H level during the ~t _3. This because, the brake fluid pressure P _w is at time t ₁ ~t _2, is held, as well as the road surface friction coefficient can be determined by keeping the braking force constant, eliminating this in increase of more brake fluid pressure The anti-skid control is not delayed.

Then, the closed state holding the EV valve 19a at the time point t ₂ when the wheel speed V _wi is less than the target wheel speed V _i × 0.85, the opening of the AV valve 20a, also
AV rises MR signal from a retriggerable timer 30 in ₁ signal rise of, by driving the pump 21a in energizing the motor 24, reducing the pressure of the brake fluid pressure P _w. Thus, wheel 1
Locking is prevented. The retriggerable timer 30
Is triggered for each rise of the AV ₁ ~AV ₃ signals, but as it emits MR signals of a predetermined time H level, the time t ₂ subsequent MR signals by re-trigger within the predetermined time in FIG. 7 to H level I keep it.

By AV valve 20a is closed at the time t ₃ when the wheel acceleration alpha _w1 by the above vacuum reaches the reference value a _1, switched to hold the brake fluid pressure P _w I closed state held coupled with the EV valve 19a,
This makes it possible to determine the degree of change in the road surface friction coefficient, and to prevent delay in canceling the anti-skid control for increasing the brake fluid pressure again when the brake fluid pressure further decreases.

During the holding of such a brake fluid pressure, while the wheel speed V _w1 by recovery of the road friction force is increased toward the vehicle speed corresponding value, the vehicle speed value corresponding wheel speed at the time t ₄ when the wheel acceleration alpha _w1 is equal to or less than the reference value a ₁ Therefore, the brake fluid pressure _Pw is increased again as follows. In other words, at the time t _4,
Comparator 33a, 34a, by the output of 35a are all L level, AV ₁ signal is maintained at L level, EV ₁ signal is determined to level by the signal from the AND gate 41a. Variable timer 42a connected to the input of the AND gate 41a, the time corresponding to the peak value αmax of the wheel acceleration alpha _w1 detected by circuit 44a T
₁ only later than time point t ₄ emits output of H level during the predetermined time T _2, also the pulse generator 43a is emitted rectangular pulses of constant frequency as shown in Figure 7. The AND gate 41a takes the logical product of these signals and the MR signal (during H level),
Maintaining the _first signal from time t ₄ to period T ₁ in the L level, then T ₂
During the time, the level is changed at the same cycle as the pulse signal from the pulse generator 43a. Therefore, T ₁ hour brake fluid pressure
Lock P _w is pressurized surge toward the master cylinder pressure, T ₂ hours in the brake fluid pressure P _w becomes be pressurized Yuruzo, corresponding to the desired slip rate maximum brake efficiency is obtained a brake fluid pressure P _w can be maintained for a long time in the vicinity of the hydraulic pressure P _L, it can shorten the braking distance.

Thereafter, the time t ₁ ′ at which the wheel deceleration α _w1 exceeds the reference value b ₁
Then, the operation proceeds to the next skid cycle, and by repeating the same operation as described above, the brake fluid pressure of the right front wheel 1 is controlled so as to maintain the ideal slip ratio, and the anti-skid such that the braking distance becomes as short as possible. Control is executed.

The left front wheel 2 and the two rear wheels 3, 4 are also similarly anti-skid controlled by the same operation as described above based on the corresponding wheel speeds _Vw2 , _Vw3 .

 Next, the operation of the wheel speed selection circuit 45 will be described.

First, when the operation of the wheel speed filters 47a to 47c, when t ₀ shown in FIG. 8, when the ignition switch to the ON state, the wheel speed filter the on signal IG
47A to 47C are input to shot pulse generation circuits 47h.
Therefore, the output-shot pulse S ₁ as shown in Figure 8 from shot pulse generating circuit 47h (g), which is supplied as a sampling pulse to the sample-and-hold circuit 47 t, the output from the wheel speed detection circuit 31a~31c this time Zero wheel speeds V _{w1 to} V _w3 are wheel speed sampling values
To hold as V _s. Further, shot pulse S ₁ is the integration circuit
It is also supplied to 47o, this integration circuit 47o is reset,
Since the integrated output V _e becomes zero, the filter output V _f1 ~V _f3 also zero output from the addition circuit 47y. in this way,
Since the filter output V _f1 ~V _f3 and the wheel speed V _w1 ~V _w3 is zero equally both outputs C ₁ and C ₂ of the comparators 47a and 47b, as shown in FIG. 8 (b) and (c) L level, NO
From R gate 47e Figure 8 (d) the output signal S _s of the H-level as shown in the output, the select signal S ₃ output from the OR gate 47g accordingly be as shown in Figure 8 (e) H Level.

Since the select signal S ₃ is supplied to the analog switch 47i, the analog switch 47i is turned on, the other select signal S ₃ is supplied inverted to the low level by the inverter 47j and the AND gates 47k and 47l, these inhibits the generation of the select signals S ₂ and S _4. At this time, since the input side of the analog switch 47i is grounded, the input voltage E of the integrator 47o becomes as shown in FIG.
And the integral output _Ve is also maintained at zero. As a result, the filter output V _f1 ~V _f3 output from the addition circuit 47y is maintained at the same zero wheel speed V _wi ~V _w3.

Thus, since the filter outputs V _{f1 to} V _f3 are zero,
The selected wheel speed V _ws output from the wheel speed selection circuit 45 is also zero, and is input to the pseudo vehicle speed calculation circuit 46.

In the pseudo vehicle speed calculation circuit 46, the wheel speed filter 15
Just like FL to 15R, by holding the selected wheel speed V _ws (= 0) in the sample and hold circuit 60 _t by the ignition switch ON signal IG, the sampling wheel speed V _s becomes zero, and the integration circuit 60 o since the integrated output V _e is reset becomes zero, the pseudo vehicle speed V _i output from the addition circuit 60y also becomes zero, the pseudo wheel speed V _i of zero
Are input to the target vehicle speed generation circuits 28a to 28c.

Thereafter, when the vehicle is started to be in an acceleration state in which the vehicle keeps going straight, for example, for the right front wheel 1, the wheel speed V _w1 output from the wheel speed detection circuit 31a is shown by a solid line in FIG. 8 (a). as rose, V _w1 at ≧ V _f1 + time t ₁ to be 1km / h, the comparison output C ₁ of the comparator 47a in the wheel speed filter 47A is converted to H level. However, the output of the off-delay timer 47f is until the set time T ₃ from time t ₁ elapses maintains H level is converted to L level at time t ₂ after the set time T ₃ has elapsed. Thus, between time t ₁ to time t _2, the filter output V _f1 is still kept at the same constant value as the previous wheel speed sampling value V _s (= 0), is output at time t ₂ from the OR gate 47g Select signal S
₃ changes to the L level as shown in FIG. 8 (e), and accordingly, the analog switch 47i is turned off, and
When the output of the gate 47k becomes H level, the analog switch 47m is turned on, and a negative voltage corresponding to +0.4 G is supplied as the input voltage E. Thus, increases in the integration output V _e of the integration circuit 47o is corresponding to + 0.4 G speed, summing circuit between this and the wheel speed sampling value V _s 47
The added value by y, that is, the filter output _Vf1 also increases as shown by the dotted line in FIG. 8 (a).

The filter output V _f1 is substantially equal to the wheel speed V _w1 at (V _w1 = V _f1 +1) time t _3, the comparison output C ₁ of the comparator 47a is converted to L level, NOR gate 47e accordingly Output S ₅
Is changed to the H level, the integration circuit 47o is reset, and the sample and hold circuit 47t outputs the wheel speed V at that time.
_w1 is held, and at the same time, the analog switch 47i is turned on instead of the analog switch 47m, and the integrating circuit 4
Integrating the input voltage E of 7o becomes zero, the integrated output V _e is next zero, the filter output V _f1 is held in the sampling wheel speed V _s of the at t _3.

Thereafter, since the vehicle continues to accelerate, the time t ₄
Comparison output C ₁ of the comparator 47a is converted to the H level in the timer 4
The output S of the OR gate 47g at t ₅ the set time T ₃ of 7f has elapsed
₅ is changed to the L level, and the analog switch 47m is turned on again in place of the analog switch 47i.
Increases at a speed corresponding to the integral value of the acceleration filter output V _f1 is corresponding to + 0.4 G, the output C ₁ is L level of the comparator 47a at the time point t ₆ of the filter output V _f1 is substantially equal to the wheel speed V _w1 , The integration circuit 47o is reset, and the sample and hold circuit 47t holds the wheel speed V _w1 at that time. Thereafter, holding the wheel speed V _w1 filter output V _f1 is in the period from the time point t ₆ ~t _7, rises at a speed corresponding to + 0.4 G between time t ₇ ~t _8, between the time point t ₈ ~t ₉ holding the wheel speed V _w1 at time t _8, rises at a speed corresponding to + 0.4 G between time t ₉ ~t _10, the wheel speed V _w1 at time t ₁₀ in the period from the time point t ₁₀ ~t ₁₁ Hold, time t
₁₁ rises at a speed corresponding to + 0.4 G between ~t _12, time t ₁₂ ~t
Holding the wheel speed V _w1 at time t ₁₂ between ₁₃ rises at a speed corresponding to + 0.4 g in the period from the time point t ₁₃ ~t _14, the constant-speed running state when t ₁₄ after the acceleration state is ended , The wheel speed V _w1 at time t ₁₄
Hold.

Then, to release the depression of the accelerator pedal at time t _16,
If the brake pedal 16 is depressed in place of this, the wheel speed V _w1 decreases with respect to the filter output V _f1 , so that the comparison output C ₂ of the comparator 47b becomes as shown in FIG. 8 (c). , inverted to H level at the time t ₁₇ the set time T ₃ of the timer 47f has elapsed, the output S ₃ of the OR gate 47g is inverted to H level as shown in Figure No. 8 (e), the aND gate Four
The output of 7l is inverted to H level and the analog switch 47n is turned on. Thereby, since the positive voltage corresponding to -1.2 g is supplied to the integration circuit 47o as the input voltage E, increases in the negative direction at a speed the integrated output V _e is corresponding to -1.2 g, which adder circuit 47y , The filter output V _f1 gradually decreases as shown by the dotted line in FIG. 8 (a).

Thereafter, the filter output V _f1 is substantially equal to the wheel speed V _w1 at time t _18, the comparison output C ₂ of the comparator 47b is inverted to L level, FIG. 8 is an output S ₅ of NOR gate 47e accordingly because inverted to H level as shown (d), the as shown from the shot pulse generator circuit 47h in FIG. 8 g, shot pulse S ₁ is output, together with the integration circuit 47o is reset, in a sample hold circuit 47t Wheel speed V _{w1 at} that time
Holds, then tire integrating circuit integrating an input voltage E the set time T ₃ correspond to -1.2G at time t ₁₈ which has passed the 47f 47o
In integrated filter output V _f1 is decreased, holding the wheel speed V _W1 of the time at the time t ₁₉ to the filter output V _f1 is substantially equal to the wheel speed V _w1 at the sample hold circuit 47 t.

Then, the filter outputs _Vf1 and _{Vf2 of the} front wheels, which are the non-drive wheels, are selected high by the select high switch 48. That is, when the vehicle is in a straight running state, the wheel speeds _Vw1 and _Vw2 of the left and right front wheels are substantially equal, and either one is selected.When the vehicle is in a turning state, the wheels on the outer wheel side are compared with the wheel speeds on the inner wheel side. Since the speed increases, the wheel speed on the outer wheel side is selected.

The select output _VfF selected by the select high switch 48 is supplied to the select switch 49. At this time,
The select switch 49 does not select the rear-wheel-side filter output _Vf3 as the driving wheel because the above-described MR signal is at the L level when the vehicle is stopped and in the non-braking state.
The selection output _VfF of the non-driven wheel is selected, and this is output to the pseudo vehicle speed calculation circuit 46. Therefore, for example, when a wheel spin occurs on the rear wheel side serving as a drive wheel during acceleration running or running on a low friction coefficient road surface such as a rainy road, a snowy road, a frozen road, or the like, the rear wheel side filter output Vf ₃ is increased. since there be selected, without affecting a wheel spin calculation of the pseudo vehicle speed V _i to be described later, it is possible to calculate the correct pseudo vehicle speed V _i which follows the actual vehicle speed.

Next, the operation of the pseudo vehicle speed calculation circuit 46 (the specific structure is shown in FIG. 2) will be described.

First, the operation of the pseudo vehicle speed calculation unit 200 will be described with reference to the wheel speed selection circuit 4.
The case where the selected wheel speed V _ws selected in 5 is the filter output V _f1 and the vehicle is in the non-braking state will be described.

This pseudo vehicle speed calculation unit 200 is provided with the wheel speed filter 4 described above.
Since it has the same configuration as the 7A～47C, the vehicle is at a non-braking state is not the output C ₂ of the comparator 60b becomes the H level, the timer 60f set time T ₃ and the wheel speed filter 47A~ When set time T ₃ of the timer 47f of 47C is assumed to be equal, and Figure 8 the same waveform delayed by a set time T ₃ of the timer 60f to the filter output V _f1 as a chain line shown in (a).

Next, the operation of the pseudo vehicle speed calculation circuit 46 at the beginning of braking will be described.

When the vehicle is running in a non-braking state and running, as described above, any of the filter outputs V _f1 and V _f2 of the front wheel side wheel speeds V _w1 and V _{w2 serving} as non-driving wheels in the wheel speed selection circuit 45. Is selected as the select output V _ws ,
In this state, when the brake pedal 16 is depressed to enter the braking state, the filter output of the non-driven wheels is selected high by the wheel speed selection circuit 45 until the state where the skid cycle in which the MR signal becomes H level is started is performed. Keep V _fF selection. Therefore, the pseudo vehicle speed calculating circuit 46, the pseudo vehicle speed V _i is calculated based on the front wheel side of the select output V _fF.

When the brake pedal 16 is depressed, for example, as shown in FIG. 10, first, the filter output _VfF shown by the one-dot chain line on the front wheel side, which is the non-driven wheel to which no driving force is transmitted, is reduced. Subsequently, the filter output _Vf3 on the rear wheel side, which is shown by a thin solid line that is the driving wheel to which the driving force is transmitted, decreases (in FIG. 10, the set time T of the timer 60f of the pseudo vehicle speed calculation unit 200). ₃ is shown as being chosen to be a very small value). Becomes this state, first, the front wheel side of the select output V _fF is V _fF ≦ V _i -1km /
Output C ₂ of the comparator 60b becomes h is converted to H level. At this time, since the MR signal is continued L level, the output of the AND gate G ₃ of the selection signal generation circuit 153 maintains the L level, the order FF154 is maintained the reset state and the output is L level maintain. Therefore, the output of inverter 159 maintains the H level, and select output V
In time t _{1 that fF} is decreased, since the _{V FR ≧ V i> V fF} , the comparison output of the window comparator 157 becomes an H level, A
While selecting signal SL ₂ outputted from the ND gate 161 becomes the H level, the comparison output of the comparator 155 becomes H level, the comparison output of the comparator 156 is maintained at L level, the output of AND gate 158 is L maintaining the level selection signal SL ₁ outputted from the aND gate 160 is maintained at L level. By selecting signal SL ₂ of the H level is input to the change-over switch 149, the slope generating circuit 148a for generating a tilt signal this selector switch 149 is equivalent to -0.6G
And the slope signal corresponding to -0.6G is changed to the reference slope m.
Is output as The reference gradient m is supplied to the analog switch 60n of the pseudo vehicle speed calculation unit 200 via the addition circuit 151 and the limiter 152.

In this point t _1, and the output C ₂ of the comparator 60b becomes the H level, since the setting time T ₃ of the timer 60f is selected to an extremely small value, the output S ₅ of the OR gate 60g is immediately L
The analog switch 60n is turned on, and the reference gradient m corresponding to -0.6 G is supplied to the integration circuit 60o as the integration input voltage E. Therefore, by integrating the output V _e of the integration circuit 60o increases in the negative direction at a speed corresponding to -0.6G, as the pseudo vehicle speed V _i output from the addition circuit 60y is thick solid line shown in FIG. 10 It will decrease at a rate equivalent to -0.6G.

Then, the pseudo vehicle speed V _i is to become filter output V _f3 or more driving wheels at the time point t _2, and the select signal SL ₂ comparison output of the window comparator 157 is turned to L level turns to L level, instead of this comparator Since the comparison output of 156 turns to the H level, the output of the AND gate 158 also goes to the H level, and the selection signal output from the AND gate 160 accordingly.
SL ₁ becomes the H level. Therefore, the changeover switch 149 is
Switching to the side of the slope generation circuit 148b that generates a slope signal corresponding to 1.2G, the slope signal corresponding to -1.2G is changed to the reference slope m.
Is supplied to the analog switch 60n via the addition circuit 151 and the limiter 152, and is supplied to the integration circuit 60o as the integration input voltage E. Therefore, integration output V _e of the integration circuit 60o is to increase in the negative direction at a speed corresponding to -1.2 g, equivalent to -1.2 g pseudo vehicle speed V _i is from time t ₂ as shown in FIG. 10 Decrease at the speed you do.

Thus, when the front wheel side of the select output V _fF as a non-drive wheel at the start of braking is reduced, since the deceleration gradient of the pseudo vehicle speed V _i is set to a relatively small value (-0.6G equivalent), the pseudo vehicle speed V _i is rapidly decreased with the wheel speed reduction of non-driven wheels, a wheel locking tendency is delayed is the wheel speed of the slip determination of the rear wheels 3 and 4 as a drive wheel in antiskid control circuit 18 as described above be a can be reliably prevented, then the pseudo vehicle speed V _i is V _i> V _fF, V _f3, the deceleration gradient of the pseudo vehicle speed V _i is changed to a relatively large value (-1.2 g equivalent) Runode, or become pseudo vehicle speed V _i is the braking distance prematurely deceleration start point due to a large value longer, it is possible to prevent that the no-brake state.

Next, the operation of calculating the reference gradient m and the corrected gradient m 'during braking is determined by selecting wheel speed V _ws , pseudo vehicle speed V _i , C _i C signal,
A case where the right front wheel brake hydraulic pressure P _w , the output of the comparator 35a, and the EV ₁ and AV ₁ signals are respectively as shown in FIG. 9 will be described.

Pressure increasing counter 90a by the action described above per Figure 5, the comparator output 34a is reset every re-increasing pressure beginning to falls, by integrating the L level EV ₁ signal time a re-pressure increase signal skid Increase the right front wheel re-intensification amount every cycle
It is detected as shown in the figure. The booster counters 90b and 90c also integrate the L-level EV ₂ signal and L-level EV ₃ signal time of the corresponding system by the same operation to detect the re-boosting amount of the left front wheel and the rear two wheels for each skid cycle, These are for example ninth
Assume that it is as shown in the figure.

While the re-pressure increase amount of the right front wheel 1 (the output of the pressure increase counter 90a) is equal to or more than the set value indicating the high friction road, the comparator 94 outputs an H level signal. On the high friction road as at time points t ₁ and t ₂ in the drawing, the pressure increasing counter 90a
Is reset by α _w1 <a ₁ (when re-pressure increase is started), the shot pulse generation circuit 95 generates a shot pulse.
Input to AND gate 96. The comparator 97 outputs an H level signal when the absolute value | m | of the reference gradient m determined as described later is 0.4 G or less, that is, when the road is a low friction road during the previous skid cycle. Is supplied to the AND gate 96.

Further, the lock time determination circuit 99 is reset by the operation described above with reference to FIG. 6 every time the wheel is locked when the output of the comparator 35a rises, integrates the wheel lock time, and locks the right front wheel 1 every skid cycle. Detect time.
The comparator 103 sets the output to the L level on the high friction road where the level is equal to or less than the set value, and the NOT gate 104 sets the output to the H level and supplies the output to the AND gate 96.

The AND gate 96 is a low friction path during the previous skid cycle when the output of the comparator 97 is at the H level.
When the output of H is at the H level and on the high friction road during the current skid cycle, the shot pulse generation circuit 95 detects the start of pressure increase again on the high friction road and generates a shot pulse.
9 outputs the shot pulse as seen in the figure the time t _2. That is, the AND gate 96 outputs a shot pulse at the start of re-pressure increase after the transition from the low friction road to the high friction road.

AND gate 9 unless there is a transition from a low friction road to a high friction road
6 keeps the output at the L level, and
51 together are switched to each solid line position, the output level of the OR gate G ₄ are dependent on the output level of the AND gate G _1. Here, assuming that the anti-skid control has not yet been performed through the braking and the MR signal is at the L level, the selected wheel speed V _ws becomes V _i -1 km / h or less by the above-described braking.
When the G ₂ signal changes to the G level, the selected wheel speed V _ws is set to V _b (0) and V ₀ (see FIG. 9) in the sampling and holding circuits 141a and 141b, respectively, at the rise of the C ₂ signal. Sampled and sampled and held 14
At 1c and 141d, the count values from the timer counter 141 are sampled as T _b (0) and T ₀ , respectively. Further, at the beginning of the braking in which the MR signal is at the L level, as described above, the changeover switch 149 is switched to the slope generating circuit 148a or 148b, and the reference gradient m is set to the gradient set by the gradient generating circuit 148a or 148b. It is determined to correspond. By the way, since the outputs of the pressure increase counters 90a to 90c are initially saturated as shown in FIG. 9, the correction gradient m 'obtained by adding these to the reference gradient m by the adding circuit 151 is supplied to the limiter 152 as shown in FIG. is limited to, is intended such as the Figure 9 the pseudo vehicle speed V _i to as operation described above based on this.

Pseudo vehicle speed V _i is Figure 9 in time t ₃ after consistent with the select wheel speed V _ws, at the time point t ₄ rises again C ₂ signal, the anti-skid control is already initiated, MR signals are at the H level are therefore, F through the aND gate G ₃ these two signals
When F154 is set and its H level output, the selection signals SL ₁ and SL ₂ output from the AND gates 160 and 161 are both at L level, and the changeover switch 149 is switched to the division circuit 147 side. The H-level MR signal prohibits the output of the AND gate G ₁ is inverted by the NOT gate G _2, keeping the sample-and-hold circuit 141a, the sampling value V _0, T ₀ of 141c remain above and, in G ₂ signal The selected wheel speed V _b (I) at that time in synchronization with the rise (time t _{4 in} FIG. 9) (see FIG. 9)
Is newly sampled by the circuit 141b, and the count value T _b (1) from the timer counter 142 at the same time is newly sampled by the circuit 141d. On the other hand, the subtraction circuit 14
From 5 the difference ΔV _b (1) between the selected wheel speed V _b (0) at the time of the first sampling and the selected wheel speed V _b (1) at the time of the second sampling, that is, ΔV _b (1) = V _b (0) with -V _b (1) is output, the count value T _b at the sampling time of the first round from the subtracting circuit 146 (0), the count value at the sampling instant for the second time T _b Difference ΔT from (1)
_b (1), i.e. _{ΔT b (1) = T b} (0) -T b (1) are output, these difference values [Delta] V _b (1), the division circuit 147 on the basis of the [Delta] T _b (1) is [Delta] V _{b (1) / ΔT b (1} ) = performs calculation of m, and inputs the calculated value m to the adding circuit 151 as the slope information, from V _b (0) to V _b (1). Addition circuit 1
51 calculates the pressure increase counter addition to modifying the slope m of the output 90 a to 90 c 'in reference slope m, FIG. 9 during the time t ₅ ~ based on this
The slope of the pseudo vehicle speed V _i to be operational in excluding the foregoing can be made compatible with the road surface friction conditions at between t _6.

Thereafter, between FIG. 9 during the time t ₇ ~t _8, between _{t 9 ~t 10, t 11 ~t} 12
During, in between t ₁₃ ~t _14, similarly to the reference slope m and modifications slope m and 'together with the determined corrected slope m' pseudo speed V _i based on is calculated.

Meanwhile, when after the transition from the low friction road to a high friction road, the AND gate 96 at time t ₂ to re-increase pressure starts to output the shot pulse, this shot pulse switch 50, 5
Simultaneously switched 1 instantly dotted position, facing the sample hold circuit 141a, the 141c through the OR gate G _4, circuit at each said point in time in these sample-and-hold circuits 14
The sample and hold values _Vb = _Vb (3) (see FIG. 9) and _Tb = _Tb (3) (not shown) of 1b and 141d are resampled.

Therefore, V _b (3) in place subsequent the _{V 0, T 0, T b} (3)
Is used, in the period from the time point t ₁₅ ~t ₁₆ and t ₁₇ after,
These 'together is determined, corrected slope m' by the same action based on reference slope m and modifications slope m by calculating the pseudo vehicle speed V _i based on is performed, the pseudo vehicle speed more road surface friction state Can be matched.

In the above embodiment, the inclination generating circuits 148a and 148
The case where the tilt signal is switched in two stages by b has been described. However, the present invention is not limited to this, and as shown in FIG. 11, the tilt signals of -0.3G, -0.6g and -1.2G are generated. One of providing a slope generating circuit, the filter output V _f1 of these discharge driving wheels, V _f2, may be selected by comparing the filter output V _f3 and pseudo vehicle speed V _i of the drive wheels, an additional 4 or more A gradient generating circuit may be provided.

In the above embodiment, the filter output corresponding to the non-driven wheel of the wheel speed selection circuit 45 is selected by the high switch.
The case of selecting high at 48 has been described. However, the present invention is not limited to this. For example, when the MR signal is at the L level, the filter output is set to the select low state of selecting the lower one of the filter outputs V _f1 and V _f2 , and the MR signal is set to the H level. It may be used as the select-high state when a level, in this case, high pseudo vehicle speed V _i by the inner and outer wheel speed difference during cornering can be prevented from being calculated.

Furthermore, in the above-described embodiment, the case where the anti-skid control device is configured by an electronic circuit has been described. However, the present invention is not limited to this, and the arithmetic processing may be performed using a microcomputer.

Further, in the above-described embodiment, the case where the wheel speed on the rear wheel side is detected by the common wheel speed sensor has been described. However, the present invention is not limited to this, and the wheel speed sensors are separately provided for the left and right wheels on the rear wheel side. It may be.

Further, in the above-described embodiment, the description has been given of the rear wheel drive vehicle.

In each of the above embodiments, the case where the present invention is applied to a drum type brake is shown. However, the present invention can be similarly applied to a disk type brake.

Further, in each of the embodiments described above, the case where the wheel cylinder is controlled by the hydraulic pressure is described, but it is needless to say that the present invention is not limited to this, and other liquids or gases such as air can be applied.

〔The invention's effect〕

As described above, according to the present invention, during non-braking, the pseudo vehicle speed is calculated based on the wheel speed detection values of the non-driving wheels, and the wheel speed detection values of the non-driving wheels and the driving wheels are pseudo at the beginning of braking. When the pseudo vehicle speed is intermediate between the detected values of both wheel speeds, the deceleration gradient of the first rate of change is small, and when the pseudo vehicle speed is larger than the detected value of both wheel speeds, the second deceleration gradient is larger than the first rate of change. Since it was configured to set the deceleration gradient of the change rate,
A deceleration gradient corresponding to the actual vehicle speed despite the deceleration of the non-driving wheels at the start of deceleration, while calculating the pseudo vehicle speed that is not affected by the wheel spin of the driving wheels based on the wheel speed detection value of the non-driving wheels Is calculated, and the effect of being able to perform accurate anti-skid control by preventing the tendency of the wheels to lock due to a decrease in the pseudo vehicle speed is obtained.

[Brief description of the drawings]

FIG. 1 is an overall system configuration diagram when the present invention is applied to an anti-skid control device, FIG. 2 is a block diagram showing an example of a pseudo vehicle speed calculation circuit, and FIG. 3 is a wheel speed selection circuit and a selection signal formation circuit. FIG. 4 is a block diagram showing an example of a wheel speed filter, FIG. 5 and FIG.
FIG. 7 is a time chart for explaining the operation of the booster counter and the lock time determination circuit in the pseudo vehicle speed calculation circuit of FIG. 2; FIG. 7 is a waveform chart for explaining the operation of the anti-skid control device; FIG. 2 is a waveform diagram for explaining the operation of the pseudo vehicle speed calculation circuit shown in FIG.
FIG. 10 is a waveform chart for explaining the operation at the start of braking, and FIG. 11 is a waveform chart similar to FIG. 10 for explaining another embodiment of the present invention. In the drawing, 1 is a right front wheel, 2 is a left front wheel, 3 and 4 are rear wheels, 1a to 4a are wheel cylinders, 16 is a brake pedal, 17a to 17c are actuators, 18 is an anti-skid control circuit, 19a to 19c
Is an inflow valve, 20a to 20c is a discharge valve, 21a to 21c is a pump, 24 is a pump drive motor, 26a to 26c is a wheel speed sensor, 27 is a pseudo vehicle speed generator, 28a to 28c is a target wheel speed generation circuit, 30 is Retriggerable timer, 31a to 31c are wheel speed detection circuits, 32a to 3
2c is a wheel acceleration detection circuit, 45 is a wheel speed selection circuit, 46 is a pseudo vehicle speed calculation circuit, 47A to 47C are wheel speed filters, 48 is a select high switch, 49 is a select switch, 99 is a lock time determination circuit, and 100 is a reference. A gradient determining unit, 148a and 148b are gradient generating circuits, 149 is a changeover switch, 153 is a selection signal forming circuit,
154 is a flip-flop, 155 and 156 are comparators, 157
Is a window comparator, 200 is a pseudo vehicle speed calculation unit, 300 is a re-pressure increase amount detection unit, and 400 is a reference gradient change unit.

Claims (1)

(57) [Claims] A first wheel speed detecting means for detecting a wheel speed of a non-driving wheel of the vehicle; a second wheel speed detecting means for detecting a wheel speed of a driving wheel of the vehicle; and the first wheel speed. A pseudo vehicle speed generator that calculates a pseudo vehicle speed that decelerates at a rate of change with respect to a predetermined time based on the wheel speed detection value of the detection unit, a pseudo vehicle speed of the pseudo vehicle speed generation device, and a wheel speed detection value of each of the wheel speed detection units. And a brake pressure control means for controlling a fluid pressure of a brake cylinder disposed on each wheel based on the first and second wheel speed detection means and the second wheel speed detection means. The wheel speed detection value is compared with the pseudo vehicle speed of the pseudo vehicle speed generator, and the first rate of change that is small when the pseudo vehicle speed is halfway between the two wheel speed detection values is larger than the two wheel speed detection values. Sometimes a second change greater than the first rate of change Pseudo vehicle speed generator of anti-skid control apparatus comprising the gradient setting means for setting each of the.