JP2811749B2 - Anti-skid control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an anti-skid control that controls the hydraulic pressure of a braking cylinder disposed on each wheel during braking to prevent the wheels from locking. It relates to improvement of equipment.

[Conventional technology]

As a conventional anti-skid control device, for example, there is one described in Japanese Patent Publication No. 41-17082.

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 a pseudo vehicle speed. Since the speed is high, the pseudo vehicle speed becomes lower than the actual vehicle speed. Therefore, a straight line drawn at a predetermined gradient from the select high wheel speed value at the start of rapid deceleration is set 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 multi-wheel braking device to the reduced pressure state is performed. There were unresolved issues. In particular, when the vehicle travels on a low friction coefficient road surface such as a snowy road or a frozen road, a wheel spin easily occurs during acceleration, and a malfunction of the anti-skid control is likely to occur.

Therefore, the present invention has been made by focusing on the unsolved problem of the conventional example described above. At the time of acceleration of the vehicle, it is considered that wheel spin may occur, and at least the highest wheel speed is ignored. It is another object of the present invention to provide an anti-skid control device in which the pseudo vehicle speed is not affected by the wheel spin.

[Means for solving the problem]

In order to achieve the above object, an anti-skid control device according to the present invention has a basic configuration as shown in FIG.
Acceleration detecting means for detecting longitudinal acceleration of the vehicle, wheel speed detecting means for detecting speeds of a plurality of wheels, wheel speed selecting means for selecting a wheel speed detected value of each wheel speed detecting means, and the acceleration detecting means Pseudo vehicle speed calculating means for calculating a pseudo vehicle speed based on the longitudinal acceleration of the vehicle and the selected wheel speed of the wheel speed selecting means, based on the pseudo vehicle speed of the pseudo vehicle speed calculating means and the wheel speed detection value of the wheel speed detecting means. An anti-skid control device comprising: a braking pressure control unit configured to control a fluid pressure of a braking cylinder disposed on each wheel; and an acceleration state detection unit configured to detect an acceleration state of the vehicle. At least at the time of braking, selecting a maximum value among the wheel speed detection values of the wheel speed detection means, and selecting a wheel speed lower than the maximum value when the acceleration state detection means detects an acceleration state. It is characterized by being composed.

[Action]

In the present invention, at least at the time of braking, the maximum value of the wheel speed detection values of the wheel speed detection means is selected by the wheel speed selection means, and the pseudo vehicle speed is obtained based on the maximum value. A pseudo vehicle speed corresponding to the vehicle speed can be obtained, and accurate anti-skid control can be performed.

On the other hand, when the acceleration state is detected by the acceleration state detection unit, by selecting a wheel speed lower than the maximum value of the wheel speed detection value by the front wheel speed selection unit, based on the wheel speed of the wheel that does not generate wheel spin, A pseudo vehicle speed that follows the actual vehicle speed can be obtained based on this and the longitudinal acceleration detection value, and by using this pseudo vehicle speed to determine the lock state of each wheel, it is possible to prevent malfunction and prevent an incorrect Skid control can be performed.

〔Example〕

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

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

In the figure, 1FL and 1FR are front wheels, 1RL and 1RR are rear wheels, and these wheels 1FL to 1RR have wheel cylinders 2FL to 2RR as braking cylinders, respectively.
Wheel speed sensors 3FL to 3RR that output pulse signals according to the wheel rotation speeds of the wheels 1FL to 1RR are attached.

Each wheel cylinder 2FL-2RR has a brake pedal 4
The master cylinder pressure from the master cylinder 5, which generates two systems of master cylinder pressures in accordance with the depression of the actuator, is supplied via the actuators 6FL to 6RR.

As shown in FIG. 3, each of the actuators 6FL to 6RR 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.
A series circuit of an electromagnetic outflow valve 9, a hydraulic pump 10, and a check valve 11 connected in parallel with the electromagnetic inflow valve 8;
And an accumulator 12 connected to a hydraulic line between the hydraulic pumps 10.

Then, the electromagnetic inflow valves 8 of the actuators 6FL to 6RR,
The electromagnetic outflow valve 9 and the hydraulic pump 10 are provided with wheel speed sensors 3FL to 3FL.
A hydraulic pressure control signal EV from a controller 14 to which wheel speed pulse signals P _{FL to} P _{RR from RR} are inputted and a longitudinal acceleration detection value of a longitudinal acceleration sensor 13 for detecting longitudinal acceleration attached to the vehicle body is inputted. , AV and MR.

Here, the longitudinal acceleration sensor 13, as shown in FIG. 5, when the acceleration or deceleration of the vehicle does not act, a positive neutral voltage V _N, which when the forward acceleration (backward deceleration) is applied a voltage higher than the neutral voltage V _N in proportion to, and outputs the longitudinal acceleration detection value to lower positive voltage neutral voltage V _N in proportion thereto when forward deceleration (backward acceleration) is applied.

The controller 14 receives the wheel speed pulse signals P _{FL to} P _RR from the wheel speed sensors 3 _{FL to 3 RR} ,
From the turning radius of ~ 1RR and the peripheral speed of the wheel (wheel speed) Vw _FL ~ V
a wheel speed calculating circuit 15FL～15RR for calculating a w _RR, a wheel speed selecting circuit 16 for selecting the wheel speed Vw _FL ~Vw _RR of the wheel speed calculating circuit 15FL～15RR, selected by the wheel speed selecting circuit 16 longitudinal acceleration detected value of the select wheel speed Vw _s and longitudinal acceleration sensor 13 and is input, the pseudo vehicle speed based on these
A pseudo vehicle speed calculating circuit 17 for calculating the V _i, the pseudo vehicle speed V _i and the wheel speed V output from the pseudo vehicle speed calculation circuit 17
and a braking pressure control circuit 18 for performing anti-skid control during braking based on w _FL , Vw _FR and Vw _R, and a control signal output from the braking pressure control circuit 18 is transmitted through the drive circuits 22a to 22c. To the actuators 6FL to 6RR.

Wheel speed selecting circuit 16, as shown in FIG. 4, when the select signal S _E has the logical value "1", selects the maximum wheel speed among the wheel speeds Vw _FL ~Vw _RR, the select signal S _E wheel speed Vw _FL, and a select switch SS as wheel speed selecting means for outputting them as a select wheel speed Vw _s by selecting the minimum wheel speed among the Vw _RR, the select switch when but a logical value "0" and a selection signal generation circuit 19 as acceleration state detecting means for forming the select signal S _E for SS.
Here, the select signal forming circuit 19 is a longitudinal acceleration sensor.
Longitudinal acceleration detected value of 13 is supplied to one input side, set value _N set to the neutral voltage V _N corresponding to 0g is supplied to the other input side, when ≦ _N that is, when a non-accelerating state When the logical value is "1",> _N , that is, when the vehicle is in the acceleration state, the comparator 19a outputs a comparison output of the logical value "0", and the output of the comparator 19a and the control from the braking pressure control circuit 18 described later are performed. It is composed of an OR circuit 19b for taking the logical sum of the signal MR, the select switch S output of the OR circuit 19b as the select signal S _E
S to be supplied.

As shown in FIG. 4, the pseudo vehicle speed calculation circuit 17 includes an output correction circuit 20 for correcting a longitudinal acceleration detection value output from the longitudinal acceleration sensor 13 and a corrected acceleration detection value _c output from the output correction circuit 20. , the pseudo vehicle speed generating circuit 21 for calculating a pseudo vehicle speed V _i from the select wheel speed Vw _s and the control in the signal MR
And the pseudo vehicle speed output from the pseudo vehicle speed generation circuit 21.
V _i is input to the braking pressure control circuit 18.

Here, the output correction circuit 20, absolute value circuit 20b to the subtraction circuit 20a for subtracting the neutral voltage V _N from the longitudinal acceleration detection value output from the longitudinal acceleration sensor 13, acceleration and deceleration _s of the subtraction circuit 20a is supplied And the offset value output circuit 20c
If, and an adding circuit 20d for adding the output of the absolute value circuit 20b and the offset value output circuit 20c, by subtracting the neutral voltage V _N from the acceleration detected value of the longitudinal acceleration sensor 13 in the subtracting circuit 20a, forward The actual acceleration / deceleration _s is calculated by setting the acceleration (reverse deceleration) as a positive voltage in proportion to this and the forward deceleration (reverse acceleration) as a negative voltage in proportion to this, and the absolute value circuit 20b calculates The acceleration / deceleration _s of the subtraction circuit 20a is converted into an absolute value and input to the addition circuit 20d. The offset value output circuit 20c outputs an arbitrary predetermined offset value for correcting the absolute acceleration / deceleration _s to the adding circuit 20d.
Correspond to 0.3g. The addition circuit 20d outputs an acceleration / deceleration correction value _c obtained by offsetting the absolute acceleration / deceleration _s by 0.3 g by adding the two inputs.

Pseudo vehicle speed generating circuit 21, as shown in FIG. 5, the comparator 21a to select wheel speed Vw _s outputted from the select switch SS is input, and 21b, a dead zone of ± 1km / h to the pseudo vehicle speed V _i Adder 21c to set and supply to other inputs of comparators 21a and 21b
And a subtractor 21d, and a NOR gate 21e to which the output signals C ₁ and C _{2 of} the comparators 21a and 21b are supplied. The comparator 21a determines that Vw _H ≧
Outputs a high-level output C ₁ at V _i +1 km / h and outputs
1b outputs the output C ₂ high level when the _{Vw H <V i -1km / h} . Accordingly, NOR gate 21e, the outputs C _1, C ₂ and outputs an output signal S ₅ of high level when _{V i -1km / h ≦ Vw H} <V i + 1km / h which both become low level. Output signal of NOR gate 21e
S _5, the off-delay timer 21f, are input to the OR gate 21g and a shot pulse generator circuit 21h. Off-delay timer 21f is started by the fall of the signal from the NOR gate 21e, and outputs a high level signal by a predetermined time T _3, this
Supply to OR gate 21g.

The output of the OR gate 21g is supplied to the gate of the analog switch 21i as a select signal S _3, it is supplied to one input of the AND gate 21k, 21 inverted by the inverter 21j. The other input of the AND gate 21k, C ₁ signal, also C ₂ signal is supplied to the other input of the AND gate 21, an AND gate 21k, 21 outputs the select signal S ₂ of, S ₄ Are supplied to the gates of the analog switches 21m and 21n. The analog switch 21i outputs the select signal S
₃ is turned on during the high level, the supply voltage E to the integration circuit 21o is set to zero, and the analog switch 21m outputs the selection signal S ₂
At a high level, 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 integrated into an integrating circuit 21o.
Is supplied to the analog switch 21n becomes a high level during the on state of the select signal S _4, and supplies a voltage E corresponding to the acceleration correction value _c from the adder circuit 20d to the integration circuit 21o. In addition, the selection of + 0.4g and + 10g is made by the switch 21
The switch 21p is set to +0.4 g while the controlling signal MR from the anti-skid control circuit 17 is at the logical value “0”.
Is selected during anti-skid control in which the control signal MR has the logical value “1”.

Integrator circuit 21o is intended an amplifier 21q, known consisting of a capacitor 21r and an analog switch 21s, is reset when the analog switch 21s is turned on by the high level reset signals S ₁ to its gate, the reset signal S ₁
After disappearing, the voltage E is continuously integrated. Reset signals S ₁ is to obtain by-shot pulse from the shot pulse generating circuit 21h, the shot pulse generating circuit 21
h outputs first one shot pulse when the engine starts as a reset signals S ₁ by an ignition-on signal IG, then outputs the shot pulse for each output signal S ₅ of NOR gate 21e rises as a reset signals S ₁ I do.

Reset signals S ₁ is other to the sample-and-hold circuit 21
This circuit is also used to reset the buffer amplifier 21.
u, 21v, and well known consisting capacitor 21w and an analog switch 21x, select wheel speed Vw _s is input.
The sample and hold circuit 21t outputs the high-level reset signal S ₁
The reset when the analog switch 21x is turned on, continues to store the wheel speed Vw _s at that time as wheel speed sampling value V _s, and inputs it to the adder circuit 21y. The addition circuit 21y calculates the integration value of the integration circuit 21o. Was added to the wheel speed sampling value V _s, and inputs to the brake pressure control circuit 18 and the added value V _s + V _e as a pseudo vehicle speed V _i.

The braking pressure control circuit 18 determines the wheel speeds Vw _{FL to} Vw _R and the pseudo vehicle speed V
Wheel cylinder 2 provided on each wheel 1FL-1RR based on _i
Actuators 6FL to 6R that control the supply pressure to FL to 2RR
As shown in FIG. 2, the microcomputer 25 includes a microcomputer 25 having at least an input interface circuit 25a, an output interface circuit circuit 25d, an arithmetic processing unit 25b, and a storage device 25c. The following anti-skid control processing is executed.

This anti-skid control processing is performed for a predetermined time, for example, 20 ms.
This is executed as a timer interrupt process for each ec. In this process, AS indicates a control flag, L indicates a decompression timer, and these are shifted from step to step at the end of the previous anti-skid control and cleared to zero. While the control flag AS is set to "1", the control-in-progress signal MR having the logical value "1" is output from the select signal forming circuit 19 and the pseudo vehicle speed generating circuit 21.
Is output to

That is, when the process of FIG. 6 is started, first, in step, the current wheel speed detection value Vwi _iN output from the wheel speed calculation circuit 15i (i = FL, FR, RL, RR) is read. And the wheel speed detection value Vw _iN read in steps from the wheel speed detection storage tank V _{w i-1} read during the previous process.
Is subtracted to calculate the wheel speed change amount per unit time, that is, the wheel acceleration / deceleration wi, and stores it in a predetermined storage area of the storage device 25c. After reading V _i , the process proceeds to step S1 to calculate the slip ratio Si by performing the calculation of the following equation (1).

Then, a control signal for controlling the actuator 6i is output based on the wheel acceleration / deceleration wi calculated in the step and the slip ratio Si calculated in the step.

That is, the slip ratio Si is a predetermined value S set in advance.
₀ (for example, 15%), the control flag AS and the pressure reduction timer L are both zero, and the wheel acceleration / deceleration wi is between the preset deceleration threshold α and acceleration threshold β, ie, α <
At the time of non-braking and the initial stage of braking, where wi <β, the process shifts to the step through the steps (1) to (4) to set a rapid pressure increase mode in which the pressure of the actuator 6i is a pressure corresponding to the pressure of the master cylinder 5. In this rapid pressure increase mode, the control signals EV and AV for the actuator 6i are both set to the logical value “0”, the inflow valve 8 of the actuator 6i is opened, and the outflow valve 9
Are respectively controlled to be in the closed state.

Therefore, when the vehicle is in the non-braking state in which the brake pedal 4 is not depressed, the pressure of the master cylinder 5 is substantially zero, so that the pressure of the wheel cylinder 2i is also maintained substantially zero, and the non-braking state is maintained. At the initial stage of the braking operation with the pedal 4 depressed, the pressure of the wheel cylinder 2i is rapidly increased in accordance with the increase in the pressure of the master cylinder 5, and a braking state is established.

When the vehicle enters the braking state, the wheel speed Vwi gradually decreases, and accordingly, the wheel deceleration wi increases as shown by a curve 1 in FIG. 7, and the wheel deceleration wi exceeds the deceleration threshold α. Then, the process shifts from step to step to enter a high pressure side holding mode in which the pressure of the actuator 6i is held at a constant value. In the high-pressure side holding mode, the control signal EV for the actuator 6i is set to the logical value "1" and the control signal AV is set to the logical value "0" to close the inflow valve 8 and close the outflow valve 9 of the actuator 6i. Each state is controlled to maintain the internal pressure of the wheel cylinder 2i at the immediately preceding pressure.

However, even in this holding mode, with the braking force to the wheel is acting, the wheel deceleration w _i as indicated by the curve l of FIG. 7 increases, the slip ratio Si
Also increase.

When the slip ratio Si exceeds the predetermined value S _0, and the wheel deceleration w _i is maintained less than the acceleration threshold value β is
Shifts from step through step to step, set to "1" to the control flag AS as well as set to a predetermined value L ₀ in advance set the decompression timer L, in the control of the logic value "1" in response thereto Actuator 6i by outputting signal MR
Of the hydraulic pump 10 is operated. For this reason, the process shifts from step to step through step, and a pressure reduction mode is set in which the pressure of the actuator 6i is gradually reduced. In this pressure reduction mode, the control signal EV and AV for the actuator 6i are both set to the logical value “1”, the inflow valve 8 of the actuator 6i is closed, the outflow valve 9 is opened, and the pressure held in the wheel cylinder 2i is reduced. The pressure is returned to the master cylinder 5 via the outflow valve 9, the hydraulic pump 10 and the check valve 11, and the internal pressure of the wheel cylinder 2i is reduced.

When the this reduced pressure mode, the braking force applied to the wheels is reduced, the wheel speed detected value Vw _i a while maintaining the reduced state, and therefore the wheel deceleration w _i and slip rate S is a curve l of Figure 7 continuing the upward trend as shown, but then decreasing rate of the wheel speed detected value Vw _i is shifted to the accelerating state decreases.

This increases the wheel acceleration w _i is the positive direction in accordance with, the wheel acceleration w _i is equal to or higher than the acceleration threshold value beta, the process proceeds to step through step from step.

In this step, the pressure reduction timer L is cleared to "0", and then the process proceeds to the above step.

Therefore, in the determination in the step, L = 0, and the processing shifts to the step. Since w _i ≧ β, the processing shifts to the step and the control flag AS is set to “1”. Then, the mode shifts to the low pressure side holding mode in which the pressure of the actuator 6i is held on the low pressure side. In the low pressure side holding mode, the control signal EV is controlled to the logical value “1” and the control signal AV is controlled to the logical value “0” in the same manner as in the high pressure side holding mode, so that the internal pressure of the wheel cylinder 2i is immediately before. Hold at pressure.

Thus, when the holding mode of the low-pressure side, the inner pressure of the wheel cylinder 2i becomes constant value in the low-pressure side, the wheel speed detected value Vw _i continues to accelerated conditions. For this reason, wheel acceleration / deceleration
w _i increases in the positive direction, and the slip ratio Si decreases.

When the slip ratio Si is less than the set value S _0, the process proceeds from step to step, because it is clear to the decompression timer L is "0" in the last low-pressure side holding mode, the process proceeds directly to step, said low pressure Continue the side hold mode.

Also in the low-pressure side holding mode, for the wheels, the braking force acts, the rate of increase in the wheel speed detected value Vw _i gradually decreases, the wheel acceleration w _i is the acceleration threshold value β
When it is less than, it moves from step to step,
Since w _i > α, the process proceeds to the step where the control flag AS
Is “1”, the process proceeds to the step.

In this step, the pressure oil from the master cylinder 5 is intermittently supplied to the wheel cylinder 2i, and the internal pressure of the wheel cylinder 2i is increased in a stepwise manner, so that the mode is set to a gradual pressure increasing mode. In this gradual pressure increase mode, the control signal EV for the actuator 6i is alternately repeated at a predetermined interval with a logical value “0” and a logical value “1”, and the control signal AV is set at a logical value “0” to set the inflow valve of the actuator 6i. 8, open and close at predetermined intervals,
By closing the outflow valve 9, the wheel cylinder
The internal pressure of 2i is gradually increased stepwise.

In the gradual pressure increase mode, the pressure increase of the wheel cylinder 2i becomes gradual, so that the braking force on the wheel 1i gradually increases, the wheel 1i is decelerated, and the wheel speed detection value Vw
_i decreases.

Thereafter, when the wheel acceleration w _i is less than the deceleration threshold alpha, the process proceeds from step to step, becomes the hold mode of the high-pressure side, then the slip ratio Si is set slip ratio
When the S ₀ or more, the process proceeds to step through step from step, then step, the so proceeds to step through, become reduced pressure mode, subsequent low pressure holding mode, slow increase mode, the high pressure side holding mode, vacuum mode repeated Thus, an anti-skid effect can be exhibited.

Incidentally, when the speed of the vehicle has decreased to some extent, may slip ratio Si is restored to below the set slip ratio S ₀ in the pressure decrease mode, at this time, the process proceeds from step to step, to set the pressure reduction mode, as described above since vacuum timer L in step is set to a predetermined setting value L _0, the process proceeds to step, so that the process proceeds to step since by subtracting the predetermined set value "1" of the vacuum timer L. Therefore, when the process of shifting from step to step is repeated and the pressure reduction timer L becomes "0", the process shifts to step through step to step, shifts to the gradual pressure increase mode, and shifts to the high pressure side holding mode. Then, the mode is shifted to the gradual pressure increase mode.

Then, when the vehicle satisfies the control ending condition such as when the vehicle speed becomes close to the stop or when the number of times of selection of the gentle pressure increasing mode becomes a predetermined value or more, it is determined that the control is completed by the determination of the step. Then, the process proceeds from this step to the step, where the pressure reduction timer L and the control flag AS are cleared to "0", and then proceeds to the step to set the rapid pressure increase mode and terminate the anti-skid process.

Therefore, when the vehicle is stopped with the brake pedal depressed, the hydraulic pressure of the master cylinder 5 is applied to the wheel cylinders 2i as it is, and the vehicle can be kept stationary, and when the depression of the brake pedal 4 is released, Since the hydraulic pressure of the master cylinder 5 becomes zero, the internal pressure of the wheel cylinder 2i is maintained at zero,
No braking force is applied to the wheel 1i.

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

Assuming that the vehicle is in a parking state and the key switch is turned on in this state, the controller 14 is turned on. Therefore, the output correction circuit 20 of the pseudo vehicle speed calculating circuit 17, is zero as acceleration _s obtained by subtracting the neutral voltage V _N from the acceleration detected value of the longitudinal acceleration sensor 13 is shown in Figure No. 8 (f), the addition circuit From 20d, the acceleration / deceleration correction value _{c obtained} by adding the absolute value of the acceleration / deceleration _{s by} the offset value 0.3g to the pseudo vehicle speed generation circuit 21 is output as shown in FIG. 8 (g).

On the other hand, the anti-skid control is not performed in the braking pressure control circuit 18, and the control-in-progress flag AS is reset to “0”.
The control-in-progress signal MR becomes a logical value "0" to maintain the rapid pressure increase mode, the inflow valve 8 of the actuators 6FL to 6RR is controlled to be open, and the outflow valve 9 is controlled to be closed, and the hydraulic pump is controlled. 10 is stopped, and the brake fluid pressure output from the master cylinder 5 in accordance with the amount of depression of the brake pedal 4 is supplied to the wheel cylinders 2FL to 2RR as they are via the actuators 6FL to 6RR.

At this time, since the vehicle is at a stop, longitudinal acceleration detected value of the longitudinal acceleration sensor 13 is a neutral voltage V _N,
The comparison output of the comparator 19a of the select signal generating circuit 19 is a logic value "1", the select signal S _E is a logical value output from the OR circuit 19b "1", and the select switch SS is the wheel speed Vw _FL ~ It is in a select high state in which the maximum value is selected from Vw _RR .

Once t ₀ shown from the state in FIG. 8, when the ignition switch to the ON state, the ON signal IG is input to the shot pulse generator circuit 21h of the pseudo vehicle speed generating circuit 21. Therefore, the output-shot pulse S ₁ as shown in Figure 8 from shot pulse generating circuit 21h (i), which it was reset is supplied to the sample hold circuit 21t, which is selected by the select switch SS in this case select-high wheel speed Vw _s (= 0) is kept as the wheel speed sampling value V _s. Further, shot pulse S ₁ is the integration circuit 21o
The also supplied, the integrating circuit 21o is reset, the integrator output V _e is to become zero, even becomes zero pseudo vehicle speed V _i output from the addition circuit 21y. Thus, since the pseudo vehicle speed V _i and the select high wheel speed Vw _s is zero equally both
The comparator 21a and the output C ₁ and C ₂ of 21b is in the low level as shown in FIG. 8 (b) and (c), the output from the NOR gate 21e of the high level as shown in Figure 8 (d) signal S ₅ is outputted, a high level as shown in select signal S ₃ also Figure 8, which is output from the OR gate 21g (e) accordingly.

Since the select signal S ₃ is supplied to the analog switch 21i, the analog switch 21i is turned on, the other select signal S ₃ is supplied is inverted to the AND gate 21k and 21 to the low level by the inverter 21j, these inhibits the generation of the select signals S ₂ and S _4. At this time, since the input side of the analog switch 21i is grounded, the input voltage E of the integration circuit 21o becomes as shown in FIG.
And the integral output _Ve is also maintained at zero. As a result, the pseudo vehicle speed V _i output from the addition circuit 21y
It is kept at the same zero wheel speed sampling value V _s.

Then, by starting the vehicle, when the acceleration state, the output is high acceleration detected value of the neutral voltage V _N that represents the forward acceleration state from the longitudinal acceleration sensor 13, whereby the comparison output of the comparator 19a of the select signal generation circuit 19 Is inverted to the logical value “0”, and the controlling signal MR of the braking pressure control circuit 18 is also the logical value “0”.
Since maintaining the select signal S _E of logic value "0" from the OR circuit 19b is output. Therefore, select switch SS
Is controlled to a select low state in which the minimum value among the wheel speeds Vw _{FL to} Vw _RR is selected.

Then, rising as the select low wheel speed Vw _L is a bold line shown in FIG. 8 (a), at time t ₁ as the _{Vw L ≧ V i + 1km /} h,
Comparison output C ₁ of the comparator 21a turns to a high level. However, the output of the off-delay timer 21f is until the set time T ₃ from time t ₁ elapses maintaining a high level is converted at time t ₂ after the set time T ₃ has elapsed at a low level. Thus, between time t ₁ to time t _2, the pseudo vehicle speed V _i 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 21g that the select signal S ₃ is converted to the low level as shown in Figure No. 8 (e), by the output of the same time the aND gate 21k when the analog switch 21i is turned off becomes the high level in response to this, the analog switch 21m Is turned on and +0.4
A negative voltage corresponding to g is supplied as input voltage E.
Therefore, integration output V _e of the integration circuit 21o increases at a speed corresponding to the corrected acceleration detection value _c, the addition value or the pseudo vehicle speed V _i also FIG. 8 by the addition circuit 21y between this and the wheel speed sampling value V _s In (a), it rises as shown by the dotted line.

Then, a pseudo vehicle speed V _i is substantially equal to the select-low wheel speed _{Vw L (Vw L = V i} +1) time t _3, the comparison output C ₁ of the comparator 21a is converted to a low level, in response to this NOR the output S ₅ of the gate 21e is converted to a high level, the integration circuit 21o and the sample hold circuit 21t is reset together, which an analog switch 21i is turned on instead of the analog switch 21m same time, the integration input of the integrator circuit 21o if the voltage E becomes zero, the integrated output V _e becomes zero, the pseudo vehicle speed V _i is the time t ₃
It is held in the sampling speed V _s of at.

Thereafter, since the vehicle continues to accelerate, the time t ₄
In comparison output C ₁ of the comparator 21a is converted to a high level, the timer 2
The output S of the OR gate 21g at t ₅ the set time T ₃ of the 1f has elapsed
₅ is changed to a low level, and the analog switch 21m is turned on again in place of the analog switch 21i.
Pseudo vehicle speed V _i is increased at a speed corresponding to the integral value of the acceleration corresponding to + 0.4 g, the output of the comparator 21a at the time point t ₆ of the pseudo vehicle speed V _i is substantially equal to the select-low wheel speed Vw _L is low by converting to, the integration circuit 21o and the sample hold circuit 21t is reset to hold the select low wheel speed Vw _L at that time by the sample-and-hold circuit 21t.
Thereafter, select low wheel speed pseudo vehicle speed V _i is in the period from the time point t ₆ ~t ₇
Holding the Vw _L, time t ₇ ~t increased at a speed corresponding to + 0.4 g between _8, select low wheel speed Vw at time t ₈ in the period from the time point t ₈ ~t ₉
Hold _L, and the rise at a speed corresponding to + 0.4 g in the period from the time point t ₉ ~t _10, select low wheel speed at the time t ₁₀ in the period from the time point t ₁₀ ~t ₁₁ V
holds w _L, rises at a speed corresponding to + 0.4 g in the period from the time point t ₁₁ ~t _12, holds the select low wheel speed Vw _L at time t ₁₂ in the period from the time point t ₁₂ ~t _13, time t ₁₃ ~t increased at a speed corresponding to + 0.4 g between _14, a constant speed running condition after the time t ₁₄ the acceleration state is ended, the longitudinal acceleration detected value of the longitudinal acceleration sensor 13 becomes the neutral voltage V _N , The comparison output of the comparator 19a of the select signal forming circuit 19 becomes a logical value “1”, and the select signal S _E
There select switch SS is switched to a select-high state becomes logical value "1", the highest wheel speed Vw _H in the wheel speed Vw _FL ~Vw _RR is selected, and holds it as a pseudo vehicle speed V _i. As described above, in the acceleration state where the wheel spin may occur, the lowest wheel speed Vw among the wheel speeds Vw _{FL to} Vw _{RR is obtained.
L} is selected, since the pseudo vehicle speed V _i is calculated by the pseudo vehicle speed generating circuit 21 based on this is calculated, the pseudo vehicle speed V _i rises stepwise without vibrations despite variations in wheel speed , yet the actual value approximating the vehicle speed V _c at that time.

Then, to release the depression of the accelerator pedal at time t _15,
When braking state depress the brake pedal 4 Alternatively, the select-high wheel speed Vw _H is reduced with respect to the pseudo vehicle speed V _i, as the comparison output of the comparator 21b is shown in Figure No. 8 (c) , inverted to high level, setting the timer 21f time T ₃
Once t ₁₆ but have passed, the output of the OR gate 21g is inverted to the low level as shown in Figure No. 8 (e), AN
The output of the D gate 21 is inverted to a high level, and the analog switch 21n is turned on. As a result, the acceleration / deceleration correction value _c output from the addition circuit 20d of the output correction circuit 20 is supplied to the integration circuit 21o as the input voltage E, so that the integrated output increases in the negative direction according to the acceleration / deceleration correction value _c. This is supplied to the adding circuit 21y, so that the pseudo vehicle speed V _i
Gradually decrease as shown by the dotted line in FIG. 8 (a).

Then, the pseudo-vehicle speed V _i at time t ₁₇ the select high wheel speed V
When substantially equal to w _H, the comparison output C ₂ of the comparator 21b is inverted to the low level, the output S ₅ of NOR gate 21e in response to this eighth
Because inverted to the high level as shown in FIG. (D), as shown from the shot pulse generator circuit 21h in FIG. 8 (i), shot pulse S ₁ is output, together with the integration circuit 21o is reset, the sample-and-hold holding the select-high wheel speed Vw _H at that time in the circuit 21t, then adding circuit 2 outputs the correction circuit 20 at time t ₁₈ the set time T ₃ of the timer 21f has elapsed
Pseudo vehicle speed V _i is reduced acceleration and deceleration correction value _c output from 0d integrated to the integration circuit 21o, select the time at t ₁₉ to the pseudo vehicle speed V _i is substantially equal to the select high wheel speed Vw _H The high wheel speed Vw _H is held by the sample hold circuit 21t.

In this braking state, the braking pressure control circuit 18 is activated, and as shown in FIG. 9, the braking forces on the wheel cylinders 2FL-2RR provided on the wheels 1FL-1RR are individually subjected to anti-skid control.

At this time, the wheel speed Vw _FL of the front left wheel 1FL serving as the non-drive wheel changes as shown by the thin line in FIG. 9A, and the wheel speed Vw _RL of the rear left wheel 1RL serving as the drive wheel changes as shown in FIG. Assuming that the pseudo-vehicle speed calculation circuit 17 has changed with a phase delay with respect to the front wheels as shown by the one-dot chain line in FIG.
At the beginning of braking before setting the decompression mode at 18, the ninth
As shown in FIG. 5D, the control-in-progress signal MR maintains the logical value "0", but is not in the accelerating state.
Serves as the output of the comparator 19a is a logic value "1", the select signal S _E of logic value "1" is output to the select switch SS, the highest select-high wheel speed Vw _H in this order select switch SS ( = I have selected the Vw _FL) as the select wheel speed Vw _s. Therefore, by Figure 9 time t ₂₁ from the select wheel speed Vw _s decreases, as described above, the pseudo vehicle speed V _i at time t ₂₂ which is delayed from the time t ₂₁ by the set time T ₃ of the timer 21f is first As shown by the dotted line in FIG. 9A, the speed decreases at a speed corresponding to the acceleration / deceleration correction value _c . Then, the pseudo vehicle speed V _i at time t ₂₃ substantially coincides with the select wheel speed _{Vw s (= Vw H) (} V i ≧ Vw s -1), as described above, the integration circuit 21o and the sample hold circuit 21t is reset The pseudo vehicle speed V
_i is held constant value equal to the wheel speed sampling value V _s.

Thereafter, when the set time T ₃ of the timer 21f expires at time t _25, decreases at a rate that the pseudo vehicle speed V _i again according to the deceleration correction value _c. Then, when t ₂₈ to substantially equal to the wheel speed Vw _RL after the select-high wheel speed, the integration circuit 21o and the sampling hold circuit 21t is reset, the pseudo vehicle speed V _i is equal to the wheel speed sampling value V _s constant is held at the value, then the pseudo vehicle speed V _i at time t ₃₀ starts to decrease, the time t
₃₁ is maintained at a constant value equal to the sampled value V _s of the wheel speeds Vw _FL of the front wheels 2FL to be select high wheel speed Vw _H at time t ₃₁ between ~t _32. V _i ≧ Vw _FL between time t _{31 and} time t ₃₂
Since a +1, the output S ₃ of the OR gate 21g becomes low level when t ₃₃ the set time T ₃ of the timer 21f has elapsed,
The analog switch 21m is turned on. At this time, as will be described later, the anti-skid control is being performed by the braking pressure control circuit 18, and the control start in-progress signal MR has the logical value "1" as shown in FIG. 9 (d). Switch 21p
There + has been switched to negative voltage corresponding to 10 g, so this is input to the integration circuit 21o as integrating an input voltage E, sharply increased at a rate integral output V _e from the integrator circuit 21o is corresponding to + 10 g, which also it increases sharply pseudo vehicle speed V _i with the.

Then, at time t _33, the pseudo vehicle speed V _i is substantially equal to the wheel speed Vw _FL as a select-high, the pseudo vehicle speed V _i is the wheel speed Vw
Is held in the wheel speed sampling value V _s of the _FL, the state is maintained until the time t ₃₄ the set time T ₃ of the timer 21f expires.

Then, the time t ₃₄ after, and the pseudo vehicle speed V _i between time t ₃₅ is decreased, retain the wheel speed sampling value V _s of the wheel speeds Vw _FL at time t ₃₆ in the period from the time point t ₃₅ ~t _37, It decreased in the period from the time point t ₃₇ ~t _39, holding the wheel speed sampling value V _s of the wheel speed Vw _R at that time at the time point t _39.

In this manner, a pseudo vehicle speed generating circuit 21, despite the wheel speed variation caused vibrations in the anti-skid control, and substantially follows the actual vehicle speed V _c of the two-dot chain line shown in FIG. 9 (a) a pseudo vehicle speed V _i can be generated. In particular, the output correction circuit 20 _sets the absolute value of the acceleration / deceleration _s based on the acceleration detection value of the longitudinal acceleration sensor 13 to a predetermined offset value (0.3
Since the g) so as to obtain the deceleration correction value _c obtained by adding, at the moment when the pseudo vehicle speed V _i and the select high wheel speed Vw _H matches is that necessarily occur, the acceleration detection value of the longitudinal acceleration sensor 13 it is possible to suppress errors caused when integrating, and that exactly to correspond to the actual vehicle speed V _c.

On the other hand, in the braking pressure control circuit 18, for example, when the front left wheel 2FL is described, since the processing of FIG. 6 is executed,
As shown in FIG. 9 (c), the wheel acceleration w _FL from the start of braking at the time t ₂₁ is increased in the deceleration direction as shown FIG. 9 (b), the time exceeds the deceleration threshold alpha t ₂₄ in setting the hold mode of the high-pressure side, then the slip ratio S _FL is time set slip ratio S ₀ (e.g., 15%) time point namely the wheel speed Vw _FL exceeds a is equal to or less than 85% of the pseudo vehicle speed V _i t ₂₆ in setting the pressure reduction mode, to recover the wheel speed Vw _FL is set to hold mode the low pressure side at the time t ₂₉ to the wheel acceleration w _FL exceeds the acceleration threshold value beta, further wheel deceleration w _FL is less than the acceleration threshold value beta set the slow increase mode at the time t ₃₁ to be, wheel acceleration and deceleration w
Set the hold mode of the high-pressure side at a time t _{36 which FL} exceeds the deceleration threshold alpha, set the pressure decrease mode when t ₃₇ that the slip ratio S _FL exceeds the set slip ratio S _0, these modes braking state The operation is repeated until the vehicle is released or the vehicle speed becomes an extremely low speed state equal to or lower than the predetermined vehicle speed, so that an accurate anti-skid effect is exhibited.

In the above-described embodiment, the case where the pseudo vehicle speed calculation circuit 17 is configured by an electronic circuit has been described. However, the present invention is not limited to this, and the calculation process may be performed using a microcomputer.

In the above embodiment, the case where the wheel speed of each wheel is detected has been described. However, the present invention is not limited to this, and a common wheel speed sensor may be provided for the left and right wheels on the driving wheel side.

Furthermore, as in the above embodiment, to select the running state in select high wheel speed Vw _H other than the acceleration state as the wheel speed selected value, selects the select high wheel low select low wheel speed Vw _L than speed in the acceleration state has been described as being not limited thereto, for example, anti-skid control is being selects the select high wheel speed Vw _H, high select the next highest wheel speed Vw _H during other driving In a vehicle that selects the second wheel speed, the third highest select third wheel speed may be selected in addition to the select low wheel speed. Further, in the case of a two-wheel drive vehicle having rear wheels or front wheels as in the above-described embodiment, a higher wheel speed of non-drive wheels that substantially follow the vehicle speed may be selected. Therefore, it is preferable to select the select low wheel speed from the viewpoint of safety.

Further, in the above-described embodiment, the case where the longitudinal acceleration sensor 13 is applied as the acceleration state detecting means has been described.However, the present invention is not limited to this, and it is determined that the direct acceleration state has detected an increase in the throttle opening. Alternatively, the vehicle may be simulated as an acceleration state when the automatic transmission is in the non-braking state and the gear position of the shift is in an accelerating state. Alternatively, when the gear position of the manual transmission can be accelerated, the clutch is connected, and the throttle opening is further increased, it may be determined that the vehicle is in the accelerated state.

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

Further, in the above-described embodiment, the case where a microcomputer is applied as the braking pressure control circuit 18 has been described. However, the present invention is not limited to this, and electronic circuits such as a comparison circuit, an arithmetic circuit, and a logic circuit are combined and configured. You can also.

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

Furthermore, in each of the embodiments described above, the case where the wheel cylinder is controlled by the hydraulic pressure is described. However, 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. According to the present invention, when the acceleration state detection means detects that the vehicle is in an acceleration state,
The wheel speed selection means selects a wheel speed lower than the maximum value among the wheel speed detection values of the wheel speed detection means, and the pseudo vehicle speed calculation means calculates the pseudo vehicle speed based on the wheel speed selection value. Therefore, when a wheel spin occurs at the driving wheel during acceleration of the vehicle, the wheel speed other than the wheel speed at which the wheel spin occurred is selected, so that the pseudo vehicle speed is affected by the wheel spin. Can be avoided, and the malfunction of the anti-skid control is reliably prevented,
The effect that accurate anti-skid control can be performed is obtained.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram showing a schematic configuration of the present invention, FIG. 2 is a block diagram showing one embodiment of the present invention, FIG. 3 is a configuration diagram showing an example of an actuator, and FIG. FIG. 5 is a characteristic diagram showing the relationship between the longitudinal acceleration of the longitudinal acceleration sensor and the output voltage, FIG. 6 is a flowchart showing an example of the processing procedure of the braking pressure control circuit, and FIG. FIGS. 8 and 9 show control maps of the braking pressure control circuit, and are waveform diagrams in an acceleration state and a deceleration state, respectively, for explaining the operation of the present invention. In the figure, 1FL and 1FR are front wheels, 1RL and 1RR are rear wheels, 2FL to 2RR are wheel cylinders (braking cylinders), 3FL to 3RR are wheel speed sensors, 4 is a brake pedal, 5 is a master cylinder, and 6F.
L to 6RR are actuators, 8 is an inflow valve, 9 is an outflow valve, 10
Is a hydraulic pump, 13 is a longitudinal acceleration sensor, 14 is a control, 15FL-15RR is a wheel speed calculation circuit, 16 is a wheel speed selection circuit, 17 is a pseudo vehicle speed calculation circuit (pseudo vehicle speed calculation means), 18 is a braking pressure control circuit, SS is a select switch (wheel speed selecting means), 19 is a select signal forming circuit (acceleration state detecting means), 20 is a correction circuit, 21 is a pseudo vehicle speed generating circuit, and 25 is a microcomputer.

Claims (1)

(57) [Claims] An acceleration detecting means for detecting longitudinal acceleration of a vehicle, a wheel speed detecting means for detecting speeds of a plurality of wheels,
Wheel speed selecting means for selecting a wheel speed detection value of each wheel speed detecting means; pseudo vehicle speed calculating means for calculating a pseudo vehicle speed based on longitudinal acceleration of the acceleration detecting means and a selected wheel speed of the wheel speed selecting means; An anti-skid having braking pressure control means for controlling a fluid pressure of a brake cylinder disposed on each wheel based on a pseudo vehicle speed of the pseudo vehicle speed calculating means and a wheel speed detection value of the wheel speed detecting means. In the control device,
An acceleration state detection means for detecting an acceleration state of the vehicle, wherein the wheel speed selection means selects a maximum value among the wheel speed detection values of the wheel speed detection means at least at the time of braking, and accelerates by the acceleration state detection means. An anti-skid control device, wherein a wheel speed lower than the maximum value is selected when a state is detected.