JPH068098B2 - Anti-skidding control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an anti-skid control device that independently controls the braking hydraulic pressures of a plurality of wheels, and in particular, one of at least two wheel speeds satisfies a predetermined condition. The present invention relates to an anti-skid control device that controls the braking hydraulic pressure of other wheels by selecting the above.

(Prior Art) Conventionally, in an anti-skid control device that independently controls the braking fluid pressures of the front left and right wheels and the rear left and right wheels, the braking fluid pressures of the left and right front wheels are independently calculated by a comparison calculation based on each wheel speed. On the other hand, for the rear wheel, select high for the wheel speed of the left and right front wheels is selected, and the brake fluid pressure for the rear wheel is controlled by comparison calculation based on the higher front wheel speed. The system is adopted (Japanese Patent Publication No. 41-17082).
Etc.).

(Problems to be Solved by the Invention) However, in the conventional four-wheel anti-skid control device that adopts the select high method, the wheel speed of the rear wheel is only a predetermined speed with respect to the wheel speed of the front wheel due to the inner wheel difference during turning. Because of the low relationship, the rear wheels are apparently in a slip state during turning. In particular, the speed difference due to the inner wheel difference is constant even if the vehicle speed changes.When the vehicle turns at low speed, the slip ratio due to the inner wheel difference becomes large, and in anti-skid control during turning, the slip ratio of the rear wheel becomes larger than it actually is and braking As the wheel speed decreases, the braking fluid pressure reduction rate increases so that the slip rate is suppressed.
There is a problem that the braking performance is deteriorated and the braking stop distance is extended.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and the braking hydraulic pressures of the left front wheel, the right front wheel, and the rear wheel of the vehicle can be independently controlled. , Each of the left and right front wheels is provided with a front wheel control unit for controlling the respective brake hydraulic pressures based on the result of the comparison calculation between the wheel speeds at which the left and right front wheels are individually detected and the pseudo vehicle speed obtained based on the wheel speeds. In the rear wheel, one of the pseudo vehicle speeds of the left and right front wheels obtained by the front wheel control unit of each of the left and right front wheels is input, and the input pseudo vehicle speed,
In the anti-skid control device including the rear wheel control unit that controls the braking fluid pressure based on the result of the comparison calculation with the wheel speed detected by the rear wheel, each of the left and right front wheels obtained by the front wheel control unit. If the difference between the simulated vehicle speed values is less than or equal to a predetermined amount, one of the simulated vehicle speeds of the left and right front wheels is output to the rear wheel control unit, and the difference between the simulated vehicle speed values of the left and right front wheels is equal to a predetermined amount. If it exceeds, the selecting means is provided for correcting one of the pseudo vehicle speeds of the left and right front wheels to a slower value by a predetermined value and outputting it to the rear wheel control section.

(Operation) In the anti-skid control device of the present invention, in each of the left and right front wheels, the front wheel control unit compares the wheel speed detected for each of the left and right front wheels with the pseudo vehicle speed obtained based on the wheel speed. Based on the above, the braking fluid pressure of each front wheel is controlled independently, and in the rear wheel, when the difference between the pseudo vehicle speed values of the left and right front wheels obtained by the front wheel control unit is less than a predetermined value, If one of the pseudo vehicle speeds of the left and right front wheels is output to the rear wheel control unit and the difference between the pseudo vehicle speed values of the left and right front wheels is equal to or more than a predetermined amount, among the pseudo vehicle speeds of the left and right front wheels. Then, the faster one is corrected to a slower value by a predetermined value and output to the rear wheel control unit, and the rear wheel control unit, based on the result of the comparison calculation between the input pseudo vehicle speed and the wheel speed detected by the rear wheel, Controls the braking fluid pressure on the rear wheels.

(Embodiment) FIG. 1 is an explanatory view showing a system configuration of the present invention together with a hydraulic system.

First, the configuration will be described. 1a, 1b and 1c are anti-skid control circuits, and the anti-skid control circuit 1a is provided for the right front wheel FR.
b is provided for the left front wheel FL, and the anti-skid control circuit 1c is provided commonly for the left and right rear wheels RR and RL. Wheel speed sensors 2a, 2b, 2c output anti-skid control circuits 1a to 1c, respectively, with AC signals having a frequency proportional to the rotation of the wheels. The wheel speed sensor 2c for the rear wheel is provided on the right front wheel RR. However, actually, it is provided on a propeller shaft or the like that transmits the driving force to the left and right rear wheels RR and RL.

Front wheel anti-skid control circuit (front wheel control unit) 1a, 1
b is a pseudo vehicle speed Vc1, Vc2 that approximates the vehicle speed at the time of braking based on the wheel speeds of the left and right front wheels detected by the wheel speed sensors 2a, 2b by a circuit process which will be clarified later.
To occur.

The pseudo vehicle speeds Vc1 and Vc2 as the control amounts calculated by the anti-skid control circuits 1a and 1b for the front wheels are given to the select low switch SW1, and the select low switch SW1 is the pseudo vehicle speed Vc1 from the anti-skid control circuits 1a and 1b. Of Vc2 and Vc2, the contact is switched so as to compare and select the lower pseudo vehicle speed. Further, the anti-skid control circuits 1a and 1b output pseudo vehicle speeds K · Vc1 and K · Vc2 corrected by multiplying the pseudo vehicle speeds Vc1 and Vc2 by a predetermined correction coefficient K (where 0 <K ≦ 1), and select high. It is given to the switch SW2. This select high switch SW2 is a modified pseudo vehicle speed K · Vc1 and K
・ Switch the contact so that the higher value of Vc2 is selected and output. The select output of the select low switch SW1 and the select output of the select high switch SW2 are given to the select high switch SW3. The select high switch SW3 compares and selects the pseudo vehicle speed having a higher value or the corrected pseudo vehicle speed. It is supplied to the wheel anti-skid control circuit 1c (rear wheel control unit).

That is, the selecting means is constituted by the select low switch SW1, the select high switches SW2 and SW3, and the function of selecting the pseudo vehicle speed with respect to the anti-skid control circuit 1c of the rear wheels will be described. First, as in the case of turning braking, the left and right front wheels are selected. Pseudo vehicle speeds Vc1 and Vc2 and wheel speeds Vw1 and Vc, which are calculated when one wheel is locked due to a control error or a low μ condition after a speed difference due to the inner wheel difference occurs in the wheel speeds.
w2 and modified pseudo vehicle speeds K · Vc1, K · Vc2
Changes with the passage of time as shown in FIG.
In FIG. 2, the correction coefficient K is set to, for example, K = 0.85, and the case where the wheel speed on the front wheel left FL side is lower than that on the front wheel right FR is taken as an example.

When the pseudo vehicle speed and the corrected pseudo vehicle speed shown in FIG. 2 are obtained, first, since the pseudo vehicle speed Vc2 is lower than c1 between times to and t1, the select low switch SW1 selects the pseudo vehicle speed Vc2. On the other hand, the select high switch SW2 selects the higher K / Vc1 of the corrected pseudo vehicle speeds. The pseudo vehicle speed Vc2 selected by the select low switch SW1 and the corrected pseudo vehicle speed K · Vc1 selected by the select high switch SW2 are given to the select high switch SW3 and corrected by the select high switch SW3. Since the pseudo vehicle speed Vc2 is higher than Vc1, the larger pseudo vehicle speed Vc2 is selected and supplied to the rear wheel anti-skid control circuit 1c.

Next, at time t1, select low switch SW1
Although the selected output of the select high switch SW2 does not change, the pseudo vehicle speed Vc2 becomes smaller than the corrected pseudo vehicle speed K · Vc1 at the time t1, and the higher corrected pseudo vehicle speed K · Vc1 is selected by the select high switch SW3. , Is supplied to the anti-skid control circuit 1c for the rear wheels.

That is, as shown by the solid line in FIG. 3, the pseudo vehicle speeds Vc1 and Vc
The pseudo vehicle speed is selected by the select low until the speed difference with respect to c2 has a predetermined difference ΔV. When the predetermined speed difference ΔV is obtained, the pseudo vehicle speeds Vc1 and Vc2 are set to high and the select high is obtained. The pseudo vehicle speed, for example, K · Vc1 obtained by multiplying Vc1 by a predetermined coefficient K, is output to the anti-skid control circuit 1c for the rear wheels to realize a selective characteristic.

In FIG. 3, select low and select high are switched according to a predetermined speed difference ΔV, but the timing of time t1 at which select low is switched to select high is the pseudo vehicle speed V.
It can also be determined by the ratio Vc2 / Vc1 of c1 and Vc2. In this case, since the correction coefficient K = 0.85, it is sufficient to switch from select low to select high when the pseudo vehicle speed ratio Vc2 / Vc1 becomes 0.85 or less.

Referring again to FIG. 1, the hydraulic pressure coefficient will be described taking the front wheel right FR as an example.

Inflow valve (hereinafter referred to as EV valve) in the hydraulic system of the right front wheel FR
4a and an outflow valve (hereinafter referred to as AV valve) 5a are provided to supply the hydraulic pressure from the master cylinder 3 to the inlet of the EV valve 4a, connect the outlet of the EV valve 4a to the wheel cylinder 6a of the right front wheel FR, and It is connected to the inlet of the AV valve 5a. The outlet of the AV valve 5a is connected to the inlet of a liquid pressure pump 7a for liquid recovery, and the accumulator 8a is provided on the pump inlet side.
Are connected. The outlet of the hydraulic pump 7a is a tuck valve 9a.
Is connected to the master cylinder 3 side. EV valve 4a
And the AV valve 5a is connected to the E from the anti-skid control circuit 1a.
Wheel cylinder 6 driven by V and AV signals
The braking hydraulic pressure for a is increased, maintained, and reduced. That is, the braking hydraulic pressure is increased by opening the EV valve 4a and supplying the hydraulic pressure from the master cylinder 3 to the wheel cylinder 6a, and at this time, the AV valve 5a is closed. The braking hydraulic pressure is maintained by closing the EV valve 4a and the AV valve 5a to contain the hydraulic pressure in the wheel cylinder 6a. Further, the brake fluid pressure is reduced by closing the EV valve 4a and simultaneously opening the AV valve 5a to collect the fluid in the wheel cylinder 6a to the master cylinder 3 side via the fluid pressure pump 7a.

Such a hydraulic system includes a left front wheel FL and left and right rear wheels RR,
The RL has the same configuration. However, as the master cylinder 3, a two-system master cylinder that independently generates two systems of hydraulic pressure is used, and independent hydraulic pressure is supplied to the front wheel side and the rear wheel side. Further, a hydraulic pump 7 for collecting the liquid from the wheel cylinder 6a in order to reduce the braking hydraulic pressure.
a is driven by the MR signal from the anti-skid control circuit 1a, and this MR signal is continuously output during the anti-skid control.

FIG. 4 is a circuit block diagram showing one embodiment of the anti-skid control circuit 1a for the right front wheel FR in FIG.
The anti-skid control circuit 1b for the left front wheel FL also has exactly the same circuit configuration.

In FIG. 4, 10 is a wheel speed detection circuit, which performs F / V conversion of a detection signal from the wheel speed sensor 2a, that is, an AC signal having a frequency proportional to the rotation of the wheel, and outputs the wheel speed Vw as a voltage signal. . An acceleration / deceleration detection circuit 11 differentiates the wheel speed Vw to detect the acceleration / deceleration αw. A pseudo vehicle speed detection circuit 13 generates a pseudo vehicle speed Vc1 which approximates the vehicle body speed based on the wheel speed Vw when the comparator 12 detects the set deceleration b1 as will be described later. . The pseudo vehicle speed detection circuit 13 also generates a pseudo vehicle speed Vc1 to the select low switch SW1 and a corrected pseudo vehicle speed K · Vc1 to the select high switch SW2 provided to supply the pseudo vehicle speed to the rear wheels.

Reference numeral 14 denotes a target wheel speed generation circuit, which has a slip ratio λ at which the coefficient of friction with the road surface becomes maximum at the pseudo vehicle speed Vc1, for example, λ =
The coefficient 0.85 corresponding to 0.15 is multiplied, and Vi = 0.85 × Vc is output as the target wheel speed Vi.

Reference numerals 15, 16 and 17 denote comparators, and the comparator 15 compares the wheel speed Vw with the target wheel speed Vi to detect a predetermined slip ratio. The comparator 16 uses the acceleration / deceleration αw and the set acceleration a1.
And the set acceleration a1 is detected and the a1 signal is output. Further, the comparator 17 determines the acceleration / deceleration αw and the set deceleration b1.
Are compared with each other, and the b1 signal is output by detecting the set deceleration b1. The outputs of the comparators 15 and 16 are input to the AND gate 18, and the side of the comparator 16 is an inverting input. The AND gate 18 outputs an AV signal, and the buffer amplifier 1
It is supplied to the AV valve 5a via 9. Also, the comparator 1
The outputs 6 and 17 and the AV signal from the AND gate 18 are input to the OR gate 20, and the OR gate 20 produces an EV signal from the logical sum of the three input signals and supplies it to the EV valve 4a via the buffer amplifier 21. .

The control mode of the braking hydraulic pressure based on the acceleration / deceleration αw and the slip ratio λ obtained by the comparison calculation of the comparators 15 to 17, the AND gate 18, and the OR gate 24 is determined based on the following Table-1.

Further, the combination of EV and AV signals for giving the control mode of Table 1 is as shown in Table 2 below.

Reference numeral 22 is a retrigger timer for producing an MR signal, which is triggered by the rise of the AV signal from the AND gate 18 to the H level and produces a timer output for a fixed time, for example, 2 seconds from the trigger. Further, the set time of the retrigger timer 22 is set to a period exceeding the A signal generation period, that is, one antiskid cycle. Therefore, during the antiskid control, the retrigger is repeated by the AV signal and the antiskid control continues. And continuously outputs the timer signal, that is, the MR signal. M from this retrigger timer 22
The R signal is a pump motor 23 that drives the hydraulic pump 7a.
Activate a. Further, the timer output of the retrigger timer 22, that is, the MR signal is also given to the pseudo vehicle speed detection circuit 13, and is used as a signal for the pseudo vehicle speed detection circuit 13 to discriminate between the first cycle and the second cycle of the antiskid control. To be

FIG. 5 is a pseudo vehicle speed detection circuit 1 in the embodiment of FIG.
It is a circuit block diagram showing 3.

The pseudo vehicle speed detection circuit shown in FIG. 5 has a set deceleration b1.
It has a function of generating a pseudo vehicle speed having a straight line inclination in which the wheel speeds obtained when the above are obtained are obtained.

First, the configuration will be described. Reference numerals 24, 25, 26, and 27 are sample hold circuits, and the sample hold circuit 24 sample-holds the wheel speed Vw when the set deceleration b1 is obtained in the first cycle as an initial value Vo. Further, the sample hold circuit 25 samples and holds the time when the set deceleration b1 is obtained in the first cycle as the initial value To, and the initial values Vo and To are held until the anti-skid control ends. On the other hand, the sample and hold circuit 26 sets the wheel speed Vw every time the set deceleration b1 is obtained.
Is sampled as Vb and held until the next set deceleration b1 is obtained. In addition, the sample hold circuit 27
Also, when the set deceleration b1 is obtained, the time at that time is set as Tb to sample and hold until the set deceleration b1 is obtained next.

Reference numeral 28 denotes a counter which outputs a time signal t, which detects the start of the anti-skid control by turning on a brake switch by, for example, depressing the brake pedal, starts counting clock pulses, and increases with time. Are supplied to the sample hold circuits 25 and 27. Also, the AND gate 29 and the inverter 30 are the first
It is provided to supply the b1 signal obtained only in the first cycle to the sample and hold circuits 24 and 25. Since the MR signal is at the L level in the first cycle, the output AND gate 29 is allowed by the inversion by the inverter 30. In this state, the sample and hold circuits 24 and 25 are driven by the b1 signal obtained in the first cycle to sample and hold the initial base values Vo and To, respectively. On the other hand, in the second and subsequent cycles, the MR signal becomes H level and the hydraulic pump is driven before the b1 signal in the second cycle is obtained. Therefore, the AND gate 9 is driven by the L level output of the inverter 30. Is prohibited and b after the second cycle
The operation of the sample hold circuits 24 and 25 by one signal is prohibited. The sample hold circuits 26 and 27
With respect to (3), the b1 signal is directly applied, and the sample hold of the wheel speed Vb and the time Tb is performed every time the set deceleration b1 is obtained.

Reference numerals 31 and 32 denote subtractors, and 33 denotes a divider. The subtractors 31, 32 and the divider 33 calculate the gradient Ab of the pseudo vehicle speed after the second cycle. That is, the subtractor 31
Detects a speed difference of (Vo-Vb), and the subtractor 32 detects a time difference of (Tb-To), that is, an elapsed time. In the divider 33, Ab = (Vo-Vb) The inclination Ab is calculated as / (Tb-To).

34 is a changeover switch, and the setting device 3 is used in the first cycle.
The inclination A is switched to the 5 side and fixedly set by the setter 35.
o is taken out, the second cycle and thereafter are switched to the divider 33 side, and the inclination Ab calculated by the divider 33 is taken out. That is, the slope Ab calculated by the divider 33 cannot be calculated only with the initial values Vo and To in the first cycle, and is calculated in the second and subsequent cycles. The fixed inclination Ao is used.

The switching operation of the changeover switch 34 is performed by the AND gate 36.
And RF-FF37. That is, in the first cycle, since the MR signal is at the L level even if the b1 signal is obtained, the RS-FF 37 is in the reset state and the output Q = L.
At the level, the changeover switch 34 is changed over to the setter 35 side as shown. Next, when the b1 signal is obtained in the second cycle, since the MR signal is already at the H level, the RS-FF 37 is set by the b1 signal obtained through the AND gate 36 and the output Q = H level. Then, the changeover switch 34 is changed over to the divider 33 side.

Reference numeral 38 denotes a multiplier, which multiplies the slope Ao or Ab obtained through the changeover switch 34 and the elapsed time (t-Tb) for each cycle obtained by the subtractor 39 to obtain the slope Ao or Ab with the passage of time. Get increasing output. 40
Is a subtracter, which subtracts the output of the multiplier 38 using the wheel speed Vb held by the sample hold circuit 26 as an initial value to generate a pseudo vehicle speed Vc that decreases from the wheel speed Vb at a slope Ao or Ab with time. . This subtractor 4
The pseudo vehicle speed Vc of 0 is given to the target wheel speed generation circuit 14 of the next stage shown in FIG. Also, the subtractor 40
Is output by the select high switch 41 at the pseudo vehicle speed V.
A comparison selection that becomes a high selection with respect to w is performed, and the signal selected by the selection high switch 41 is supplied as the pseudo vehicle speed Vc1 to the selection low switch SW1 shown in FIG. It is multiplied by a predetermined correction coefficient K and is output to the select high switch SW2 of FIG. In addition, select low switch S
Pseudo vehicle speed Vc1 signal to W1 is select high switch 4
Pseudo vehicle speed Vc and wheel speed Vw selected high by 1
However, the pseudo vehicle speed Vc may be used as it is.

Next, referring to the time chart of FIG. 6, the operation of the pseudo vehicle speed detection circuit shown in FIG. 5 and the comparison calculation of the EV and AV signals for hydraulic pressure control by the anti-skid control circuit shown in FIG. Will be explained.

First, assuming that the anti-skid control is started by the braking at the time to, the coefficient of the clock pulse is started by the counter 28 of the pseudo vehicle speed detection circuit shown in FIG. 5, and the time signal t increasing with the passage of time is generated. Is output. Subsequently, when the set deceleration b1 is obtained at the time t1 of the first cycle, the sample hold circuits 24 to 27 perform the sample hold operation, and the wheel speed V at the time t1.
o and time To are sampled and held. However, since the inclination Ab cannot be calculated by the divider 33 in the first cycle, the changeover switch 34 is changed over to the setter 35 side by the output Q = L level of the RS-FF 37, and the multiplier 38 is changed over. Setting device 3 obtained via 34
Slope Ao of 5 and elapsed time from the subtractor 39 (t-Tb)
And the pseudo vehicle speed Vc that decreases from the wheel speed Vo at time t1 with the slope Ao is output from the subtractor 40. Subtractor 40
The output of is given to the select high switch 41,
When the wheel speed Vw is equal to or lower than the pseudo vehicle speed Vc, the pseudo vehicle speed Vc is selected by the select high. When the wheel speed Vw recovers and exceeds the pseudo vehicle speed Vc, the wheel speed Vw is selected and the pseudo vehicle speed Vc1 which is a combination of the two is selected. Select low switch SW
In addition to outputting to 1, the multiplier 42 multiplies the correction coefficient K and outputs the corrected pseudo vehicle speed K · Vc1 to the select high switch SW2.

Next, when the set deceleration b1 of the second cycle is obtained at time t2, the sample hold circuits 24 and 25 and the initial value Vo are set.
, And To are still held, the wheel speed Vb1 and the time Tb1 at the time t2 are sampled and held by the sample and hold 26 and 27, the RS-FF 37 is set by the b1 signal of the second cycle, and the changeover switch 34 divides. Since it is switched to the side of the device 33, the slope Ab1 calculated by the divider 33 is output to the multiplier 38, and the slope Ab1 calculated by the subtractor 40 is the wheel speed Vb1 at time t2 as an initial value. The pseudo vehicle speed Vc that decreases with the passage of time is output, the pseudo vehicle speed Vc1 is output to the select low switch SW1 via the select high switch 41, and the pseudo vehicle speed K · Vc1 corrected by the multiplier 42 is output to the select high switch SW2. Output to. Hereinafter, similarly, the calculation process of the pseudo vehicle speed is repeated every time the set deceleration b1 is obtained.

On the other hand, the calculation of the EV and AV signals in the anti-skid control circuit shown in FIG. 4 is a comparison calculation between the set deceleration αw and the slip ratio λ shown in Table 1 above, and is shown in the time chart of FIG. The EV and AV signals are generated as described above, and as is clear from Table 2, the combination of the EV and AV signals repeats increasing, holding, depressurizing, and holding of the braking fluid pressure every skid cycle. The MR signal is A
Retrigger timer 2 due to rising of V signal to H level
It is continuously output during the anti-skid control with the trigger of 2. At the end of the anti-skid control, the drive of the pump motor is stopped for a predetermined time, for example, 2 seconds after the AV signal finally rises to the H level. There is.

FIG. 7 is a circuit block diagram showing one embodiment of the rear wheel anti-skid control circuit 1c in the embodiment of FIG. The rear wheel anti-skid control circuit has a main part that is identical to the front wheel anti-skid control circuit shown in FIG. 4, and the comparator 12 and the pseudo-circuit provided in the anti-skid control circuit shown in FIG. The difference is that the vehicle speed detection circuit 13 is removed and the pseudo vehicle speed for the front wheels selected by the select high switch SW3 shown in FIG. 1 is directly input to the target wheel speed generation circuit 14c.

Next, the overall operation of the above-described embodiment will be described. First, during straight braking with a small speed difference between the left and right front wheels, as is clear from the graphs showing the selection characteristics of FIGS. The lower one of the pseudo vehicle speeds Vc1 and Vc2 of the left and right front wheels is selected and supplied to the anti-skid control circuit 1c for the rear wheels, and the anti-skid control of the rear wheels by the select low is executed in the straight braking. There is.

Next, at the time of turning braking, for example, when the braking is performed by turning left, the wheel speed of the left front wheel FL located inside becomes lower than the wheel speed of the right front wheel FR located outside, and the wheel speeds of the left front wheel FL become lower. The pseudo vehicle speed and the modified pseudo vehicle speed shown in FIG. In this case, until the speed difference or ratio between the pseudo vehicle speeds Vc1 and Vc2 reaches a predetermined value, the anti-skid control of the rear wheels by the select low similar to that during straight braking is performed, but the predetermined speed difference or speed ratio is used. Is obtained, high selection is performed to select a corrected high pseudo vehicle speed, and the high selected pseudo vehicle speed is corrected by the correction coefficient K in order to remove the influence of the slip ratio increase due to the inner wheel difference. Therefore, with Select Hi without modification, it is possible to reliably prevent the rear wheels from becoming locked by anti-skid control of the rear wheels, and even when turning braking, the rear wheels do not lock and sufficient braking performance is achieved. It can be demonstrated to shorten the braking stop distance.

Furthermore, even if one of the left and right front wheels punctures during control even during the forward braking, the high-selection of the corrected pseudo vehicle speed similar to that during turning braking is performed from the speed difference with the normal wheel due to the puncture. Thus, the anti-skid control of the rear wheels can be performed, and the pseudo vehicle speed of the front wheels on the normal side is always selected to continue the anti-skid control of the rear wheels.

FIG. 8 shows another embodiment of the pseudo vehicle speed detection circuit generated on the front wheel side for use in the rear wheel anti-skid control of the present invention, which is a modification of the circuit block A in FIG. is there.

That is, the subtractor 40, the select high switch 41, and the multiplier 42 are the same, but a changeover switch 52 that switches the output of the multiplier 42 and the output of the select high switch 41 is provided, and the changeover switch 52 is the threshold speed of the comparator 50. Vt
The switching is made by detecting h. That is, the ninth
As shown in the characteristic graph in the figure, select high switch 4
When the pseudo vehicle speed Vc1 from 1 is less than or equal to the threshold speed Vth = 50 Km / h, the changeover switch 52 is switched to the multiplier 40 by the L level output of the comparator 50, and the multiplier 42 multiplies the correction coefficient K, for example, K = 0.85. Modified pseudo vehicle speed 0.85
When the pseudo vehicle speed Vc1 is higher than the threshold speed Vth, the comparator 5 is output.
With the H level output of 0, the changeover switch 52 is changed over to the select high switch 41 side, and the pseudo vehicle speed Vc1 is output as it is without being corrected. That is, the correction coefficient K = 1 is output.

In the embodiment of FIG. 8, as the pseudo vehicle speed Vc1 increases, the influence of the inner wheel difference decreases, so the threshold speed Vth is reduced.
The pseudo vehicle speed is corrected by the predetermined coefficient K only when the vehicle speed is as follows.

Similar to the embodiment of FIG. 8, FIG. 10 is an embodiment of the present invention showing another modified example of the portion of the circuit block A in the pseudo vehicle speed detection circuit shown in FIG. The embodiment of FIG. 10 is characterized in that the multiplier 42 calculates a correction coefficient K such that K = (1−α · 1 / Vc) and multiplies it by the pseudo vehicle speed Vc1. According to the correction coefficient K as shown in the characteristic graph of FIG.
Can realize a correction characteristic that continuously changes from an initial value of 0.85 toward K = 1 as the pseudo vehicle speed V1 increases.

FIG. 12 is a block diagram showing another embodiment of the pseudo vehicle speed selection system for the rear wheel anti-skid control according to the present invention. In the embodiment of FIG. 1, the pseudo vehicle speeds Vc1 and Vc2 are set to select low. In this embodiment, the pseudo vehicle speeds Vc1 and Vc2 are set to select high by the select high switch SW10, and the corrected pseudo vehicle speeds K · Vc1 and K · Vc2 are set to select high by the select high switch SW20, and the select high switches SW10 and S10.
The select output of W20 is switched to the select high switch SW20 side of the select high corrected when the predetermined speed difference is obtained by the changeover switch SW30. Due to the switching control of the changeover switch SW30, the pseudo vehicle speed V
A subtracter 60 for detecting the absolute value of the difference between c1 and Vc2 and a comparator 62 for comparing the speed difference with a predetermined value δ are provided.
When the absolute value of the speed difference due to 0 is less than or equal to the predetermined value δ, the selector switch SW30 is closed to the select high switch SW10 side by the L level output of the comparator 62, and when the predetermined speed difference δ or more is obtained, H of the comparator 62 is obtained. Changeover switch 3 with level output
0 is switched to the select high switch SW20 side. That is, the select high switch SW10, the select high switch SW20, the changeover switch SW30, the subtractor 60, and the comparator 62 constitute the selecting means.

According to the select system shown in FIG. 12, the pseudo vehicle speed supplied to the rear wheel anti-skid control circuit 1c shown in FIG. 13 can be obtained.

That is, taking the case where the pseudo vehicle speed Vc1 is higher than Vc2 due to turning braking or the like as an example, the highest pseudo vehicle speed Vc1 is selected at times t0 to t1, and a predetermined speed difference δ is obtained at time t1. Higher modified simulated vehicle speed KV
Switch to the selection of c1.

As described above, also in the embodiment of FIG. 12, when the speed difference between the left and right front wheels is small as in the case of straight-ahead braking, anti-skid control of the rear wheels is performed by the select high, and the speed difference between the left and right front wheels is large as in the case of turning braking. When it becomes, the pseudo vehicle speed selected high can be modified to eliminate the influence of the difference in the inner wheels and used for the anti-skid control of the rear wheels.In both the straight braking and the turning braking, the braking of the rear wheel anti-skid control is performed. Performance can be guaranteed.

(Effect of the Invention) As described above, according to the present invention, in each of the left and right front wheels, the front wheel control unit performs a comparison calculation between the wheel speed at which each of the left and right front wheels is detected and the pseudo vehicle speed obtained based on the wheel speed. Based on the results of the above, the braking fluid pressure of each front wheel is controlled independently, and in the rear wheel, when the difference between the pseudo vehicle speed values of the left and right front wheels obtained by the front wheel control unit is less than a predetermined value, Outputs one of the left and right front wheel simulated vehicle speeds to the rear wheel control unit, and when the difference between the respective left and right front wheel simulated vehicle speed values is greater than or equal to a predetermined value, each of the left and right front wheel simulated vehicle speeds. Whichever is faster is corrected by a predetermined value to a slower value and output to the rear wheel control unit.The rear wheel control unit is based on the result of comparison calculation between the input pseudo vehicle speed and the wheel speed detected by the rear wheels. By comparing the braking fluid pressure on the rear wheels, comparison selection can be performed. During straight-ahead braking, where the difference in wheel speed between the left and right front wheels is small, the anti-skid control of the rear wheels can be performed based on one of the pseudo vehicle speeds of the left and right front wheels. When the difference between the pseudo vehicle speed values of the left and right front wheels of interest exceeds a predetermined value, the pseudo vehicle speed is not used as it is for the anti-skid control of the rear wheels,
In order to perform anti-skid control of the rear wheels based on the pseudo vehicle speed corrected by multiplying a predetermined coefficient K so as to remove the influence of the slip ratio due to the inner wheel difference that occurs during turning braking, It is possible to reliably prevent the control that apparently increases the slip ratio of the rear wheels due to the difference in the inner wheels, prevents the rear wheels from being locked during turning braking, and ensures a sufficient rear wheel braking force. The braking performance in control can always be guaranteed regardless of the running state.

Further, even if the wheel punctures during straight braking and a speed difference occurs in the wheel speed, anti-skid control of the rear wheel is performed by correcting the comparatively selected pseudo vehicle speed value similar to that during turning braking, and the puncture is performed. The anti-skid control of the rear wheel based on the wheel speed of the wheel is surely prevented from being performed, and the braking can be safely stopped even if the wheel is punctured during braking.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the system configuration of the present invention together with a hydraulic system, FIGS. 2 and 3 are time charts showing an example of pseudo vehicle speed selecting operation for rear wheel control in FIG. 1, and FIG.
1 is a circuit block diagram showing an embodiment of the front wheel anti-skid control circuit of FIG. 1, FIG. 5 is a circuit block diagram showing an embodiment of the pseudo vehicle speed detection circuit of FIG. 4, and FIG. 4 and 5 are time charts showing the control operation, FIG. 7 is a circuit block diagram showing one embodiment of the rear wheel anti-skid control circuit in FIG. 1, and FIG. 8 is another embodiment of the present invention. FIG. 9 is a circuit block diagram shown in FIG. 9, FIG. 9 is a graph showing a correction characteristic according to the embodiment of FIG. 8, FIG. 10 is a graph showing a correction characteristic according to another embodiment of the present invention, and FIG.
FIG. 12 is a graph showing correction characteristics according to the embodiment of the figure, FIG. 12 is a block diagram showing another embodiment of the pseudo vehicle speed selection system used in the present invention, and FIG. 13 is rear wheel control according to the embodiment of FIG. 2 is a time chart showing a pseudo vehicle speed selection operation for. 1a, 1b: Anti-skid control circuit (front wheel control unit) 1c: Anti-skid control circuit (rear wheel control unit) 2a, 2b, 2c: Wheel speed sensor 3: Master cylinder 4a, 4b, 4c: Inflow valve (EV valve) 5a, 5b, 5c: Outflow valve (AV valve) 6a, 6b, 6c: Wheel cylinder 7a, 7b, 7c: Hydraulic pump 8a, 8b, 8c: Accumulator 9a, 9b, 9c: Check valve 10: Wheel speed detection circuit 11: acceleration / deceleration detection circuit 13: pseudo vehicle speed detection circuit 14: target wheel speed generation circuit 12, 15, 16, 17: comparator 18, 29, 36: AND gate 19, 21: buffer amplifier 20: OR gate 22: retrigger timer 23a : Pump motor 24, 25, 26, 27: Sample and hold circuit 28: Counter 30: Inverter 31, 32, 39 40: subtracter 33: divider 34 and 52: selector switch 35: setting device 37: RS-FF 38, 42: multiplier

Claims (1)

[Claims] 1. A brake fluid pressure for a left front wheel, a right front wheel, and a rear wheel of a vehicle can be independently controlled. For each of the left and right front wheels, a wheel speed at which each of the left and right front wheels is detected, and the wheel speed are detected. The pseudo vehicle speed obtained based on the front wheel control unit that controls each braking hydraulic pressure based on the result of the comparison calculation, and the rear wheel includes the left and right front wheels of the left and right front wheels. Enter either one of the pseudo vehicle speeds,
Between the input pseudo vehicle speed and the wheel speed detected by the rear wheel,
In an anti-skid control device that includes a rear wheel control unit that controls the braking hydraulic pressure based on the result of the comparison calculation, the difference between the respective simulated vehicle speed values of the left and right front wheels obtained by the front wheel control unit is less than or equal to a predetermined amount. In this case, one of the simulated vehicle speeds of the left and right front wheels is output to the rear wheel control unit, and when the difference between the simulated vehicle speed values of the left and right front wheels exceeds a predetermined amount, the simulated vehicle speeds of the left and right front wheels are simulated. An anti-skid control device comprising: a selecting unit that corrects which one of the vehicle speeds is slower by a predetermined value and outputs the corrected value to the rear wheel control unit.