JPS63170157A - Antiskid controller - Google Patents

Abstract

PURPOSE:To secure the maximum braking efficiency, by plural pieces of a G sensor at the time of controlling brake fluid pressure for decompression on the basis of the pseudo-speed found by integrating the body acceleration detected by the G sensor, and selecting the minimum one among plural pseudo- speed to be operated. CONSTITUTION:When a brake pedal is operated, fluid pressure out of a master cylinder 3 is fed to a wheel cylinder 2 by way of an inflow valve 4, braking a wheel 1. During this braking, when the wheel has come to a lock trend, the inflow valve 4 is closed, making it keep the brake fluid pressure. Otherwise, the inflow valve 4 is closed and simultaneously an outflow valve is opened, and a pump 7 is driven, decompressing the brake fluid to some extent. In this case, there are provided with two G sensors 11 and 22 which detect body acceleration, and body deceleration or output of these sensors is integrated, thereby finding a pseudo-speed. And, the minimum one among these operated pseudo- speed is selected, and when well speed becomes specifically related to a slip against the pseudo-speed, making a controller perform the decompressing control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an anti-skid control device for controlling brake fluid pressure so as to obtain maximum braking efficiency while preventing wheel lock during vehicle braking. .

(Prior art) Anti-skid control devices basically prevent wheel lock by reducing brake fluid pressure when the wheel speed has a predetermined slip relationship with the vehicle speed. This Doppler radar is expensive and impractical for detection, so for example,
As described in Publication No. 305, it has been proposed that a G sensor detects vehicle body acceleration (negative means deceleration), the detection result is integrated by a pseudo vehicle speed generation circuit to obtain a pseudo vehicle speed, and this is used as the vehicle speed. .

(Problem to be solved by the invention) However, in such a configuration, the G
When the sensor outputs a value indicating a significantly smaller vehicle body deceleration than the actual one due to an abnormality such as a failure, the pseudo vehicle speed is set to a value larger than the actual vehicle speed. In this case, the anti-skid control device incorrectly determines that the wheel speed is in a predetermined slip relationship with the pseudo vehicle speed even though the wheels are not locked, and the stopping distance is reduced due to unnecessary brake fluid pressure reduction. This creates a risk of significant stretching.

(Means for Solving the Problem) In order to solve this problem, the present invention provides a plurality of G sensors and a plurality of pseudo vehicle speed generation circuits, and provides the most of the pseudo vehicle speeds found by each set of G sensors and pseudo vehicle speed generation circuits. A pseudo vehicle speed selection means is provided which selects a lower speed and contributes to anti-skid control.

(Function) Each G sensor individually detects the vehicle body acceleration, and the corresponding pseudo vehicle speed generation circuit obtains the pseudo vehicle speed individually by integrating these vehicle body accelerations. The pseudo-vehicle speed selection means selects the lowest of all the pseudo-vehicle speeds, and the anti-skid control device reduces brake fluid pressure to prevent wheel locking when the wheel speed reaches a predetermined slip relationship with respect to the lowest pseudo-vehicle speed. do.

By the way, in this anti-skid control, when there is an abnormality in the G sensor, the corresponding pseudo vehicle speed generation circuit abnormally increases the pseudo vehicle speed relative to the actual vehicle speed. However, in this case, the pseudo vehicle speed selection means does not select this abnormally high pseudo vehicle speed but selects the lowest pseudo vehicle speed, so the anti-skid control described above is accurately executed even when the G sensor is abnormal, and the wheels are locked. It is possible to avoid the danger of unnecessary brake fluid pressure reduction due to a misjudgment, resulting in a significant increase in stopping distance.

Furthermore, the probability that all G sensors become abnormal is close to 0, and the reliability of anti-skid control can be greatly improved.

(Example) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIGS. 1 and 2 show an embodiment of the anti-skid control device of the present invention, which is constructed by applying the idea of the present invention to the anti-skid control device described in Japanese Patent Application Laid-open No. 128054/1983.

First, the overall configuration will be explained with reference to Fig. 1. 1 indicates wheels, 2
is the wheel cylinder, 3 is the brake master cylinder, 4 is the inflow valve (hereinafter referred to as EV valve), 5 is the outflow valve (hereinafter referred to as AV valve), 6 is the accumulator, 7 is the pump,
8 indicates check valves, respectively. Under normal conditions, the EV valve 4 is open, the AV valve 5 is closed, and the pump 7 is stopped. Here, when the brake pedal is depressed, the hydraulic pressure 9 from the master cylinder 3 is converted into the brake hydraulic pressure P via the EV valve 4 and is supplied as is to the wheel cylinder 2 to brake the wheel 1.

If the wheels 1 tend to lock during this braking, the BV valve 4 is turned to H.
The brake fluid pressure Pw is maintained despite the increase in the master cylinder fluid pressure P by closing from the level [EV double signal, or the EV valve 4 is closed and the AV valve 5 is opened by the H level AV signal, and the pump 7 by the H level MR signal, the brake fluid pressure P is reduced. In addition, the brake fluid pressure for the reduced pressure is stored in the accumulator 6.
It is then collected by the pump 7 and returned to the master cylinder 3 via the check valve 8.

The EV double signal AV signal and MR double signal level are determined by the anti-skid control circuit 9, and this circuit includes a signal from a rotation sensor 10 that detects the number of rotations of the wheel 1, and detects vehicle body acceleration (negative means deceleration). Signals G, , G2 from a plurality of (two in the illustrated example) similar G sensors 11 and 22 and a signal from a brake switch 23 that is turned ON during braking are manually input. Note that the rotation sensor 10 outputs an AC signal with a frequency proportional to the rotation speed of the wheel 1.
1.22 is an analog voltage G proportional to the vehicle acceleration.
G2 is output, and the anti-skid control circuit 9 is configured as shown in FIG.

In FIG. 2, the AC signal from the rotation sensor 10 is frequency-voltage converted by the wheel speed detection circuit 12 into a voltage proportional to the wheel rotation speed, and from this and a constant corresponding to the wheel rotation radius, the wheel circumferential speed ( Wheel speed) Find vw. Wheel speed V
w times signal wheel acceleration/deceleration detection circuit 13, comparator 14
and a plurality of (two in the illustrated example) similar pseudo vehicle speed generation circuits 15a, 15b, and the wheel acceleration/deceleration detection circuit 1.
3 calculates the wheel acceleration/deceleration αW by differentiating the wheel speed vw and sends the corresponding signal to the comparator 16.3. Supply to 17.

The pseudo vehicle speed generating circuits 15a and 15b are also input with the vehicle body acceleration signal GllG2 from the corresponding G sensor 11.22, which is inverted and amplified by the inverting amplifier 18 and input to the integrator 19. The pseudo vehicle speed generation circuit 15a will be representatively explained. The integrator 19 includes a sample-and-hold circuit 21, and this circuit calculates the wheel speed vw=VW(t) at the time t every time the sampling signal S1 is input.
is sampled and held and sent to the adder 20. When the brake switch 23 is not braking, the transistor 36 is non-conductive, and the power supply terminal 2 is output. is set to the same voltage as the brake switch 23.
It is assumed that during braking when the transistor 36 is closed, the conduction of the transistor 36 causes grounding.

The lower one of the pseudo vehicle speeds Vill' Vi2 obtained by the pseudo vehicle speed generating circuits 15a and 15b is selected by a select low switch 37 as a pseudo vehicle speed selection means, and is manually inputted to the target wheel speed generating circuit parator 14 as a select low pseudo vehicle speed vi.

Comparator 14 outputs a wheel lock level signal that satisfies v, < v+xO, 85, comparator 16
is wheel deceleration α. It is assumed that the comparator 17 outputs an H level signal when the wheel acceleration α0 is greater than or equal to the acceleration reference value b1, and the comparator 17 outputs an H level signal when the wheel acceleration α0 is greater than or equal to the acceleration reference value 81. These comparators 14. The output of 16°17 is input to the OR gate 25, and the output of this OR gate is ORed.
An EV multiplied signal is supplied to the EV valve 4 via a gate 26 and an amplifier 27. Also, the output of comparator 14.17 is A
The ND gate 28 is manually input, and the signal from the comparator 17 is input as an inverted input. The output of AND gate 28 is amplifier 2
AVVS2 is supplied as an AV signal via 9.

The output of the AND gate 28 is also supplied to a retrigger timer 30, and this timer is triggered every time the output of the AND gate 28 rises, and outputs an MR multiplied signal at H level for a certain period of time longer than one skid cycle. Therefore,)
The 4R signal remains at H level during anti-skid control, and the transistor 31 is turned on and the power supply V is turned on.

The pump 7 can be driven by the power supply +Va through the ON state of the relay contact.

The wheel acceleration/deceleration α1 is further input manually to a peak value detection circuit 33, which is reset each time the output of the comparator 16 rises, and detects the peak value α1- of the acceleration α1 for each skid cycle. Next stage variable timer 3
4 outputs a pulse signal having one cycle of a positive polarity pulse with a constant pulse width T2 and a negative polarity pulse with a variable pulse width T1 while the output of the OR gate 25 is at L level, and outputs an initial positive pulse to the OR gate 25. It is assumed that the signal is emitted with a delay of 16 hours, which is the same as the variable pulse width, from the fall of the output. It is assumed that the variable timer 34 increases the above T1 as the wheel acceleration peak value α1a increases. The pulse signal from the variable timer 34 and the MR multiplied signal are input to the AND gate 35, and the output of the AN[l gate 35 is input to the OR gate 26.

The operation of the above embodiment will be explained next.

First, the operation of the pseudo vehicle speed generating circuits 15a and 15b will be explained for the circuit 15a. During non-braking, when the brake switch 23 is turned off, the sampling signal S1 and the ripple hold circuit 21 always keep V, (t) equal to Vw. In order to do this, the pseudo vehicle speed Vi1 from the adder 20 is set to the same value as the wheel speed vw. However, since the wheel speed vw substantially matches the actual vehicle speed during non-braking, there is no problem even if Vll=Vw. During braking, when the wheel speed no longer corresponds to the vehicle speed, the signals S, S2 disappear, so the sample and hold circuit 21 supplies the signals to the braking start momentary switch 37.

1 pseudo vehicle speed generation circuit 15b uses the output G2 of the G sensor 22 to generate ljJ pseudo vehicle speed VI2 by the same action as described above.
is determined and supplied to the select low switch 37.

The select low switch 37 selects the lower of the pseudo vehicle speeds Vi1+Vi2, and sets this as the select low pseudo vehicle speed v1.
It is supplied to the target wheel speed generation circuit 24 as a signal.

Here, the anti-skid control action will be explained in the case where the wheel speed vw, wheel acceleration/deceleration α, and target wheel speed vtxo, 85, are as shown in FIG. 4 (however, vc is the actual vehicle speed shown for reference). .

When the wheel speed Vi starts to decrease with respect to the actual vehicle speed vc due to an increase in the brake fluid pressure Pw due to the braking operation, and the wheel deceleration αi becomes lower than the deceleration reference value b1 at an instant t1, the comparator 1
The output of comparator 6 rises to H level, and at this time, comparator 1
Since the output of 4.17 is L level, [the output of the OR gate 25 which gives the EV multiplied signal is H level, and the output of the AND gate 28 which gives the AV signal is L level, EV
=H level AV=L level, so the brake fluid pressure Pw switches from pressure increase to pressure holding at instant t.

Due to this pressure holding, the wheel speed vo becomes the target wheel speed v1 x 0.85.
At instant t2, when the output of the comparator 14 rises to the H level and becomes EV=AV=H level, the brake fluid pressure P. is depressurized. Note that the retrigger timer 30 is activated by the H level output of the AND gate 28 at instant t2, and the pump 7 is driven by the H level MR signal, so that the above pressure reduction is possible.

Due to the decrease in brake fluid pressure Pw from instant t2, the car's theoretical speed vw
starts to recover to the actual vehicle speed VC, and when the wheel acceleration α1 becomes equal to or higher than the acceleration reference value 81 at instant t3, the comparator 1
7 output becomes H level, EV=H level, AV=L
By reaching the level, the brake fluid pressure Pw is switched to being maintained. Due to this pressure holding, the peak value αff1 of the wheel acceleration α,
a>1 1 is obtained, this peak value is detected by the circuit 33, and the set time T1 in the variable timer 34 is set to the peak value α□
Determined according to X1.

Next, the wheel acceleration α at instant t. When becomes lower than the acceleration reference value a1, the output of the comparator 17 falls to the L level, and EV=AV=L level, thereby increasing the brake fluid pressure Pw i7] 11++'! Wow. Also, instantly,
When the output of the comparator 17 falls to the L level, the output of the OR gate 25 also falls to the L level, and the variable timer 34 is activated. Therefore,
From instant t4, variable timer 34, after a delay of set time T1 determined by peak value αIIaX1, alternately emits a positive pulse of fixed time T2 and a negative pulse of set time TI.

Since this pulse signal is outputted as an EV multiplied signal via the AND gate 35, the brake fluid pressure Pw increases and maintains the pressure at the moment t, increases for a set time T1, and maintains for a fixed time T2. The brake fluid pressure P reaches the lock fluid pressure Pt at which the maximum braking efficiency can be obtained by gradually increasing the pressure due to this, and then slightly exceeds this.

This gradual pressure increase causes wheel deceleration α. becomes equal to or greater than the deceleration reference value b1 at instant t5, instant 1. Similarly, the brake fluid pressure is maintained at EV=H level and AV=L level, and thereafter the brake fluid pressure can be reduced at instant t6.
At instant t7, the brake fluid pressure is maintained, and then at instant t
8, the next skid cycle is executed in which the brake fluid pressure is switched to a gradual pressure increase.

By the way, it was instant. In the gradual pressure increase, since the peak value α,...2 of the wheel acceleration α8 detected after the instant t7 is smaller than the initial α□81, the set time T1 in the variable timer 34 is shortened, and the above-mentioned The brake fluid pressure P can be restored to the lock fluid pressure PL at a slower speed.

By repeating this skid cycle, the brake fluid pressure P
w is controlled to be near the lock hydraulic pressure Pt, and maximum braking efficiency can be achieved while preventing wheel lock.

By the way, due to an abnormality in the G sensor 11 or 22, the output G1
Or if G2 disappears, the corresponding pseudo vehicle speed generation circuit 15
a or 15b significantly increases the pseudo vehicle speed Vt+ or Vt2. In this case, the select low switch 37 selects the lower pseudo vehicle speed v1□ or Vil as Vt, and functions so that the higher pseudo vehicle speed is not used for anti-skid control. Therefore, even if an abnormality occurs in the G sensor, the anti-skid control will not be performed haphazardly using the output thereof, and regular anti-skid control can be continued using the normal output of the G sensor.

FIG. 3 shows an example of a circuit that not only issues a warning when the above abnormality occurs, but also inhibits anti-skid control so that normal braking action is executed. be.

The abnormality determination means 40 includes a subtracter 41, an absolute value circuit 42, a comparator 43, a timer 44, and a flip-flop circuit 4.
It consists of 5 parts. The subtracter 41 calculates both pseudo vehicle speeds Vll+Vt
2, the circuit 42 calculates the absolute value l
Find V++ Vt21. The comparator 43 outputs an H level signal when the G sensor is abnormal when the absolute difference in pseudo vehicle speed IV, +-Vt21 is larger than the allowable limit ε, and the timer 44 outputs a flip-flop circuit when this output remains at the H level for a predetermined time or longer. 45 is set to change its output Q to the H level, and the flip-flop circuit 45 is reset each time the ignition switch 46 is turned on to start the engine, thereby changing the output Q to the L level.

Is the output of the flip-flop circuit 45 as described above? , I R signal is input to the AND gate 47, and this AND gate is connected to the G signal that keeps the output Q of the flip-flop circuit 45 at H level.
When the sensor is abnormal, an H level signal is output while anti-skid control is being executed to maintain the MR multiplied signal at H level.

This signal is set as the set input of the flip-flop circuit 48, and the flip-flop circuit is set when the output of the AND gate 47 falls, that is, when the anti-skid control is completed in the G sensor abnormal state, and the output Q is set to H level.
It is assumed that the ignition switch 46 is reset each time the ignition switch 46 is turned on.

When the output Q of the flip-flop circuit 48 is at H level, the transistor 49 is turned ON and the abnormality alarm lamp 51 is set to the power supply +VB.
When the transistor 49 is turned on, the base of the transistor 52 is grounded and the transistor 52 is turned off. When the transistor 49 is OFF, the voltage of the power supply +Vc is applied to the base of the transistor 52, and the transistor 52 is ONL, and the coil 53a of the relay 53 is energized by the power supply +■, thereby closing the relay contact 53b. At this time, one end of each of the EV valve 4 and AVVS 2 is connected to the power supply +■8 by the relay contact 53b,
Transistor 54 depending on the level of the Bv double signal and the AV signal.
．． 55 ON, through OF [EV valve 4 and AVVS
2. Opening and closing can be controlled.

In the configuration of this example, when the G sensor is normal, lV+
Since +Vt□1≦ε, the flip-flop circuit 45 maintains the output Q at the L level. Therefore, since the output of the AND gate 47 remains at the L level, the flip-flop circuit 48 switches the ignition switch.

The reset state is maintained by turning on the switch 46, and the output Q is set to L.
level. Therefore, the transistor 49 is
On the one hand, by turning off the lamp 51, it is notified that the G sensor is normal, and on the other hand, by turning on the transistor 52, the relay contact 53b is closed, and the EV valve 4 and AVVS2 are turned on.
Normal opening/closing control (unskid control) is possible using the V signal and AV signal.

When the G sensor is abnormal, the flip-flop circuit 45 maintains the output Q at the H level by connecting l Vl+Vtz l > ε for the time set by the timer 44 or more. Therefore, M
At the instant when the anti-skid control which changes the R-times signal to the L level is completed, the output of the AND gate -+7 is lowered and the output Q of the flip-flop circuit 48 is thereafter kept at the H level. Therefore, the transistor 49 is turned on, and the lamp 51 lights up to warn of an abnormality in the G sensor, and the base of the transistor 52 is grounded to turn off this transistor.
do. Therefore, the transistor 52 keeps the relay contact 53b open, disconnects it from the EV valve 4 and the AVVS2 power supply +■, and prohibits anti-skid control in order to keep these valves in a deenergized state regardless of the Ev double signal and the AV signal. death,
Normal braking operations can be performed.

(Effects of the Invention) Thus, the anti-skid control device of the present invention has the following effects as described above.
Since multiple G-sensors and pseudo-vehicle speed generation circuits are provided, and the lowest pseudo-vehicle speed obtained from each set of G-sensors and pseudo-vehicle speed generation circuits is used for anti-skid control, it is possible to deal with an abnormality in the G-sensor. Even if the simulated vehicle speed generating circuit abnormally increases the simulated vehicle speed, anti-skid control can be performed accurately by using a lower simulated vehicle speed (the simulated vehicle speed determined by the normal G sensor and the corresponding simulated vehicle speed generating circuit). This makes it possible to avoid the risk of an unnecessary brake fluid pressure reduction resulting in an increase in stopping distance due to a misjudgment as to whether the wheels are locked.

However, if all G sensors malfunction, the above compensation cannot be obtained, but the probability that all G sensors malfunction is almost 0, and the reliability of anti-skid control can be greatly improved. can.

[Brief explanation of the drawing]

Fig. 1 is an overall system diagram showing an embodiment of the anti-skid control device of the present invention, Fig. 2 is an electronic circuit diagram showing the anti-skid control circuit of the same side device, and Fig. 3 is a processing circuit for G sensor abnormality. FIG. 4 is an operation time chart of the anti-skid control device shown in FIGS. 1 and 2. ■...Wheel 2...Wheel cylinder 3...Brake master cylinder 4...Inflow valve 5...Outflow valve 6...Accumulator 7...Pump end...Check valve 9...Anti Skid control circuit 10...Rotation sensor 11, 22...G sensor 12...Wheel speed detection circuit 13...Wheel acceleration/deceleration detection circuit 14, 16. 17... Comparator 15a, 1
5b...pseudo vehicle speed generation circuit 18...inverting amplifier
19... Bond divider 20... Adder 21... Sample hold circuit 23... Brake switch 24... Target wheel speed generation circuit 30... Retrigger timer 33... Peak value detection circuit 34. ...Variable timer 37...Select low switch (pseudo vehicle speed selection means)
Figure 1 Figure 3

Claims (1)

[Claims] 1. A pseudo vehicle speed generating circuit is provided to obtain a pseudo vehicle speed by integrating the vehicle body acceleration detected by the G sensor, and the brake fluid pressure is reduced when the wheel speed reaches a predetermined slip relationship with respect to the pseudo vehicle speed. In the anti-skid control device, a plurality of the G sensors and the pseudo vehicle speed generation circuit are provided, and the anti-skid control is performed by selecting the lowest one among the pseudo vehicle speeds obtained by each set of the G sensor and the pseudo vehicle speed generation circuit. An anti-skid control device characterized in that it is provided with a pseudo vehicle speed selection means that contributes to.