JPS60244665A - Anti-skid controller - Google Patents

Abstract

PURPOSE:To ensure the steerability at the braking time and shorten braking distance in an anti-skid controller by changing the operating method thereof to the high-select method only when sensor detects that left and right wheels run on rough road. CONSTITUTION:A micro-computer 3 occasionally calculates speed of each wheel to produce slip ratio at which a maximum braking efficiency can be obtained, whereby generating reducing and increasing signals for pressure of braking liquid. Based on the detection signal of a road face sensor 8, determination is made that the road state is bad or not. If it is determined that the road state is bad, the liquid pressures of left and right front wheels are placed under the control based on a higher one of the speeds of the left and right front wheels. On the other hand, if it is determined that the road state is good, the high-select method as above is released from the left and right front wheels and the wheels are independently controlled.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an anti-skid control device that independently controls the braking fluid pressure of four wheels, and in particular to an anti-skid control device that switches the control method for the left and right front wheels depending on the road surface condition. The present invention relates to a skid control device.

(Prior art) Conventionally, a typical anti-skid control device that independently controls the brake fluid pressure of the four wheels during sudden braking is such that the brake fluid pressure of the left and right front wheels is controlled independently based on the speed of each wheel, and the brake fluid pressure of the rear wheels is The braking fluid pressure is controlled by selecting the lowest wheel speed among all wheel speeds, or by using the front high select method.
The 1c system is known as a rear wheel low selection.

In such an anti-skid control device,
For the rear wheels, both systems use a low select system that selects the lowest wheel speed among all wheel speeds and controls the rear wheel brake fluid pressure, ensuring that the rear wheels are locked during braking. This ensures safe braking and stopping without causing spin due to rear wheel lock.

However, there are two front wheel control methods: an independent control method for the left and right wheels, and a high select method.The independent control method provides the same maneuverability as a no-brake state when braking in a corner, but it is difficult to control the front wheels when the wheels are easily locked, such as on gravel roads. On roads, braking and stopping distances are longer because independent hydraulic pressure control is performed to prevent brake failure.

On the other hand, the high select system can shorten the braking distance by effectively utilizing the resistance of gravel etc. by controlling the brakes to a slightly lock even on rough roads, but when braking in a corner, the braking distance will be higher than the inner wheel depending on the difference between the inner wheels. Since the control is based on the speed of the outer wheels, there is a risk that the inner wheels may be controlled to a certain degree of locking, making it impossible to obtain sufficient maneuverability.

(Object of the Invention) The present invention has been made in view of the above-mentioned conventional problems, and aims to achieve both ensuring maneuverability during turning braking and shortening the time required to release the brake stop button on rough roads. The present invention is characterized by providing an anti-skid control device.

(Structure of the Invention) To achieve this object, the present invention provides an anti-skid control device that employs a four-wheel independent control system, in which the left and right front wheels detect the road surface condition during braking, and only when a rough road is detected. The system switches to the high select method to shorten braking and stopping distances, and selects the independent control method under other road conditions to ensure maneuverability during turning braking.

(Embodiment) FIG. 1 is a circuit block diagram showing an embodiment of the present invention together with a hydraulic system.

First, to explain the configuration, 1a, Ib, ic,
Id is each wheel, i.e. front left wheel FL, front right wheel FR, rear left wheel R
1- and a wheel speed sensor attached to the right front wheel RR, and the wheel speed sensors 1a to 1d generate an AC signal with a frequency proportional to the rotational speed of the wheel.2 is a wheel speed sensor 1 attached to the right front wheel RR.
This is a waveform shaping circuit that inputs the outputs of a to 1d, and converts the AC signals from each wheel speed sensor 1a to 1d into a pulse signal of "0"'1". 3 performs anti-skid control by Piko 1-gram control. A microcomputer that performs calculations.

The anti-skid control calculation by the microphone computer 3 is carried out by first measuring the pulse interval of the output pulse signal from the waveform shaping circuit 2 or by counting the number of pulses within a predetermined period of time to determine the wheel speed of each wheel at any time. Based on the calculated wheel speed, it outputs an anti-skid control signal, that is, a braking fluid pressure reduction and pressure increase signal for creating a slip ratio that provides maximum braking efficiency. In addition, the undeskid control signals calculated by the microcomputer 3 include slow pressure reduction in addition to brake fluid pressure reduction and pressure increase signals.

It is also possible to perform anti-skid control with higher precision by adding pressure holding and gradual pressure increase, but in order to simplify the explanation, this embodiment will take as an example the case where pressure increase and pressure decrease undeskid control signals are output. shall be.

Reference numeral 4 denotes an actuator drive circuit, which generates a drive signal for a solenoid valve that reduces and increases the brake fluid pressure based on an anti-skid control signal from the microcomputer 3.

Reference numerals 6a, 6b, and 6c are actuators equipped with electromagnetic valves that reduce or increase brake fluid pressure in response to a drive signal from the actuator drive circuit 4, and the actuators 6a, 6b are independently installed on the left and right front wheels FL and FR. , are arranged in the middle of a conduit leading from the mask cylinder 5 to the wheel cylinders 7a, 7b of the brake units provided on the left and right front wheels FL, FR. In addition, actuator 6
C is a wheel cylinder 7a of a player unit that is commonly provided to the rear wheels RL, RR, and is provided from the mask cylinder 5 to the left and right rear wheels RL, RR.

It is placed in the middle of the conduit leading to 7b.

A road surface sensor 8 is composed of a piezoelectric element installed, for example, between a shock absorber and the vehicle body, or between a coil spring and the vehicle body, and is capable of detecting the transmission force transmitted from the road surface to the vehicle body via the suspension. 9 inputs the detection signal from the road surface sensor 8 and calculates the unsprung resonance frequency component 1.
This is a signal processing circuit that outputs the effective value of the signal component corresponding to 0 to 1.5l-1z) as a voltage signal. ) to cut the signal components caused by

For example, if you use a bypass filter with a frequency of about 5 Hz, the output of this bypass filter is
A high-frequency rectifier circuit and a smoothing circuit C are constructed. 10 is a comparator, the positive input terminal of which is given the output voltage of the signal processing circuit 9, and the negative input terminal of which is given a reference voltage V rcf corresponding to the rough road judgment level, so that the output voltage of the signal processing circuit 9 is When the voltage exceeds the reference voltage vrefLJ, it is determined that the road is rough and the microphone [l combination coater 3
produces an H level output.

Next, with reference to the flowcharts shown in Figures 2 and 3,
The operation of the illustrated embodiment will be explained.

First, in a normal running state, in block 11, based on the output signal of each wheel speed sensor 18 to 1d obtained by a waveform shaping circuit (from the output pulse signal q), the left front wheel speed Vf color, the right front wheel speed Vf color, the right front wheel Wheel speed VfL1 Left rear wheel speed V
fL and the right rear wheel speed vrr are calculated in step 1], and in the next determination block 12, it is determined whether or not the control start condition for whether sudden braking to start the anti-skid control is satisfied is satisfied. There is. The determination block 12 determines whether the control start condition is satisfied, for example, if the wheel deceleration obtained by differentiating the wheel speed is a predetermined set deceleration, for example -1.
, 0G, it is determined that the anti-skid control start condition is satisfied and the process proceeds to the next block.

When determination block 12 determines whether the control start condition is met, block 13 calculates a virtual vehicle speed V based on the wheel speed. This virtual vehicle speed can be calculated by generating a virtual vehicle speed with a predetermined slope when the set deceleration is obtained, or by using a straight line that sequentially connects the wheel speeds when the set range of 3Si degrees is obtained. Various methods can be used, such as a method for generating virtual vehicle speed.

Next, in block 14, the slip rate Sw of each wheel is calculated
do. This slip rate Sw can be subtracted by subtracting the virtual iJ speed as V and the wheel speed as Vw, and calculates it as Sw = (V-Vw)/V, and with this slip rate it tI, the slip rate of the left front wheel FL is 5flL, the slip rate of the right front wheel FR is 3fL, and the slip rate of the left rear wheel RL is 3rl.

and the slip rate 3rr of the right rear wheel RR are calculated. Subsequently, in step L1- shown in block A, rear wheel control is performed using the low selection method. Rear wheel control using this low selection method reduces the slip of the left and right rear wheels, Sr I
This is done by comparing L and Srr with the ideal slip ratio (S=0.15 Pi! degrees) that provides the greatest braking force.

That is, in the determination block 15, the slip rate of the left rear wheel R is 5r.
Compare Il with the ideal slip ratio S, and if it is greater than or equal to the ideal slip ratio S, proceed to block 17 to reduce the brake fluid pressure of the left and right rear wheels, and adjust the wheel speed so that the ideal slip ratio S is obtained. Recover. On the other hand, if the slip ratio is smaller than the ideal slip ratio S in the judgment block 15, the process proceeds to the judgment block [16].
The slip rate 3rr of the right rear wheel RR is compared with the ideal slip rate S.

In this comparison, if the ideal slip rate S or more, block 17
The brake fluid pressure of the left and right rear wheels is reduced, and the wheel speed is restored so that the ideal slip ratio S is obtained.

On the other hand, when the determination block 16 determines that the slip ratio is smaller than the ideal slip ratio S, the brake hydraulic pressure of the left and right rear wheels is increased using the block 18 to reduce the wheel speed so that the ideal slip ratio S is obtained.

When the low selection type rear wheel control shown in block 8 is completed, the flow advances to the flow shown in FIG. 3.

In the flow shown in FIG. 3, first, in block 19, it is determined whether the road surface condition is rough. That is, the output voltage of the signal processing circuit 9 based on the detection signal of the road surface sensor 8 is the reference voltage V re
When the road surface is smaller than f, the output of the comparator 10 becomes L level, it is determined that the road surface is normal, and the front wheel independent control shown in block B is started. On the other hand, the output voltage of the signal processing circuit 9 based on the detection signal of the road surface sensor 8 is the reference voltage Vref.
J:;1. When the road is above, the output of the comparator 10 becomes H level, and the road is determined to be rough, and the front wheel control is shifted to the high select method shown in block C.

First, in the front wheel independent control of block B, in the determination block 20, the slip ratio of the left front wheels F and L is 5f11. and the ideal slip ratio S, and if it is smaller than the ideal slip ratio S, the process proceeds to block 21, where the brake fluid pressure of the left front wheel is reduced and the wheel speed is lowered so that the ideal slip ratio S is achieved. When it is determined in block 20 that the slip ratio is equal to or higher than the ideal slip ratio S, the brake fluid pressure of the left front wheel F[- is reduced in block 2, and the wheel speed is restored so that the ideal slip ratio S is obtained.Next, the determination block In step 23, the slip ratio 3fr of the right front wheel FR is compared with the ideal slip ratio S, and if it is smaller than the ideal slip ratio S, the process proceeds to block 24, where the brake fluid pressure of the right front wheel FR is increased to reach the ideal slip ratio S. On the other hand, when the wheel speed is equal to or higher than the ideal slip ratio S, the process proceeds to block 25, where the brake fluid pressure is reduced, and the wheel speed is restored so that the ideal slip ratio S is obtained.

Next, when the road surface condition is determined to be rough in the determination block 19, the front wheels are controlled by the high selection method.

That is, the slip rate 5f of the front wheel FL determined by the determination block 26
Compare the slip ratio S with the ideal slip ratio S, and if it is smaller than the ideal slip ratio S, proceed to block 28 and increase the braking fluid pressure of the left and right front wheels.On the other hand, if the slip ratio is equal to or higher than the ideal slip ratio S, check block 27 Proceed to and compare the slip rate S[r of the right front wheel [:R] with the ideal slip rate S. If the slip ratio is smaller than the ideal slip ratio S, the brake fluid pressure of the left and right front wheels is increased in block 28, and if the slip ratio is greater than the ideal slip ratio S, the flow advances to block 29 to increase the brake fluid pressure of the left and right front wheels. Depressurize.

In this way, in the present invention, when the road surface condition is determined to be rough, the hydraulic pressure control for the front wheels is switched to the high select method, and the hydraulic pressure control for the left and right front wheels is controlled based on the higher wheel speed of the left and right front wheels. Because pressure control is performed,
Even when braking suddenly when driving on rough roads such as gravel roads, by controlling the left and right front wheels with a slight lock, the braking distance can be shortened compared to when the left and right front wheels are controlled independently.

Of course, when the road surface is in good driving condition, the high select system for the left and right front wheels is canceled and the left and right front wheels are controlled independently, so the brakes are not used, for example, during anti-skid control during turning braking. Maneuverability equivalent to the current condition can be ensured.

FIG. 4 is a flowchart showing another embodiment of the rear wheel low select control shown in block 8 of FIG.
(Comparing and determining the size of l, V, and rr, and when the left rear wheel R[- wheel 3ilIVrL is small, the determination block 31
Proceed to step 1 and compare the left rear wheel slip rate 3rll with the ideal slip rate S. - When the slip ratio is smaller than the ideal slip ratio S, the brake fluid pressure of the left and right rear wheels is increased in block 33, and when the slip ratio is equal to or higher than the ideal slip ratio S, the brake fluid pressure of the left and right rear wheels is decreased in block 34.

On the other hand, in the determination block 30, the wheel speed Vrr of the right rear wheels R, R is determined.
If it is determined that the slip rate is small, the process proceeds to a judgment block 32, where the slip rate 3rr of the right rear wheel RR having a low wheel speed is compared with the ideal slip rate S, and if the ideal slip rate SJ is small, the slip rate 3rr of the right rear wheel RR having a low wheel speed is compared with the ideal slip rate SJ. The brake fluid pressure of the left and right rear wheels is increased with the knob 33, and on the other hand, when the ideal slip ratio is 8 or more, the brake fluid pressure with the brake [1] is increased.
The brake fluid pressure of the left and right rear wheels is reduced using the knob 34.

FIG. 5 is a flowchart showing another embodiment of the front wheel high selection control when the road surface condition of block C shown in the flowchart of FIG. 3 is determined to be a rough road.

In the flowchart of FIG. 5, first, the determination block 3
In step 5, the wheel speeds VfL and Vfr of the left and right front wheels FL and FR are compared and determined, and when the wheel speed vr n is large, the process proceeds to judgment block 36, and the left front wheel Vf, which has a large wheel speed, is determined.
When the slip ratio 5flL is equal to or higher than the ideal slip ratio S, the brake fluid pressure of the left and right front wheels is reduced in block 38, and when it is smaller than the ideal slip ratio S, the brake fluid pressure of the left and right front wheels is increased in block 39.

' On the other hand, when it is determined in the judgment block 35 that the wheel "fJVfr is large," the process proceeds to a judgment block 37, where the slip rate Sfr of the right front wheel FR having a high wheel speed is compared with the ideal slip rate S, and the ideal slip rate is determined. When the slip ratio is greater than or equal to S, the brake fluid pressure of the left and right front wheels is reduced in block 38, and when it is smaller than the ideal slip ratio S, the brake fluid pressure of the left and right front wheels is increased in block 39.

(Effects of the Invention) As described above, according to the present invention, in an anti-skid control device that uses a four-wheel independent control method, the left and right front wheels detect the road surface condition at the time of braking, and when a rough road is detected. The system switches to the high select system, and uses an independent control system for the left and right front wheels when the road surface is smooth. The braking stopping distance due to anti-skid control can be shortened, and anti-skid control can be performed that both ensures maneuverability during braking and shortens the braking stopping distance on rough roads.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
3 is a flowchart showing the operation of the embodiment shown in FIG. 1, FIG. 4 is a flowchart showing another embodiment of the rear wheel low select control shown in FIG. 2, and FIG. 5 is a flowchart showing the rear wheel high select control shown in FIG. 3. 3 is a flowchart showing an example of control. 1a, 1b, 1c, 1d: Wheel speed sensor 2: Waveform shaping circuit 3: Microcomputer 4: Actuator drive circuit 5: Mask cylinder 6a, 6b, 6c:, 7')
7b, 7c, 7d: Wheel cylinder 8: Road sensor 9: Signal processing circuit 10: ] Parator patent applicant Nissan Motor Co., Ltd. Figure 4A Figure 5

Claims (1)

[Scope of Claims] Wheel speed sensors for detecting wheel speed or equivalent to the wheel speed are provided independently on the front left and right wheels and the rear left and right wheels, or at least independently on the front left and right wheels and the rear axle differential gear,
The control section outputs anti-skid control No. 117 in response to the wheel speed detection signal from each width wheel speed sensor, and is activated by the anti-skid control signal from the control section to reduce or increase the braking fluid pressure in the wheel cylinder. An anti-skid control device in which actuators for compressing the front and left wheels are provided independently for the front and left wheels, as well as independently for the front left and right wheels, includes a road surface sensor that detects the road surface condition, and a rough road discriminating means that determines whether the road is rough from the detection signal of the road surface sensor. , During normal times when the discrimination output of the rough road discriminating means is not obtained, the wheel speeds of the left and right front wheels are independently selected and the control section controls the front left and right wheels, and the rough road discriminating means performs the discrimination by the rough road discriminating means. Anti-skid control I characterized in that, when an output is obtained, a wheel speed selection means is provided that selects a higher wheel speed among the wheel speeds of the front left and right wheels and causes the control section to control the front left and right wheels. Device.