JPS6050061A - Controlling method of antiskid mechanism - Google Patents

Abstract

PURPOSE:To not relieve braking force too much when the road wheels slip during the acceleration of a car by a method wherein the estimated car speed to obtain the reference wheel velocity is detected from the maximum wheel velocity normally and from the medium wheel velocity when the road wheels slip during the acceleration of the car. CONSTITUTION:The maximum and minimum speeds are selected out of respective wheel velocities VWFR, VWFL and VWR. The minimum wheel velocity selected out of the remaining wheel velocity is adopted as the medium wheel velocity. When the difference DELTAVW between the maximum velocity and the medium wheel velocity exceeds the first set velocity DELTAVW0 and the condition that the time T, during which the relation DELTAV''> DELTAVW0 is satisfied, is longer than the set time T0 is established, the medium wheel velocity is adopted as the select wheel velocity VWX. On the other hand, when neither said condition is established nor DELTAVW exeeds the second set velocity DELTAVW1 after the establishment of said condition, the maximum velocity is adopted as the select wheel velocity. The first calculated velocity VSAN is calculated by subtracting the reference velocity difference from the select wheel velocities. Further, the second calculated velocity VSBN is calculated based upon the reference wheel velocity at the previous time and the reference deceleration alpha0. The larger one between both the calculated velocities is adopted as the reference wheel velocity V.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an anti-skid control method for a vehicle having three or more wheels.

[Prior art]

As a 4-wheel anti-skid control device, vehicle speed sensors are installed in the transmission that transmits power to the driving wheels, and in the left and right driven wheels, which are wheels other than the driving wheels. Based on the signals from each vehicle speed sensor, each wheel is The wheel speeds are detected, and the vehicle body speed of the vehicle is calculated from the maximum wheel speed among the detected wheel speeds by 11! : Determine the reference wheel speed from this estimated vehicle speed, compare this reference wheel speed with each wheel speed, and set the slip knob installed on each wheel so that the slip ratio of each wheel becomes the optimal slip knob ratio. A system for controlling a brake device has been proposed.

However, in this anti-skid control device, the maximum wheel speed of each wheel speed is used as a factor in creating the estimated vehicle speed. The wheel speed of the driving wheel, which is rotating at a higher speed than the driven wheel due to slip, is selected as the maximum wheel speed, and the estimated vehicle speed becomes a value larger than the actual vehicle speed. To be more specific, for example, if a vehicle starts off on a road with a relatively small coefficient of friction with its drive wheels slipping and then immediately brakes suddenly, the situation will be as shown in Figure 1. The wheel speed Vw of the driving wheel becomes a larger value than the wheel speed ■w2 of the driven wheel, which approximates the actual vehicle speed, and the estimated vehicle speed Vsb' calculated from the maximum wheel speed becomes a large value.

Therefore, the reference wheel speed Vs', which is set based on the estimated vehicle speed, is set to a value that is Δ■ smaller than the estimated vehicle speed Vsb', and serves as the criterion for loosening the brakes. At the time Ts when braking is started by the braking operation, the wheel speed of the driven wheel becomes a value larger than ■w2, and the hydraulic pressure supplied to the brake device installed on the driven wheel is controlled to be lowered, resulting in a decrease in braking force. It becomes easier.

Therefore, the vehicle body speed is set to (1) by the maximum wheel speed of the driven wheels, not the driving wheel, and this 11 is set as the semi-base wheel speed from the constant vehicle body speed, and each wheel is set based on this reference wheel speed. It is also possible to adjust the braking force of
In the case of this method, during normal braking, the reference wheel speed at the beginning of braking decreases faster than the decrease in driving wheel speed, so the control to loosen the braking force of the driving wheels is delayed, and locking occurs. It may happen.

[Purpose of the invention]

In view of such conventional problems, an object of the present invention is to detect the estimated vehicle speed for calculating the reference wheel speed from the maximum wheel speed at all times, and to detect the estimated vehicle speed from the intermediate wheel speed at the time of acceleration slip. The purpose of this detection is to prevent the braking force from being too relaxed during acceleration slipping and to prevent skids from occurring during normal braking.

[Structure of the invention]

To achieve this objective, the present invention selects the maximum speed of each wheel speed, subtracts a predetermined speed from it to obtain a first speed, and selects an intermediate speed of each wheel speed, and selects the intermediate speed of each wheel speed. Determine the second speed by subtracting the predetermined speed from
Calculate the difference between the intermediate speed and the maximum speed, and when the difference is greater than or equal to the set speed, the second speed is set as the reference wheel speed, and normally the first speed is set as the reference wheel speed. When the deceleration of the first speed or the second speed selected as the wheel speed becomes larger than the reference deceleration, the third speed decelerated by the reference deceleration from the speed at the time of increase is set as the reference wheel speed. When the first speed or the second speed becomes higher than the third speed, the first speed or the second speed is set as the reference wheel speed.

〔Effect of the invention〕

According to the present invention, when the speed difference between the maximum wheel speed and the intermediate wheel speed becomes equal to or higher than the set speed, it is determined that an acceleration slip has occurred, and the estimated vehicle speed to determine the reference wheel speed is calculated from the maximum wheel speed. , the wheel speed is switched to an intermediate wheel speed, and in other cases, the wheel speed is increased to the base < 1 by the maximum wheel speed, so that the skin F does not occur during normal braking, and the braking immediately after acceleration slips +t5. This prevents the braking force from becoming too loose. Therefore, regardless of changes in vehicle running conditions, the vehicle speed can be estimated to be close to the actual speed, and the braking force of each wheel can be adjusted so that the slip ratio of each wheel becomes the optimum slip ratio. I can do it.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram showing the overall configuration of one embodiment. The wheel speeds of the front right wheel 10 and the front left wheel 14, which are driven wheels, are detected by wheel speed sensors 12 and 16.
The wheel speeds of the right rear wheel 18 and the left rear wheel 20, which are drive wheels, are detected by a wheel speed sensor 24 provided in a transmission 22 that drives these drive wheels 18.20. On .18.2o,
Hydraulic brake devices 26.28.30, 32 are provided, respectively, and these hydraulic brake devices 26.28.30.3
The hydraulic pressure generated by the hydraulic cylinder 36 or the hydraulic pump 38 is supplied to the actuators 2 through the actuators 48, 50, and 52, respectively. The hydraulic cylinder 3G generates brake hydraulic pressure when the driver depresses the brake pedal 34, and the hydraulic pump 38 generates hydraulic pressure according to engine rotation, and is also used as, for example, a power steering pump. . The actuator 48 is connected to the hydraulic brake device 26 of the right front wheel 10 via a hydraulic line 4°, and the actuator 5o is connected to the hydraulic brake device 30. of the drive wheel 18.2o via a hydraulic line pressure line 44. 32. The actuators 48, 50, and 52 operate each hydraulic brake device 26 according to the output of the computer 46.
．． 28.30.32, and the computer 46 controls each wheel speed sensor 12.1.
A control output is generated according to the deviation state between each wheel speed detected by 6.24 and the reference wheel speed determined from this wheel speed.

As shown in FIG. 3, each actuator 4B, 50.52 includes a regulator section 53 that adjusts the /lh pressure output from the hydraulic pump 38 to a predetermined pressure, and an increase/decrease direction control solenoid for switching the increase/decrease direction of brake oil pressure. and a brake oil pressure adjustment part 56 including an increase/decrease gradient control solenoid for switching the increase/decrease gradient of the brake oil pressure into two levels, high and low. The increase/decrease direction control solenoid of the control valve section 54, for example, causes the oil pressure to decrease in the direction of decrease when energized, and the increase/decrease gradient control solenoid of the brake oil pressure adjustment section 56, for example, makes the increase/decrease gradient of the oil pressure steep when energized. It is like that.

The computer 46 in the embodiment is a general-purpose microcomputer, and as is well known, the CPU performs arithmetic operations according to a program stored in a ROM in advance. The reference wheel speed calculation routine performed by the computer 46 is a feature of the present invention, and this routine will be described in flowcharts 1 to 1 of FIG. 4.

First, wheel speeds V w pR, V w FL, and V w R of the right front wheel 10, left front wheel 14, and rear wheel 18.20 are calculated according to the outputs of the respective wheel speed sensors 12, 16, and 24. Next, this calculated "I-wheel arrest degree VwFl
? , Vwl? 1 and Vwl, the maximum value VwHa is calculated using the following formula.

Vwmax = MAX (VwFIi, VwFL, Vw
l? ) Furthermore, the minimum value Vwmin is calculated using the following equation.

Vwmin = M I N (VwFR, VwFL,
VwR) Next, the minimum value is determined from the remaining wheel speeds excluding the minimum value V w min, and is set as the intermediate wheel speed Vwmed.

Vwmed = M I N (other wheel speeds except Vwmin) Furthermore, the maximum value V w max and the intermediate wheel speed V w
ΔVw is calculated from the difference in med using the following formula.

ΔVw==Vwmax −Vwmed Here, the time during which ΔVw exceeds the first set speed ΔVwo is T, and when 1′ exceeds the set time To, the selected wheel speed Vwx is given by the following equation.

V w x = V w med Also, before the above holds true or after the above holds true, ΔVw is the second
When the speed falls below the set speed ΔVw, the selected jH wheel speed Vwx can be changed using the following equation.

Vwx=Vwmax Using the selected wheel speed Vwx determined in this way and subtracting the reference speed difference Δ■, the first calculated speed V is calculated from the following formula.
Calculate san.

Vsan=Vwx-Δ■ Here, Δ■ is calculated by the following equation using the fixed speed Vo and the speed coefficient Kv.

ΔV=Vo+Kv−Vwx In other words, the current second calculation speed Vsbn is determined.

Vsbn=Vsn-1-α0·Δ Based on the above, the reference wheel speed Vsn is determined by the following equation as the larger of the two calculated speeds.

Vsn=MAX (Vsan, Vsbn) FIG. 5 shows how the reference wheel speed Vsn switches before and after acceleration slip.

The brake oil pressure of each wheel is controlled according to the deviation state between the reference wheel speed Vsn determined in this manner and the wheel speeds VwFR, VwFL, and Vwl of each wheel. Specifically, as shown in flowchart 1 in FIG. 6, first, the reference wheel speed Vsn and the wheel speed Vwn of each wheel are compared, and the wheel speed Vwn of the corresponding wheel is lower than the reference wheel speed Vsn. If it is, the increase/decrease direction control solenoid of the corresponding actuator is turned on, and the hydraulic pressure to the corresponding brake device is relaxed. On the other hand, when the wheel speed Vwn is higher than the reference wheel speed Vsn, the increase/decrease direction control solenoid is turned off and the hydraulic pressure to the brake device is increased. Further, by dividing the difference between the current wheel speed Vwn and the previous wheel speed Vwn-1 by the sampling time Δt, the wheel deceleration Ωwn of each wheel can be determined by the following equation.

Next, the on/off state of the increase/decrease direction control solenoid is checked, and if the increase/decrease direction control solenoid is turned on, the wheel deceleration Vwn is set to the first threshold value GTI.
II, the wheel deceleration Vwn is compared with the first threshold value G
If TI11 or less, the increase/decrease gradient control solenoid is turned on to increase the gradient of the brake oil pressure and quickly lower the brake oil pressure. On the other hand, when the wheel deceleration Ω-0 exceeds the first threshold value GTold, the increase/decrease gradient control solenoid is turned off and the brake oil pressure is gradually lowered. Also, when the increase/decrease direction control solenoid is off, &J, wheel deceleration Vwn and second threshold G
Tl12 is compared, and if the wheel deceleration Vwn exceeds the second threshold cT112, the increase/decrease gradient control solenoid is turned on and the brake oil pressure is quickly increased, while the wheel deceleration ΩWn exceeds the second threshold value cT112. If it is below the threshold value GT112, the increase/decrease gradient control solenoid is turned off and the control oil pressure is gradually increased.

Each wheel speed VwFR1VwFL, V in the above embodiment
The relationship between the operating states of the increase/decrease direction control solenoid and the increase/decrease gradient control solenoid of the actuator 48 of the right front wheel 10, and the brake oil pressure of the output of the actuator 48 is shown in the seventh table.
As shown in the figure. As is clear from the figure, no acceleration slip has occurred before braking, and the reference wheel speed Vs is
The wheel speeds VwFR, VwFL, and VwR are set to be lower by a predetermined amount ΔV from the value Vwmax, which is the maximum value traced, and the deceleration of Vwmax is the reference deceleration α.
If the value is 0 or more, the deceleration is fixed at the reference deceleration α0, and when the predetermined amount Δ■ or lower speed from Vwmax becomes greater than the deceleration speed at the reference deceleration α0. , again the latter speed is the reference wheel speed V
It is considered as s.

The magnitude relationship between the reference wheel speed Vs calculated in this manner and the wheel speed VwFli of the corresponding wheel, for example, the right front wheel 10, is compared, and the wheel speed V w FR is determined as the reference wheel speed V.
Time L1, t7, t becomes smaller than s.

At step 2, the increase/decrease direction control solenoid is turned on and the brake oil pressure is decreased. Furthermore, when this brake oil pressure is set in the decreasing direction, at times t3 and t8 when the wheel deceleration V WFR exceeds the first threshold value GTI11, the increase/decrease gradient control solenoid is turned off and the brake oil pressure is decreased. The decreasing slope is made gentler.

On the other hand, at time t4, t, when the wheel speed VwFR exceeds the reference wheel speed Vs. In this case, the increase/decrease direction control solenoid is turned off, and the brake oil pressure is increased. Furthermore, when the increase/decrease direction control solenoid is turned off, the time L5, t, at which the axle deceleration*FR becomes equal to or less than the second threshold value GTI+2.

1, the increase/decrease slope control solenoid is turned off;
The gradient of increase in brake oil pressure is assumed to be gradual.

Although specific embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and includes various embodiments within the scope of the claims. For example, the speeds of all the wheels can be detected by separate wheel speed sensors and the reference wheel speed can be determined.

[Brief explanation of the drawing]

FIG. 1 is a time chart showing the reference wheel speed calculated by a conventional undesired skid control device, and FIG.
FIG. 3 is a system diagram showing the overall configuration of an embodiment of the present invention. FIG. 3 is a block diagram showing the main structure of an actuator in an embodiment. FIG. 4 is a reference wheel of a computer included in an embodiment. Flowchart showing a control flow for increasing the speed; FIG. 5 is a time chart showing changes in reference wheel speed; FIG. 6 is a flowchart showing a control flow for operating the actuator of a computer in one embodiment. , FIG. 7 is a time chart that does not show an example of operation waveforms of each part in one embodiment. 10--Right front wheel] 2.16.24--One wheel speed sensor '14-
-Left front wheel 18.20--Rear wheel 22--) Transmission 26.28.30.32--111 Hydraulic brake device 3
4----Brake pedal 36-----Hydraulic cylinder 3 days---One pressure pump 40.42.4.1-One hydraulic line 46---Computer 48.50.52 ---Actuator 53---
-Regulator section 51--m-Control valve section 56--Brake/111 pressure adjustment section Applicant: Toyota Motor Vehicle Rinyu Co., Ltd. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5

Claims (1)

[Claims] 1, 3)), detect each wheel speed of a vehicle having upper wheels, calculate a reference wheel speed from each wheel speed, and set each wheel speed so that each wheel speed matches the reference wheel speed. An anti-skid control method for adjusting the braking force applied to the wheels, the method comprises selecting the maximum speed of each wheel speed, subtracting a predetermined speed from it to obtain a first speed, and determining an intermediate speed of each wheel speed. select, subtract a predetermined speed from this intermediate speed to obtain a second speed, and further determine the difference between the intermediate speed and the maximum speed,
When the difference is greater than or equal to the set speed, the second speed is set as the reference wheel speed, and when the difference is reached, the first speed is set as the reference wheel speed, while the first speed selected as the reference wheel speed is set as the reference wheel speed. Alternatively, when the deceleration at the second speed becomes larger than the reference deceleration, the third speed, which is decelerated by the reference deceleration from the speed at the time of the increase, is set as the reference wheel speed, and the first speed or An anti-skid control method characterized in that when the second speed becomes greater than the third speed, the first speed or the second speed is set as a reference wheel speed.