JPS6189156A - Antiskid control device - Google Patents

Abstract

PURPOSE:To compute a false car speed accurately by controlling braking hydraulic pressure with the false car speed computed based on an acceleration in the car running direction at a time when a brake is applied so as to prevent an error in computing operation of a false car from taking place. CONSTITUTION:A wheel speed Vw detected by a wheel speed detector 1 is applied to a hold circuit 12 through a switch 3. And the hold circuit 12 holds the wheel speed as an initial value of an integral operation in an arithmatic circuit 6 at a time when a braking operation starts and has a function to change it over a new value when a reset signal is newly provided. A peak value detecting circuit 10 detects the peak value of a skid cycle and outputs a reset signal to the hold circuit 12. The wheel speed Vw detected by the wheel speed detector 1 and a false car speed V computed by the arithmatic circuit 6 are inputted into a control circuit 9 to compute a slip rate enabling braking hydraulic pressure to be controlled by a comparison operation.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides anti-skid control that calculates a pseudo vehicle speed based on the longitudinal acceleration of the vehicle during braking and controls the brake fluid pressure. Regarding equipment.

(Prior art) Conventionally, in an anti-skid control device that aims to prevent the vehicle from spinning during sudden braking and shorten the braking stopping distance, the value of the slip ratio obtained from the vehicle body speed and wheel speed is calculated as the JI friction coefficient with the road surface. is the maximum slip ratio (0.15 to 0.2
However, since it is not possible to detect from the wheel speed the vehicle's ground speed during braking, which is necessary to calculate the slip ratio, for example, JP-A-57
As shown in No. 11149, the vehicle speed is calculated in a pseudo manner from the longitudinal acceleration of the vehicle during braking.

Fig. 4 shows a conventional device for calculating a pseudo vehicle speed based on the longitudinal acceleration of the vehicle body. 1 is a wheel speed detector that detects the wheel speed VW, and 2 is the longitudinal acceleration 9 of the vehicle body.
3.4 is a switch that opens when the brake pedal is depressed. 5 is a hold circuit that holds the wheel speed as an initial value when the brake pedal is depressed. 6 is an integrator 7 and an integrating capacitor 8. A calculation circuit 19 calculates the pseudo vehicle speed V, and 19 is a control circuit that generates a control signal for controlling the braking fluid pressure supplied to the wheel cylinders of the brake unit by comparing the slip ratio obtained from the wheel speed Vw and the pseudo vehicle speed V. It is.

Calculation of the pseudo vehicle speed (■) in such a conventional device focuses on the fact that the value obtained by integrating acceleration (which has a negative value because it is deceleration due to braking) gives the speed. Assuming that the pedal is depressed, switch 3 opens when the brake pedal is depressed, and the wheel speed value w(to) at that time is held in the hold circuit 5 as an initial value, and at the same time, switch 4 is also opened to reset the integral. unlock. As a result, the integral value of the detected acceleration 9(t) of the acceleration detector 2 is subtracted from the initial value of the wheel speed Vw(to) at the time to when the brake pedal is depressed, and V(t)=Vw(to )−fq(t)dt The pseudo vehicle speed V(t) of the vehicle body is output from the arithmetic circuit 6 to the control circuit 9. The control circuit 9 calculates a slip ratio λ from the pseudo vehicle speed V<t> obtained from the calculation circuit 6 and the wheel speed VW(t) from the wheel speed detector 1, and performs a comparison calculation based on this slip ratio λ. Outputs a control signal for brake fluid pressure. (Problem to be Solved by the Invention) However, in the method of calculating the pseudo vehicle speed in such a conventional anti-skid control device, when the brake pedal is depressed, that is, when braking is started, the wheel Since the configuration was such that the integrated value of the longitudinal acceleration was continuously subtracted from the speed value, the longer the brake pedal was pressed, the longer the initial value held in the hold circuit changed, and the integration time in the integrator also became longer. In this case, there is a problem in that the integral error increases, resulting in a large error between the calculated pseudo vehicle speed and the actual vehicle speed.

(Means for Solving the Problems) The present invention has been made in view of such conventional problems, and it prevents the occurrence of pseudo-type calculation errors as the braking time elapses and provides accurate The purpose of this invention is to provide an anti-skid system 611 device capable of calculating a pseudo vehicle speed, and is configured as follows.

That is, a pseudo vehicle speed is calculated from the wheel speed and the longitudinal acceleration of the vehicle, and the braking fluid pressure is controlled based on this pseudo vehicle speed.
In an anti-skid control device that uses anti-skid control, we focused on the fact that the peak value of wheel speed that describes a skid cycle approximates the vehicle speed, and we calculated the wheel speed at the start of braking and the wheel speed peak obtained during braking vJ. The values are sequentially set as initial values, and the integral value of the longitudinal acceleration of the vehicle is subtracted from the sequentially set initial IlJ values to create a pseudo vehicle speed.

(Embodiment) FIG. 1 is an IC circuit block diagram showing an embodiment of the present invention.

First, to explain the configuration, 1 is the wheel speed V from the number of rotations of the wheel.
2 is an acceleration detector that detects acceleration 9 in the longitudinal direction of the vehicle; 3.4 is a switch that opens when the brake pedal is depressed to detect the start of braking; 6 is a switch that detects the start of braking; This is an arithmetic circuit that calculates the pseudo vehicle speed, which is equipped with an integrator 7 and an integrating capacitor 8. A switch 4 is connected in parallel with the integrating capacitor 8, which is connected to the integrator 7, and when the brake pedal is depressed. The integral reset is canceled by opening switch 4.

9 is the wheel speed VW detected by the wheel speed detector 1 and the calculation circuit 6
This is a control circuit that inputs the pseudo vehicle body speed V calculated in the above to determine the slip ratio λ, and outputs a control signal for controlling the brake fluid pressure by a comparison calculation based on this slip ratio.

Furthermore, in the embodiment shown in FIG. 1, the wheel speed Vw detected by the wheel speed detector 1 is given to the hold circuit 12 via the switch 3, and the hold circuit 12 outputs the signal when the switch 3 is heard by pressing the brake pedal. It has a circuit function that holds the wheel speed, that is, the wheel speed at the time when braking is started, as the initial value of the brake control in the arithmetic circuit 6, and further switches the once held initial value to a new initial value by supplying a reset signal. Has circuit function. Reference numeral 10 denotes a peak value detection circuit which inputs the wheel speed VW detected by the wheel speed detector 1, and during anti-skid control, the wheel speed Vw shows a cycle change by repeating pressure increase and decrease of the brake fluid pressure. Since the wheel speed decreases, the circuit detects the peak value of this wheel speed in the skid cycle and outputs a reset signal to the hold circuit 12 to switch from the initial value held until then to hold the detected peak value of the wheel speed. Has a function.

Next, the calculation operation of the pseudo vehicle speed according to the embodiment shown in FIG. 1 will be explained.

Figure 2 shows wheel speed V due to anti-skid 1II Jall.
This is a time chart showing changes in W, for example, at time t
When the brake pedal is depressed at o, the switch 3 is heard by the depression of the brake pedal, and the hold circuit 12 holds the wheel speed VW (to> as the initial value when braking starts), and calculates the integral of the operation Q circuit 6. When the brake pedal is depressed, the switch 4 of the arithmetic circuit 6 is also opened and the integral reset is canceled.As a result, the integrator 7 detects the acceleration in the forward direction of the vehicle detected by the acceleration detector 2! Integration of II(t) is started, and the integrator 7 outputs a pseudo vehicle speed V(t) given by the following equation to the control circuit 9.

V(t)=Vw(to)−fQ(t)d
tt# Pseudo vehicle speed V(t
) and the wheel speed Vw(t) detected by the wheel speed detector 1, the control circuit 9 outputs a brake fluid pressure control signal, and the slip rate decreases as the wheel speed VW decreases due to the increase in the brake fluid pressure. When a certain value is reached, the brake fluid pressure is switched to reduced pressure, so that the wheel speed VW again recovers toward the vehicle speed V, and the first peak value Vw (tl) is obtained at time t1. This wheel speed V
The peak value of W is detected by the peak value detection circuit 10, and the peak value detection circuit 10 outputs a reset signal to the hold circuit 12 to reset the initially held initial value yw<to), and the wheel speed at time t1. The peak value Vw(
tl) is maintained.

Therefore, from time t1, the pseudo vehicle speed V(
t) is output from the arithmetic circuit 6.

”V(t)-VW(t1)-IQ(t
) dtl.

The initial value of the integral calculation based on the detection of the peak value of the wheel speed VW is switched at time t2. when the peak value of the wheel speed VW is also detected. t3. This is done in the same way at each time t4, and when the vehicle brakes to a halt and the brake pedal is released, switch 4 is closed, an integral reset is applied, and the output of the pseudo vehicle speed V(t) is stopped. .

In addition, in the change in wheel speed VW due to the anti-skid control shown in FIG. 2, the control of the wheel speed VW by the braking fluid pressure is performed with the slip rate λ set at a slip rate λ0.15 to 0.2 that gives the maximum braking efficiency as the target slip rate. Therefore, the wheel speed Vw is actually a lower value than the vehicle speed, but it is 1! by connecting the peak values of the wheel speed Vw. The simulated vehicle speed V according to the present invention, which is determined by J, can always avoid changing the actual vehicle speed. For example, even if a change in the vehicle speed occurs due to a change in the road surface condition during braking, the simulated vehicle speed V that follows this can always be avoided. Vehicle speed can be calculated.

FIG. 3 is a circuit block diagram showing another embodiment of the present invention, and this embodiment is characterized in that the detected acceleration is corrected according to the slope of the road surface to derive a pseudo vehicle speed. .

That is, wheel speed detector 1. Acceleration detector 2. switch 3,
4. Arithmetic circuit leaking integrator 7 and integrating capacitor 8 6.
Control circuit 9. Peak value detection circuit 10 and hold circuit 1
2 is the same as the embodiment shown in FIG. 1, but includes an engine brake acceleration calculation circuit that corrects the acceleration (1(t)) detected by the acceleration detector 2 due to the slope of the road surface, and calculates the acceleration g2 caused by engine braking. 13, the engine brake acceleration 92 and the detected acceleration !II(t), there is provided a road surface acceleration calculation circuit 14 which calculates the acceleration g3 due to the inclination of the road surface. The road surface acceleration q3 is subtracted from () to provide the corrected detected acceleration to the integrator 7 of the arithmetic circuit 6.

To explain in more detail, the engine brake acceleration calculation circuit 13 is supplied with signals indicating the vehicle speed, the gear shift position of the transmission, and the clutch connection state at the time the brake pedal is depressed, that is, when braking is started. Acceleration g2 due to engine braking is calculated from the signal. In addition, in the case of a manual transmission, it is necessary to detect the vehicle speed, gear shift position, and clutch engagement state as shown in the figure, but in the case of an automatic transmission, it is necessary to detect the vehicle speed and the gear ratio of the automatic transmission. The acceleration g2 can be expressed.

Next, the road surface acceleration g3 caused by the slope of the road surface in the road surface acceleration calculation circuit 14 is determined as follows.

First, the acceleration Q(t) in the longitudinal direction of the vehicle detected by the acceleration detector 2 is the acceleration 91 caused by the brake,
It is the sum of the acceleration Q2 caused by engine braking and the acceleration g3 caused by the slope of the road surface, and can be expressed as (+ (t) = g1 + (] 2 + (+ 3). In this relational expression, the acceleration due to braking is 91 Since the brake fluid pressure has not yet increased at the start of braking, gl=0, and since the engine brake acceleration calculation circuit 13 calculates the acceleration 92 due to the engine brake at the start of braking, the acceleration q3 due to the slope of the road surface is It is given by the following formula, (+3-a (to) 12 The road surface acceleration calculation circuit 14 subtracts the engine brake acceleration g2 from the detector Urea <to> at the braking start time to, as shown in this calculation formula. The acceleration g3 due to the slope of the road surface is calculated, and the IJ11 speed g3 due to the slope of the road surface is stored during braking and output for correction calculation.

Therefore, in the embodiment shown in FIG. 3, at the time to when the brake pedal is depressed, the road surface acceleration calculation circuit 14 calculates and stores the acceleration 93 due to the slope of the road surface from the detected acceleration a(tO) and the acceleration g2 due to the engine brake. Then, the acceleration g3 due to the inclination of the road surface is subtracted from the acceleration fig (t) in the longitudinal direction of the vehicle by the machine 14 and given to the arithmetic circuit 6 as rg(t) - (J3. 6 is V (t) = Vw (to) −f ((+
(t) −(J3) dttσ (to≦1≦tl) V (t) = Vw (ti) −f
(g (ti) − (13) !lltI (ti≦ [≦ til+ ) (OL, i outputs the pseudo vehicle speed V(t) given by the number of times the peak value is obtained to the control circuit 9, and calculates the slope of the road surface. Highly accurate anti-skid control can be performed without being affected by

(Effects of the Invention) As described above, according to the present invention, the wheel speed at the start of braking and the wheel speed peak value 147 during braking are sequentially set as initial values, and from this sequentially set initial value 1n. Since the pseudo vehicle speed is calculated by subtracting the integral 1 + i of the acceleration in the direction of light rain, a new initial value for the integral calculation is set every time the peak value of the skid cycle is obtained, and the brake pedal is continuously depressed. However, by sequentially setting new initial values, the effect of integration errors can be minimized, and a more accurate pseudo vehicle speed can be calculated.

In addition, when the road surface is sloping, the acceleration detected by the acceleration detector in the longitudinal direction of the vehicle is corrected by calculating the acceleration caused by the road surface, making it even more accurate without being affected by the road surface condition. It is possible to calculate a pseudo vehicle speed.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram showing an embodiment of the present invention, Fig. 2 is a time chart showing the calculation state of the pseudo vehicle body speed according to the embodiment of Fig. 1 together with wheel speed, and Fig. 3 is a time chart showing the calculation state of the pseudo vehicle speed according to the embodiment of the present invention. FIG. 4 is a circuit block diagram showing another embodiment. FIG. 4 is a circuit block diagram showing a conventional device. 1: Wheel speed detector 2: Acceleration detector 3.4: Switch 6: Simulation circuit 7: Integrator 8: Integrating capacitor 9: Control circuit 10: Peak value detection circuit 12: Hold circuit 13: Engine brake acceleration simulation Circuit 14: Road surface acceleration calculation circuit 15: Subtractor

Claims (2)

[Claims] (1) An anti-skid control device that calculates a pseudo vehicle speed from the wheel speed detected by a wheel speed detector and the longitudinal acceleration of the vehicle detected by an acceleration detector, and controls the brake fluid pressure based on the pseudo vehicle speed. Initial value setting means for sequentially setting a wheel speed at the start of braking and a wheel speed peak value obtained during braking as initial values, and calculating the longitudinal acceleration from the initial values sequentially set by the initial value setting means. An anti-skid control device comprising: an arithmetic circuit that calculates a pseudo vehicle speed by subtracting an integral value. (2) Calculate the longitudinal acceleration of the vehicle due to engine braking from the vehicle speed or transmission gear position at the start of braking and subtract it from the acceleration detected by the acceleration detector to calculate the longitudinal acceleration due to the slope of the road surface; 2. The anti-skid control device according to claim 1, further comprising means for correcting the detected acceleration after the start of braking based on the calculated acceleration.