JPH05106499A - Throttle opening restriction method for rear-end collision prevention system - Google Patents

Abstract

PURPOSE:To improve the safety and reliability of a rear-end collision prevention system by comparing ideal deceleration acceleration with actual one based on the oil pressure of oil brakes upon deceleration to determine whether or not the brakes work well. CONSTITUTION:A oil pressure sensor 18 measures oil pressure, an actual deceleration acceleration alphad is calculated from a wheel speed obtained by a rear wheel speed sensors 12, 13, and an ideal deceleration acceleration alphai corresponding to a measured oil pressure is derived from a map, before the ratio beta of the actual deceleration acceleration alphad and the ideal one alphai is calculated. If the ratio beta is not more than a specified threshold theta, it is determined that brakes do not work well and the opening of a throttle valve is adjusted and regulated according to a set upper limit gamma so that the speed will not exceed a certain value. Therefore, this constitution prevents a rear-end collision caused by a increased stop distance due to the improper function of the brakes from being prevented even if the brakes are automatically controlled to prevent a rear-end collision.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rear-end collision prevention system for preventing rear-end collisions, and more particularly to a throttle opening limiting method of the rear-end collision prevention system for improving safety and reliability.

[0002]

2. Description of the Related Art A rear-end collision prevention system is generally constructed as shown in FIG.
_{While 0} is measured, the vehicle-to-vehicle distance sensor 2 measures the current vehicle-to-vehicle distance L _F between the host vehicle and the vehicle in front, and the speed V ₀ and the vehicle-to-vehicle distance L _F are input to the ECU 3 and EC
If U3 determines whether or not there is a rear-end collision of the vehicle with the front vehicle, and if it is determined that there is a rear-end collision risk, the ECU 3 drives the brake hydraulic pressure control means 4 of the hydraulic brake to automatically apply the braking.

At this time, to determine whether or not there is a risk of a rear-end collision, the ECU 3 calculates a vehicle stop distance L _S when the vehicle decelerates from the current speed V _{0 at a} predetermined deceleration, and this vehicle stop distance L _S is the current value. It is judged by whether the distance between vehicles is L _F or more,
If L _S <L _F , there is no danger of a rear-end collision, and if L _S ≧ L _F , there is a risk of a rear-end collision, and the brake hydraulic pressure control means 4 is driven as described above.

[0004]

In the above-described rear-end collision prevention system, when the effectiveness of the hydraulic brake is reduced due to the vapor lock, it is not possible to judge the effectiveness of the brake from the hydraulic pressure of the hydraulic brake and the deceleration. However, since the brake control is performed in the same way as usual even if the brake effectiveness becomes poor, for example, even though the brake effectiveness is poor, the brake control should be performed to prevent a rear-end collision while traveling at high speed. When you go, it is possible that the stopping distance will be longer than calculated and you will collide.

Therefore, the present invention has been made to solve the above problems, and when the braking effectiveness is poor, the opening of the throttle valve is limited to limit the vehicle speed to prevent a rear-end collision. An object of the present invention is to reliably prevent a rear-end collision due to an increase in vehicle stop distance during brake control.

[0006]

A throttle opening limiting method for a rear-end collision prevention system according to the present invention measures a vehicle speed and a vehicle-to-vehicle distance between a vehicle and a vehicle ahead by a vehicle speed sensor and an inter-vehicle distance sensor, respectively. A rear-end collision prevention system that determines whether there is a rear-end collision risk based on the speed and inter-vehicle distance and automatically brakes by controlling the hydraulic brake when there is a rear-end collision risk. At this time, the hydraulic pressure of the hydraulic brake is measured, the actual deceleration acceleration during deceleration is detected by the vehicle speed sensor, the inter-vehicle distance sensor, etc., and from the relationship between the hydraulic pressure and the deceleration acceleration obtained in advance,
An ideal deceleration acceleration corresponding to the measured value of the hydraulic pressure is derived, and by comparing the actual deceleration acceleration with the ideal deceleration acceleration, it is determined whether the hydraulic brake is effective or not, and the effectiveness is poor. In this case, the throttle opening control means limits the opening of the throttle valve to a predetermined value.

[0007]

In the present invention, the ideal deceleration acceleration is derived based on the hydraulic pressure of the hydraulic brake during deceleration, and the effectiveness of the hydraulic brake is improved by comparing the actual deceleration acceleration during deceleration with the ideal deceleration acceleration. If a defect is determined and if it is defective, the throttle opening control means limits the opening of the throttle valve. Therefore, the vehicle speed is limited so that it does not rise above a certain value, and the stop distance is reduced during brake control to prevent a rear-end collision. Is reliably prevented from extending and colliding.

[0008]

1 is a flow chart for explaining the operation of an embodiment of a throttle opening limiting method for a rear-end collision prevention system according to the present invention, and FIG. 2 is a block diagram of a rear-end collision prevention system applied.

In FIG. 2, 11 is an inter-vehicle distance sensor for measuring the inter-vehicle distance between the own vehicle and the preceding vehicle similarly to the inter-vehicle distance sensor 2 of FIG. 4, and 12 and 13 are for measuring the wheel speeds of the left and right rear wheels, respectively. Left as a vehicle speed sensor that detects the speed of the vehicle
A right rear wheel speed sensor, 14 is a battery, 15 is a brake switch which is turned on by depressing a brake pedal,
Reference numeral 16 is a brake lamp that is connected to the battery 14 through the brake switch 15 and is turned on when the brake switch 15 is turned on. Reference numeral 17 is a brake hydraulic pressure control means for controlling the hydraulic pressure of the hydraulic brake similarly to the brake hydraulic pressure control means 4 in FIG. Is a hydraulic pressure sensor for measuring the hydraulic pressure of the hydraulic brake, 19 is a throttle position sensor for detecting the position of the throttle valve, that is, the opening, and 20 is a throttle position control means together with the throttle position sensor 19 for controlling the opening of the throttle valve. The throttle opening / closing motor to be adjusted, 21 is an accelerator pedal position sensor for measuring the amount of depression of the accelerator pedal, 22 is an abnormality indicator lamp provided on the instrument panel, and 23 is a warning sound when the throttle valve opening is restricted. Is a notification means, and 24 is each sensor State of the signal and the brake switch 15 from 11～13,18,19,21 is ECU for controlling the respective portions are input.

Here, in the built-in memory of the ECU 24, the relationship between the hydraulic pressure of the hydraulic brake and the deceleration is obtained in advance and stored as a map, and as shown in FIG. The relationship with the valve opening is obtained in advance and stored as a map. The ideal deceleration acceleration corresponding to the oil pressure measured by the oil pressure sensor 18 is read from the memory and measured by the accelerator pedal position sensor 21. The opening of the throttle valve corresponding to the depression amount of the accelerator pedal is read from the memory.

Next, the control procedure will be described with reference to the flowchart of FIG.

First, as shown in FIG. 1, the ECU 24 determines whether the brake switch 15 is on (step S1). If the result of the determination is NO, that is, if the brake switch 15 is off, the throttle valve It is determined whether or not the opening degree is in the restricted state (step S2), and if the result of this determination is NO, the operation ends as it is.

On the other hand, the result of the determination in step S1 is YES.
If so, the hydraulic pressure is measured by the hydraulic pressure sensor 18, and the actual deceleration α _d is calculated from the wheel speeds by the rear wheel speed sensors 12, 13 (step S3), and the ideal corresponding to the measured hydraulic pressure. After deceleration alpha _i of is derived from the map (step S4), and the ratio between the actual deceleration alpha _d and ideal deceleration _{α i β (= α d /} α i)
Is calculated (step S5).

Here, β has a value of 1 or less.

Then, it is judged whether or not the ratio β calculated in step S5 is equal to or more than a predetermined threshold value θ (step S6). If the result of the judgment is YES, the effectiveness of the hydraulic brake is bad. Since there is no need to restrict the opening of the throttle valve, the restriction on the opening of the throttle valve is released (step S7), after which the operation ends, and step S6
If the result of the determination is NO, the effect of the hydraulic brake is poor and it is necessary to limit the opening of the throttle valve, so γ is set as the upper limit value of the opening of the throttle valve (step S8).

Next, the accelerator pedal depression amount δ _i corresponding to the upper limit value γ of the throttle opening is derived from the map, and whether or not the actual accelerator depression amount δ _d by the accelerator pedal position sensor 21 is larger than δ _i . Is determined (step S9), and if the result of this determination is NO, the actual opening of the throttle valve has not reached the upper limit value γ, so the operation ends, and the result of the determination in step S9 is YES. If so, the actual opening of the throttle valve exceeds the upper limit value γ, so the throttle opening / closing motor 2 is monitored while monitoring the signal from the throttle position sensor 19.
The throttle valve opening is adjusted to 0 by 0 (step S10), after which the operation ends.

If the result of the determination in step S2 is YES, the process proceeds to step S9.

By the way, if the effectiveness of the hydraulic brake is reduced by the vapor lock, even if the hydraulic pressure is the same, the actual deceleration α α is higher than the ideal deceleration α _{i.
Since d} becomes smaller, steps S1 and S in FIG.
The ratio β calculated by the processing of 3, S4 and S5 is “1”
The value of the ratio of α _d and α _i when the braking effectiveness is considered to be poor is set as a threshold value θ, and the braking effectiveness is calculated by comparing β calculated in step S6 with θ. Can be judged.

When it is determined that the braking effectiveness is poor, the opening of the throttle valve is adjusted and limited to the set upper limit value γ by the processing of steps S8 to S10 in FIG. It is restricted so that it does not go up, and the abnormality display lamp 22 and the notification means 23
Informs the driver that the opening of the throttle valve is in the restricted state.

Therefore, since the opening of the throttle valve is limited, even if the brake control for preventing a rear-end collision is automatically performed, the stopping distance is increased due to the ineffective braking as in the conventional case. A situation such as a rear-end collision can be reliably prevented.

[0021]

As described above, according to the throttle opening limiting method for the rear-end collision prevention system of the present invention, the hydraulic pressure is calculated by comparing the ideal deceleration based on the hydraulic pressure of the hydraulic brake during deceleration with the actual deceleration. The effectiveness of the type brake is judged to be good or bad, and if it is bad, the throttle opening control means limits the opening of the throttle valve, so that the vehicle speed can be restricted so as not to rise above a certain value, and in order to prevent a rear-end collision. When the brake control is performed, it is possible to reliably prevent the situation where the vehicle stops longer and the rear-end collision occurs, and it is possible to further improve the safety and reliability of the rear-end collision prevention system. Become.

[Brief description of drawings]

FIG. 1 is a flowchart for explaining the operation of an embodiment of a throttle opening degree limiting method for a rear-end collision prevention system according to the present invention.

FIG. 2 is a block diagram of a rear-end collision prevention system to which the present invention is applied.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is a block diagram of a conventional rear-end collision prevention system.

[Explanation of symbols]

 11 Inter-vehicle distance sensor 12, 13 Left and right rear wheel speed sensor 17 Brake hydraulic pressure control means 18 Hydraulic pressure sensor 19 Throttle position sensor 20 Throttle opening / closing motor 24 ECU

Front Page Continuation (72) Inventor Norio Omori 2-1-1 Taoyuan, Ikeda City, Osaka Daihatsu Industry Co., Ltd.

Claims (1)

[Claims] 1. A vehicle speed sensor and a vehicle-to-vehicle distance sensor measure the speed of the vehicle and the vehicle-to-vehicle distance between the vehicle and the preceding vehicle, respectively. Based on the speed and the vehicle-to-vehicle distance, it is determined whether there is a risk of a rear-end collision, and the rear-end collision is determined. Is a rear-end collision prevention system that controls the hydraulic brake to automatically apply braking when there is a danger of the following. The hydraulic pressure sensor measures the hydraulic pressure of the hydraulic brake during deceleration, and the vehicle speed sensor and the inter-vehicle distance sensor are measured. The actual deceleration acceleration during deceleration is detected by, for example, the ideal deceleration acceleration corresponding to the measured value of the hydraulic pressure is derived from the relationship between the hydraulic pressure and the deceleration acceleration obtained in advance. The effectiveness of the hydraulic brake is judged by comparison with the deceleration, and if the effectiveness is poor, the throttle opening control means sets the opening of the throttle valve to a predetermined value. Limiting the throttle opening restriction method of rear-end collision prevention system, characterized by.