JPH0512338U - Vehicle stop control device - Google Patents

Abstract

(57) [Abstract] [Purpose] To prevent sudden deceleration changes in the front-rear direction when the vehicle is stopped, to facilitate brake control of the vehicle and prevent collisions with obstacles. A first valve 7 is provided in a negative pressure circuit 6 connected to a negative pressure chamber 3 of a brake booster 2, and a second valve 12 is provided in a pressure boosting circuit 9 connecting the negative pressure chamber 3 to the atmosphere. The first valve 7 is closed and the second valve 12 is opened immediately before the stop of the obstacle sensor 1
When an obstacle in the traveling direction is detected by 7, the first valve 7 is opened and the second valve 12 is closed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for automatically adjusting a braking force when a vehicle is stopped.

[0002]

[Prior Art]

 In a conventional vehicle, if the driver steps on the brake pedal with a constant force when the brake is applied to stop, the vehicle deceleration continues and the vehicle speed continues, as indicated by X in FIG. 5 (a). When the vehicle stops, a sudden change in deceleration in the front-rear direction occurs, and the nose dive suddenly returns, causing the driver and passengers to receive an unpleasant reaction force. To avoid this phenomenon, the driver had to make a delicate brake control immediately before the vehicle stopped, and he had to pay considerable attention to driving the vehicle.

[0003]

[Problems to be solved by the device]

 The present invention is intended to prevent a sudden change in the front-rear deceleration when the vehicle is stopped to facilitate the brake control of the vehicle and prevent the vehicle from colliding with an obstacle.

[0004]

[Means for Solving the Problems]

 To achieve this object, a vehicle stop control device according to the present invention comprises an operating pressure circuit connecting an operating pressure chamber of a brake booster and an operating pressure source, a first valve provided in the operating pressure circuit, and the above-mentioned operation. It has an operating pressure reduction circuit connected to the pressure chamber, a second valve provided in the operating pressure reduction circuit, and an obstacle sensor in the vehicle traveling direction. The opening of the first valve immediately before the vehicle is stopped by the brake operation. To open the second valve, and at least close the second valve in response to the detection of an obstacle by the obstacle sensor.

[0005]

Therefore, when the driver of the vehicle tries to stop the vehicle by the brake operation, the opening degree of the first valve is reduced and the second valve is opened immediately before the stop, so that the operating pressure circuit is used until then. The operating pressure in the brake booster operating pressure chamber, which was supplied from the operating pressure source, suddenly weakens and the brake operating force decreases automatically, and the front / rear deceleration changes rapidly when the vehicle is stopped even if the brake operation is continued. At the same time, when there is an obstacle in the vehicle traveling direction, at least the second valve is closed to ensure sufficient working pressure in the brake booster working pressure chamber so that the braking force is not weakened.

[0006]

【Example】

 Hereinafter, embodiments of the present invention shown in the drawings will be specifically described. In FIG. 1, a negative pressure chamber 3 of a brake booster 2 to which a brake pedal 1 of a vehicle is connected and a negative pressure tank 5 connected to an on-vehicle engine (not shown) via a check valve 4 are connected by a negative pressure circuit 6. The negative pressure circuit 6 is provided with a first valve 7 and a pressure switch 8, and the electronic control unit 13 includes a pressure switch 8, a vehicle speed sensor 14, a vehicle longitudinal acceleration sensor 15, a brake sensor 16, and an obstacle sensor 17. Receive signals from etc.

The obstacle sensor 17 is installed in front of each of small windows formed on the left and right of the front bumper of the vehicle, and from this, for example, ultrasonic waves of about 40 KHz are output at an output sound pressure of about 100 dB every about 50 ms. The distance between the front of the vehicle and the obstacle is accurately detected by transmitting the ultrasonic wave for about 1 ms and measuring the time difference between the ultrasonic wave reflected by the obstacle in front and the reception. The electronic control unit 13 receives signals from the pressure switch 8 and each sensor and outputs an opening / closing signal to the first valve 7 and the second valve 12 to control opening / closing of both valves 7 and 12 as described later.

Next, the operation of the above device will be described with reference to FIGS. First, in the flowchart of FIG. 2, the process starts from step 20 and moves to step 21, where it is checked whether the brake pedal 1 is depressed and the brake is operating. If the brake is not operating, it returns to the original state. However, if the brake is operating, the brake sensor 16 detects this and proceeds to step 22.

That is, in FIG. 3, when the vehicle is traveling at a constant speed and the brake pedal 1 is depressed at time T1 to maintain a constant pedaling force, at this time, the first valve 7 follows the line B. Open, the second valve 12 is closed as indicated by line C, and the internal pressure of the brake booster negative pressure chamber 3 changes from atmospheric pressure to negative pressure that is approximately equal to the negative pressure tank 5 as indicated by line D. The braking force of starts to operate like the E line, and the vehicle speed decreases as the A line.

In step 22, the longitudinal acceleration is read from the vehicle longitudinal acceleration sensor 15, and in the next step 23, the control vehicle speed V is read. As shown in FIG. 4, the control vehicle speed V is low when the deceleration in the vehicle front-rear direction is as low as 0.05 to 0.1 G or less, that is, when the pedaling force of the brake pedal 1 is small and the vehicle deceleration is low. When it is small, it is set to 0 and the control device is not operated, but when the deceleration of the vehicle is higher than that, the control vehicle speed V is set to increase as the deceleration increases.

In the next step 24, it is determined whether or not a flag described later is set. If the flag is set, the process proceeds to step 28, and if not, the process proceeds to step 25 and the speed sensor 14 measures the flag. It is determined whether the vehicle speed has decreased to the control vehicle speed V. If the vehicle speed has not decreased to the control vehicle speed V, the process returns to step 20, but if the vehicle speed decreases to the control vehicle speed V, for example, 5 km / h at time T2 in FIG. 3, the process proceeds to the next step 26, and The first valve 7 is closed according to the line B, and the second valve 12 is opened according to the line C. The atmosphere adjusted by the variable orifice 11 is guided to the brake booster negative pressure chamber 3 by the pressure boosting circuit 9 and the internal pressure thereof is increased. Is increased as indicated by the D line, the boost force is reduced, and the braking force is reduced as indicated by the E line. In the next step 27, the timer starts operating and sets a flag.

In step 28, the obstacle sensor 17 determines whether or not there is any obstacle within 10 to 30 cm from the front surface of the vehicle. If no obstacle is present, the process proceeds to step 29. move on. In step 29, the pressure switch 8 judges whether the negative pressure in the negative pressure circuit 6 has decreased to a predetermined value, for example, -0.2 kgf / cm square, and if it has not decreased to the above predetermined value. The process proceeds to step 30, but if it has decreased to the predetermined value, the process proceeds to step 31. When the negative pressure in the negative pressure circuit 6 decreases to the above-mentioned predetermined value at time T3 in FIG. 3 and proceeds to step 31, the second valve 12 closes as indicated by line C and the internal pressure of the brake booster negative pressure chamber 3 at that time. Hold.

In step 30, it is determined whether the time required for stopping the vehicle set by the timer since the start of this control routine, or a time with a little extra margin has elapsed, and the set time has elapsed. If not, the process returns to step 20, but at the time T4 in FIG. 3 when the set time has elapsed and the vehicle speed has become 0 according to the line A, the process proceeds to step 32, where the first valve 7 is opened according to the line B and the above The flag is defeated, and at this time, the second valve 12 remains closed as indicated by line C, so the internal pressure of the brake booster negative pressure chamber 3 returns to the old value, the boost force also increases as before, and braking is performed as indicated by line E. Increased force ensures vehicle stops.

Next, if it is detected by the obstacle sensor 17 that there is any obstacle near the front of the vehicle at time T5 in FIG. 3, the routine proceeds from step 28 to step 33, and the first valve 7 is turned on. The second valve 12 closes as indicated by the broken line B, and closes as indicated by the broken line C. The internal pressure of the brake booster negative pressure chamber 3 immediately returns to the old state as indicated by the broken line D, and the boost force also increases as it was. The braking force increases as indicated by the E broken line. In step 33, if the second valve 12 is closed as indicated by the broken line C, the internal pressure of the brake booster negative pressure chamber 3 is kept low and does not increase even if the first valve 7 is not necessarily opened. It is possible to obtain a braking force of the size of.

As described above, when the vehicle is stopped by stepping on the brake pedal 1 with a constant pedaling force, the internal pressure of the brake booster negative pressure chamber 3 is temporarily raised immediately before the vehicle stops to boost the vehicle. Since the force is reduced and the braking force is reduced by an appropriate amount, the change in deceleration before and after the vehicle at the moment the vehicle stops is much slower than in the past, as indicated by Y in Fig. 5 (b). Even if the brake pedal 1 is stepped on with a constant pedaling force, the unpleasant reaction when the vehicle is stopped is greatly reduced, and the vehicle can always be stopped smoothly. Further, since the uncomfortable reaction does not occur when the vehicle is stopped by the braking force, the braking operation is simplified and the driving of the vehicle becomes extremely easy.

Furthermore, since the braking distance is slightly extended to reduce the boosting force when the vehicle is stopped, there is no problem in normal times, but if there is any obstacle in the immediate vicinity of the front of the vehicle, , Immediately increase the braking force as it was originally, or secure a considerable amount of braking force to surely eliminate the possibility of collision even with an obstacle in the vicinity.

In the above embodiment, the brake booster negative pressure chamber 3 is connected to the atmosphere by the pressure boosting circuit 9. However, depending on the vehicle condition, the brake booster negative pressure chamber when the vehicle is stopped may be used in the control device. If it is difficult to increase the pressure in the brake booster at a sufficient speed, the pressure air source for the active electronically controlled suspension for vehicle attitude correction mounted on the vehicle is supplied to the brake booster negative pressure chamber by the pressure increase circuit. If the same control as above is performed by connecting and using the valve provided in the pressure boosting circuit, the speed of negative pressure reduction when the brake booster negative pressure chamber is opened can be increased, and the control response can be improved. Since the control start time immediately before stopping can be delayed to further shorten the operating time of the control device, the vehicle can be stopped smoothly without extending the braking distance.

Further, in each of the above-described embodiments, a simple opening / closing valve is used as the first valve and the second valve. However, one or both of them are valves capable of adjusting the opening degree, and are controlled by an electronic control device or the like. By appropriately controlling these openings, the speed, acceleration, amount, etc. of pressure increase / decrease in the brake booster negative pressure chamber can be controlled freely, so that the function as a vehicle stop control device can be enhanced. Yes, or increase the degree of freedom in design.

Further, in each of the above embodiments, the negative pressure is used as the operating pressure of the brake booster, and the atmosphere or the pressure air source is used to reduce the operating force of the brake booster. The same control operation as above is performed by using the pressure air from the pressure air source installed in the vehicle as the pressure and using the atmosphere or a suitable negative pressure to reduce the operating force of the brake booster. It goes without saying that it can be done.

[0020]

[Effect of the device]

 When the vehicle stop control device according to the present invention is used, when the vehicle driver attempts to stop the vehicle by braking, the braking force is automatically reduced immediately before the vehicle is stopped. The deceleration changes relatively slowly so that the vehicle can be stopped smoothly without causing discomfort to the driver and passengers, which in turn has the effect of facilitating the driving of the vehicle and the direction of travel of the vehicle. When there is an obstacle in the vehicle, at least the second valve is closed to secure sufficient working pressure in the brake booster working pressure chamber so that the braking force is not weakened, so the vehicle collides with the obstacle. This can be easily avoided, and the safety as a control device can be improved.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram of an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the above embodiment.

FIG. 3 is an explanatory view of the operation of the above embodiment.

FIG. 4 is a partial operation explanatory view of the above embodiment.

FIG. 5A is a diagram for explaining the operation of the conventional apparatus, and FIG.

[Explanation of symbols]

 1 Brake Pedal 2 Brake Booster 3 Brake Booster Negative Pressure Chamber 5 Negative Pressure Tank 6 Negative Pressure Circuit 7 First Valve 9 Pressure Boosting Circuit 12 Second Valve 13 Electronic Control Device 17 Obstacle Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobutaka Oda 5-3-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (72) Inventor Akira Samejima 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Automobile Industry Co., Ltd. (72) Inventor Takeo Takeo 533-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Industry Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A working pressure circuit connecting a working pressure chamber and a working pressure source of a brake booster, a first valve provided in the working pressure circuit, a working pressure reducing circuit connected to the working pressure chamber, and the same working. A second valve provided in the pressure reduction circuit and an obstacle sensor in the vehicle traveling direction are provided, and the opening degree of the first valve is reduced to open the second valve immediately before the vehicle is stopped by a brake operation.
A vehicle stop control device configured to close at least the second valve in response to an obstacle detected by the obstacle sensor.