JP3704826B2 - Emergency brake assist device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an emergency brake assist device for assisting a driver's brake operation in an emergency or the like to shorten a stop distance.
[0002]
[Prior art]
As a conventional emergency brake assist device, for example, as shown in US Pat. No. 5,158,343, an emergency brake assist control is started when a brake operation speed is a predetermined value or more. Japanese Patent Laid-Open No. 7-76267 calculates a pedal speed threshold Seff from the brake pedal stroke amount and the vehicle speed, and starts from the stroke amount when the pedal speed exceeds the threshold Seff. A configuration is shown in which emergency brake assist control is started when the pedal speed is increased by dsB when the pedal speed of the predetermined stroke dsB does not fall below Seff. In addition, as a change characteristic of the threshold value depending on the vehicle speed, a characteristic is set that takes a minimum value at an intermediate vehicle speed, that is, a value that most easily enters emergency brake assist control, and increases before and after that.
[0003]
[Problems to be solved by the invention]
By the way, when the preceding front vehicle decelerates due to braking, the driver normally performs an operation of recognizing lighting of the brake lamp of the front vehicle and depressing the brake pedal. On the other hand, when the brake lamp of the front vehicle is not turned on or after the brake lamp is turned on, the decrease in the inter-vehicle distance is recognized to determine the necessity of the braking operation. However, since it takes more time to grasp the distance between the vehicles than when the brake lamps are turned on, it recognizes a rapid decrease in the distance between vehicles after the braking operation associated with the lighting of the brake lights. As a result, a stepping operation may be performed in which the brake pedal once released is suddenly stepped on again.
[0004]
In contrast to such a two-step operation, the conventional emergency brake assist device sets a unique stroke speed threshold value when the brake pedal is depressed at the same stroke speed from the open position at approximately the same vehicle speed. Therefore, even in an operation pattern in which a step is stepped twice during a series of decelerations, control is started at the same timing, and therefore, the amount of assist control for the second brake operation that requires more urgency is insufficient. There is an inconvenience.
[0005]
In addition, when the threshold value for starting the assist control has a minimum value at an intermediate vehicle speed and increases before and after that, the vehicle speed usually decreases during the second braking operation. Rather, the control amount may decrease.
[0006]
The present invention has been made paying attention to such problems, and provides an emergency brake assist device that can surely perform sufficient assist control even for the second and subsequent brake operations that require more emergency. It is an object.
[0007]
[Means for Solving the Problems]
The first invention defines a negative pressure chamber into which negative pressure is introduced across a diaphragm connected to a master cylinder, and a variable pressure chamber into which negative pressure or atmospheric pressure is selectively introduced. In a brake device having a negative pressure booster in which a vacuum valve for introducing negative pressure and an atmospheric valve for introducing atmospheric pressure are provided, an electromagnetic valve for electrically opening and closing the vacuum valve and the atmospheric valve is formed, and a brake pedal And a control means for driving the solenoid valve based on the output of the detection means.
[0008]
The control means operates the electromagnetic valve at a position where the atmospheric valve of the negative pressure booster is opened and the vacuum valve is shut off when the depression speed of the brake pedal calculated from the pedal stroke exceeds a predetermined threshold. When the pedal is depressed, the threshold value is decreased by a predetermined time thereafter regardless of whether or not the solenoid valve is operated .
[0009]
According to a second aspect of the present invention, a negative pressure chamber into which negative pressure is introduced across a diaphragm connected to a master cylinder and a variable pressure chamber into which negative pressure or atmospheric pressure is selectively introduced are defined. In a brake device having a negative pressure booster in which a vacuum valve for introducing negative pressure and an atmospheric valve for introducing atmospheric pressure are provided, an electromagnetic valve for electrically opening and closing the vacuum valve and the atmospheric valve is formed, and a brake pedal And a control means for driving the solenoid valve based on the output of the detection means.
[0010]
The control means operates the electromagnetic valve at a position where the atmospheric valve of the negative pressure booster is opened and the vacuum valve is shut off when the pedal depression force exceeds a predetermined threshold, and when the brake pedal is depressed , Regardless of whether or not the solenoid valve is operated, the threshold value is decreased for a predetermined time thereafter.
[0011]
In a third aspect of the invention, the threshold value in the first or second aspect of the invention is sequentially set to be smaller as the number of times the brake is depressed within a predetermined time.
[0012]
According to a fourth invention, in each of the above-mentioned inventions, a means for detecting the speed of the vehicle is provided, and the threshold value of the depression speed of the brake pedal is set smaller as the vehicle speed is higher .
[0013]
According to a fifth invention, in each of the above inventions, the threshold value that is decreased as the brake pedal is depressed is gradually increased to an initial value within a predetermined time thereafter .
[0014]
[ Effect of the invention ]
The configuration of a negative pressure booster in which a negative pressure chamber and a variable pressure chamber are defined with a diaphragm connected to a master cylinder interposed therebetween is common. That is, for example, an intake pipe negative pressure generated downstream of a throttle valve of a gasoline engine or a negative pressure from a vacuum pump is always introduced into the negative pressure chamber as an operating negative pressure. In one of the variable pressure chambers, when the brake is not activated, the atmospheric valve is closed and the introduction of the atmospheric air is shut off, and the vacuum valve is opened and the negative pressure similar to that of the negative pressure chamber is introduced. There is no difference. On the other hand, when the brake pedal is depressed, the vacuum valve is closed and the introduction of the negative pressure is interrupted, and the atmospheric valve is opened to introduce the atmospheric pressure into the variable pressure chamber. As a result, a pressure difference is generated between the negative pressure chamber and the variable pressure chamber, and this acts as an assist force added to the brake pedal depression force by the driver and acts on the master cylinder, so that a boosting action is obtained.
[0015]
In the brake device equipped with such a negative pressure booster, in the first invention, basically, the electromagnetic valve is driven to a position where the assist force is generated when the depression speed of the brake pedal exceeds a predetermined threshold value. When the brake pedal depressing speed is equal to or lower than the threshold value, the control apparatus operates so that the electromagnetic valve is held at a position where no assist force is generated .
[0016]
Next, when the brake depressing operation is performed twice or more within a predetermined time from the first brake depressing operation, the threshold value is higher than the previous value regardless of the presence or absence of the assist during the first brake depressing operation. Is set to a small value, the assist force will be applied to the second and subsequent braking operations even at a lower brake pedal depression speed, and this will support the second and subsequent braking operations with a high degree of urgency. The sufficient braking force will be exhibited.
[0017]
The second invention has means for detecting the brake pedal depression force in place of the pedal stroke in the first invention as means for detecting depression of the brake pedal, and the first invention is obtained by comparing the depression force with a threshold value. The same control is performed.
[0018]
In the third invention, in a situation where the brake pedal is depressed many times within a certain time, it is estimated that the urgency is higher as the number of times the brake pedal is depressed, so the threshold value in the first or second invention is set. In response to the increase in the number of times the brake is depressed within a predetermined time, the urgent level is increased by sequentially setting a smaller value.
[0019]
In the fourth aspect of the invention, the higher the vehicle speed is, the easier it is to enter the assist control with respect to the second and subsequent brake pedal operations. Therefore, accurate brake assist control is performed according to the vehicle speed.
[0020]
According to the fifth aspect of the invention, the shorter the stepping-on interval of the brake pedal within the predetermined time, the smaller the threshold value for the subsequent stepping. In general, it is estimated that the shorter the stepping-on interval, the higher the urgency level is. Therefore, accurate brake assist control corresponding to the urgency level is performed by this control.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an outline of an embodiment of the present invention. FIG. 1 is an overall configuration diagram, and FIG. 2 is a configuration diagram of a negative pressure booster.
[0022]
First, the configuration will be described. In FIG. 1, 20 is an accelerator pedal operated by the driver, 21 is a brake pedal operated by the driver, 22 is an accelerator stroke sensor for detecting the operation amount of the accelerator pedal, and 23 is an operation amount of the brake pedal. A brake stroke sensor to be detected, 24 is an engine, and 25 is a negative pressure booster. 26 is a master cylinder, 27 is each wheel, and the rotation speed is detected by a sensor 28. Although 29 is a control apparatus and the details are mentioned later, the detection information of the accelerator stroke sensor 22, the brake stroke sensor 23, and the wheel speed sensor 28 is input, and the control signal which drives the solenoid 5 of the negative pressure booster 25 is output.
[0023]
As shown in FIG. 2, the negative pressure booster 25 includes a power piston 10 that contracts the master cylinder 26, and the negative pressure chamber 2 and the variable pressure chamber 1 are partitioned by the power piston 10 and the diaphragm 14. The power piston 10 moves against the diaphragm return spring 15 due to the differential pressure generated between the negative pressure chamber 2 and the variable pressure chamber 1, and a load corresponding to the boost is applied to the push rod 8 and the master cylinder 26 via the reaction disk 9. introduce.
[0024]
The negative pressure chamber 2 communicates with an intake pipe (downstream of the throttle valve) of an engine (not shown) and a vacuum pump to introduce an operating negative pressure.
[0025]
The variable pressure chamber 1 can communicate with the negative pressure chamber 2 via the negative pressure passage 11 of the power piston 10. When the opening of the negative pressure passage 11 is opened away from the valve body 3 as a vacuum valve, the negative pressure is increased. A negative pressure from chamber 2 is introduced.
[0026]
On the other hand, the variable pressure chamber 1 can communicate with the outside through the atmospheric pressure passage portion 4 of the valve body 3, and the atmospheric pressure passage portion 4 is opened apart from the valve seat 12 provided in the cylindrical plunger 7. And atmospheric pressure is led. That is, in this case, an atmospheric valve is configured by the atmospheric pressure passage portion 4 and the valve seat 12 of the valve body 3.
[0027]
When the brake is not operated, the valve seat 12 of the plunger 7 is seated on the atmospheric pressure passage portion 4 as shown in the figure by the urging force of the return springs 13a and 13b and is closed, and the valve body 3 is separated from the negative pressure passage 11. This is opened, so that the pressures in the negative pressure chamber 2 and the variable pressure chamber 1 are equal.
[0028]
When the brake is operated, the plunger 7 supporting the return spring 13a is moved leftward in the drawing with respect to the power piston 10 as the operating rod 6 is pushed into the power piston 10 and the brake pedal 21 is depressed. Then, the valve body 3 slides by the elastic restoring force of the return spring 13a to close the negative pressure passage 11. At the position where the negative pressure passage 11 begins to close, the atmospheric pressure passage portion 4 is still closed. When the plunger 7 further advances from this position, the valve body 3 is seated in the opening of the negative pressure passage 11 in the state where it is seated. Since the above cannot move, the valve seat 12 of the plunger 7 leaves | separates from the valve body 3, and the atmospheric pressure passage part 4 opens. As a result, atmospheric pressure is introduced into the variable pressure chamber 1, and the power piston 10 is pushed leftward in the figure against the spring 15 due to the pressure difference between the negative pressure chamber 2 and the variable pressure chamber 1, and the master cylinder 26 is moved in the contracting direction. Energize.
[0029]
On the other hand, a solenoid 5 that electromagnetically drives the plunger 7 is provided in the power piston 10 in order to perform brake assist that automatically operates the negative pressure booster 25 in an emergency.
[0030]
That is, when a predetermined drive current is supplied to the solenoid 5 by the control device 29, the plunger 7 is attracted to the left in the figure against the spring 16 by the electromagnetic force of the solenoid 5, thereby closing the negative pressure passage 11 and atmospheric pressure. The passage portion 4 moves forward to a position where the passage portion 4 is opened, whereby the power piston 10 biases the master cylinder 26 in the contracting direction.
[0031]
Next, the emergency brake assist operation in the above configuration will be described with reference to the flowchart of FIG. 3 or FIG. The control in FIG. 3 detects the depression of the brake pedal from the stroke, and the control in FIG. 4 also detects from the pedal force. The difference between them is only this point. 3 will be mainly described, and portions different from those in FIG. 4 are indicated in parentheses.
[0032]
The control routine shown in FIG. 3 or 4 is an interrupt processing routine executed at a predetermined cycle. First, at step 101, the brake stroke value (brake pedal depression force) is read, and at step 102, the vehicle speed is read.
[0033]
Next, in step 103, it is determined whether or not the brake pedal is depressed from the stroke value (depression force value). If it is depressed, the process proceeds to step 104. If not, the process proceeds to step l14.
[0034]
In step 104, the brake stroke change amount ΔBS (brake pedal force change amount ΔPS) is calculated, and in step 105, the maximum value ΔBSmax (ΔPSmax) is obtained by comparing with the previously stored ΔBS. Update. That is, ΔBSmax (ΔPSmax) represents the maximum brake stroke speed (maximum pedaling force) generated during a series of braking.
[0035]
Next, in step 106, a threshold value determining coefficient k1 is set based on the timer determined in steps 119 and 120 described later. This timer is an integration counter managed by the brake-off time after the assist control is activated. As shown in FIG. 5, the determination of kl is made such that a small value k1s is selected when the timer value is within 2 seconds, and a large value (in this case, an initial value) klb is selected when the timer value is 2 seconds or more. Or as shown in FIG. 6, it is good also as a characteristic which linearly increases from k1s to k1b and it resets with progress of brake-off time.
[0036]
In step 1007, a threshold value determining coefficient k2 is set based on the vehicle speed. As shown in FIG. 7, a smaller value of k2 is selected as the vehicle speed increases. In step 108, a brake stroke speed threshold value (brake pedal force threshold value) k is determined from the coefficients kl and k2 obtained in steps 106 and 107. In this case, k = kl * k2.
[0037]
In step l09, it is determined whether the maximum braking stroke speed ΔBSmax (ΔPSmax) during braking obtained in step 105 is greater than a threshold value k. Flag 1 indicating whether or not is set, and brake assist control is started in step l12. That is, the solenoid 5 is driven so that the vacuum valve of the negative pressure booster is closed and the atmospheric valve is opened, and the atmospheric pressure is introduced into the variable pressure chamber 1 to generate a differential pressure with respect to the negative pressure chamber 2. Generate hydraulic pressure with a wheel cylinder.
[0038]
If the maximum brake stroke speed ΔBSmax (ΔPSmax) is less than or equal to the threshold value k in step l09, the flag l is cleared in step lll, the vacuum valve of the negative pressure booster is opened in step l13, and the atmospheric valve is The solenoid 5 is driven so as to reach the initial closed position, and the control is terminated. Note that even if the energization of the solenoid 5 is interrupted, the initial position is reached by the biasing force of the springs 13a and 13b.
[0039]
If it is determined in step 103 that the brake is not depressed, the maximum brake stroke speed ΔBSmax (ΔPSmax) is cleared in step 114. Next, it is determined whether or not the flag l indicating whether or not the assist control has been performed is set in step 115, and if it is reset, it is managed by the brake-off time after the assist control is activated in step l20. Clear the timer to end control. If the flag 1 is set, if the vehicle speed is less than or equal to the predetermined value in step l6, the timer managed by the brake-off time after the assist control is activated in step 120 is cleared and the control is terminated. This is the control for the second depression, which is the main point of the main kit, only when the vehicle speed is high and the urgency is high.
[0040]
Next, in step 117, it is determined whether or not the timer has exceeded a predetermined value, in this case, 2 seconds. If not, the timer is incremented in step 119. Otherwise, the flag l is cleared in step 118. In step 120, the timer is cleared and the control is terminated. The meaning of step ll7 is to determine that a pattern in which the brake is stepped on again after a certain amount of time of brake off is a normal brake operation, not an emergency brake operation to be brake-assisted.
[Brief description of the drawings]
FIG. 1 is an overall schematic configuration diagram of an embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a booster according to an embodiment of the present invention.
FIG. 3 is a flowchart showing the contents of a control operation according to an embodiment of the present invention.
FIG. 4 is a flowchart showing the contents of a control operation according to an embodiment of the present invention.
FIG. 5 is a characteristic diagram showing a setting example of a threshold value with respect to a brake pedal depression speed.
FIG. 6 is a characteristic diagram showing another setting example of a threshold value for a brake pedal depression speed.
FIG. 7 is a characteristic diagram showing a setting example of a threshold value according to the vehicle speed.
[Explanation of symbols]
1 Transformer chamber 2 Negative pressure chamber 3 Valve body (vacuum valve)
4 Atmospheric pressure passage 5 Solenoid (solenoid valve)
6 Operating rod 7 Plunger 8 Push rod 9 Reaction disk 10 Power piston 11 Negative pressure passage 12 Valve seat (atmospheric valve)
13a Return Spring 13b Return Spring 14 Diaphragm 15 Diaphragm Return Spring 16 Spring 20 Accelerator Pedal 21 Brake Pedal 22 Accelerator Stroke Sensor 23 Brake Stroke Sensor 24 Engine 25 Negative Pressure Booster 26 Master Cylinder 27 Vehicle Wheel 28 Wheel Rotation Speed Sensor 28
29 Controller

Claims (5)

A negative pressure chamber into which negative pressure is introduced across a diaphragm connected to the master cylinder and a variable pressure chamber into which negative pressure or atmospheric pressure is selectively introduced are defined, and negative pressure is introduced into the variable pressure chamber. In a brake device with a negative pressure booster that is provided with a vacuum valve and an atmospheric valve that introduces atmospheric pressure, the vacuum valve and the atmospheric valve are formed as electromagnetic valves that electrically open and close, and the depression of the brake pedal is the pedal stroke And a control means for driving the solenoid valve based on the output of the detection means. The control means has a brake pedal depression speed calculated from the pedal stroke exceeding a predetermined threshold value. while the air valve of the vacuum booster actuates the solenoid valve in a position open vacuum valve is blocked when the, when the brake pedal is depressed, either in the presence or absence of operation the solenoid valve Warazu then a predetermined time only the emergency brake assist apparatus characterized by being configured to reduce the threshold. A negative pressure chamber into which negative pressure is introduced across a diaphragm connected to the master cylinder and a variable pressure chamber into which negative pressure or atmospheric pressure is selectively introduced are defined, and negative pressure is introduced into the variable pressure chamber. In a brake device with a negative pressure booster that is provided with a vacuum valve and an atmospheric valve that introduces atmospheric pressure, the vacuum valve and the atmospheric valve are formed as electromagnetic valves that electrically open and close, and the depression of the brake pedal is the pedal depression force And a control means for driving the solenoid valve based on the output of the detection means. The control means is configured to control the atmospheric pressure of the negative pressure booster when the pedal depression force exceeds a predetermined threshold value. while operating the solenoid valve to position the valve is open vacuum valve to shut off, when the brake pedal is depressed, to reduce the subsequent predetermined time only the threshold or without actuating said solenoid valve Emergency brake assist device, characterized in that the sea urchin configuration.   3. The emergency brake assist device according to claim 1, wherein the threshold value is sequentially set to be smaller in accordance with an increase in the number of times the brake is depressed within a predetermined time. 4. The vehicle according to claim 1 , further comprising means for detecting a vehicle speed, wherein a threshold value of a brake pedal depression speed is set to be smaller as the vehicle speed is higher. Emergency brake assist device.   The emergency brake assist device according to any one of claims 1 to 4, wherein a threshold value that is decreased as the brake pedal is depressed is gradually increased to an initial value within a predetermined time thereafter.

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