JP2008100603A - Braking control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a braking control device capable of preventing occurrence of any secondary accident in a rear end collision, and reducing an impact applied to one's own vehicle. <P>SOLUTION: The braking control device for controlling the braking force of a brake device 10 provided on a wheel of a vehicle comprises a collision detection means 41 for detecting the collision of the vehicle, and an acceleration detection means 43 for detecting the acceleration in the longitudinal direction of the vehicle. After the collision detection means 41 detects the collision, the braking force is generated in the braking device 10 when the acceleration detected by the acceleration detection means 43 is below the predetermined threshold. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a braking control device that is provided in a vehicle such as an automobile and automatically generates a braking force at the time of a rear collision.

In order to prevent a secondary accident from occurring at the time of a rear collision of an automobile, it has been proposed to decelerate the vehicle by automatically operating a brake regardless of the operation of the driver.
For example, conventionally, it is known that a comparison signal corresponding to the longitudinal acceleration of a vehicle is compared with a predetermined threshold, and a brake signal is generated that triggers a vehicle brake when the comparison signal exceeds the threshold ( For example, see Patent Document 1).
JP 2000-219111 A

However, in the prior art in which braking of the brake is immediately started in response to the detection of the collision, the impact due to the collision is increased by the braking force of the brake, and there is a possibility that damage to the vehicle is increased.
The subject of this invention is providing the braking control apparatus which prevents generation | occurrence | production of the secondary accident at the time of a rear collision, and reduces the impact added to the own vehicle.

The present invention solves the above-described problems by the following means.
According to a first aspect of the present invention, there is provided a braking control device for controlling a braking force of a brake device provided on a wheel of a vehicle, a collision detection means for detecting a rear collision of the vehicle, and an acceleration in a longitudinal direction of the vehicle. Acceleration detecting means, and after the collision detecting means detects a rear collision, when the acceleration detected by the acceleration detecting means falls below a predetermined threshold, the braking device generates braking force. A braking control device.

According to a second aspect of the present invention, in the braking control device according to the first aspect, the collision detection means detects a rear collision based on acceleration in the front-rear direction of the vehicle and information on deployment of the airbag of the vehicle. This is a braking control device.
According to a third aspect of the present invention, in the braking control device according to the first or second aspect, the brake device is a mechanical brake that is driven by an electric actuator and used as a parking brake of the vehicle. A braking control device.
According to a fourth aspect of the present invention, in the braking control device according to the third aspect, after the collision detection unit detects a collision and before the acceleration detected by the acceleration detection unit falls below a predetermined threshold, The brake control device is characterized in that the actuator performs preliminary drive to reduce the play of the mechanical brake.

According to the present invention, the following effects can be obtained.
(1) After the detection of the rear collision, when the acceleration is larger than a predetermined threshold, the vehicle is allowed to move forward in a state where the acceleration due to the impact immediately after the collision is large by not performing braking by the brake device. It is possible to reduce the impact and prevent the impact from increasing due to braking.
After that, impact energy is absorbed by deformation of the rear of the vehicle body, etc., and the braking force is generated after the acceleration is reduced and falls below the threshold value. It is possible to prevent the occurrence of secondary accidents caused by jumping out in an unintended direction.
(2) The accuracy of collision detection can be improved by detecting a collision based on acceleration in the front-rear direction of the vehicle and information related to the deployment of the airbag of the vehicle.
For example, even when longitudinal acceleration due to a collision is applied to the vehicle, if there is deployment information on the front airbag or side airbag, it is determined that the vehicle has crashed forward or sideward, and the rear collision By not performing this determination, it is possible to accurately detect a rear collision.
(3) By performing the above-described braking using a mechanical brake (electric parking brake) that is driven by an electric actuator and used as a parking brake of the vehicle, energization to the braking control device and the electric actuator is started after the braking is started. The braking force can be maintained even when stopped. In addition, if the vehicle is already equipped with an electric parking brake, an acceleration sensor, and the like, the present invention can be easily applied with almost no mechanical modification of the vehicle.
(4) After the detection of the rear collision, before the acceleration falls below the threshold value (starts braking), the driving force is reduced from the activation of the electric parking brake by performing a pre-driving that reduces the play of the mechanical brake by the electric actuator. The time lag that occurs until the occurrence of the braking force is reduced, and the braking force can be generated at an appropriate timing.

  An object of the present invention is to provide a braking control device that prevents the occurrence of a secondary accident at the time of a rear collision and reduces the impact applied to the host vehicle. After the detection, the problem was solved by starting the braking by the electric parking brake when the acceleration became a predetermined threshold value or less.

Embodiments of a braking control apparatus to which the present invention is applied will be described below.
FIG. 1 is a block diagram illustrating a configuration of an electric parking brake device including a braking control device of an embodiment.
In the embodiment, the vehicle is an automobile such as a passenger car.
The electric parking brake device includes a parking brake 10, an actuator unit 20, a battery 30, an electric parking brake controller (hereinafter simply referred to as “controller”) 40, an operation switch 50, and a vehicle side unit 60.

  The parking brake 10 is a braking device that prevents the vehicle from moving when the vehicle is parked or the like, for example, by braking the wheels of the vehicle. The parking brake 10 is provided on each of the wheel hub portions of the left and right rear wheels of the vehicle. The parking brake 10 includes a brake drum (not shown) disposed on the inner diameter side of a rotor of a disc brake used as a foot brake (main brake) and a brake shoe (not shown) that pressurizes and contacts the inner diameter side of the brake drum during braking. It is a so-called drum-in-disk type mechanical brake.

The actuator unit 20 drives the shoe of the parking brake 10 and makes a transition between a braking state in which the parking brake 10 generates a braking force and a released state in which the braking force is not substantially generated. The actuator unit 20 includes a parking brake cable 21 and is fixed to, for example, the under floor side of the luggage floor portion of the vehicle.
The actuator unit 20 is, for example, for reducing the rotational force of a DC motor by a reduction gear train to rotate a lead screw, and pulling or relaxing the parking brake cable 21 by an equalizer screwed to the lead screw.

  The parking brake cables 21 are provided corresponding to the left and right parking brakes 10, respectively, and have flexibility so as to be deformed according to a stroke of a rear suspension (not shown). The parking brake cable 21 is a Bowden cable that brings the parking brake 10 into a braking state by being pulled, and releases the parking brake 10 by being relaxed.

  Here, the actuator unit 20 has a function of adjusting the braking force of the parking brake 10 in the braking state by adjusting the traction force applied to the parking brake cable 21. The adjustment of the traction force is performed by controlling the power supply to the actuator unit 20 to change the stroke for pulling the parking brake cable 21. For this reason, the actuator unit 20 has a stroke sensor (not shown) that detects the traction stroke. It has.

The battery 30 is a secondary battery that is used as a main power source for a vehicle electrical system, and generates, for example, a DC 12V terminal voltage. The battery 30 includes a plus terminal 31 and a minus terminal 32.
The plus terminal 31 is connected to each electrical component such as the controller 40 via wiring (harness). As shown in FIG. 1, the wiring for supplying power from the plus terminal 31 to the controller 40 is provided with an ignition wiring 31a and a constant connection wiring 31b. The ignition wiring 31a is inserted at its intermediate portion with an ignition relay I which is switched between conduction and interruption in conjunction with the on / off of the ignition switch, and is energized when the engine, which is the driving power source of the vehicle, is on (running). is there. The always-connected wiring 31b is always energized regardless of the operation of the ignition switch, and is used for holding various data in the ECU 41 of the controller 40 or the like.
The minus terminal 32 is grounded to the metal part of the vehicle body.

The controller 40 controls the actuator unit 20 to change the traction force of the parking brake cable 21 to switch the parking brake 10 between the released state and the braking state, and also changes the braking force. Control device), which includes an ECU 41, a relay 42, and a G sensor 43.
The controller 40 also functions as a braking control device that automatically causes the parking brake 10 to perform braking in order to prevent a secondary accident in the event of a rear collision of the vehicle. This function will be described in detail later.

The ECU 41 determines whether or not the parking brake 10 needs to be braked in accordance with inputs from the operation switch 50 and the vehicle-side unit 60, and also performs a CPU that performs additional pulling control for increasing the braking force when the vehicle stops on an inclined road. I have.
Further, the ECU 41 has a function of detecting a current value of electric power supplied to the actuator unit 20 via the relay 42.
Further, the ECU 41 also functions as a collision detection unit that detects a rear collision based on the output of the G sensor 43. This collision detection function will be described in detail later.

  The relay 42 is a power supply unit that supplies driving power to the actuator unit 20 in accordance with a control signal output from the ECU 41. The relay 42 has a function of reversing the polarity of the driving power in order to make the transition of the parking brake 10 from the braking state to the release state and from the release state to the brake state, and when the actuator unit 20 is not driven. Is in a neutral state where conduction with the actuator unit 20 is interrupted.

  The G sensor 43 includes an acceleration sensor that detects acceleration in the front-rear direction of the vehicle, and is an acceleration detection unit that inputs the output to the ECU 41.

  The operation switch 50 is an operation unit for a user such as a driver to input a manual selection operation of a braking state and a release state of the parking brake 10, an additional operation, and an auto mode selection operation. A push button switch mounted on an instrument panel (not shown) of the vehicle is provided. The operation switch 50 transmits the input to the controller 40, and the controller 40 supplies driving power to the actuator unit 20 in response to this to drive the parking brake 10.

  The vehicle unit 60 includes, for example, an engine control unit (ECU) that controls the engine of the vehicle, a transmission control unit (TCU) that controls a transmission (transmission), and a safety control that performs vehicle stability control including ABS control. The unit includes a vehicle integration unit that comprehensively controls other electrical components of the vehicle, and communicates with the controller 40 via a CAN communication system that is a kind of in-vehicle LAN, and includes a vehicle speed sensor 61.

  The vehicle speed sensor 61 is provided, for example, in the wheel hub portion of each wheel, and is used for detecting the vehicle traveling speed (body speed) by outputting a vehicle speed pulse signal corresponding to the rotational speed of the tone wheel that rotates with the wheel. Is. Here, the vehicle speed sensor 61 generates a vehicle speed pulse signal corresponding to the vehicle speed at a speed equal to or higher than the detection lower limit speed.

The vehicle-side unit 60 sends, for example, engine speed, throttle opening, engine coolant temperature, exhaust temperature, transmission shift position, foot brake operation status (brake lamp switch signal), vehicle Information such as speed (vehicle speed) is provided sequentially. In the automatic operation mode, the controller 40 shifts the parking brake 10 from the braking state to the release state when it is determined that the vehicle shifts from the stopped state to the traveling state based on these inputs.
On the other hand, when the controller 40 determines that the vehicle has shifted from the traveling state to the stopped state (stop determination), the controller 40 determines that the parking brake 10 needs to be braked, and supplies driving power to the actuator unit 20 to supply the parking brake. 10 is shifted from the release state to the braking state.

Next, the operation at the time of a rear collision in the braking control device of the embodiment will be described.
FIG. 2 is a flowchart showing braking control at the time of a rear collision. Hereinafter, the steps will be described step by step.

<Step S01: Ignition On Determination>
The ECU 41 of the controller 40 determines whether or not the ignition switch I is currently turned on based on whether or not the ignition wiring 31a is energized. If the ignition switch I is on, the ECU 41 proceeds to step S02. If off, the ECU 41 proceeds to step S01. repeat.

<Step S02: Front / Rear G Abnormal Change Determination>
The ECU 41 detects the presence or absence of an abnormal change in acceleration in the longitudinal direction of the vehicle detected based on the output of the G sensor 43. Specifically, the ECU 41 is detected based on the output of the G sensor 43 rather than the rear collision determination acceleration which is a threshold set in advance in consideration of determining the acceleration due to the normal traveling and the acceleration due to the rear collision. If the acceleration is high, the process proceeds to step S03. Otherwise, the process returns to step S01 and the subsequent processing is repeated.

<Step S03: Determination of existence of rear collision>
The ECU 41 determines that the vehicle has undergone a rear collision, sets a rear collision flag, and proceeds to step S04.

<Step S04: Electric parking brake preliminary drive start>
The ECU 41 outputs a control signal to the relay 42, starts energization of the actuator unit 20, and starts preliminary driving of the parking brake 10.
The preliminary driving of the parking brake 10 starts the pulling of the parking brake cable 21 by driving the actuator unit 20 from the release side to the braking side, and each mechanism unit such as the actuator unit 20, the parking brake cable 21, and the parking brake 10 is operated. Inevitably, this structure reduces play. This preliminary drive is performed within a range in which the parking brake 10 does not substantially generate a braking force, and the drive is stopped immediately before the parking brake 10 substantially generates a braking force.
Proceed to step S05.

<Step S05: Determination of Return to Normal G Normal Value>
The ECU 41 monitors the acceleration in the longitudinal direction of the vehicle detected based on the output of the G sensor 43. If this acceleration is smaller than the braking start acceleration that is a preset threshold value, the longitudinal G returns to a normal value. As a result, the process proceeds to step S06. In other cases, step S05 is repeated assuming that the front and rear G are still taking abnormal values.
FIG. 3 is a graph illustrating an example of a history of longitudinal acceleration of the vehicle at the time of a rear collision of the vehicle and at a normal time (when starting in normal driving). In FIG. 3, the horizontal axis indicates time, the vertical axis indicates acceleration, and the vertical axis indicates the acceleration side and the lower side indicates the deceleration side.

As shown in FIG. 3, the acceleration at the time of a rear collision suddenly rises immediately after the collision, and its peak value is larger than that at the normal time. Immediately after taking the peak value, the acceleration rapidly decreases due to the impact energy absorbed by the deformation of the rear part of the vehicle body, and thereafter gradually decreases while gradually decreasing the acceleration decrease rate per unit time. .
The rear collision determination acceleration described above is set to a magnitude of acceleration that does not occur during normal operation and can be generated during a rear collision.
On the other hand, the braking start acceleration is set smaller than the rear collision determination acceleration.

<Step S06: Electric parking brake braking>
The ECU 41 outputs a control signal to the relay 42, starts energizing the actuator unit 20, and starts braking the parking brake 10. At this time, the target braking force of the parking brake 10 is set to the maximum braking force. As a result, the parking brake 10 is driven by the actuator unit 20 until a maximum braking force is generated, and the vehicle decelerates and finally stops.

According to the embodiment described above, the following effects can be obtained.
(1) When the acceleration is greater than a predetermined braking start acceleration after the detection of the rear collision, the parking brake 10 is not used to allow the vehicle to move forward in a state where the acceleration immediately after the collision is large. Thus, the impact can be mitigated and the impact applied to the vehicle by braking can be prevented from increasing.
After that, impact energy is absorbed by deformation of the rear of the vehicle body, etc., and the acceleration is reduced and the braking force is generated after the braking start acceleration is reduced. It is possible to prevent the occurrence of secondary accidents caused by the being pushed and popping out in the direction unintended by the driver.

(2) By performing automatic braking at the time of a rear collision by using an electric parking brake device, the braking force is maintained even when the energization to the actuator unit 20 or the like is stopped due to vehicle damage after the braking is started. be able to.
In addition, since the actuator unit 20 is configured to drive the parking brake 10 via the flexible parking brake cable 21, the parking brake cable can be used even when the actuator unit 20 falls off the vehicle body due to damage to the vehicle body. Since the traction of the vehicle 21 can be maintained and the braking force can be maintained, the vehicle can be prevented from starting to move.
Furthermore, if the vehicle is already equipped with an electric parking brake device and an acceleration sensor, the present invention can be easily applied with almost no mechanical modification of the vehicle.

(3) After detecting the rear collision, before the acceleration falls below the braking start acceleration (starts braking), the actuator unit 20 is energized, and the actuator unit is within a range in which the parking brake 10 does not substantially generate braking force. 20, by performing preliminary driving to reduce the play of the parking brake cable 21 and the parking brake 10, the time lag of the braking force generated due to such play is reduced, and the braking force is generated at an appropriate timing. Can be made.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) Although the embodiment uses the electric parking brake to perform braking control at the time of a rear collision, the present invention is not limited to this, and similar braking control is performed using a hydraulic brake (service brake). You may go. Furthermore, it is good also as a structure which brakes together using a hydraulic brake and an electric parking brake.
(2) In the embodiment, after the detection of a rear collision, braking is performed using the maximum braking force of the electric parking brake as the target braking force when the longitudinal acceleration of the vehicle falls below a predetermined threshold. However, the present invention is not limited to this, and a configuration may be adopted in which braking is performed with different braking forces depending on the magnitude of impact caused by a collision.
(3) In addition to the configuration of the embodiment, the collision detection unit acquires information related to the deployment of the airbag of the vehicle, and detects a rear collision based on the acceleration in the longitudinal direction of the vehicle and the information related to the deployment of the airbag. It is good also as a structure. For example, when the deployment information of the front airbag or the side airbag is acquired from the airbag control device that controls the deployment of the airbag, it is determined that the vehicle has undergone a front collision or a side collision instead of a rear collision. The automatic braking may not be performed. According to such a configuration, a rear collision can be detected with higher accuracy.
(4) The configuration of the electric parking brake device is not limited to that of the embodiment, and can be changed as appropriate.
For example, the parking brake of the embodiment uses a drum arranged on the inner diameter side of a brake disc for a foot brake, but the parking brake may be of other types, for example, a foot brake. The disc brake or drum brake for brake and its friction material may be shared and integrated with the parking brake.
Further, the parking brake of the embodiment uses an electric actuator fixed on the body side and drives the parking brake via a parking brake cable. However, the present invention is not limited to this, and for example, the electric actuator is a wheel. The present invention can also be applied to a so-called built-in type electric parking brake provided on the hub side and integrated with the parking brake.

It is a block diagram which shows the structure of the Example of the electric parking brake containing the braking control apparatus to which this invention is applied. It is a flowchart which shows the braking control at the time of the back collision in the electric parking brake apparatus of FIG. It is a graph which shows an example of the log | history of the acceleration at the time of the rear collision of a vehicle, and normal time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Parking brake 20 Actuator unit 21 Parking brake cable 30 Battery 40 Controller 41 ECU
42 relay 43 G sensor 50 operation switch 60 vehicle side unit 61 vehicle speed sensor

Claims (4)

In a braking control device for controlling the braking force of a braking device provided on a vehicle wheel,
A collision detection means for detecting a rear collision of the vehicle;
Acceleration detecting means for detecting acceleration in the longitudinal direction of the vehicle,
After the collision detection means detects a collision, the braking control apparatus generates a braking force when the acceleration detected by the acceleration detection means falls below a predetermined threshold. The braking control device according to claim 1, wherein
The braking control device according to claim 1, wherein the collision detection unit detects a rear collision based on acceleration in the front-rear direction of the vehicle and information on deployment of the airbag of the vehicle. In the braking control device according to claim 1 or 2,
The brake control device according to claim 1, wherein the brake device is a mechanical brake driven by an electric actuator and used as a parking brake of the vehicle. In the braking control device according to claim 3,
After the collision detection means detects a collision and before the acceleration detected by the acceleration detection means falls below a predetermined threshold, the electric actuator performs a preliminary drive to reduce the play of the mechanical brake. A braking control device characterized by the above.

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