JP2015047980A - Brake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device capable of sufficiently reducing the speed of a vehicle within a control termination time of automatic brake control when the automatic brake control is executed in a situation in which a road has a low friction coefficient.SOLUTION: A brake control device of the invention comprises: a collision detection part detecting the collision of a vehicle; a brake force control part performing control to automatically keep constant brake force generated until a control termination time when the collision of the vehicle is detected; a set part setting the control termination time; and a deceleration detection part, when the collision of the vehicle is detected by the collision detection part, detecting an actual deceleration pertaining to the vehicle at a time point when it can be estimated that the constant brake force is generated by the brake force control part. The set part, when the actual deceleration detected by the deceleration detection part is low, sets the control termination time longer than that at the time when the actual deceleration is high.

Description

  The present invention relates to a brake control device.

  2. Description of the Related Art Conventionally, a brake control device that generates a constant deceleration for a certain period of time after the first collision is detected in order to reduce the damage caused by a secondary collision by continuously running the vehicle while maintaining the post-collision speed after the collision. It has been reported. In such a conventional brake control device, when a vehicle collision is detected, automatic brake control is performed in which control is performed so that a constant braking force is automatically generated until the control end time.

  In recent years, a technique for changing the control end time according to the vehicle speed after collision detection has been reported. For example, in the brake control device described in Patent Document 1, the collision mode is distinguished by the vehicle speed after the first collision detection, and the control end time of the automatic brake control is changed accordingly.

JP 2012-1091 A

  By the way, the friction coefficient of the road surface varies depending on the environment around the vehicle. For example, in situations where the road surface is wet due to rain or other factors and the friction coefficient of the road surface is low, the actual deceleration actually applied to the vehicle is lower than the required deceleration for generating a constant braking force by automatic brake control. Become. In such a situation, there is a possibility that the speed of the vehicle cannot be sufficiently reduced by the automatic brake control performed after the collision in the related art.

  As described above, in the conventional technology, in the automatic brake control in which control is performed so as to automatically generate a constant braking force until the control end time when a vehicle collision is detected, for example, in a situation where the friction coefficient of the road surface is low. There is a possibility that the speed of the vehicle cannot be lowered sufficiently to a speed at which the damage reduction effect is expected.

  The present invention has been made in view of the above circumstances, and in a situation where the actual deceleration applied to the vehicle is low due to the automatic brake control performed after the collision of the vehicle, the speed of the vehicle is sufficiently lowered by the automatic brake control. An object of the present invention is to provide a brake control device that can perform the above-described operation.

  The brake control device according to the present invention includes a collision detection unit that detects a vehicle collision, and a braking force that performs control so that a constant braking force is continuously generated automatically until a control end time when the vehicle collision is detected. When the collision of the vehicle is detected by the control unit, the setting unit for setting the control end time, and the collision detection unit, it can be predicted that the constant braking force is generated by the braking force control unit. A deceleration detecting unit that detects an actual deceleration applied to the vehicle at a time point, and the setting unit detects that the actual deceleration is low when the actual deceleration detected by the deceleration detecting unit is low. The control end time is set longer than when the time is high.

  In the above brake control device, the setting unit has a difference between a required deceleration for generating the constant braking force by the braking force control unit and the actual deceleration detected by the deceleration detection unit, When it is equal to or greater than a predetermined threshold, it is preferable to set a control end time longer than an initial set value set in advance as the control end time before the time point.

  In the brake control device, the setting unit is set in advance as a condition for ending the vehicle speed at the time point and the control that is automatically performed by the braking force control unit so as to continuously generate the constant braking force. It is preferable to set a value obtained by dividing the difference from the set end vehicle speed set value by the actual deceleration detected by the deceleration detection unit as a control end time longer than the initial set value.

  The brake control device according to the present invention extends the control end time of the automatic brake control in a situation where a constant braking force cannot be sufficiently generated by the automatic brake control performed after the vehicle collision. Accordingly, the brake control device according to the present invention can sufficiently reduce the vehicle speed by the automatic brake control even in a situation where the actual deceleration applied to the vehicle is low due to the automatic brake control performed after the vehicle collision. There is an effect that can be done.

FIG. 1 is a diagram illustrating a configuration of a brake control device. FIG. 2 is a flowchart showing the automatic brake control process. FIG. 3 is a diagram showing the deceleration realized by the automatic brake control. FIG. 4 is a flowchart showing the control end time changing process. FIG. 5 is a diagram illustrating an example of the control end time change timing.

  Hereinafter, an embodiment of a brake control device according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same.

  An embodiment of a brake control device will be described with reference to FIGS. 1 is a diagram showing the configuration of a brake control device, FIG. 2 is a flowchart showing automatic brake control processing, FIG. 3 is a diagram showing deceleration realized by automatic brake control, and FIG. 4 is control end time changing processing. FIG. 5 is a diagram illustrating an example of the control end time change timing.

  The configuration of the brake control device will be described with reference to FIG. The brake ECU 1 is a brake control device that controls the braking force of the vehicle. The brake ECU 1 is electrically connected to at least the airbag ECU 2, the wheel speed sensor 3, the acceleration sensor 4, and the brake actuator 5. The brake ECU 1 performs arithmetic processing based on various signals input from the airbag ECU 2, the wheel speed sensor 3, and the acceleration sensor 4. The brake ECU 1 controls the braking force of the vehicle by outputting a brake control signal to the brake actuator 5 based on the calculation processing result and operating the brake actuator 5.

  The airbag ECU 2 is an airbag control device that controls an airbag mechanism (not shown) mounted on the vehicle. The airbag mechanism is a mechanism that deploys an airbag to protect an occupant when a collision accident occurs. The airbag ECU 2 is electrically connected to at least a collision detection sensor (not shown), an airbag mechanism, and the brake ECU 1. The collision detection sensor is attached to the front surface, the right side surface, the left side surface, the rear surface, and the like of the vehicle, and outputs a collision occurrence signal to the airbag ECU 2 when it detects a vehicle collision. The airbag ECU 2 controls the airbag mechanism by outputting an airbag control signal to the airbag mechanism when a collision occurrence signal is input from the collision detection sensor. The airbag ECU 2 controls the airbag mechanism and simultaneously outputs a collision occurrence signal input from the collision detection sensor to the brake ECU 1.

  The wheel speed sensor 3 is a wheel speed detection device that is provided for each wheel and detects each wheel speed. Each wheel speed sensor 3 detects a wheel speed that is a rotational speed of each wheel. Each wheel speed sensor 3 outputs a wheel speed signal indicating the detected wheel speed of each wheel to the brake ECU 1. The brake ECU 1 calculates the vehicle speed, which is the traveling speed of the vehicle, based on the wheel speed of each wheel input from each wheel speed sensor 3. The brake ECU 11 may calculate the vehicle speed based on the wheel speed input from at least one of the wheel speed sensors 3.

  The acceleration sensor 4 is an acceleration detection device that detects acceleration applied to the vehicle body. For example, the acceleration sensor 4 detects the acceleration applied to the vehicle body when the vehicle is accelerated or decelerated. After detecting the acceleration of the vehicle, the acceleration sensor 4 outputs an acceleration signal corresponding to the detected acceleration to the brake ECU 1.

  The brake actuator 5 is a brake control device that controls driving of a brake mechanism (not shown) mounted on the vehicle according to a brake control signal input from the brake ECU 1. The brake actuator 5 controls the hydraulic pressure of a wheel cylinder provided in the brake mechanism, for example. The brake actuator 5 is electrically connected to the brake ECU 1 and its operation is controlled by the brake ECU 1. The brake ECU 1 operates the brake actuator 5 according to the brake control signal to adjust the brake hydraulic pressure of the wheel cylinder. In other words, the brake actuator 5 is a device for automatically controlling the braking force by the brake, and includes a solenoid or a motor of a mechanism that receives a brake control signal output from the brake ECU 1 and supplies hydraulic oil to the wheel cylinder. By driving, the brake hydraulic pressure is controlled to generate a desired braking force. In this way, the brake actuator 5 adjusts the deceleration by controlling the braking force acting on the vehicle.

  Here, the brake actuator 5 can automatically generate a constant deceleration for a certain period of time when a vehicle collision is detected. Specifically, the brake actuator 5 performs automatic control so as to automatically generate a certain braking force until the control end time when a vehicle collision is detected in accordance with a brake control signal input from the brake ECU 1. Brake control can be executed. In this automatic brake control, the brake actuator 5 is controlled by the brake ECU 1 for the control end time of the automatic brake control. The control end time is a time set as a condition for ending the automatic brake control performed after the vehicle collision. In the present embodiment, the brake actuator 5 ends the automatic brake control when the control continuation time counted from the start of the automatic brake control reaches the control end time. An initial set value is set as the control end time until a predetermined condition is satisfied. The initial set value is a value calculated as a time required for decelerating the vehicle speed at the time of the vehicle collision or immediately before the collision to the target vehicle speed by applying a constant braking force to the vehicle by the automatic brake control.

  The brake ECU 1 performs various arithmetic processes for performing automatic brake control in the following various processing units. The brake ECU 1 includes at least a collision detection unit 1a, a braking force control unit 1b, a setting unit 1c, and a deceleration detection unit 1d.

  The collision detection unit 1a is a collision detection unit that detects a vehicle collision. The collision detection unit 1a detects a vehicle collision based on a collision occurrence signal input from the airbag ECU 2 to the brake ECU 1.

  The braking force control unit 1b is a braking force control unit that performs control so as to automatically generate a constant braking force until the control end time when a vehicle collision is detected. The braking force control unit 1b outputs a brake control signal that instructs the brake actuator 5 to automatically generate a certain braking force until the control end time when a collision of the vehicle is detected by the collision detection unit 1a. Thus, the brake actuator 5 is caused to execute automatic brake control.

  The setting unit 1c is setting means for setting a control end time of automatic brake control. An initial set value is set in advance for the control end time until a predetermined condition is satisfied. The setting unit 1c sets the control end time of the automatic brake control to be longer than the initial setting value when the predetermined condition is satisfied.

  The deceleration detection unit 1d detects the actual deceleration applied to the vehicle at a time when the braking force control unit 1b can predict that a certain braking force is generated when a collision of the vehicle is detected by the collision detection unit 1a. This is the deceleration detection means. The deceleration detection unit 1d detects an actual deceleration applied to the vehicle based on an acceleration signal input from the acceleration sensor 4 to the brake ECU 1.

  Here, the point in time when the braking force control unit 1b can predict that a constant braking force is generated is, in other words, for generating a constant braking force by the automatic brake control executed by the braking force control unit 1b. This is a point in time at which the required deceleration is predicted to be reached (hereinafter sometimes referred to as “control end time change timing”). For example, when the road surface is wet due to the influence of rain or the like and the road surface friction coefficient is low, the actual deceleration actually applied to the vehicle is considered to be lower than the required deceleration at this time.

  Therefore, when the actual deceleration detected by the deceleration detection unit 1d is low, the setting unit 1c sets the control end time for automatic brake control to be longer than when the actual deceleration is high. Thereby, even if the actual deceleration applied to the vehicle is low due to the automatic brake control performed after the vehicle collision, the vehicle speed can be sufficiently reduced by the automatic brake control.

  Details of the automatic brake control process and the control end time change process executed by the brake control device of the embodiment will be described below.

  The automatic brake control process will be described with reference to FIG. Note that the processing of steps S10 to S70 in FIG. 2 is repeatedly executed at short calculation cycles (for example, 50 msec, 100 msec, etc.).

  The brake ECU 1 determines whether or not it is outside the automatic brake control for performing control so as to automatically generate a constant braking force until the control end time when a vehicle collision is detected (step S10).

  In step S10, for example, the brake ECU 1 is out of automatic brake control when the automatic brake control command value as a flag indicating that automatic brake control is being executed has not been output (or has been initialized). (That is, automatic brake control is not being executed) (step S10: Yes). In this case, the brake ECU 1 determines whether or not a start condition for automatic brake control is satisfied (step S20).

  In step S20, for example, when the brake ECU 1 detects a vehicle collision by receiving a collision occurrence signal input from the airbag ECU 2 to the brake ECU 1, the brake ECU 1 determines that a start condition for automatic brake control is satisfied ( Step S20: Yes). In this case, the brake ECU 1 executes an automatic brake control start process (step S30).

  In step S30, for example, the brake ECU 1 outputs a brake control signal for causing the brake actuator 5 to start automatic brake control. That is, the brake ECU 1 outputs to the brake actuator 5 a brake control signal for instructing to automatically generate a certain braking force until the control end time is reached after the vehicle collision is detected in step S20. Thus, the brake actuator 5 is caused to execute automatic brake control. As the control end time, an initial set value (for example, 3 seconds as a time required to decelerate to 10 km / hour after a collision at 100 km / hour) is set in advance until a predetermined condition is satisfied.

  For example, as shown in FIG. 3, the brake ECU 1 starts automatic brake control by outputting a brake control signal in step S30 (control start in FIG. 3), and automatic brake control end processing is performed in step S70 described later. Until it is performed (the end of control in FIG. 3), control for generating a constant deceleration is performed.

  Returning to FIG. 2, in step S <b> 30, the brake ECU 1 further outputs a brake control signal for starting the automatic brake control to the brake actuator 5, and the automatic brake as a flag indicating that the automatic brake control is being executed. Outputs the control command value. Thereafter, the process returns to the next calculation cycle, and the process is repeated from the process of step S10.

  In step S20, the brake ECU 1 determines that the automatic brake control start condition is not satisfied when no vehicle collision is detected (step S20: No). Also in this case, the brake ECU 1 returns from the process to the next calculation cycle, and repeats the process from the process of step S10.

  Returning to step S10 again, assuming that the process of step S30 has been executed, the description of this process will be continued.

  In step S30, when the automatic brake control command value has been output, the brake ECU 1 determines that it is not out of the automatic brake control (that is, the automatic brake control is being executed) (step S10: No). In this case, the brake ECU 1 executes a control duration integration process for automatic brake control (step S40). The control continuation time is a time during which the control is continued after the automatic brake control is started. For example, in step S40, the brake ECU 1 counts up the control continuation time from the time point determined as No in step S10, and refers to the counted up value in the subsequent steps. Then, after the next step, the brake ECU 1 compares the separately provided control end time with the counted control continuation time.

  The brake ECU 1 executes a control end time changing process for performing a process such as estimating whether or not to change the control end time by estimating the friction coefficient of the road surface after executing the control duration integration process in step S40. (Step S50).

  Details of the control end time changing process executed in step S50 will be described with reference to FIGS.

  The brake ECU 1 determines whether it is the control end time change timing (step S51). Specifically, in step S51, the brake ECU 1 determines that a constant braking force can be predicted to be generated by the braking force control unit 1b (that is, the automatic braking control executed by the braking force control unit 1b performs a certain period of time). It is determined whether it is predicted that the required deceleration for generating the braking force has been reached.

  As shown in FIG. 5, the control end time change timing is when a predetermined time has elapsed after the start of the automatic brake control. This is because it takes a predetermined time from the start of the automatic brake control until the constant braking force is achieved (until the brake control hydraulic pressure command value in FIG. 5 becomes a constant value). Furthermore, even if the brake control hydraulic pressure command value becomes a constant value, considering that there is a slight time lag (response delay) until the brake hydraulic pressure of the wheel cylinder corresponding to the brake control hydraulic pressure command value actually comes out, The control end time change timing is set when a little time has elapsed after the brake control hydraulic pressure command value has reached a certain value. Thus, in order to estimate the correct μ of the road surface, the control end time change timing is a point in time when the brake control hydraulic pressure command value is in a steady state and includes a time considering response delay (control end time in FIG. 5). Change timing). As an example, the control end time change timing is set to 500 msec when the initial value of the control end time is set to 3 seconds as the time required to decelerate to 10 km / hour after a collision at 100 km / hour. The

  As described above, in step S51, it is determined whether it is the control end time change timing at which the control end time used when determining the end of the automatic brake control based on the control continuation time should be changed from the initial set value. This control end time change timing is shown in FIG. 5 because it is determined based on the difference between the required deceleration when controlling to generate a certain braking force and the actual deceleration actually generated in the vehicle body. In this way, it is predicted that a constant brake control hydraulic pressure command value can be output by automatic brake control, and the timing is set as early as possible.

  Returning to FIG. 4, when the brake ECU 1 determines in step S51 that it is before the control end time change timing (step S51: before timing), the process proceeds to step S52, and the control end time is set to the initial set value [s]. 4 is terminated, and the process proceeds to step S60 in FIG. That is, if the brake ECU 1 determines that it is before the control end time change timing, it is before the brake control hydraulic pressure command value rises to a constant steady state, and therefore remains at the initial set value.

In step S51, when the brake ECU 1 determines that it is the control end time change timing (step S51: during timing), the brake ECU 1 determines whether the road surface friction coefficient is low at the control end time change timing (step S53). ). For example, in step S53, the brake ECU 1 determines that the conditional expression | (assumed vehicle body deceleration) − (current vehicle body deceleration) | ≧ [control vehicle end time change necessary vehicle body deceleration difference] (1)
It is determined whether or not the above is satisfied.

  Here, the assumed vehicle body deceleration is a deceleration applied to the vehicle body assumed at the control end time change timing. That is, the assumed vehicle body deceleration corresponds to the requested deceleration at the time when it can be predicted that a certain braking force is generated by the braking force control unit 1b. The current vehicle body deceleration is a deceleration actually applied to the current vehicle body at the control end time change timing. The current vehicle body deceleration is detected by the acceleration sensor 4 at the control end time change timing. In other words, the current vehicle body deceleration corresponds to the actual deceleration applied to the vehicle at the time when it can be predicted that a certain braking force is generated by the braking force control unit 1b. In this case, the current vehicle body deceleration can be handled as a value corresponding to the road surface μ. The vehicle body deceleration difference required to change the control end time is a difference in deceleration set in advance as a value that can be determined that it is necessary to change the control end time in order to increase the control duration of the automatic brake control. For example, the vehicle body deceleration difference required to change the control end time is a value (for example, 0.2 to 0.5 G) that is predicted to be low if the deceleration difference of this degree is present at the control end time change timing. ) In advance.

If it is determined that the conditional expression (1) is satisfied in step S53 (step S53: Yes), that is, the brake ECU 1 determines that the friction coefficient of the road surface is low, the brake ECU 1 calculates the control end time to be changed ( Step S54). As an example, assuming that the assumed vehicle deceleration is 1 G, the current vehicle deceleration is 0.5 G when the road surface μ is low, and the vehicle deceleration difference required to change the control end time is 0.5 G, the assumed vehicle deceleration and the current The difference from the vehicle deceleration is 0.5G. Since this value is 0.5 G or more of the vehicle body deceleration difference that requires changing the control end time, the brake ECU 1 determines that the conditional expression (1) is satisfied. Here, G is 0.98 (m / s ² ).

  In step S54, it is assumed that the current vehicle body deceleration is smaller than the assumed vehicle body deceleration due to factors such as a low road surface μ, and it is assumed that the current vehicle body deceleration is equivalent to the road surface μ. That is, the current vehicle deceleration is treated as a road surface μ equivalent value. Then, the time required to decelerate to the end vehicle speed set value on the road surface μ is calculated by the following calculation formula or the like, and the value is reset to the control end time. The end vehicle speed set value is set in advance to a value that can sufficiently reduce accident damage. For example, the end vehicle speed set value is set to 0 km / hour or 10 km / hour.

Specifically, the brake ECU 1 calculates the following equation: control end time = {(current vehicle speed) − (end vehicle speed set value)} / current vehicle body deceleration (2)
Is used to calculate the control end time to be changed. As an example, the current vehicle speed at the control end time change timing is 70 km / hour, the end vehicle speed setting value set in advance as a condition for terminating the automatic brake control is 10 km / hour, and the current vehicle body deceleration that is equivalent to the road surface μ is The above formula (2) is calculated after multiplying the current vehicle deceleration 0.5G by the gravitational acceleration 9.8G (“control end time = (70−10) / (0.5 × 9.8) = 12.24 "). Here, since the control continuation time compared with the control end time is counted after starting the automatic brake control, the control end time has elapsed from the start of the automatic brake control to the control end time changing timing. Time (500 msec) must also be considered. Then, the control end time in this case is 12.74 seconds obtained by adding 0.5 seconds to 12.24 seconds, which is about 13 seconds. That is, the control end time is about 13 seconds from the brake control start timing at which the automatic brake control is started.

  Thus, when the actual deceleration detected by the deceleration detection unit 1d is low, the setting unit 1c of the brake ECU 1 sets the control end time of the automatic brake control to be longer than when the actual deceleration is high. . Specifically, the setting unit 1c includes a required deceleration (for example, 1G) for generating a constant braking force by the braking force control unit 1b and an actual deceleration (for example, detected by the deceleration detection unit 1d). If the difference from 0.5G) is equal to or greater than a predetermined threshold (for example, 0.5G), the control duration time before the time point (control end time change timing) at which a constant braking force can be predicted to be generated A control continuation time (for example, 13 seconds) longer than an initial setting value (for example, 3 seconds) set in advance is set.

  And brake ECU1 complete | finishes the process shown in FIG. 4, and transfers to the process of step S60 of FIG. After changing the control end time in step S54, the brake ECU 1 executes automatic brake control within the changed control end time.

  In step S53, when it is determined that the conditional expression (1) is not satisfied (step S53: No), that is, when it is determined that the road surface friction coefficient is high, the brake ECU 1 proceeds to step S51. Then, the process of FIG. 4 is terminated while the control end time remains the initial set value, and the process proceeds to the process of step S60 of FIG.

  In step S51, if the brake ECU 1 determines that it is after the control end time change timing (step S51: after timing), the process shown in FIG. 4 is ended, and the process proceeds to step S60 in FIG. .

  Returning to FIG. 2, the description of the processing of FIG. 2 will be continued from step S60. The brake ECU 1 determines whether or not an automatic brake control end condition is satisfied (step S60).

  In step S60, for example, the brake ECU 1 determines that “the host vehicle speed ≦ the end vehicle speed set value” when the vehicle speed is less than the end vehicle speed set value, or “control continue” when the control duration time reaches the control end time. It is determined that the condition for ending the automatic brake control is satisfied at “time ≧ control end time” (step S60: Yes). In this case, the brake ECU 1 executes an automatic brake control end process (step S70).

  In step S70, for example, the brake ECU 1 outputs a brake control signal for terminating the automatic brake control to the brake actuator 5. In step S70, the brake ECU 1 further outputs a brake control signal for terminating the automatic brake control to the brake actuator 5, and initially sets an automatic brake control command value as a flag indicating that the automatic brake control is being executed. Turn into. Thereafter, the process returns to the next calculation cycle, and the process is repeated from the process of step S10.

  In step S60, the brake ECU 1 determines that “the host vehicle speed> the end vehicle speed set value” when the vehicle speed is larger than the end vehicle speed set value, or “the control duration time” when the control duration time has not reached the control end time. It is determined that the condition for ending automatic brake control is not satisfied at <control end time> (step S60: No). In this case, the brake ECU 1 returns this process, shifts to the next calculation cycle, and repeats this process from the process of step S10.

  In addition, in step S60 of FIG. 2, the brake ECU 1 may determine that the automatic brake control end condition is satisfied when the driver's accelerator operation is performed. This is to prevent the vehicle from stopping in a location such as an oncoming lane that is not intended by the driver by executing automatic brake control after the first collision. In this case, since the airbag is deployed after the first collision, the automatic brake control is continued during the period in which the driver cannot confirm the situation (for example, about 1.6 seconds), the airbag is contracted and the driver If the accelerator operation is performed after being able to be confirmed (for example, after about 1.6 seconds), the automatic brake control is terminated.

  Further, in step S54 of FIG. 4, the brake ECU 1 assumes that the vehicle wheel speed sensor 3 has failed in the first collision, and controls the current vehicle speed of the above formula (2) from the vehicle speed immediately before the collision. The current vehicle speed predicted at the end time change timing may be used. In addition, the brake ECU 1 may use the vehicle speed immediately before the collision as the current vehicle speed of the calculation formula (2). In addition, even if the vehicle wheel speed sensor 3 fails in the first collision, the brake ECU 1 is input from the wheel speed sensor 3 that is not out of the wheel speed sensors 3 installed on each wheel. The vehicle speed may be calculated based on the wheel speed to be used as the current vehicle speed in the above formula (2).

  In the above embodiment, the fixed value of 3 seconds has been described as an example of the time required to drop from 100 km / hour to 10 km / hour as the initial setting value of the control end time of the automatic brake control. It is not limited. The initial setting value of the control end time of the automatic brake control depends on the vehicle speed after the collision to the time required to drop from the vehicle speed immediately before the collision (for example 60 km / hour) to the end vehicle speed setting value (for example 10 km / hour) The value calculated in this way may be used.

  As described above, the brake control device according to the embodiment performs automatic brake control for generating a constant deceleration for a certain time after detecting a collision. Here, the brake control device according to the embodiment is different from the conventional technique in which the automatic brake control is ended based on a control end time assuming a typical condition (for example, when the road surface friction coefficient is high). The brake control device according to the embodiment changes, for example, to a secondary collision by changing the control end time to be longer when the automatic brake control is activated under conditions different from the assumption (for example, when the road surface friction coefficient is low). Can reduce the damage caused by accidents.

  Specifically, the brake control device according to the embodiment compares the required deceleration value to be generated by the automatic brake control with the actual deceleration of the vehicle body after starting the automatic brake control, and the difference is large The actual deceleration at that time is treated as a road surface μ equivalent value. Then, the brake control device of the embodiment recalculates the control end time, which is the automatic brake control end condition, and sets the control end time longer than the initial set value. As described above, the brake control device according to the embodiment automatically brakes the vehicle speed after the collision in order to extend the control end time of the automatic brake control after the collision when the deceleration (acceleration) due to the braking after the collision is low. It can be lowered sufficiently by control.

  For example, in the conventional braking control device that changes the control end time according to the vehicle speed after the collision detection, the control end time can be changed according to the vehicle speed after the collision detection, but when the automatic brake control is performed The control end time cannot be changed in consideration of the friction coefficient of the road surface that affects the actual vehicle deceleration that occurs. Therefore, in the conventional braking control device, when the friction coefficient of the road surface is low, there is a possibility that the vehicle speed cannot be reduced to the end vehicle speed set value within the control end time of the automatic brake control performed after the collision. . On the other hand, the brake control device according to the embodiment can increase the speed reduction amount within the control end time as much as possible, thereby reducing the damage of the secondary collision as much as possible.

1 Brake ECU (brake control device)
2 Airbag ECU
3 Wheel speed sensor 4 Acceleration sensor 5 Brake actuator

Claims (3)

A collision detection unit for detecting a vehicle collision;
A braking force control unit that performs control to automatically generate a constant braking force until the control end time when a collision of the vehicle is detected;
A setting unit for setting the control end time;
Deceleration detection for detecting an actual deceleration applied to the vehicle at a time when the braking force control unit can predict that the constant braking force is generated when a collision of the vehicle is detected by the collision detection unit And
With
The setting unit sets the control end time longer when the actual deceleration detected by the deceleration detection unit is lower than when the actual deceleration is high. . The setting unit
When the difference between the required deceleration for generating the constant braking force by the braking force control unit and the actual deceleration detected by the deceleration detection unit is equal to or greater than a predetermined threshold, 2. The brake control device according to claim 1, wherein a control end time longer than an initial set value set in advance as the control end time is set in advance. The setting unit
A difference between the vehicle speed of the vehicle at the time point and an end vehicle speed setting value set in advance as a condition for ending the control performed so as to automatically generate the constant braking force by the braking force control unit, The brake control device according to claim 2, wherein a value obtained by dividing the actual deceleration detected by the deceleration detection unit is set as a control end time longer than the initial set value.

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