JP2011202736A - Brake control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device that prevents a vehicle from starting to move when a braking device has a failure, even if a driver has not recognized the failure of the braking device.SOLUTION: When receiving a brake failure signal from a brake failure sensor 6, a brake ECU 1 sends an alarm signal to an alarm device 8 and sends a brake failure signal to a power train ECU 2. The power train ECU 2 releases a clutch 12 in a power train 5 when receiving the brake failure signal. In addition, the power train ECU makes the clutch 12 engage when an inclination of a road where the vehicle runs is uphill.

Description

  The present invention relates to a vehicle braking control device that controls a braking force of a vehicle.

  As a brake in a vehicle, a vehicle including a main brake that suppresses braking of a wheel such as a drum brake and a parking brake that is mainly used when the vehicle is parked is known. Here, when the parking brake is operated, the main brake is often stopped. However, if the parking brake fails during operation, the vehicle may start to move. 2. Description of the Related Art A vehicle braking control device that prevents such movement of a vehicle is known (see, for example, Patent Document 1). This vehicle braking control device detects a failure of a parking brake and activates a main brake to stop the vehicle when the parking brake fails and no braking force is applied to the vehicle.

Japanese Patent Laid-Open No. 10-280640

  By the way, in recent years, a vehicle that performs stop holding control for holding a stopped state of a stopped vehicle is known in addition to performing braking control when performing traveling control. In such a vehicle, if a brake failure occurs during stop holding control, there is a problem that the vehicle starts to move. Here, the vehicle braking control device disclosed in Patent Document 1 can cope with a parking brake failure but cannot cope with a main brake failure. If a brake failure occurs during the stop and hold control, the vehicle may start to move without the driver recognizing the brake failure. For this reason, there has been a problem that the vehicle may move before the driver copes with a failure of a braking device such as a brake.

  Therefore, an object of the present invention is to provide a braking control device capable of preventing the vehicle from starting even when a failure occurs in the braking device, even if the driver does not recognize the failure of the braking device. There is to do.

  A braking control device according to the present invention that has solved the above problems includes a clutch interposed between a drive source and a wheel, a braking device that applies a braking force to the wheel, and a condition other than the driver's stop request operation. A brake control device for a vehicle capable of performing a brake control for applying a braking force to the vehicle and a stop-holding control for holding the vehicle in a stop state in accordance with the braking device abnormality detecting means for detecting an abnormality of the brake device And a clutch opening / closing control means for controlling opening / closing of the clutch, and performing clutch release control for releasing the clutch when an abnormality of the braking device is detected.

  In the braking control device according to the present invention, when an abnormality of the braking device is detected, clutch release control for releasing the clutch is performed. For this reason, when an abnormality occurs in the braking device, the connection between the power source such as the engine and the wheel is released regardless of the driver's recognition, and the driving force is not transmitted to the wheel. Therefore, even if the driver does not recognize the failure of the braking device when the failure occurs in the braking device, the vehicle can be prevented from moving.

  Here, the vehicle is provided with gradient detection means for detecting the road surface gradient of the road on which the vehicle travels, and the clutch opening / closing control means is a clutch engagement control for engaging the clutch when the gradient detected by the gradient detection means is an upward gradient. It can be set as the aspect which performs.

  Thus, when the road surface gradient of the road on which the vehicle travels is an uphill slope, the vehicle moves backward when the clutch is released. If the vehicle moves backward without being recognized by the driver, there is a possibility that it will come into contact with the following vehicle. Therefore, clutch engagement control for engaging the clutch is performed when the road surface gradient of the road on which the vehicle is traveling is an upward gradient. For this reason, when the road surface gradient of the road on which the vehicle travels is an upward gradient, the vehicle is given a driving force forward by a creep force to the driving source. Accordingly, when an abnormality occurs in the braking device on an uphill slope, the vehicle can be prevented from moving backward even if the driver does not recognize the abnormality in the braking device.

  According to the braking control device of the present invention, when a failure occurs in the braking device, the vehicle can be prevented from starting even when the driver does not recognize the braking device failure.

It is a block block diagram of the braking control apparatus which concerns on this invention. It is a flowchart which shows the process sequence in a braking control apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. For the convenience of illustration, the dimensional ratios in the drawings do not necessarily match those described.

  FIG. 1 is a block diagram of a braking control apparatus according to the present invention. As shown in FIG. 1, the braking control apparatus according to the present embodiment includes a brake ECU (Electronic Control Unit) 1 and a powertrain ECU 2 connected to the brake ECU 1. A brake failure sensor 6 is connected to the brake ECU 1, and a G sensor 3 and an inter-vehicle distance sensor 4 are connected to the power train ECU 2.

  In addition, a power train 5 is connected to the power train ECU 2, and a brake actuator 7 is connected to the brake ECU 1. The power train ECU 2 is an ECU that performs overall control of the power train 5, and the brake ECU 1 is an ECU that controls the brake actuator 7. The brake actuator 7 applies a braking force to the wheels W.

  The G sensor 3 is attached to the body of the vehicle, for example, and detects the road surface gradient of the road on which the vehicle is traveling by detecting the inclination of the vehicle in the front-rear direction. The G sensor 3 transmits a road surface gradient signal based on the detected road surface gradient to the powertrain ECU 2.

  The inter-vehicle distance sensor 4 is composed of a millimeter wave sensor, for example, and is attached to a front grill of the vehicle. The inter-vehicle distance sensor 4 detects the inter-vehicle distance between the preceding vehicle and the host vehicle. The inter-vehicle distance sensor 4 transmits an inter-vehicle distance signal related to the detected inter-vehicle distance to the powertrain ECU 1.

  The power train 5 includes an engine 11, a clutch 12, and a shaft 13 that transmits the driving force of the engine 11 to the wheels W. The clutch 12 can be opened and closed in accordance with a clutch opening / closing signal transmitted from the power train ECU 2. When the clutch 12 is released, the transmission of the driving force of the engine 11 to the wheels W is interrupted, and the driving force is not applied to the wheels W. When the clutch is closed (engaged), the driving force of the engine 11 is transmitted to the wheels W. When the driving force of the engine 11 is transmitted to the wheels W, the wheels W rotate and the vehicle travels.

  A brake pedal sensor and an auto cruise control (hereinafter referred to as “ACC”) ECU (not shown) are connected to the brake ECU 1. The brake ECU 1 calculates the operation amount of the brake actuator 7 according to the operation amount of the brake pedal detected by the brake pedal sensor, and operates the brake actuator 7 according to the calculated operation amount.

  In addition, the ACC ECU performs traveling control that follows the preceding vehicle based on the vehicle speed and acceleration of the own vehicle and the preceding vehicle, and the inter-vehicle distance between the own vehicle and the preceding vehicle, and stops the own vehicle. When the stop holding control for holding the state to be started is started, a stop holding control start signal is transmitted to the brake ECU 1. The brake ECU 1 starts the stop holding control when it receives the stop holding control start signal. When performing the stop holding control, the brake ECU 1 operates the brake actuator 7 so as to apply a braking force of a magnitude that stops the vehicle to the wheels W.

  The brake failure sensor 6 is connected to the brake actuator 7 and detects a brake failure. The brake failure sensor 6 monitors, for example, the hydraulic pressure in the brake actuator 7, and a brake signal is transmitted from the brake ECU 1. However, when the hydraulic pressure does not increase, a brake failure signal is detected. Is transmitted to the brake ECU 1.

  The brake ECU 1 transmits a stop holding control signal to the powertrain ECU 2 when the stop holding control is being performed. Further, when a brake failure signal transmitted from the brake failure sensor 6 is received during stop holding control, a brake abnormality signal is transmitted to the powertrain ECU 2.

  The power train ECU 2 determines the engagement state of the clutch 12 in the power train 5 based on a shift position signal transmitted from a shift lever (not shown) and a wheel speed signal transmitted from a wheel speed sensor. When the engagement state is determined, the power train ECU 2 transmits a clutch engagement signal or a clutch release signal, which is a clutch opening / closing signal corresponding to the determined engagement state, to the clutch 12 in the power train 5 to engage the clutch 12. Controls the overall state.

  Further, the clutch 12 in the power train 5 according to the stop holding signal and brake abnormality signal transmitted from the brake ECU 1, the road surface gradient signal transmitted from the G sensor 3, and the inter-vehicle distance signal transmitted from the inter-vehicle distance sensor 4. And the clutch open / close signal corresponding to the determined engagement state is transmitted to the power train 5. Further, the powertrain ECU 2 stores the estimated variation in road surface gradient detected by the G sensor 3. The road on which the vehicle travels when the difference between the estimated slope value estimated based on the road slope signal transmitted from the G sensor 3 and the stored estimated variation exceeds 0 It can be determined that the road surface slope is surely a downward slope.

  Further, an alarm device 8 is connected to the brake ECU 1. The alarm device 8 includes sound output means such as a speaker. The brake ECU 1 transmits an alarm signal to the alarm device 8 when a brake failure signal is transmitted from the brake failure sensor 6. In the alarm device 8, when an alarm signal is transmitted from the brake ECU 1, warning information indicating that an abnormality has occurred in the brake is output from the sound output means.

  Next, a processing procedure in the braking control device according to the present embodiment will be described. FIG. 2 is a flowchart showing a processing procedure in the braking control apparatus. As shown in FIG. 2, in the braking control device according to the present embodiment, first, it is determined whether stop holding control is performed in the brake ECU 1 (S1). The determination as to whether or not stop holding control is being performed is made based on whether or not a stop holding control start signal has been transmitted from the ACC ECU. In the ACC ECU, when the braking amount exceeds a predetermined braking amount threshold value, a stop holding control start signal for starting the stop holding control is transmitted to the brake ECU 1. As a result, when it is determined that the stop holding control is not performed, the determination in step S1 is repeated until the stop holding control is performed.

  On the other hand, if it is determined that the stop holding control is being performed, it is determined whether or not a brake abnormality has occurred (S2). The determination of the brake abnormality is made based on whether or not a brake failure signal is transmitted from the brake failure sensor 6. As a result, when it is determined that the brake failure signal has not been transmitted and the brake abnormality has not occurred, the process returns to step S1 to repeat the determination of whether or not stop holding control is being performed.

  If it is determined that a brake abnormality has occurred, the brake failure signal has been transmitted, the brake ECU 1 transmits an alarm signal to the alarm device 8, outputs warning information from the alarm device 8, and issues an alarm. (S3). Furthermore, the brake ECU 1 transmits a brake abnormality signal to the power train ECU 2.

  Subsequently, the powertrain ECU 2 determines whether the clutch 12 is opened or closed. In determining whether the clutch 12 is to be opened or closed, the road surface gradient of the road on which the vehicle travels is estimated based on the road surface gradient signal transmitted from the G sensor 3, the estimated gradient estimated value, and the pre-stored estimated variation Find the difference. Then, it is determined whether or not the difference between the gradient estimated value and the estimated variation exceeds 0 (S4).

  As a result, when it is determined that the difference between the estimated slope value and the estimated variation exceeds 0, it can be determined that the road surface slope of the road on which the vehicle is traveling is surely a downward slope. In this case, there is little fear that the vehicle will move backward even if the clutch 12 is released. Therefore, a clutch release signal for releasing the clutch 12 is transmitted to the clutch 12 in the power train 5, the clutch 12 is released (S10), and the process is terminated.

  On the other hand, when it is determined that the difference between the gradient estimated value and the estimated variation does not exceed 0 (0 or less), it is determined whether or not the following equation (1) is satisfied (S5).

Gradient estimate + Estimated variation + Creep MAX <0 (1)
In the equation (1), creep MAX refers to the maximum value of the creep force applied to the wheel W when the clutch 12 is engaged.

  Here, when it is determined that the above equation (1) is satisfied, the road on which the vehicle travels is an upward slope, but it is considered that the slope is such that the vehicle does not move backward due to creep force. In this case, the power train ECU 2 transmits a clutch engagement signal to the clutch 12, engages the clutch 12 (S11), and ends the process.

  On the other hand, if it is determined that the expression (1) is not satisfied, it is determined whether or not the vehicle is moving (S6). The determination as to whether or not the vehicle is moving is made based on the wheel speed signal transmitted from the wheel speed sensor. As a result, when it is determined that the vehicle is not moving, there is no fear of contact with the surroundings of the vehicle due to the movement of the vehicle, and thus the control is terminated as it is.

  If it is determined that the vehicle is moving, it is determined whether the vehicle is moving forward (S7). The determination as to whether or not the vehicle is moving is made based on the inter-vehicle distance signal transmitted from the inter-vehicle distance sensor and the wheel speed signal transmitted from the wheel speed sensor. Here, when the inter-vehicle distance from the preceding vehicle is short and the vehicle is traveling, it is determined that the vehicle is moving forward.

  As a result, when it is determined that the vehicle is moving forward, a clutch release signal for releasing the clutch 12 is transmitted to the clutch 12 in the power train 5 to release the clutch 12 (S8). In this way, the forward movement of the vehicle is stopped by removing the creep force applied to the wheels W that can be placed on the vehicle that is moving forward.

  On the other hand, if it is determined that the vehicle is not moving forward, the vehicle is moving backward. In this case, a clutch engagement signal for engaging the clutch 12 is transmitted to the clutch 12 in the power train 5 to engage the clutch 12 (S12). Thus, by applying a creep force to the wheels W, the backward movement of the vehicle is suppressed.

  Thereafter, it is determined whether or not there has been a driver operation (S9). Examples of the driver's operation here include depression of an accelerator pedal and a brake pedal, steering operation of a steering wheel, operation of a shift lever, and the like. As a result, when it is determined that there has been a driver operation, the driver operation can be prioritized. Therefore, the process is terminated as it is. On the other hand, if it is determined that the driver has not operated, the process returns to step S7 to repeat the determination of whether or not the vehicle has moved.

  As described above, in the braking control device according to the present embodiment, when an abnormality occurs in the brake, a warning is given to the driver, and the clutch 12 in the power train 5 is released. For this reason, when an abnormality occurs in the brake, the connection between the engine 11 and the wheel W is released regardless of the driver's recognition, and the driving force is not transmitted to the wheel W. Therefore, it is possible to prevent the vehicle from moving even when the driver has not recognized the brake failure when the brake has failed. For this reason, the unexpected behavior of the vehicle until the driver recognizes the brake failure can be prevented, and a margin time until the driver copes with the brake failure can be gained.

  Further, in the braking control device according to the present embodiment, the road surface gradient of the road on which the vehicle travels is detected, and when the road surface gradient is an upward gradient, clutch engagement control for engaging the clutch 12 is performed. For this reason, when the road surface gradient of the road on which the vehicle travels is an upward gradient, a forward driving force is applied to the vehicle by the creep force of the engine 11. Therefore, when a brake abnormality occurs on an uphill slope, the vehicle can be prevented from moving backward even if the driver does not recognize the brake abnormality.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, the braking control by ACC is taken as an example, but other control for applying a braking force to the vehicle may be used. In the above-described embodiment, a vehicle using an engine as a drive source is targeted. However, an electric vehicle using a motor as a drive source can also be targeted. Furthermore, in the above-described embodiment, the road gradient is determined using the gradient estimated value and the estimated variation. However, the road gradient may be determined using only the gradient estimated value.

  DESCRIPTION OF SYMBOLS 1 ... Brake ECU, 2 ... Power train ECU, 3 ... G sensor, 4 ... Inter-vehicle distance sensor, 5 ... Power train, 6 ... Brake failure sensor, 7 ... Brake actuator, 8 ... Alarm device, 11 ... Engine, 12 ... Clutch , 13 ... shaft, W ... wheel.

Claims (2)

Brake control that includes a clutch interposed between the drive source and the wheel, and a braking device that applies braking force to the wheel, and that applies braking force to the vehicle in accordance with conditions other than the driver's stop request operation And a braking control device for a vehicle capable of stopping and holding control for holding the vehicle in a stopped state,
Braking device abnormality detecting means for detecting abnormality of the braking device;
Clutch opening and closing control means for controlling the opening and closing of the clutch,
A vehicle brake control device that performs clutch release control for releasing the clutch when an abnormality of the brake device is detected. Gradient detection means for detecting the road gradient of the road on which the vehicle travels,
2. The vehicle braking control device according to claim 1, wherein the clutch opening / closing control unit performs clutch engagement control for engaging the clutch when the gradient detected by the gradient detection unit is an upward gradient.

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