JP5946293B2 - Abnormality detection device for brake negative pressure sensor - Google Patents

Description

  The present invention relates to an abnormality detection device for a brake negative pressure sensor for detecting a negative pressure of a brake booster.

  In vehicles such as automobiles, when the brake pedal is depressed, the force (depression force) input to the brake pedal is amplified by the negative pressure of the brake booster, and the amplified force is transmitted from the brake booster to the master cylinder. In the master cylinder, a hydraulic pressure corresponding to the force input from the brake booster is generated. Then, the hydraulic pressure of the master cylinder is transmitted to the wheel cylinders provided on each wheel, and the braking force is applied from each brake to the wheels by the hydraulic pressure of each wheel cylinder.

  A brake negative pressure sensor is provided to detect the negative pressure of the brake booster. Based on the detection value of the brake negative pressure sensor, for example, the negative pressure of the brake booster is controlled in order to exhibit good braking performance. Therefore, if an abnormality occurs in the brake negative pressure sensor, the negative pressure of the brake booster cannot be controlled to a suitable negative pressure, which affects the brake performance.

  Therefore, various methods for detecting abnormality of the brake negative pressure sensor have been proposed. In one example of this method, when the brake negative pressure sensor detection value does not change at a substantially constant value (when it is fixed), the brake negative pressure sensor signal line may be broken. Judged to have occurred.

Japanese Patent Laid-Open No. 10-157613

  However, in the above-described method, there is a risk that a brake negative pressure sensor abnormality may be erroneously detected in a vehicle having a function of automatically operating a brake by detecting the presence of an obstacle such as a vehicle ahead, that is, a so-called automatic brake function. There is.

  An object of the present invention is to provide an abnormality detection device for a brake negative pressure sensor that can satisfactorily detect an abnormality of a brake negative pressure sensor in a vehicle having an automatic brake function.

In order to achieve the above object, an abnormality detection device for a brake negative pressure sensor according to the present invention includes a brake booster for assisting a brake operation by a driver and a brake negative pressure sensor for detecting the negative pressure of the brake booster. , Used for a vehicle having an automatic brake function for automatically operating a brake regardless of the brake operation. The abnormality detection device includes an automatic brake operation determination means for determining whether or not the brake is being operated by the automatic brake function, and a fluctuation amount of an output of the brake negative pressure sensor during operation of the brake is within a predetermined range A fluctuation amount determining means for determining whether or not the brake is in operation, and the automatic brake operation determining means determines that the brake is not being operated by the automatic brake function, and the fluctuation amount determining means determines the fluctuation amount. When it is determined that the value is within the predetermined range, the count value of the sticking condition establishment counter is incremented, and when the count value of the sticking establishment counter reaches a predetermined value of 1 or more , an abnormality occurs in the brake negative pressure sensor. And an abnormality determining means for determining that it is in progress.

  In order to determine whether or not an abnormality has occurred in the brake negative pressure sensor, it is determined whether or not the brake is being operated by the automatic brake function. Further, it is determined whether or not the fluctuation amount of the output of the brake negative pressure sensor during the operation of the brake is within a predetermined range.

  Since the operation of the brake by the automatic brake function is irrelevant to the brake operation by the driver, the negative pressure of the brake booster that assists the brake operation does not change during the operation of the brake by the automatic brake function. Therefore, even when the brake is operating, the output of the brake negative pressure sensor hardly changes. Therefore, whether or not an abnormality has occurred in the brake negative pressure sensor based on the determination of whether or not the fluctuation amount of the output of the brake negative pressure sensor is within a predetermined range during the operation of the brake by the automatic brake function. If determined, an abnormality in the brake negative pressure sensor is erroneously detected.

  Therefore, while the brake is being operated by the automatic brake function, it is not determined that an abnormality has occurred in the brake negative pressure sensor even if the fluctuation amount of the output of the brake negative pressure sensor is within a predetermined range. If the amount of fluctuation in the output of the brake negative pressure sensor is within a predetermined range during the operation of the brake that does not depend on the automatic brake function, that is, during the operation of the brake by the driver, the brake negative pressure sensor is abnormal. It is determined that it has occurred.

  Thereby, in a vehicle having an automatic brake function, it is possible to prevent erroneous detection of an abnormality of the brake negative pressure sensor and to detect abnormalities of the brake negative pressure sensor satisfactorily.

  ADVANTAGE OF THE INVENTION According to this invention, in the vehicle which has an automatic brake function, abnormality of a brake negative pressure sensor can be detected favorably.

FIG. 1 is a block diagram illustrating a configuration of a vehicle to which an abnormality detection apparatus according to an embodiment of the present invention is applied. FIG. 2 is a flowchart showing the flow of the abnormality determination process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram illustrating a configuration of a vehicle to which an abnormality detection apparatus according to an embodiment of the present invention is applied.

  The vehicle 1 is an automobile that uses the engine 2 as a drive source.

The output of the engine 2 includes a torque converter 3 and a continuously variable transmission (CVT: Continuously
It is transmitted to the drive wheels of the vehicle 1 via a variable transmission 4.

  A starter (starting motor) 5 is provided along with the engine 2. The stopped engine 2 starts after cranking by the starter 5.

  An alternator 6 is provided in association with the engine 2.

  The rotation of the output shaft of the engine 2 is transmitted to the rotation shaft (rotor) of the alternator 6. When the rotating shaft of the alternator 6 rotates, the rotation is converted into electric power, and electric power is output from the alternator 6.

  Each wheel of the vehicle 1 is provided with a brake 7. A brake pedal 8 that is operated by a driver's (user) foot is provided in the passenger compartment of the vehicle 1. The brake pedal 8 is connected to a brake booster 10 provided integrally with the master cylinder 9.

  When the brake pedal 8 is depressed, the pedal force input to the brake pedal 8 is transmitted to the brake booster 10. The pedaling force transmitted to the brake booster 10 is amplified (boosted) by the negative pressure of the brake booster 10 and input from the brake booster 10 to the master cylinder 9. In the master cylinder 9, a hydraulic pressure corresponding to the force input from the brake booster 10 is generated.

  The hydraulic pressure in the master cylinder 9 is transmitted to the ABS actuator 11. The ABS actuator 11 incorporates a valve for controlling the hydraulic pressure of a wheel cylinder provided in the brake 7 of each wheel, a pump for returning the brake fluid to the master cylinder 9, and the like. The hydraulic pressure transmitted from the master cylinder 9 to the ABS actuator 11 is distributed and transmitted to the wheel cylinders of the brakes 7. A braking force is applied from the brake 7 to the wheel by the hydraulic pressure of the wheel cylinder.

  The vehicle 1 has an automatic brake function for detecting the presence of an obstacle such as a vehicle ahead and automatically operating the brake 7. For the automatic brake function, a hydraulic pressure control valve 12 for transmitting the hydraulic pressure to the ABS actuator 11 is provided in a system different from the hydraulic pressure of the master cylinder 9. Regardless of the operation of the brake pedal 8, the hydraulic pressure control valve 12 is opened, the hydraulic pressure is transmitted to the ABS actuator 11, and the hydraulic pressure is distributed from the ABS actuator 11 to the wheel cylinders of the brakes 7. A braking force is automatically applied from the brake 7 to the wheel.

  The vehicle 1 is further provided with a battery 13.

  The battery 13 is charged with electric power output from the alternator 6. A starter 5 and the like are electrically connected to the battery 13. Drive power is supplied from the battery 13 to the starter 5. A relay 14 is interposed on the power supply path from the battery 13 to the starter 5.

  The vehicle 1 is also provided with a plurality of ECUs (electronic control units) including a CPU and a memory. The ECU includes an engine ECU 21, a CVTECU 22, an ABS ECU 23, a PCSECU 24, and an idle stop ECU 25. The engine ECU 21, the CVTECU 22, the ABS ECU 23, the PCSECU 24, and the idle stop ECU 25 can communicate with each other using a CAN (Controller Area Network) communication protocol.

  The engine 2 is connected to the engine ECU 21 as a control target.

  The CVT ECU 22 is connected to the continuously variable transmission 4 as a control target.

  The ABS ECU 23 is connected to the ABS actuator 10 and the hydraulic pressure control valve 12 as control targets. The ABS ECU 23 detects the wheel speed sensor 26 for detecting the rotational speed (wheel speed) of each wheel, the brake negative pressure sensor 27 for detecting the negative pressure of the brake booster 10, and the hydraulic pressure of the master cylinder 9. A hydraulic pressure sensor 28 is connected. The ABS ECU 23 calculates the wheel speed of each wheel based on the detection signal input from the wheel speed sensor 26, and obtains the average value of each wheel speed as the vehicle speed (body speed), for example. The ABS ECU 23 acquires the negative pressure of the brake booster 10 based on the detection signal input from the brake negative pressure sensor 27. Then, the ABS ECU 23 transmits a command for controlling the rotational speed of the engine 2 to the engine ECU 21 so that the negative pressure of the brake booster 10 becomes a suitable negative pressure, for example. Further, the ABS ECU 23 acquires the hydraulic pressure of the master cylinder 9 based on the detection signal input from the hydraulic pressure sensor 28.

  Connected to the PCSECU 24 is a laser radar 29 for measuring a distance from an obstacle such as a vehicle in front of the vehicle 1 at regular intervals. Further, the vehicle speed is input from the ABS ECU 23 to the PCSECU 24. The PCSECU 24 acquires the distance between the vehicle 1 and an obstacle ahead thereof based on the detection signal input from the laser radar 29, and there is a possibility of collision between the vehicle 1 and the obstacle based on the distance and the vehicle speed. Determine if there is.

  When the PCSECU 24 determines that there is a possibility of collision between the vehicle 1 and the obstacle, an automatic brake command is transmitted from the PCSECU 24 to the ABS ECU 23. In response to this automatic brake command, the ABS ECU 23 executes control for the automatic brake function (automatic brake control), the hydraulic control valve 12 is controlled, and braking force is automatically applied from the brake 7 to the wheels. The

  A relay 14 is connected to the idle stop ECU 25 as a control target. The vehicle 1 has an idle stop function, and the idle stop ECU 25 executes control for the idle stop function (idle stop control). For the idle stop control, information such as the engine speed is input from the engine ECU 21 to the idle stop ECU 25, the vehicle speed and the hydraulic pressure of the master cylinder 9 are input from the ABS ECU 23, and the steering torque is input from the EPS ECU 24.

  In the idle stop control, when the driver depresses the brake pedal 8 while the vehicle 1 is traveling and the hydraulic pressure in the master cylinder 9 becomes equal to or higher than a predetermined pressure, is the predetermined stop condition established by the idle stop ECU 25? It is repeatedly judged whether or not. The stop condition is, for example, a condition that the vehicle speed is zero and the brake pedal 8 is depressed for a certain time or more. When the stop condition is satisfied, an engine stop command is output from the idle stop ECU 25 to the engine ECU 21, and the engine 2 is stopped (idle stop) by the engine ECU 21.

  For example, when the foot is released from the brake pedal 8 while the engine 2 is stopped by the idle stop control, the restart condition is satisfied, and the relay 14 is turned on by the idle stop ECU 25. When the relay 14 is turned on, the engine 2 is started through cranking by the starter 5.

  FIG. 2 is a flowchart showing the flow of the abnormality determination process.

  While the ignition key switch of the vehicle 1 is on, the ABS ECU 23 repeatedly executes an abnormality determination process for determining whether an abnormality has occurred in the brake negative pressure sensor 27.

  In the abnormality determination process, first, it is determined whether or not an operation that fluctuates the negative pressure of the brake booster 10 has been performed (step S1). Specifically, for example, it is checked whether the increase / decrease in vehicle speed has been repeated a predetermined number of times or more. The vehicle speed increases and decreases when an accelerator pedal (not shown) and the brake pedal 8 are stepped on alternately. Therefore, when the vehicle speed increases or decreases a predetermined number of times or more, it is estimated that the negative pressure of the brake booster 10 is fluctuating, and it is determined that an operation that fluctuates the negative pressure of the brake booster 10 is performed. Further, even when the brake pedal 8 is depressed for a predetermined time or longer, it is estimated that the negative pressure of the brake booster 10 is fluctuating, and it is determined that an operation that fluctuates the negative pressure of the brake booster 10 has been performed. Is done.

  When an operation that fluctuates the negative pressure of the brake booster 10 is not performed (NO in step S1), the abnormality determination process is immediately terminated.

  When an operation that fluctuates the negative pressure of the brake booster 10 is performed (YES in step S1), it is confirmed that automatic brake control is not being executed (step S2).

  If the automatic brake control is not executed (YES in step S2), the output of the brake negative pressure sensor 27 (the negative voltage obtained from the output voltage value of the brake negative pressure sensor 27 or the detection signal of the brake negative pressure sensor 27) It is determined whether or not the fluctuation amount is equal to or less than a predetermined amount (step S3). The predetermined amount is set to a value close to zero. That is, it is determined whether or not the output of the brake negative pressure sensor 27 is substantially constant and fixed.

  If the fluctuation amount of the output of the brake negative pressure sensor 27 is not less than the predetermined amount (NO in step S3), the abnormality determination process is terminated.

  When the fluctuation amount of the output of the brake negative pressure sensor 27 is equal to or less than the predetermined amount (YES in step S3), the count value of the fixing condition satisfaction counter provided in the memory of the ABS ECU 23 is incremented (+1) (step S4). When the ignition key switch of the vehicle 1 is turned on, the count value of the fixing condition satisfaction counter is reset to zero.

  Thereafter, it is checked whether or not the count value of the fixing condition satisfaction counter has reached a predetermined value (step S5). The predetermined value is set to a value of 1 or more.

  If the count value of the fixing condition satisfaction counter has not reached the predetermined value (NO in step S5), the abnormality determination process is terminated.

  When the abnormality determination process is repeatedly executed and the count value of the fixing condition satisfaction counter reaches a predetermined value (YES in step S5), some abnormality is caused in the brake negative pressure sensor 27, for example, the signal line of the brake negative pressure sensor 27 is disconnected. Is determined to occur (step S6). Then, the abnormality determination process is terminated, and for example, fail-safe control when an abnormality occurs in the brake negative pressure sensor 27 is executed.

  When it is determined that an operation that fluctuates the negative pressure of the brake booster 10 has been performed, if the automatic brake control is being executed (YES in step S2), the fluctuation amount of the output of the brake negative pressure sensor 27 It is not determined whether or not is less than the predetermined amount, the count value of the fixing condition satisfaction counter is reset to 0 (step S7), and the abnormality determination process is terminated.

  Thus, in order to determine whether or not an abnormality has occurred in the brake negative pressure sensor 27, it is determined whether or not automatic brake control is being performed. Further, it is determined whether or not the fluctuation amount of the output of the brake negative pressure sensor 27 during operation of the brake 7 is within a predetermined amount or less.

  Since the operation of the brake 7 by the automatic brake control is irrelevant to the brake operation by the driver, the negative pressure of the brake booster 10 that assists the brake operation does not fluctuate during the execution of the automatic brake control. Therefore, even when the brake 7 is in operation, the output of the brake negative pressure sensor 27 hardly changes. Therefore, whether or not an abnormality has occurred in the brake negative pressure sensor 27 is determined based on the determination as to whether or not the fluctuation amount of the output of the brake negative pressure sensor 27 is equal to or less than a predetermined amount during execution of the automatic brake control. If determined, an abnormality in the brake negative pressure sensor 27 is erroneously detected.

  Therefore, if the automatic brake control is being executed, it is not determined that an abnormality has occurred in the brake negative pressure sensor 27 even if the fluctuation amount of the output of the brake negative pressure sensor 27 is a predetermined amount or less. If the amount of change in the output of the brake negative pressure sensor 27 is equal to or less than a predetermined amount during operation of the brake 7 not based on automatic brake control, that is, during operation of the brake 7 by the driver's brake operation, the brake negative pressure sensor 27 is determined to be abnormal.

  Thereby, in the vehicle 1 having the automatic brake function, it is possible to prevent erroneous detection of the abnormality of the brake negative pressure sensor 27 and to detect the abnormality of the brake negative pressure sensor 27 satisfactorily.

  As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form.

  For example, the vehicle 1 is not limited to an automobile that uses the engine 2 as a drive source, but may be a hybrid car that uses an engine and a motor as drive sources, or an electric car that uses a motor as a drive source.

  Although the vehicle 1 having the idle stop function is taken up, the abnormality detection device for the brake negative pressure sensor according to the present invention is naturally applicable to a vehicle having no idle stop function.

  In addition, various design changes can be made to the above-described configuration within the scope of the matters described in the claims.

DESCRIPTION OF SYMBOLS 1 Vehicle 10 Brake booster 23 ABSECU (Abnormality detection apparatus, automatic brake operation determination means, fluctuation amount determination means, abnormality determination means)
27 Brake negative pressure sensor

Claims (1)

A brake booster for assisting a brake operation by a driver and a brake negative pressure sensor for detecting a negative pressure of the brake booster, and used for a vehicle having an automatic brake function for automatically operating a brake regardless of the brake operation. A device for detecting an abnormality of the brake negative pressure sensor,
Automatic brake operation determining means for determining whether or not the brake is being operated by the automatic brake function;
A fluctuation amount determining means for determining whether or not a fluctuation amount of the output of the brake negative pressure sensor during operation of the brake is within a predetermined range;
When it is determined by the automatic brake operation determining means that the brake is not being operated by the automatic brake function, and the fluctuation amount determining means determines that the fluctuation amount is within the predetermined range, the fixing condition A brake determining unit that increments a count value of the establishment counter and determines that an abnormality has occurred in the brake negative pressure sensor when the count value of the fixation condition establishment counter reaches a predetermined value of 1 or more , Negative pressure sensor abnormality detection device.

Images