JP5359369B2 - Brake control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brake control device for specifying whether or not an output of a stroke sensor is normal. <P>SOLUTION: This brake control device determines target braking force based on an output value of a stroke sensor 46 for detecting stepping amount of a brake pedal and an output value of a master cylinder pressure sensor 48 for detecting pressure of a master cylinder for feeding working liquid. An accelerator operation detection means detects the operation of an accelerator pedal. A deciding part 78 decides that the output of the stroke sensor 46 is not normal when the operation of the accelerator pedal is detected by the accelerator operation detecting part 74, and the output of the stroke sensor 46 does not satisfy a normal relation with the output of the master cylinder pressure sensor 48. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a brake control device for a vehicle.

  2. Description of the Related Art In recent years, many electronically controlled brake systems that control the braking force of each wheel so as to give an optimum braking force to the vehicle according to the traveling state of the vehicle have been adopted as a vehicle brake control device. In such an electronically controlled brake system, the output of a stroke sensor that detects the amount of depression of the brake pedal and the output of a master cylinder pressure sensor that detects the pressure of the master cylinder that sends hydraulic fluid in accordance with the amount of depression of the brake pedal. Based on this, the target braking force is determined. If an abnormality occurs in the output of the stroke sensor, there may be a difference between the amount of depression of the brake pedal and the braking force applied to the vehicle. Therefore, the malfunction of the output of the stroke sensor should be detected appropriately.

  In Patent Literature 1, it is determined whether the time change rate of the output value of the stroke sensor and the time change rate of the output value of the master cylinder pressure sensor are within the normal range. A vehicle control device is disclosed that includes an abnormality determination unit that determines that an abnormality has occurred in at least one of them.

JP 2007-112160 A

  By the way, according to Patent Document 1, it can be determined that either the stroke sensor or the master cylinder pressure sensor is not normal, but it is difficult to determine which sensor is not normal.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a brake control device that can appropriately determine whether or not the output of the stroke sensor is normal.

In order to solve the above-described problem, an aspect of the present invention provides an output value of a stroke sensor that detects the depression amount of a brake pedal and an output value of a master cylinder pressure sensor that detects the pressure of a master cylinder that sends out hydraulic fluid. A brake control device for determining a target braking force on the basis of an accelerator operation detecting means for detecting an operation of an accelerator pedal, an operation of the accelerator pedal being detected by the accelerator operation detecting means, and an output of a stroke sensor and a master cylinder pressure sensor Determining means for determining that the output of the stroke sensor is not normal when the output of the stroke sensor does not satisfy the normal relationship. This determination means determines that the output of the stroke sensor is not normal when the output value of the stroke sensor is greater than the reference stroke output value corresponding to the output value of the master cylinder pressure sensor.

  According to this aspect, it is possible to specify that the output of the stroke sensor is not normal by detecting the operation of the accelerator pedal. Specifically, if the output of the stroke sensor and the output of the master cylinder pressure sensor do not satisfy the normal relationship, it can be understood that the output of either sensor is not normal. Therefore, the brake control device of this aspect determines which sensor output is not normal by using the accelerator operation detection means. Generally, if the driver is depressing the accelerator pedal, the driver is not depressing the brake pedal. Therefore, if the accelerator pedal is depressed, it is estimated that the brake pedal is not depressed. For example, if a braking request is obtained from the output of the stroke sensor and the brake pedal is not depressed, the output results of the sensors are contradictory, and therefore it can be specified that the output of the stroke sensor is not normal. Thereby, it is possible to accurately identify which output of the stroke sensor and the master cylinder pressure sensor is not normal using the accelerator operation detection means.

Determine the constant unit, when bigger than a predetermined value than the reference stroke output value an output value of the stroke sensor, the output of the stroke sensor may be determined not to be normal. If the output value of the stroke sensor is larger than the reference stroke output value, a braking request is obtained from the output of the stroke sensor. At this time, when the operation of the accelerator pedal is detected, it is possible to specify that the output of the stroke sensor is not normal because the logic is inconsistent.

According to another aspect of the present invention, a target braking force is determined based on an output value of a stroke sensor that detects a depression amount of a brake pedal and an output value of a master cylinder pressure sensor that detects a pressure of a master cylinder that sends out hydraulic fluid. A brake control device that detects the operation of the accelerator pedal, and the operation of the accelerator pedal is detected by the accelerator operation detection unit, and the relationship between the output of the stroke sensor and the output of the master cylinder pressure sensor is normal. And determining means for determining that the output of the stroke sensor is not normal when the condition is not satisfied. The determination means is a braking request from the output value of the stroke sensor are obtained, when a braking request from the output value of the master cylinder pressure sensor can not be obtained, the output of the stroke sensor is determined not to be normal. The determination means may determine that the output of the stroke sensor is not normal when the output value of the stroke sensor is greater than or equal to a predetermined threshold value. Thereby, the determination means can accurately determine whether or not the output value of the stroke sensor and the output value of the master cylinder pressure sensor satisfy a normal relationship.

  A stroke correction unit that corrects the output of the stroke sensor when the determination unit determines that the output of the stroke sensor is not normal may be further provided. Since it is specified that the output of the stroke sensor is not normal, it is possible to correct the output of the stroke sensor instead of the master cylinder pressure sensor. Even if it is determined that the output of the stroke sensor is not normal, the brake control can be maintained without switching to the brake mode that does not use the output of the stroke sensor.

  The stroke correction means corrects the output value of the stroke sensor to a reference stroke output value corresponding to the output value of the master cylinder pressure sensor once the determination means determines that the output of the stroke sensor is not normal. Also good. Thereby, for example, when the braking request cannot be obtained from the output value of the master cylinder pressure sensor, the correction can be performed until the braking request cannot be obtained from the output value of the stroke sensor.

  If the required stroke braking amount obtained from the output value of the stroke sensor exceeds the upper limit value of the required braking amount corresponding to the output value of the master cylinder pressure sensor, the required braking amount limit is limited to the upper limit value. And a means. The stroke correction means may change the correction amount of the output of the stroke sensor depending on whether or not the stroke braking request amount is limited to the upper limit value.

  A standby time deriving unit that derives the standby time until the correction of the output of the stroke sensor is performed based on the vehicle speed detected by the vehicle speed detecting unit may be further provided. The stroke correction means may correct the output of the stroke sensor after the standby time has elapsed if the determination means determines that the output of the stroke sensor is not normal. Depending on the vehicle speed, the standby time for starting the correction of the output of the stroke sensor can be adjusted.

  According to the present invention, it is possible to appropriately determine whether or not the output of the stroke sensor is normal.

It is a figure which shows the structure of the brake control apparatus which concerns on embodiment. It is a figure which shows the normal relationship between the output of a stroke sensor, and the output of a master cylinder pressure sensor. It is a figure which shows the function structure of ECU which concerns on embodiment. It is a figure which shows the relationship between the output value of the stroke sensor which concerns on embodiment, and the stroke braking request amount obtained from the output value of a stroke sensor. It is a flowchart which shows the correction process of the stroke sensor which concerns on embodiment.

  FIG. 1 is a diagram illustrating a configuration of a brake control device 10 according to the embodiment. A brake control device 10 shown in FIG. 1 constitutes an electronically controlled brake system (ECB) for a vehicle, and brakes for four wheels of a vehicle based on an operation amount of a brake pedal 12 as a brake operation member by a driver. Is optimally controlled.

  The brake pedal 12 is connected to a master cylinder 14 that delivers hydraulic fluid in accordance with the amount of depression by the driver. The brake pedal 12 is provided with a stroke sensor 46 for detecting the amount of depression.

  The stroke sensor 46 according to the embodiment is a non-contact Hall IC type magnetic sensor. The stroke sensor 46 is provided on the rotating shaft of the brake pedal 12 and is supplied with a current from a power supply unit (not shown). Further, the stroke sensor 46 performs temperature correction or the like on the detected value in the Hall IC circuit, and outputs the result to an ECU (Electronic control unit) 200.

  The vehicle speed sensor 45 detects vehicle speed information of the vehicle and outputs the detected value to the ECU 200. The wheel speed sensor may detect vehicle speed information of the vehicle. The accelerator sensor 47 detects the amount of depression of an accelerator pedal (not shown) and outputs the detected value to the ECU 200. The accelerator sensor 47 functions as an accelerator operation detection unit that detects an operation of the accelerator pedal.

  A stop lamp switch (not shown) detects whether or not the brake pedal 12 is depressed. The stop lamp switch is used for lighting control of a brake lamp provided at the rear of the vehicle. For example, when the brake pedal 12 is depressed by the driver, the stop lamp switch is turned on and the brake lamp is turned on. When the depression of the brake pedal 12 is released, the stop lamp switch is turned off and the brake lamp is turned off. To do.

  Connected to the first output port 14a of the master cylinder 14 is a stroke simulator 24 that creates a pedal stroke according to the depression force of the brake pedal 12 by the driver.

  A simulator cut valve 23 is provided in the middle of the flow path connecting the master cylinder 14 and the stroke simulator 24. The simulator cut valve 23 is a normally closed electromagnetic on-off valve that opens when energized and closes when de-energized. The master cylinder 14 is connected to a reservoir tank 26 for storing hydraulic fluid.

  A brake hydraulic control pipe 18 for the right front wheel is connected to the first output port 14a of the master cylinder 14, and the brake hydraulic control pipe 18 is a wheel cylinder for the right front wheel that applies a braking force to the right front wheel. It is connected to 20FR. A brake hydraulic control pipe 16 for the left front wheel is connected to the second output port 14b of the master cylinder 14, and the brake hydraulic control pipe 16 is used for the left front wheel that applies a braking force to the left front wheel. It is connected to the wheel cylinder 20FL.

  A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 16 for the left front wheel. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when not energized and switched to closed when energized.

  A right master cylinder pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel. Is provided with a left master cylinder pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side. Hereinafter, the right master cylinder pressure sensor 48FR and the left master cylinder pressure sensor 48FL are collectively referred to as “master cylinder pressure sensor 48” as appropriate.

  In the brake control device 10, when the brake pedal 12 is depressed by the driver, the stroke sensor 46 detects the amount of depression, which is detected by the right master cylinder pressure sensor 48FR and the left master cylinder pressure sensor 48FL. The depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the master cylinder pressure.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump including two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. Further, as the accumulator 50, an accumulator 50 that converts the pressure energy of the hydraulic fluid into pressure energy of an enclosed gas such as nitrogen and stores it is employed.

  The accumulator 50 stores the hydraulic fluid whose pressure has been increased to, for example, about 14 to 22 MPa by the oil pump 34. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / discharge pipe 28. When the pressure of the hydraulic fluid in the accumulator 50 is abnormally increased to, for example, about 25 MPa, the relief valve 53 is opened and the high pressure operation is performed. The liquid is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects the outlet pressure of the accumulator 50, that is, the pressure of the working fluid in the accumulator 50.

  The high-pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel through the pressure increasing valves 40FR, 40FL, 40RR, 40RL. It is connected to the cylinder 20RL. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary. A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20.

  Further, the wheel cylinder 20FR for the right front wheel and the wheel cylinder 20FL for the left front wheel are connected to the hydraulic supply / discharge pipe 28 via the pressure reducing valve 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  Wheel cylinders for detecting the wheel cylinder pressure, which is the pressure of the hydraulic fluid acting on the corresponding wheel cylinder 20, in the vicinity of the wheel cylinders 20FR to 20RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel Pressure sensors 44FR, 44FL, 44RR and 44RL are provided. Hereinafter, the wheel cylinder pressure sensors 44FR to 44RL are collectively referred to as “wheel cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the oil pump 34, the accumulator 50, and the like constitute the hydraulic actuator 81 of the brake control device 10. The hydraulic actuator 81 is controlled by the ECU 200.

  The ECU 200 functions as a control unit that controls the wheel cylinder pressure in the wheel cylinders 20FR to 20RL. The ECU 200 is a nonvolatile memory such as a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, and a backup RAM that can retain stored contents even when the engine is stopped. An A / D converter for converting an analog signal input from a memory, an input / output interface, various sensors, and the like into a digital signal and taking it in, a timer for timing, and the like are provided.

  The ECU 200 is electrically connected to various actuators including the hydraulic on-off valves 81FR, 22FL, the simulator cut valve 23, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, and the like.

  The ECU 200 is electrically connected to various sensors / switches that output signals for use in control. That is, the ECU 200 receives a signal indicating the pedal stroke of the brake pedal 12 from the stroke sensor 46, receives a signal indicating the master cylinder pressure from the master cylinder pressure sensor 48, and turns on / off the brake lamp from the stop lamp switch. The signal shown is input.

  In the brake control device 10 configured as described above, when the brake pedal 12 is depressed by the driver, the ECU 200 calculates the target braking force of the vehicle from the pedal stroke representing the depression amount of the brake pedal 12 and the master cylinder pressure. A target hydraulic pressure that is a target value of the wheel cylinder pressure of each wheel is obtained in accordance with the calculated target braking force. Then, the ECU 200 controls the pressure increasing valve 40 and the pressure reducing valve 42 so that the wheel cylinder pressure of each wheel becomes the target hydraulic pressure.

  By the way, the stroke sensor 46 outputs the supply voltage as an output voltage as it is in order to prevent the output from becoming unstable when the supply voltage supplied from the power supply unit decreases. At this time, if the target braking force is determined based on the output voltage of the stroke sensor 46, a braking force unintended by the driver may be generated. On the other hand, when the supply voltage of the stroke sensor 46 decreases, the master cylinder pressure does not increase unless the brake pedal 12 is depressed. Therefore, a braking request may be obtained from the output of the stroke sensor 46, and a braking request may not be obtained from the output of the master cylinder pressure sensor 48.

  Therefore, the ECU 200 determines whether the output of the stroke sensor 46 and the master cylinder pressure sensor 48 satisfies a normal relationship, for example, so that the output of either the stroke sensor 46 or the master cylinder pressure sensor 48 is not normal. Can be determined. However, in this determination, the ECU 200 cannot identify which output of the stroke sensor 46 and the master cylinder pressure sensor 48 is not normal. In the embodiment, which sensor output is not normal is specified by the method described below.

  The ECU 200 according to the embodiment detects whether or not the accelerator pedal is depressed based on the output of the accelerator sensor 47. Generally, if the driver is depressing the accelerator pedal, the brake pedal 12 is not depressed. Therefore, the ECU 200 estimates that the brake pedal 12 is not depressed if the accelerator pedal is depressed. When a braking request is obtained from the output of the stroke sensor 46 and it can be estimated from the depression of the accelerator pedal that the brake pedal 12 is not depressed, the results obtained from the output of the stroke sensor 46 and the output of the accelerator sensor 47 conflict. .

  Therefore, the ECU 200 determines whether the relationship between the output of the master cylinder pressure sensor 48 and the output of the stroke sensor 46 is normal, the braking request obtained from the output of the stroke sensor 46, and whether or not the accelerator pedal is depressed. It is determined whether there is a contradiction, and whether the output of the stroke sensor 46 is normal is specified. For example, if there is no braking request from the master cylinder pressure sensor 48, there is a braking request from the stroke sensor 46, and the accelerator pedal is depressed, the ECU 200 specifies that the output of the stroke sensor 46 is not normal. Thereby, it is possible to specify which output of the stroke sensor 46 and the master cylinder pressure sensor 48 is not normal by using other sensors.

  Further, the ECU 200 specifies that the output of the stroke sensor 46 is not normal, and corrects the output of the stroke sensor 46. By performing the correction, even if it is determined that the output of the stroke sensor 46 is not normal, the brake control can be maintained without switching to the brake mode in which the output of the stroke sensor 46 is not used.

  If the accelerator pedal is depressed, it is normal that the brake pedal 12 is not depressed, but an operation in which the driver depresses the accelerator pedal and the brake pedal 12 at the same time (hereinafter referred to as “two-step operation”). There are rare cases to do. Further, the initial response of the master cylinder pressure is slow, and there is a region where the output of the master cylinder pressure sensor 48 hardly changes even when the brake pedal 12 is lightly depressed.

  When the brake pedal 12 is lightly depressed by the driver's foot weight or the like in both stepping operations, the output of the master cylinder pressure sensor 48 does not change much because the initial response of the master cylinder pressure is slow. At this time, even when the output of the stroke sensor 46 is normal during the two-step operation, there is no braking request from the master cylinder pressure sensor 48, there is a braking request from the stroke sensor 46, and the accelerator pedal is depressed. It can be established. Note that if the driver depresses the brake pedal 12 strongly, the master cylinder pressure rises beyond the region where the response is low.

  FIG. 2 shows a normal relationship between the output of the stroke sensor 46 and the output of the master cylinder pressure sensor 48. The vertical axis represents the output of the master cylinder pressure sensor 48, and the horizontal axis represents the output of the stroke sensor 46. A solid line 92 indicates a normal relationship between the output of the stroke sensor 46 and the output of the master cylinder pressure sensor 48. A solid line 92 indicates that the output relationship between the sensors is not proportional and the initial response of the master cylinder pressure when the brake pedal 12 is depressed is dull.

  For example, if the relationship between the output value of the stroke sensor 46 and the output value of the master cylinder pressure sensor 48 is within a predetermined value from the solid line 92, the ECU 200 determines that the normal relationship is satisfied. If the output value 46 is within a predetermined value from the reference stroke output value ST0 corresponding to the output value PMC0 of the master cylinder pressure sensor 48, it is determined that the normal relationship is satisfied.

  When the output value of the stroke sensor 46 is within the range of ST0 to ST1, the output of the master cylinder pressure sensor 48 does not change much. Therefore, even if the brake pedal 12 is depressed in this range, it is difficult to accurately determine whether the relationship between the two is normal using the output value from the master cylinder pressure sensor 48. The range from the output value ST0 to the output value ST1 and the range from the output value PMC0 to the output value PMC1 are referred to as an initial response region where the master cylinder pressure response is slow.

  Here, if the brake pedal 12 is lightly depressed during the two-step operation, the master cylinder pressure sensor 48 may indicate the output value PMC0 and the stroke sensor 46 may indicate the output value ST1. At this time, depending on the magnitude of the predetermined value, even if the output of the master cylinder pressure sensor 48 and the output of the stroke sensor 46 are normal, the ECU 200 determines that the normal relationship is not satisfied. Therefore, for example, by setting the predetermined value to a value larger than | ST1-ST0 |, it is possible to accurately determine whether the output value of the stroke sensor 46 and the output value of the master cylinder pressure sensor 48 satisfy a normal relationship. .

  On the other hand, if the output of either the stroke sensor 46 or the master cylinder pressure sensor 48 exceeds the initial response region, it can be accurately determined whether the output value satisfies the normal relationship. For example, if the output of the master cylinder pressure sensor 48 is the output value PMC2, if the output value of the stroke sensor 46 deviates from the reference stroke output value ST2 by a predetermined value or more, the ECU 200 causes the stroke sensor 46 and the master cylinder pressure sensor 48 to move. It is determined that one of the outputs is not normal.

  FIG. 3 shows a functional configuration of the ECU 200 according to the embodiment. The ECU 200 includes a sensor value acquisition unit 72, an accelerator operation detection unit 74, a determination unit 78, a standby time derivation unit 80, a stroke correction unit 82, a braking request amount calculation unit 84, a braking request amount limit unit 86, an upper limit value holding unit 88, And a control unit 90.

  The sensor value acquiring unit 72 includes an output value of the stroke sensor 46 (hereinafter referred to as “stroke output value”), an output value of the master cylinder pressure sensor 48 (hereinafter referred to as “master output value”), an output value of the vehicle speed sensor 45, and an accelerator sensor. 47 output values are obtained.

  The braking request amount calculation unit 84 receives the stroke output value and the master output value from the sensor value acquisition unit 72. The braking request amount calculation unit 84 calculates a stroke braking request amount based on the stroke output value, and calculates a master braking request amount based on the master output value. The braking request amount calculation unit 84 may receive the stroke output value corrected by the stroke correction unit 82 and calculate the stroke braking request amount. The braking request amount calculation unit 84 supplies the calculated braking request amount to the braking request amount restriction unit 86 and the determination unit 78.

  The requested braking amount restriction unit 86 restricts the requested stroke braking amount to the upper limit value if the requested stroke braking amount exceeds the upper limit value of the requested braking amount corresponding to the output value of the master cylinder pressure sensor 48. The upper limit value may be set in a range where an error can be allowed from the master braking request amount obtained from the output value of the master cylinder pressure sensor 48, and is set to a value larger than the master braking request amount. The upper limit value may be stored as a two-dimensional map. Further, the difference between the upper limit value and the master braking request amount may be decreased as the master braking request amount increases. Thereby, the dullness of the initial response of the master cylinder pressure sensor 48 can be absorbed.

  Here, with reference to FIG. 4, the stroke braking request amount limiting process will be described. FIG. 4 shows the relationship between the output value of the stroke sensor 46 according to the embodiment and the required stroke braking amount obtained from the output value of the stroke sensor 46. The vertical axis represents the required stroke braking amount obtained from the output value of the stroke sensor 46, and the horizontal axis represents the output value of the stroke sensor 46.

  The required braking amount calculation unit 84 calculates the required stroke braking amount Gx according to the stroke output value ST5 and supplies it to the required braking amount limiting unit 86. At this time, the braking request amount restriction unit 86 determines the upper limit value M according to the master output value. The requested braking amount restriction unit 86 outputs the upper limit value M as a new requested stroke braking amount M to the control unit 90 because the requested stroke braking amount Gx exceeds the upper limit value M corresponding to the master output value.

  On the other hand, if the stroke braking request amount does not exceed the upper limit value corresponding to the master output value, the braking request amount limiting unit 86 outputs the received stroke braking request amount to the control unit 90 as it is.

  The output of the master cylinder pressure sensor 48 with independent wiring and less influence on the voltage fluctuation of the power supply unit is more reliable than the output of the stroke sensor 46. By restricting the stroke braking request amount with the upper limit value corresponding to the master output value, it is possible to limit the stroke braking request amount so as not to deviate significantly from the highly reliable master braking request amount. The upper limit holding unit 88 holds an upper limit corresponding to the master output value.

  Returning to FIG. The control unit 90 determines the target hydraulic pressure of the hydraulic actuator 81 based on the limited stroke braking request amount and the master braking request amount. The control unit 90 gives a current value corresponding to the determined target oil pressure to the electromagnetic control valve of the hydraulic actuator 81. The control unit 90 may determine the target hydraulic pressure by acquiring the corrected stroke braking request amount from the stroke correction unit 82.

  The accelerator operation detection unit 74 receives the output value of the accelerator sensor 47 and detects the operation of the accelerator pedal. The accelerator operation detection unit 74 supplies the detected information to the determination unit 78.

  The determination unit 78 detects that the accelerator pedal operation is detected by the accelerator operation detection unit 74, and the output of the stroke sensor 46 is normal when the output of the stroke sensor 46 and the output of the master cylinder pressure sensor 48 do not satisfy the normal relationship. It is determined that it is not. Specifically, the determination unit 78 detects the operation of the accelerator pedal by the accelerator operation detection unit 74, and the output value of the stroke sensor 46 is greater than the reference stroke output value corresponding to the output value of the master cylinder pressure sensor 48 by a predetermined value or more. If it is larger, it is determined that the output of the stroke sensor 46 is not normal. The reference stroke output value is determined according to the master output value, and may be a reference value indicating an ideal relationship between the stroke output value and the master output value. Further, the reference stroke output value may be held as a two-dimensional map. The determination unit 78 may determine that the normal relationship is not satisfied if the output value of the master cylinder pressure sensor 48 is smaller than the reference master output value corresponding to the output value of the stroke sensor 46 by a predetermined value or more.

  Specifically, from the determination result that the normal relationship is not satisfied, it is confirmed that one of the outputs of the stroke sensor 46 and the master cylinder pressure sensor 48 is not normal, and that the braking request is obtained from the output of the stroke sensor 46. Lead. Further, since the operation of the accelerator pedal is detected, it is estimated that the brake pedal 12 is not depressed. Thereby, it is specified with high accuracy whether the output of the stroke sensor 46 or the master cylinder pressure sensor 48 is not normal using the other sensors.

  By determining whether or not the deviation is greater than or equal to the predetermined value from the reference stroke output value, it is possible to give the reference stroke value a certain width and suppress excessive determination that the deviation within the predetermined value from the reference value is not normal. The predetermined value may be set to a value larger than a value based on the initial response area, for example, a value larger than | ST1-ST0 | in FIG. Further, the predetermined value may change according to the master output value or the stroke output value. For example, when the master cylinder pressure is small, the initial responsiveness is slow, so the predetermined value may be set to a relatively large value, and when the master cylinder pressure increases and increases, the predetermined value may be set to a relatively small value. . By providing the predetermined value, it is possible to suppress the determination that it is not excessively normal. In addition, by setting the predetermined value to a relatively large value, the accuracy of determining whether or not the normal relationship is satisfied is improved.

  The determination unit 78 determines that the output of the stroke sensor 46 is not normal when the operation of the accelerator pedal is detected, the braking request is obtained from the stroke output value, and the braking request is not obtained from the master output value. Good. “A braking request cannot be obtained from the stroke output value” means that the stroke output value is within a minute value from the zero point of the output of the stroke sensor 46. Further, the fact that the braking request cannot be obtained from the master output value means that the master output value is within a minute value from the zero point of the output of the master cylinder pressure sensor 48.

  The determination unit 78 determines that the output of the stroke sensor 46 is not normal when the output value of the stroke sensor 46 is equal to or greater than a predetermined threshold value and a braking request cannot be obtained from the output value of the master cylinder pressure sensor 48. When the brake pedal 12 is depressed to a certain extent and the stroke output value is equal to or greater than a predetermined threshold, the relationship between the two is accurately determined by determining whether the stroke output value and the master output value satisfy a normal relationship. can do. Moreover, it is possible to prevent the correction of the output of the stroke sensor 46 from being executed when the operation is a double stepping operation and the output of the stroke sensor 46 is normal. The predetermined threshold may be determined based on the initial response area.

  The stroke correction unit 82 corrects the output of the stroke sensor 46 when the determination unit 78 determines that the stroke sensor 46 is not normal. Specifically, the stroke correction unit 82 may perform correction based on the difference between the reference stroke output value corresponding to the master output value and the stroke output value. Even if it is determined that the stroke sensor 46 is not normal, the brake control can be maintained without switching to the brake mode that does not use the output of the stroke sensor. In order to suppress a sudden change in braking force, the stroke correction unit 82 may correct the difference between the reference stroke output value and the stroke output value so as to gradually decrease.

  Once the determination unit 78 determines that the output of the stroke sensor 46 is not normal, the stroke correction unit 82 sets the output value of the stroke sensor to the reference stroke output value corresponding to the output value of the master cylinder pressure sensor. It may be corrected. That is, the stroke correction unit 82 corrects the output of the stroke sensor 46 after the operation of the accelerator pedal is detected and the stroke output value is determined to be larger than the reference stroke output value corresponding to the master output value. Is corrected while the braking request continues. The period during which the braking request is continued refers to the period during which a stroke output value greater than the zero point is continuously output.

  If the determination unit 78 determines that the braking request is not obtained from the master output value and the output of the stroke sensor 46 is not normal, the stroke correction unit 82 obtains the braking request from the output value of the stroke sensor 46. You may correct it until it runs out. That is, the stroke correction unit 82 determines that the braking request is not obtained from the master output value by the determination unit 78 and corrects the stroke braking request amount to be zero.

  For example, as shown in FIG. 2, if the output of the stroke sensor 46 indicates the output value ST2, it means that the determination unit 78 can reliably determine whether the normal relationship is satisfied outside the range of the initial response region. If the depression of the accelerator pedal is also detected, it can be reliably determined that the output of the stroke sensor 46 is not normal. Once it is determined that the braking request is not normal, correction is performed until the braking request is not obtained from the output value of the stroke sensor 46 while the braking request continues. Thereby, it can correct | amend even if the shift | offset | difference of a reference stroke output value and a stroke output value becomes below a predetermined value.

  When the determination means determines that the output of the stroke sensor 46 is not normal, the stroke correction unit 82 changes the correction amount of the output of the stroke sensor 46 depending on whether or not the stroke braking request amount is limited to the upper limit value. It's okay. The stroke correction unit 82 acquires an upper limit value corresponding to the master output value from the upper limit value holding unit 88.

  Here, it demonstrates with reference to FIG. This is the stroke output value ST5, and the upper limit value M is determined according to the master output value at this time. The requested braking amount restriction unit 86 restricts the requested stroke braking amount Gx corresponding to the stroke output value ST5 to the upper limit value M. At this time, if the stroke correction unit 82 corrects the output of the stroke sensor 46 within a range equal to or higher than the output value ST4 corresponding to the upper limit value, the stroke braking request amount M does not change even if the stroke correction unit 82 corrects it so as to decrease rapidly. Therefore, the stroke correction unit 82 corrects the output value ST5 so that it quickly becomes the output value ST4. Thereby, when the output of the stroke sensor 46 is not normal while suppressing the change in the braking force applied to the driver, the stroke correction unit 82 can correct quickly.

  On the other hand, if the required stroke braking amount is equal to or less than the upper limit value, the stroke correction unit 82 corrects the output value of the stroke sensor 46 so as to gradually decrease. Thereby, the change of the braking force given to the driver can be moderated.

  From the above, when the stroke braking request amount is limited to the upper limit value, the stroke correction unit 82 corrects the stroke output value so as to rapidly decrease to the stroke output value corresponding to the upper limit value, and the stroke braking request amount. If is less than the upper limit, the stroke output value is corrected so as to gradually decrease. As a result, it is possible to quickly reduce the output of the limited extra stroke sensor 46 while suppressing changes in the braking force applied to the driver.

  A vehicle speed detection unit (not shown) detects the vehicle speed of the vehicle based on the output value of the vehicle speed sensor 45 and supplies it to the standby time deriving unit 80. The standby time deriving unit 80 derives the standby time until the output of the stroke sensor 46 is corrected based on the vehicle speed detected by the vehicle speed detecting unit. In addition, you may use the well-known technique which detects the vehicle speed of a vehicle as a vehicle speed detection part.

  When the determination unit 78 determines that the output of the stroke sensor 46 is not normal, the stroke correction unit 82 corrects the output of the stroke sensor 46 after the standby time has elapsed.

  For example, if the stroke correction unit 82 corrects the output of the stroke sensor 46 immediately after the determination unit 78 determines that the stroke sensor 46 is not normal, the possibility of correcting the output of the stroke sensor 46 during a two-step operation increases. There is also a possibility of performing correction excessively. On the other hand, if it is determined that the stroke sensor 46 is not normal and the correction of the output of the stroke sensor 46 is delayed, the braking pad continues to generate and the brake pads generate excessive heat.

  For example, when the vehicle speed is high, it is less likely that the vehicle is traveling on a curve than when the vehicle speed is low, and it is more likely that the vehicle is going straight. If the vehicle is traveling straight, it is less likely to be braked than if the vehicle is traveling on a curve, and if the vehicle speed is high, the possibility of two-step operation is reduced. Further, when the same braking force is applied to the brake pad when the vehicle speed is high and when the vehicle speed is low, the amount of heat generated by the braking force is greater when the vehicle speed is high. Therefore, if the stroke correction unit 82 performs correction with a shorter standby time when the vehicle speed is high than when the vehicle speed is low, heat generation of the brake pad can be suppressed. By adjusting the standby time for starting the correction of the output of the stroke sensor 46 depending on the vehicle speed, it is possible to suppress excessive correction while suppressing heat generation of the brake pad.

  FIG. 5 is a flowchart showing a correction process of the stroke sensor 46 according to the embodiment. First, the sensor value acquisition unit 72 acquires the stroke output value, the master output value, the output of the vehicle speed sensor 45, and the output of the accelerator sensor 47 (S10). The accelerator operation detection unit 74 detects the operation of the accelerator pedal (S12).

  The determination unit 78 determines whether or not the output of the stroke sensor 46 is normal based on whether or not the operation of the accelerator pedal is detected and whether or not the stroke output value is larger than a reference stroke output value corresponding to the master output value ( S14). Thereby, it can identify that the output of the stroke sensor 46 is not normal. The determination unit 78 determines that the output of the stroke sensor 46 is not normal when the operation of the accelerator pedal is detected, the braking request is obtained from the stroke output value, and the braking request is not obtained from the master output value. Also good.

  The determination unit 78 determines that the output of the stroke sensor 46 is not detected when the operation of the accelerator pedal is not detected or the output value of the stroke sensor 46 is not larger than the reference stroke output value corresponding to the output value of the master cylinder pressure sensor 48. It determines with it being normal (Y of S14). If it is determined that the stroke sensor 46 is normal, the correction process is terminated.

  When the operation of the accelerator pedal is detected and the stroke output value is larger than the reference stroke output value corresponding to the master output value, the determination unit 78 determines that the output of the stroke sensor 46 is not normal (N in S14).

  After determining that the stroke sensor 46 is not normal by the determination unit 78, the stroke correction unit 82 determines whether or not the standby time derived based on the vehicle speed detection unit that detects the vehicle speed of the vehicle has passed (S16). The stroke correction unit 82 does not correct until the standby time elapses (N in S16), and corrects the output of the stroke sensor 46 after the standby time elapses (Y in S16) (S18).

  The present invention has been described above based on the embodiment. According to the present invention, when the malfunction of the outputs of the stroke sensor 46 and the master cylinder pressure sensor 48 is determined, it can be determined that the malfunction has occurred in the stroke sensor 46 depending on whether or not the accelerator pedal is depressed. The 46 outputs can be corrected.

  It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

  For example, means other than the stroke sensor 46 and the master cylinder pressure sensor 48 may be used to detect whether or not the brake pedal 12 is depressed. Specifically, it may be determined whether or not the brake pedal 12 is depressed based on the output of the stop lamp switch.

  DESCRIPTION OF SYMBOLS 10 Brake control apparatus, 12 Brake pedal, 14 Master cylinder, 14a 1st output port, 14b 2nd output port, 16, 18 Brake hydraulic control pipe, 20 Wheel cylinder, 22FR Right solenoid on-off valve, 22FL Left solenoid on-off valve, 23 Simulator cut valve, 24 stroke simulator, 26 reservoir tank, 28 hydraulic supply / discharge pipe, 30 high pressure pipe, 32 motor, 34 oil pump, 40 pressure increasing valve, 42 pressure reducing valve, 44 wheel cylinder pressure sensor, 45 vehicle speed sensor, 46 stroke sensor 47 accelerator sensor, 48 master cylinder pressure sensor, 50 accumulator, 51 accumulator pressure sensor, 53 relief valve, 70 piston rod, 72 sensor value acquisition unit, 74 accessor Operation control unit, 78 determination unit, 80 standby time derivation unit, 81 hydraulic actuator, 82 stroke correction unit, 84 braking request amount calculation unit, 86 braking request amount limit unit, 88 upper limit value holding unit, 90 control unit, 200 ECU .

Claims (9)

In a brake control device that determines a target braking force based on an output value of a stroke sensor that detects a depression amount of a brake pedal and an output value of a master cylinder pressure sensor that detects a pressure of a master cylinder that sends out hydraulic fluid.
An accelerator operation detecting means for detecting an operation of an accelerator pedal;
Determining that the output of the stroke sensor is not normal when the operation of the accelerator pedal is detected by the accelerator operation detection means and the output of the stroke sensor and the output of the master cylinder pressure sensor do not satisfy a normal relationship and means, the,
The determination means determines that the output of the stroke sensor is not normal when the output value of the stroke sensor is larger than a reference stroke output value corresponding to the output value of the master cylinder pressure sensor. apparatus. 2. The brake control according to claim 1 , wherein the determination unit determines that the output of the stroke sensor is not normal when the output value of the stroke sensor is larger than a predetermined value by the reference stroke output value. apparatus.   In a brake control device that determines a target braking force based on an output value of a stroke sensor that detects a depression amount of a brake pedal and an output value of a master cylinder pressure sensor that detects a pressure of a master cylinder that sends out hydraulic fluid.
  An accelerator operation detecting means for detecting an operation of an accelerator pedal;
  Determining that the output of the stroke sensor is not normal when the operation of the accelerator pedal is detected by the accelerator operation detection means and the output of the stroke sensor and the output of the master cylinder pressure sensor do not satisfy a normal relationship Means, and
  The determination means determines that the output of the stroke sensor is not normal when a braking request is obtained from the output value of the stroke sensor and no braking request is obtained from the output value of the master cylinder pressure sensor. Brake control device. The brake control device according to claim 3 , wherein the determination unit determines that the output of the stroke sensor is not normal when the output value of the stroke sensor is equal to or greater than a predetermined threshold value. The brake according to any one of claims 1 to 4 , further comprising stroke correction means for correcting the output of the stroke sensor when the determination means determines that the output of the stroke sensor is not normal. Control device.   6. The brake control device according to claim 5, wherein if it is determined that the output of the stroke sensor is not normal, the stroke correction unit corrects until a braking request cannot be obtained from the output value of the stroke sensor. . The stroke correction means, once determined by the determination means that the output of the stroke sensor is not normal, the output value of the stroke sensor becomes a reference stroke output value corresponding to the output value of the master cylinder pressure sensor. The brake control device according to claim 5 or 6 , wherein the correction is performed as follows. If the required stroke braking amount obtained from the output value of the stroke sensor exceeds the upper limit value of the required braking amount corresponding to the output value of the master cylinder pressure sensor, the required stroke braking amount is limited to the upper limit value. A braking request amount limiting means;
The brake according to any one of claims 5 to 7, wherein the stroke correction means changes a correction amount of the output of the stroke sensor depending on whether or not the stroke braking request amount is limited to the upper limit value. Control device. Standby time deriving means for deriving a waiting time until the output of the stroke sensor is corrected based on the vehicle speed detected by the vehicle speed detecting means;
The stroke correction means, wherein when the output of the stroke sensor is determined not to be normal by the determining means, after the elapse of the waiting time, according to claim 5 to 8, characterized in that for correcting the output of the stroke sensor The brake control apparatus in any one.

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