JP2003220943A - Braking control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a vehicle attitude by preventing a malfunction made when a system failure such as a sensor disconnection occurs, in a braking control system for driving an electric actuator to generate braking force. <P>SOLUTION: If a detection voltage v<SB>0</SB>of a thrust sensor is not higher than a set value XV to cause a failure determination, a piston of a corresponding wheel is returned first to form a non-braking state, and if the state lasts for longer than a set time Ys, a sensor failure is determined to execute failure processing. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric braking control device.

[0002]

2. Description of the Related Art Conventionally, an electric braking control device for obtaining a braking force by pressing and separating a friction material by a motor to and from a rotating body that rotates together with wheels has been known. For example, JP-A-63
It is known from Japanese Patent No. 242764. In such an electric braking control device, a braking force sensor that detects the braking force that is generated is provided, and the control unit determines that the braking force detected by the braking force sensor is, for example, the pedal operation force of the driver. The feedback control is executed so as to match the corresponding target braking force. As the braking force sensor, a sensor that detects the pressing force that presses the friction material against the rotating body or a sensor that detects the relative position between the friction material and the rotating body can be used.

However, in the above-mentioned prior art, when a disconnection occurs between the braking force sensor and the control device for some reason, the sensor output becomes 0, and the driver performs a braking operation. When the control is performed, the control means determines that the friction material and the rotating body are separated and the braking force is not generated. Therefore, even if the friction material is pressed against the rotating body during the braking control, the output value of the braking force sensor is not generated, and therefore the control is continued in the direction in which the friction material is pressed against the rotating body. In this case, the braking is one-sided, which may adversely affect the vehicle behavior.

The present invention has been made in view of such a problem, and when a system abnormality such as disconnection of a sensor occurs in a braking control device for generating a braking force by driving an electric actuator. The purpose is to prevent the vehicle from malfunctioning and stabilize the vehicle posture.

[0005]

In order to achieve the above object, the invention according to claim 1 is a braking device for generating a braking force by pressing a pressing member against a rotating member that rotates integrally with a wheel. An electric actuator that is included in the braking device and that applies thrust to the pressing member against the rotating member; and a control unit that controls the braking of the electric actuator based on the input from the input unit. The braking control device is provided with an abnormality detecting means for detecting a system abnormality, and when the abnormality detecting means detects a system abnormality, the control means presets fail-safe control for the wheel in which the abnormality has occurred. The method is characterized by executing.

According to a second aspect of the present invention, in the braking control device according to the first aspect, the input means includes a thrust sensor for detecting a thrust force applied to the pressing member by the electric actuator, and the control means. In the braking control, the feedback control based on the detection position of the thrust sensor is executed, and the abnormality detecting means detects the abnormality of the thrust sensor. The invention described in claim 3 is the invention according to claim 2.
In the braking control device described in (1), the thrust sensor is configured such that the output value decreases as the thrust increases, and conversely the output value increases as the thrust decreases. It is characterized in that it is determined to be abnormal when the value is less than. According to a fourth aspect of the present invention, in the braking control device according to the third aspect, in the case where the abnormality detection unit is in a state where the output value of the thrust sensor is below a predetermined value for a predetermined period of time or more. It is characterized in that it is determined to be abnormal.

The invention described in claim 5 is the same as claim 1
The braking control device according to any one of claims 1 to 4, wherein the control means sets the wheel in which an abnormality is detected to a non-braking state during fail-safe control.

The invention according to claim 6 provides the invention according to claim 2.
The braking control device according to any one of claims 1 to 5, further comprising, as the input unit, an operating position unit that detects an operating position of an electric actuator, and the control unit controls the thrust sensor in the abnormality detection wheel during fail-safe control. The feedback control based on the detected value is stopped, and the operation control of the electric actuator is continued based on the operation position detecting means.

[0009]

According to the invention described in claim 1, when the abnormality detecting means detects a system abnormality, the control means sets a fail-safe preset for the wheel in which the abnormality has occurred. Execute control. The preset fail-safe control is, for example, a control for bringing a wheel in which an abnormality has occurred into a non-braking state as in the invention according to claim 5, or according to claim 6. As in the invention, the feedback control based on the detection value of the sensor in which the abnormality has occurred is stopped,
It may be control for executing control based on normal sensor detection. By executing the fail-safe control in this way, it is possible to prevent malfunction due to an abnormality.

According to another aspect of the invention, the control means comprises:
At the time of braking control, the thrust force (which corresponds to the braking force being generated) applied by the electric actuator to the pressing member is detected by the thrust sensor, and the feedback control is executed based on the detected value. Here, when an abnormality occurs in the thrust sensor, the abnormality detection means detects this and the control means executes the fail-safe control as described above.
As described above, in the configuration in which the control unit executes the feedback control, when an abnormality such as a wire breakage occurs in the thrust sensor, the electric actuator actually presses the pressing member against the rotating member to generate the braking force. However, there is a possibility that an erroneous operation such as continuing to operate the electric actuator may occur when it is determined that this operation has not been performed, but this erroneous operation can be prevented in the present invention.

According to the third aspect of the invention, the thrust sensor has a maximum output value when the electric actuator is in the non-driving state and the pressing member does not apply the thrust to the rotating member. On the other hand, when the electric actuator is driven and the pressing member applies a thrust to the rotating member, the output value of the thrust sensor decreases toward the minimum value. Therefore, when the thrust sensor is disconnected, its output value becomes the minimum value, that is, it falls below a predetermined value which does not normally occur, and therefore the abnormality detecting means determines that it is abnormal.
As described above, the thrust sensor is configured to have the maximum value when the thrust is not generated and the minimum value when the maximum thrust is generated, so that the output value becomes 0 due to the disconnection.
When it becomes, it becomes possible to judge this as abnormal. By the way, in general, in a sensor that detects the load used as a thrust sensor, the output value when the thrust (load) is not generated is the minimum value, so it is erroneous that thrust is not generated even when the wire is broken. Judgment is made, but by setting the output characteristic to the opposite characteristic as described above, it is possible to detect the case where the output value becomes 0 due to the disconnection as an abnormality. Further, in the invention according to the fourth aspect, it is determined as abnormal when the state in which the output value of the thrust sensor is below the predetermined value continues for a predetermined time or more. This makes it possible to eliminate erroneous detection such as when the output value is momentarily reduced due to noise or the like, and improve the abnormality detection accuracy.

According to the fifth aspect of the invention, as described above, when an abnormality occurs, the wheel in which the abnormality is detected is brought into the non-braking state, so that the braking force is generated only in the abnormality-causing wheel due to a malfunction. It is possible to prevent this, and thereby to stabilize the posture of the vehicle.

According to the sixth aspect of the invention, when an abnormality occurs, the feedback control based on the detection value of the thrust sensor of the wheel in which the abnormality occurs is stopped, but the control for the abnormality wheel is continued. As a result, it is possible to prevent the braking force from becoming unbalanced while securing a high braking force.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A braking control device according to an embodiment of the present invention will be described below. FIG. 1 is a configuration explanatory view showing a main part of a braking control device of an embodiment corresponding to the inventions described in all claims.

In the figure, BR indicates a braking device.
The braking device BR is of an electric type, and a pair of brake pads 2a and 2b as pressing members are provided on the right end portion of the caliper housing 1 in the drawing, and between the brake pads 2a and 2b. A brake rotor 3 as a rotating member that rotates integrally with a wheel (not shown) is arranged, and a braking force can be generated by sandwiching the brake rotor 3 by both brake pads 2a and 2b.

One of the brake pads 2a and 2b is supported so as to be movable in the left-right direction with respect to the caliper housing 1, and a piston 41 is provided on the back surface thereof. A piston rod 4 is provided on the rear surface with a thrust sensor 5 interposed. The piston rod 4 is supported so as to be movable in the left-right direction in the figure with respect to the caliper housing 1, and the rotation of a motor 6 as an electric actuator provided coaxially is decelerated via a speed reducer 9. Further, the rotation-linear conversion mechanism 7 is configured to be converted into axial displacement and transmitted. As the thrust sensor 5, a load cell, a piezoelectric sensor, a semiconductor load sensor, a magnetic field type load sensor or the like is used. Further, the motor 6 is provided with a position detection device 8 that detects the position of the brake pad 2a based on the rotation amount of the motor 6.

The motor 6 is driven by a motor drive current output from a motor driver 11 as control means. The motor driver 11 includes a required thrust force sent from the main controller 10 as a control unit, a thrust force sensor value (actual thrust force) sent from the thrust force sensor 5, and a position detection value sent from the position detection device 8.
The motor drive current to be output is determined based on the wheel speed sensor value sent from the wheel speed sensor 25 (see FIG. 2). The main controller 10 and the motor driver 11 are connected by CAN communication.

FIG. 2 is an overall view of the braking control device of the embodiment. As shown in this drawing, the motor 6 shown in FIG.
A motor driver 11 is provided for each wheel. Further, the main controller 10 includes a yaw rate sensor 21 and a lateral acceleration (hereinafter,
Acceleration is written as G) sensor 22, front and rear G sensor 2
3, while the detection value is input from the steering angle sensor 24, a signal related to the driving state of the engine is transmitted from the engine control unit ECU to the AT control unit AC.
A signal related to the output torque of the wheel is input from U, and a signal is input from the accessory ACC. Further, the main controller 10 includes a first stroke sensor 31 and a second stroke sensor 32 that detect a stroke amount of the brake pedal BP, and a pedal force that detects a pedal force on the brake pedal BP in order to detect a braking operation of the driver. Sensor 3
A signal is input from the terminal 3.

Therefore, the main controller 10
The required braking force is calculated based on various input signals, and the motor 6 is driven via the motor driver 11 toward this target value. In this case, for example, the motor 6 is driven based on the detection value of the position sensor 8 in a short cycle of about 0.3 msec. Also, longer than this, for example, 0.8-1
Based on the detection value of the thrust sensor 5 in a cycle of msec, it is determined whether or not the thrust corresponding to the target value is generated,
Feedback control for increasing / decreasing the drive amount of the motor 6 is executed as necessary.

Next, the fail-safe control, which is a feature of this embodiment, will be described. Prior to this description, the output characteristics of the thrust sensor 5 will be described first. The output characteristic of the thrust sensor 5 used in the embodiment is, as shown in FIG. 3, a large preset thrust (load, for example, about 35 kN, which is set to a thrust that is not generated by a normal braking operation). In this case, it becomes 0V, and as the thrust becomes smaller, it becomes proportionally larger toward the maximum output value 5V.

The structure for obtaining such output characteristics will be described with reference to the circuit diagram of FIG. 4. The thrust sensor 5 has a detecting section 51 and an output inverting section 52. That is, the detection unit 51 of the thrust sensor 5 has four resistors R1, R2,
A bridge circuit including R3 and R4 is provided, and a voltage difference (v1> v) is applied to the outputs v1 and v2 according to the detected thrust (load).
2) is produced. This part has the same configuration as a general load sensor (thrust sensor). The outputs v1 and v2 form a detection voltage v0 based on the voltage difference of v2-v1 that is opposite to the voltage difference formed by the output inverting unit 52 in the detecting unit 51. This output inversion unit 5
2 is four resistors R5, R6, R7, R8 and a comparator 5
3 and the resistance values are set to R5 = R6 and R7 = R8. Based on this configuration, the output inversion unit 52
Then, the detection voltage v0 which is the final output is v0 = 5V + (v2-v1)  (R7 / R5), and the output characteristic thereof is the characteristic shown in FIG. 3 described above.

Next, based on the flowchart of FIG.
The fail-safe control executed by the main controller 10 and the motor driver 11 will be described.
In step 501, it is determined whether or not the detection voltage v0 of the thrust sensor 5 is equal to or less than a preset set value XV,
If v0 ≦ XV, the process proceeds to step 502 and v0> X
If it is V, the process returns to step 501. Here, in the case of the present embodiment, assuming that the maximum load detected by the thrust sensor 5 is set to 35 kN, XV is 30 kN.
A value corresponding to, for example, in the characteristic shown in FIG. 3, XV =
It is set to 0.71V. Note that this step 501
The part that makes the determination corresponds to the abnormality detecting means of the invention described in claims 1 to 3.

In step 502, it is judged that the thrust is abnormally large, and in the braking device BR provided with the thrust sensor 5 that detects this abnormal value, the motor 6 is moved in the direction of returning the piston 4 (of the wheel). Is started, and the count (t) of the timer that measures the elapsed time determined to be v0 ≦ XV in step 501 is started. In addition, in this step 502, the part that performs the process of returning the piston 4 corresponds to the part that executes the fail-safe control of the invention described in claim 5.

At the next step 503, it is judged whether or not the count value t of the timer has exceeded a preset set time Ys. If t <Ys, the process returns to step 501, but if t ≧ Ys. Proceeds to step 504 to make a sensor abnormality determination, and further to the next step 505.
At, the abnormal time process is executed. The part that performs the process of step 503 corresponds to the abnormality detecting means described in claim 4.

As an example of the abnormality processing in step 505, if one example is shown, the operation of the motor 6 is prohibited for the wheel that has been determined to be abnormal, and the remaining three wheels are braked. in this case,
It is preferable to control the braking force of the wheels on the left and right sides, which are prohibited from operating, to be higher so that the left and right wheels can balance the braking force. Further, as another abnormality processing, the braking of the wheel determined to be abnormal and the wheel on the diagonal thereof is prohibited, and the braking is performed only on the remaining two diagonal wheels. That is, when it is determined that the left front wheel is abnormal, braking of the left front wheel and the right rear wheel is prohibited, and braking is performed by the right front wheel and the left rear wheel during braking. In this case, the braking force can be balanced on the left and right, and the yaw moment can be prevented from occurring.

Further, as another abnormality processing, for the wheel in which the abnormality has occurred, feedback control based on the output of the thrust sensor 5 is not performed, but output based on the position detection value of the motor 6 detected by the position detection device 8 is performed. Execute control. In this case, since feedback is not performed but control toward the target value can be executed, a braking force close to the desired braking force can be generated. Further, as another abnormal time process, it is also possible to estimate the braking force generated by adding the detected wheel speed or the rate of change of the wheel speed to this and execute feedback control based on this estimated value. Is. The part that performs the process of step 505 described above corresponds to the part that executes the feedback control according to claims 5 and 6.

As described above, in the braking control device of the embodiment, when the thrust sensor 5 is broken, preset fail-safe control is executed to set the piston 4 of the wheel. After returning to the non-braking state, the braking control is performed on the other three wheels or the two wheels by the preset abnormal time processing, or the feedback control is stopped only for the abnormal wheel and the position detection device 8 is performed. Based on the output control. Therefore, the malfunction due to the abnormal value of the thrust sensor 5 does not continue to be executed, and it is possible to prevent the vehicle posture from being adversely affected by the braking force due to the malfunction.

As shown in FIG. 3, the thrust sensor 5 has the maximum output value when no thrust is applied, whereas when thrust is applied, the output value decreases toward the minimum value. Because of the configuration, the thrust sensor 5 has an output value of 0 at the time of disconnection and can judge that this is abnormal. In this way, it becomes possible to easily judge the disconnection.

Further, in this embodiment, the thrust sensor 5
When the output value of is less than the set value XV, first, the wheel is brought into the non-braking state, the first stage fail-safe control is executed, and thereafter, when this state exceeds the set time Ys,
Since the final fail-safe control is executed, the final fail-safe control is not executed in the case of a temporary output abnormality due to noise or the like, and the control accuracy can be improved.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and changes in design within the scope not departing from the gist of the present invention can be made. Even if it exists, it is included in the present invention. For example, the configuration of the braking device BR and the like is not limited to that shown in the figure. The point is that a pressing member such as a brake pad is pressed against a rotating member such as a rotor by an electric actuator, and its thrust is detected. The configuration is not limited to the one shown in the embodiment as long as the sensor is provided. Therefore, the thrust sensor 5 is not limited to that shown in the embodiment, and means other than the motor 6 may be used as the electric actuator.

Further, in the embodiment, the two-step control is executed as the fail-safe control, but only one of them may be executed. Further, the fail-safe control is not limited to the control shown in the embodiment, and may be displayed so that the traveling is stopped because an abnormality has occurred.

[Brief description of drawings]

FIG. 1 is a configuration explanatory diagram showing a braking control device according to an embodiment of the present invention.

FIG. 2 is an overall view showing a braking control device of an embodiment.

FIG. 3 is an output characteristic diagram of the thrust sensor of the embodiment.

FIG. 4 is a circuit diagram showing a thrust sensor according to an embodiment.

FIG. 5 is a flowchart showing a flow of fail-safe control of the braking control device according to the embodiment.

[Explanation of symbols]

BR brake device 2a, 2b Brake pad (pressing member) 3 Brake rotor (rotating member) 5 Thrust sensor 6 Motor (electric actuator) 10 Main controller (control means) 11 Motor driver (control means)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3D046 BB01 HH00 HH08 HH25 HH26                       HH51 MM13 MM14                 3D048 BB02 CC49 HH66 HH68 HH70                       RR01 RR02 RR11 RR25 RR35                 3D049 BB02 CC07 HH51 RR01 RR02                       RR05 RR09 RR10 RR13

Claims (6)

[Claims] 1. A braking device that presses a pressing member against a rotating member that rotates integrally with a wheel to generate a braking force, and a thrust included in the braking device in a direction that presses the rotating member against the pressing member. In a braking control device including an electric actuator that provides a control signal and a control unit that controls the braking of the electric actuator based on an input from an input unit, an abnormality detection unit that detects a system abnormality is provided, and the control unit is The braking control device is characterized in that, when a system abnormality is detected by the abnormality detecting means, preset fail-safe control is executed for the wheel in which the abnormality has occurred. 2. The braking control device according to claim 1, wherein the input unit includes a thrust sensor that detects a thrust force applied to the pressing member by the electric actuator, and the control unit controls the thrust force during braking control. A braking control device, wherein feedback control is executed based on a detection position of a sensor, and the abnormality detection means detects an abnormality of a thrust sensor. 3. The braking control device according to claim 2, wherein the thrust sensor has a configuration in which the output value decreases as the thrust increases, and conversely the output value increases as the thrust decreases. A braking control device characterized in that it is judged to be abnormal when the output value of the thrust sensor falls below a predetermined value. 4. The braking control device according to claim 3, wherein the abnormality detecting unit determines that the abnormality has occurred when a state where the output value of the thrust sensor is below a predetermined value continues for a predetermined time or longer. A braking control device having a configuration. 5. The braking control device according to any one of claims 1 to 4, wherein the control means sets a wheel in which an abnormality is detected to a non-braking state during failsafe control. apparatus. 6. The braking control device according to claim 2, further comprising an operating position means for detecting an operating position of the electric actuator as the input means, wherein the control means performs fail safe control. The braking control device is characterized in that the feedback control based on the detection value of the thrust sensor in the abnormality detection wheel is stopped, and the operation control of the electric actuator is continued based on the operation position detecting means.