JP5730694B2 - Electric disc brake device - Google Patents

Description

  The present invention relates to a disc brake device that uses an electric motor to generate a braking force on a disc rotor.

  The electric disc brake device generates a braking force by pressing a brake pad against a disc rotor using an electric motor in response to a braking request generated by a driver's brake pedal operation. Due to wear due to contact between the brake pads and the disk rotor, a difference in thickness occurs in the disk rotor. Therefore, a method of controlling the pressing force of the brake pad according to the braking request is preferable to a method of controlling the movement amount of the brake pad according to the braking request.

  For example, Patent Document 1 includes a load sensor that detects a pressure applied by a friction pad positioned on the inner side of the disk rotor, and controls the pressing of the friction pad by a motor based on an output signal from the load sensor. Is described.

Japanese Patent Laid-Open No. 10-281191 JP 2007-238034 A

  As in the technique described in Patent Document 1, whether only the pressure applied to the disk rotor by the friction pad on the inner side is detected, is the fluctuation in the pressure applied due to the rotor wall thickness difference or the rotor runout? There is a problem that cannot be distinguished.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for distinguishing between rotor thickness difference and rotor runout in an electric disk brake device.

  An electric disc brake device according to an aspect of the present invention includes a disc rotor that rotates together with a wheel, an inner brake pad and an outer brake that are disposed to face the friction sliding surfaces on the vehicle inner side and the vehicle outer side of the disc rotor, respectively. A pad, an electric motor that presses the inner brake pad and the outer brake pad against the friction sliding surface via a drive mechanism, and a first force that detects the pressing force of the inner brake pad on the friction sliding surface. Detection by one pressing force detection unit, a second pressing force detection unit that detects pressing force of the outer brake pad against the friction sliding surface, detection by the first pressing force detection unit, and the second pressing force detection unit Based on the signal, the pressing force of the inner brake pad and the outer brake pad by the electric motor is controlled. Comprising a motor control section.

  According to this aspect, the rotor wall thickness difference and the rotor runout can be distinguished by detecting the pressing force on both the inner side and the outer side of the disk rotor.

  When the phase difference between the detection signal from the first pressing force detection unit and the detection signal from the second pressing force detection unit is greater than or equal to a predetermined value, the motor control unit does not control the pressing force from the electric motor. It may be. If the phase difference between the detection signal on the inner side and the detection signal on the outer side is greater than or equal to a predetermined value, it can be determined that the rotor runout has occurred, not the load fluctuation due to the thickness difference of the disk rotor. . In the case of rotor runout, by not controlling the motor, it is possible to reduce the operating frequency of the motor and reduce the load on the motor.

  According to the present invention, it is possible to distinguish between rotor thickness difference and rotor runout in the electric disk brake device.

1 is a schematic configuration diagram of an electric disc brake device according to an embodiment of the present invention. It is a functional block diagram of brake ECU. (A), (b) is a graph explaining the phase difference of the detection signal of the inner side by a 1st pressing force detection part, and the detection signal of the outer side by a 2nd pressing force detection part.

  FIG. 1 is a schematic configuration diagram of an electric disc brake device 100 for a vehicle according to the present embodiment. In FIG. 1, the brake unit 10 is shown as a cross-sectional view. The brake unit 10 is a kind of so-called disc brake, and is configured to generate a braking force in response to a command from the brake ECU 60.

  The brake unit 10 includes a disk rotor 16 that rotates with a vehicle wheel (not shown), brake pads 14a and 14b as friction materials, and a caliper 12 that moves the brake pad.

  The inner brake pad 14 a is disposed on the inner side of the disk rotor 16, and the outer brake pad 14 b is disposed on the outer side of the disk rotor 16. The brake pads 14 a and 14 b are supported so as to be slidable in the axial direction of the disk rotor 16. A claw portion 18 extending vertically downward from the caliper 12 is disposed on the back portion of the outer brake pad 14b. A piston 20 is attached to the back of the inner brake pad 14a.

  An electric motor 30 is disposed inside the caliper 12. The electric motor 30 is a driving unit that presses the brake pads 14a and 14b toward the disc rotor 16 during braking and separates the brake pads 14a and 14b from the disc rotor 16 during non-braking.

  The aforementioned piston 20 is connected to the output shaft of the electric motor 30. A ball screw mechanism 24 for converting the rotational movement of the output shaft of the electric motor 30 into the linear movement of the piston 20 is disposed inside the piston 20. An encoder 32 is also provided in the caliper 12. The encoder 32 detects the rotation angle of the electric motor 30 and transmits it to the brake ECU 60.

  A brake pedal 56 operated by a driver is installed in the vehicle interior. When the brake pedal 56 is stepped on by the driver, the operation amount is detected by the sensor 58 and transmitted to the brake ECU 60. Alternatively, the brake depression force may be detected by a sensor and transmitted to the brake ECU 60. The brake ECU 60 gives a drive signal to the electric motor 30 so as to exert a braking force according to the operation amount.

  When the electric motor 30 is driven, the piston 20 moves in the right direction in the drawing, that is, in the direction of the brake pad 14a. As a result, the brake pad 14 a attached to the tip of the piston 20 is pressed against the friction sliding surface 16 a inside the vehicle body of the disc rotor 16. At this time, due to the reaction force of the piston 20, the caliper 12 moves in the direction opposite to the moving direction of the piston 20 (left direction in the figure). Then, the brake pad 14 b is pressed against the friction sliding surface 16 b on the vehicle outer side of the disc rotor 16 by the claw portion 18 at the tip of the caliper 12. As a result, the disc rotor 16 is pinched by the pair of brake pads 14a and 14b, and braking force is generated on the wheels.

  When the brake pedal 56 is not operated, the electric motor 30 moves the piston 20 to a predetermined zero point position so that the brake pads 14 a and 14 b are positioned with a predetermined clearance from the disk rotor 16. .

  An inner load sensor 28a is installed on the back surface of the inner brake pad 14a, and an outer load sensor 28b is installed on the back surface of the outer brake pad 14b. The load sensors 28a and 28b detect the pressing force of the brake pads 14a and 14b against the disc rotor 16, respectively, and transmit the detection signals to the brake ECU 60.

  FIG. 2 is a block diagram showing a configuration of the brake ECU 60 shown in FIG. Each block can be realized by hardware such as a computer CPU or memory, or a mechanical device, and can be realized by software such as a computer program. Here, the blocks are realized by their cooperation. It is drawn as a functional block. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by a combination of hardware and software.

  The brake ECU 60 controls the brake unit 10 so as to generate a braking force in accordance with a brake pedal operation amount or a pedaling force by the driver. The brake ECU 60 includes a first pressing force detection unit 62a, a second pressing force detection unit 62b, a phase difference determination unit 64, a braking force calculation unit 66, and a motor control unit 68.

  The braking force calculation unit 66 calculates the braking force generated on the wheels according to the operation amount or the pedaling force detected by the sensor 58.

  The first pressing force detection unit 62a receives a detection signal for detecting the pressing force of the inner brake pad 14a against the disc rotor 16 from the inner load sensor 28a. The second pressing force detector 62b receives a detection signal for detecting the pressing force of the outer brake pad 14b against the disc rotor 16 from the outer load sensor 28b.

  The motor control unit 68 controls the pressing of the inner brake pad 14a and the outer brake pad 14b by the electric motor 30. That is, the motor control unit 68 causes the electric motor 30 to press the brake pads 14a and 14b against the disc rotor 16 with a pressing force set in advance with respect to the braking force calculated by the braking force calculation unit 66. Control. At this time, a feedback loop is formed by a detection signal of the pressing force received by the first pressing force detection unit 62a and the second pressing force detection unit 62b.

  The phase difference determination unit 64 obtains the phase difference between the detection signal from the first pressing force detection unit and the detection signal from the second pressing force detection unit, and determines whether this phase difference is equal to or greater than a predetermined value. When the phase difference is less than the predetermined value, the phase difference determination unit 64 instructs the motor control unit 68 to control the pressing force to be constant in accordance with fluctuations in detection signals from the inner side load sensor 28a and the outer side load sensor 28b. Command. When the phase difference is greater than or equal to a predetermined value, the phase difference determination unit 64 instructs the motor control unit 68 to hold the electric motor 30 in that state.

  Hereinafter, the determination by the phase difference determination unit 64 will be described.

  FIGS. 3A and 3B are graphs for explaining the phase difference between the inner detection signal from the first pressing force detection unit and the outer detection signal from the second pressing force detection unit.

  FIG. 3A shows a case where the phase difference between the detection signal of the inner side load sensor 28a and the detection signal of the outer side load sensor 28b is relatively small during vehicle braking. When the phase difference is small, it is determined that there is a thickness difference. FIG. 3B shows a case where the phase difference between the detection signal of the inner load sensor 28a and the detection signal of the outer load sensor 28b is larger than a predetermined value during vehicle braking. When the phase difference is large, it is determined that the rotor is shaken.

  The inner side load sensor 28 a and the outer side load sensor 28 b are installed at substantially the same positions on both sides of the disk rotor 16. Therefore, when the rotor runout occurs, a phase difference of about 180 ° is generated between the detection signal from the inner side load sensor 28a and the detection signal from the outer side load sensor 28b. Therefore, the predetermined value is set to a value close to 180 °, and if there is a phase difference greater than the predetermined value, it is determined that the rotor is shaken. The predetermined value is preferably set experimentally by using a brake unit in which rotor runout occurs and a brake unit in which no rotor runout occurs.

  In an electric disc brake device that performs feedback control using a conventional single load sensor, is the load variation detected by the sensor caused by a disc rotor thickness difference or rotor runout? Could not be distinguished. Therefore, even when the rotor runout is the cause, controlling the electric motor in the same way as when the thickness difference is causing the brake unit may cause abnormal vibrations or increase the frequency of motor operation. There was a risk that the motor would burn.

  On the other hand, according to the electric disc brake device according to the present embodiment, the load sensors for detecting the pressing force of the brake pads against the disc rotor are provided on both the inner side and the outer side, and the two load sensors are detected. Based on the phase difference of the signal, the rotor run-out and the wall thickness difference are distinguished. In addition, when the rotor is shaken, the motor is not driven by following the load fluctuation, so that unnecessary operation of the electric motor can be suppressed while suppressing brake vibration.

  The present invention has been described based on the embodiments. These embodiments are merely examples, and modifications such as any combination of the embodiments, each component of the embodiment, and any combination of each processing process are also within the scope of the present invention. It will be understood by those skilled in the art.

  The present invention is not limited to the above-described embodiments, and various modifications such as design changes can be added based on the knowledge of those skilled in the art. The configuration shown in each drawing is for explaining an example, and can be appropriately changed as long as the configuration can achieve the same function.

  DESCRIPTION OF SYMBOLS 10 Brake unit, 12 Caliper, 14a Inner side brake pad, 14b Outer side brake pad, 16 Disc rotor, 16a, 16b Friction sliding surface, 20 Piston, 28a, 28b Load sensor, 30 Electric motor, 56 Brake pedal, 60 Brake ECU, 62a 1st pressing force detection part, 62b 2nd pressing force detection part, 64 phase difference determination part, 66 braking force calculation part, 68 motor control part, 100 electric disc brake device.

Claims (1)

A disk rotor that rotates with the wheels;
An inner side brake pad and an outer side brake pad respectively disposed relative to the friction sliding surfaces on the vehicle inner side and the vehicle outer side of the disk rotor;
An electric motor that presses the inner brake pad and the outer brake pad against the friction sliding surface via a drive mechanism;
A first pressing force detector for detecting a pressing force of the inner brake pad against the friction sliding surface;
A second pressing force detector for detecting a pressing force of the outer brake pad against the friction sliding surface;
A motor control unit for controlling the pressing force of the inner brake pad and the outer brake pad by the electric motor based on detection signals from the first pressing force detection unit and the second pressing force detection unit;
Equipped with a,
When the phase difference between the detection signal from the first pressing force detection unit and the detection signal from the second pressing force detection unit is greater than or equal to a predetermined value, the motor control unit does not control the pressing force from the electric motor. Electric disc brake device characterized by.

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