JP2010006165A - Electric disc brake - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a sense of incongruity of a driver when detecting a pad contact position, in an electric disc brake. <P>SOLUTION: An electric motor 26 is rotated based on a control signal by a vehicle control controller 9, and its rotation is reduced by a differential reduction mechanism 21, and is converted into linear motion of a piston 19 by a ball lamp mechanism 20, and braking force is generated by pressing brake pads 13A and 13B to a disc rotor D by the piston 19. When detecting displacement in the return direction of an accelerator pedal by an accelerator sensor 8, the pad contact position being a reference of a rotary position of the electric motor 26 is detected. Since the pad contact position is detected when the accelerator pedal for starting deceleration of a vehicle starts to be returned, the sense of incongruity of the driver caused by generation of little braking force in pad contact can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electric disk brake for a vehicle that generates a braking force by pressing a brake pad against a disk rotor by an electric motor.

  As an electric disc brake, for example, the rotary motion of the rotor of the electric motor is converted into a linear motion of the piston using a rotation-linear motion conversion mechanism such as a ball screw mechanism or a ball ramp mechanism, and the brake pad is pressed against the disc rotor by the piston. It is known to generate a braking force by causing The electric disc brake detects a depression force (or displacement amount) of a brake pedal by a driver with a sensor, and a control device controls rotation of the electric motor based on the detected value, thereby generating a desired braking force. be able to.

  In this type of electric disc brake, there is one that detects a pad contact position where the brake pad contacts the disc rotor as a reference for controlling the braking force during braking, the pad clearance during non-braking, and the like. The pad contact position can be detected by actually bringing the brake pad into contact with the disc rotor and monitoring the change in load applied to the electric motor or the change in the signal of the thrust sensor.

  Electric disc brakes are constantly changing due to the effects of brake pad wear, heat generation during braking, changes in ambient temperature, vehicle vibration, acceleration, etc. In order to increase the control accuracy of electric disc brakes It is necessary to detect and calibrate the pad contact position with considerable frequency. However, when the pad contact position is detected, the brake pad is actually brought into contact with the disc rotor, so that a slight braking force is generated, and the vehicle is inadvertently decelerated while the vehicle is running. May give a sense of incongruity.

Therefore, for example, in Patent Document 1, the driver's operation of the accelerator pedal is monitored by an accelerator pedal switch or the like, and when the accelerator pedal is turned off (when the amount of depression of the accelerator pedal is 0), the pad contact position is detected. Techniques to perform are disclosed. Thus, normally, when the accelerator pedal is turned off, the vehicle decelerates, so that it is possible to reduce the driver's uncomfortable feeling that occurs when a slight braking force is generated by detecting the pad contact position.
JP 2003-194115 A

  However, the technique described in Patent Document 1 has the following problems. Normally, the vehicle starts decelerating when the accelerator pedal starts to be returned from the depressed state. However, when the depressing amount is zero when the accelerator pedal is detected to be off by the accelerator pedal switch, the vehicle has already decelerated. A slight braking force generated by detection of the pad contact position may be uncomfortable for the driver. If the accelerator pedal is not completely returned, the pad contact position is not detected even though the vehicle is decelerating with a sufficient deceleration. Furthermore, if the driver does not intend to decelerate and the accelerator pedal is slowly returned to the off position, the pad contact position is detected in a slight deceleration state, and the driver feels uncomfortable. Will give.

  The present invention has been made in view of the above points, and aims to provide an electric disc brake for a vehicle that can reduce a driver's uncomfortable feeling when detecting a pad contact position. To do.

  In order to solve the above-described problems, the present invention provides an electric motor, a rotation-linear motion conversion mechanism that converts the rotational motion of the electric motor into linear motion, and a brake pad by linear motion of the rotation-linear motion conversion mechanism. An electric vehicle for vehicle comprising a pad pressing member that presses the disk rotor, a rotational position detecting means for detecting the rotational position of the electric motor, and a control means for controlling the braking force based on the rotational position of the electric motor. In the disc brake, an accelerator sensor for detecting the displacement of the accelerator pedal of the vehicle is provided, and the control means detects the displacement in the return direction of the accelerator pedal by the accelerator sensor, and the brake pad is applied to the disc rotor. It is characterized by detecting the contact position of the contacting pad.

  According to the electric disc brake according to the present invention, since the pad contact position is detected when the accelerator pedal for starting deceleration of the vehicle starts to be returned, the driver caused by the generation of a slight braking force at the time of pad contact. Can reduce the sense of incongruity.

  A schematic configuration of the electric disc brake according to the present embodiment is shown in FIG. As shown in FIG. 1, an electric disc brake 1 is connected to an electric disc brake main body 2 (only one is shown) provided on each of the front, rear, left and right wheels of an automobile as a vehicle, and a brake pedal 3 to be connected to the brake pedal. 3, a stroke simulator 4 that applies an appropriate operating force to the stroke 3, a stroke sensor 5 that detects the stroke of the brake pedal 3, a wheel speed sensor 6 that detects the rotational speed of each wheel, and a tilt of the vehicle body An inclination sensor 7 that detects the displacement of the accelerator pedal, a vehicle control controller 9 (control means) that supplies a control signal to the electric disc brake main body 2 based on the detection of various sensors including these sensors. A battery 10 for supplying power to each of these devices and an ignition switch 11 are provided. The vehicle controller 9, the electric disc brake main body 2, and the various sensors described above are interconnected by an in-vehicle network (CAN) and an electric signal line so that a control signal and a detection signal can be exchanged. ing. Electric power is supplied from the battery 10 to the electric disc brake body 2.

  The electric disc brake main body 2 is a caliper floating disc brake, which is a disc rotor D that rotates with a wheel, a carrier 12 that is fixed to a non-rotating portion (not shown) on the vehicle body side such as a suspension member, and a disc rotor. A pair of brake pads 13A and 13B arranged on both sides of D and supported by the carrier 12 and arranged so as to straddle the disk rotor D and supported so as to be movable along the axial direction of the disk rotor D with respect to the carrier 12 The caliper main body 14 is provided.

  The caliper body 14 is integrally formed with a cylindrical cylinder portion 15 having a through hole that opens to face one side of the disk rotor D, and a claw portion 16 extending from the cylinder portion 15 to the opposite side across the disk rotor D. Is formed. A piston unit 17 and a motor unit 18 are provided in the cylinder portion 15 of the caliper body 14.

  The piston unit 17 includes a bottomed cylindrical piston 19 (pad pressing member) that is slidably fitted to the cylinder portion 15, and a ball ramp mechanism 20 (rotation-linear motion conversion mechanism) housed inside the piston 19. ) And the differential reduction mechanism 21 and the pad wear compensation mechanism 22 are integrated. In the ball ramp mechanism 20, a ball 25 (steel ball) is interposed in an inclined groove between the rotary disk 23 and the linear motion disk 24. By rotating the rotary disk 23 and the linear motion disk 24 relative to each other, The ball 25 rolls between the inclined grooves, and the rotating disk 23 and the linearly moving disk 24 are relatively moved in the axial direction according to the rotation angle. Thereby, rotational motion is converted into linear motion. In the present embodiment, the rotation-linear motion conversion mechanism is the ball ramp mechanism 20, but it may be a ball screw mechanism, a roller ramp mechanism, a precision roller screw mechanism, or the like.

  The differential reduction mechanism 21 is interposed between the ball ramp mechanism 20 and the electric motor 26 of the motor unit 18, and decelerates the rotation of the rotor 27 of the electric motor 26 by a predetermined reduction ratio. It is transmitted to the rotating disk 23. The pad wear compensation mechanism 22 makes the ball ramp mechanism 20 follow by advancing the adjustment screw 28 against the wear of the brake pads 13A and 13B (change in contact position with the disc rotor D).

  The motor unit 18 incorporates an electric motor 26 and a resolver 29 (rotational position detecting means). The rotor 27 is rotated by energizing the coil of the stator 30 of the electric motor 26 and the ball ramp mechanism 20 is driven via the differential reduction mechanism 21. At this time, the rotational position of the rotor 27 is detected by the resolver 29.

  The electric disc brake main body 2 is provided with a motor controller 31 that controls the rotation of the electric motor 26. The motor controller 31 supplies a control current to the electric motor 26 while monitoring the rotational position of the rotor 27 detected by the resolver 29 based on a control signal from the vehicle controller 9 to control the amount of rotation of the rotor 27.

Next, the operation of the electric disc brake body 2 will be described.
Based on the operation of the brake pedal 3 by the driver detected by the stroke sensor 5, the vehicle controller 9 supplies a control signal to the motor controller 31, and the motor controller 31 supplies a control current to the electric motor 26 based on this control signal. Supply and rotate the rotor 27. The rotation of the rotor 27 is decelerated at a predetermined reduction ratio by the differential reduction mechanism 21 and converted into a linear motion by the ball ramp mechanism 20 to advance the piston 19. As the piston 19 advances, one brake pad 13B is pressed against the disk rotor D, and the caliper body 14 moves due to the reaction force, and the claw portion 16 presses the other brake pad 13A against the disk rotor D to apply braking force. Is generated. The wear of the brake pads 13A and 13B is compensated by the adjustment screw 28 of the pad wear compensation mechanism 22 moving forward to cause the ball ramp mechanism 20 to follow the wear.

  Further, the vehicle controller 9 uses various sensors such as a wheel speed sensor 6, a tilt sensor 7, an accelerator sensor 8, and the like to rotate each wheel, vehicle speed, vehicle acceleration, steering angle, vehicle lateral acceleration, and vehicle body tilt. By detecting the vehicle state such as the accelerator pedal depression amount and controlling the rotation of the electric motor 26 based on these detections, boost control, anti-lock control, traction control, vehicle stabilization control, slope start assistance Control or the like can be executed.

  The vehicle controller 9 controls the rotational position of the electric motor 26 on the basis of the pad contact position where the brake pads 13A and 13B are in contact with the disk rotor D when executing the control of the electric disk brake body 2 described above. Next, detection of the pad contact position will be described.

  First, from the non-braking state, the electric motor 26 is rotated, the piston 19 is moved backward by a predetermined amount, and moved to a position where the brake pads 13A and 13B do not contact the disc rotor D reliably. Here, normally, in the non-braking position, the brake pads 13A and 13B are separated from the disk rotor D with a constant pad clearance, but there is a possibility that slight contact may occur due to thermal expansion during braking. Therefore, the piston 19 is moved backward in consideration of this.

  Next, the piston 19 is advanced to monitor the energization current of the electric motor 26, that is, the load. When the energization current of the electric motor 26 exceeds a predetermined value, or when the increase amount of the energization current exceeds a predetermined value, it is detected that the brake pads 13A and 13B are in contact with the disc rotor D, and the piston is detected from that position. The position where the electric motor 26 is rotated by a predetermined amount in the direction in which 19 is moved backward is determined as a new pad contact position, and the pad contact position is updated. The detection and update of the pad contact position is executed with a predetermined frequency and condition. The detection of the pad contact position is not limited to the above, and may be performed based on a signal from a thrust sensor separately provided in the electric disc brake body 2.

  At this time, if there is a brake operation by the driver, a brake control by the vehicle controller 9, or an acceleration operation of the vehicle such as depression of the accelerator pedal by the driver, the detection of the pad contact position is stopped, and the pad Do not update the contact position.

  In addition, at the time of high temperature immediately after braking of the brake pads 13A and 13B, or when uneven wear occurs, the detection accuracy of the pad contact position may be lowered. The update value may be determined by reflecting a value obtained by multiplying the difference from the value by a certain ratio (for example, 1/10).

Next, the timing of detection and update of the pad contact position by the vehicle controller 9 will be described with reference to FIG.
Based on the detection of the accelerator sensor 8, the displacement of the accelerator pedal is monitored to determine whether or not the accelerator pedal is displaced in the return direction (step S1). When the accelerator pedal is displaced in the return direction, it is determined whether another brake control for the electric disc brake body 2 is not executed (brake force = 0) (step S2). Here, the other brake control means other than the detection of the pad contact position including the above-described brake operation by the driver and automatic brake control such as traction control by the vehicle controller 9, vehicle stabilization control, and slope start assist control. Means control.

  In step S1, when the accelerator pedal is displaced in the return direction, it is further determined whether or not the displacement speed in the return direction of the accelerator pedal is equal to or greater than a predetermined value. When it is equal to or greater than the predetermined value, the process may proceed to step S2.

  And when the other brake control to the electric disc brake main body 2 is not performed, the detection of a pad contact position is performed. That is, as described above, first, the electric motor 26 is rotated and the piston is moved backward by a predetermined amount to move to a position where the brake pads 13A and 13B do not reliably contact the disk rotor D (step S3). Next, the piston 19 is moved forward (step S4), the energization current of the electric motor 26 is monitored, and whether or not the energization current exceeds a predetermined value or whether or not the increase amount of the energization current exceeds a predetermined value. Is determined (step S5).

  When the energization current of the electric motor 26 exceeds a predetermined value, or when the increase amount of the energization current exceeds a predetermined value, it is detected that the brake pads 13A and 13B are in contact with the disc rotor D, and the piston is detected from that position. The position where the electric motor 26 is rotated by a predetermined amount in the direction in which 19 is moved backward is determined as a new pad contact position (step S6), and the pad contact position is updated (step S7).

  As described above, when the accelerator pedal moves in the return direction, or in addition to this, when the displacement speed in the return direction of the accelerator pedal is equal to or higher than a predetermined value, the vehicle is in a state of starting deceleration. Even if the brake pads 13A and 13B come into contact with the disk rotor D and slightly brake force by detecting the position, it is difficult for the driver to feel uncomfortable. Thereby, the uncomfortable feeling given to the driver by the detection of the pad contact position can be reduced.

  In the above embodiment, the detection of the pad contact position may be performed at the same time for all four wheels. However, by performing the detection for each wheel or for each of several wheels, the vehicle deceleration due to the braking force generated at the time of pad contact is performed. It is possible to further reduce the uncomfortable feeling given to the driver by reducing the. In this case, by detecting the pad contact position for every two front wheels, for every two rear wheels, or for every two front and rear wheels in a diagonal position, the braking force generated at the time of detection of the pad contact position The balance can be canceled and the generation of the yaw moment can be suppressed.

In the above embodiment,
(1) When the vehicle deceleration based on the detection of the wheel speed sensor 6 or the acceleration sensor (not shown) is a predetermined value or more,
(2) When the shift position of the transmission is below a predetermined low speed gear,
(3) When the gradient based on the detection of the tilt sensor 7 is a predetermined value or more,
By detecting the position of the pad contact point when it is determined that a predetermined deceleration has occurred in the vehicle by combining means for reliably detecting or estimating that a certain amount of deceleration has occurred in the vehicle The uncomfortable feeling given to the driver can be further reduced.

  In this embodiment, the accelerator sensor 8 detects the displacement of the accelerator pedal, but may detect other parameters representing the displacement of the accelerator pedal, such as the opening of the throttle of the engine.

Here, the characteristics of the above embodiment will be described below.
The vehicle controller 9 (control means) detects the displacement in the return direction of the accelerator pedal of the vehicle, and detects the pad contact position when the displacement speed of the accelerator pedal is equal to or higher than a predetermined value.

  The vehicle controller 9 (control means) detects the pad contact position for every two front wheels or every two rear wheels.

  The vehicle controller 9 (control means) detects the pad contact position for every two front and rear wheels in a diagonal position of the vehicle.

1 is a block diagram showing a schematic configuration of an electric disc brake according to an embodiment of the present invention. 2 is a flowchart showing detection control of a pad contact position by a vehicle controller of the electric disc brake shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Electric disc brake, 8 Accelerator sensor, 9 Vehicle controller (control means), 13A, 13B Brake pad, 19 Piston (pad pressing member), 20 Ball ramp mechanism (rotation-linear motion conversion mechanism), 26 Electric motor, 29 Resolver (rotational position detection means), D disk rotor

Claims (1)

An electric motor, a rotation-linear motion conversion mechanism that converts the rotational motion of the electric motor into linear motion, a pad pressing member that presses a brake pad against the disc rotor by the linear motion of the rotation-linear motion conversion mechanism, and the electric motor In an electric disk brake for a vehicle, comprising: a rotational position detecting means for detecting a rotational position of the motor; and a control means for controlling a braking force based on the rotational position of the electric motor.
An accelerator sensor for detecting displacement of an accelerator pedal of the vehicle is provided, and the control means detects the displacement of the accelerator pedal in the return direction by the accelerator sensor, and the brake pad contacts the disc rotor. An electric disc brake characterized by performing position detection.

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