KR20130054051A - Electro mechanical brake system and control method thereof - Google Patents

Abstract

PURPOSE: An electric brake device and a control method thereof are provided to supply accurate and stable control of braking power by estimating rigidity change of the electric brake device and by controlling clamping power according to the rigidity change. CONSTITUTION: When a pedal effort of a brake pedal is detected, targeted clamping power is extracted. A motor rotation angle and the amount of currents supplied to a motor are detected in a state in which a motor is operated so that an electric brake is operated. Rigidity change of the electric brake is extracted from the amount of the currents and the motor rotation angle. The amount of the currents supplied to the motor according to the rigidity change of the electric brake is controlled so that the targeted clamping power is followed. [Reference numerals] (AA) Start; (BB) No; (CC) Yes; (DD) End; (S101) Operating state; (S102) Detect the pedal effort of a brake pedal; (S103) Calculate a target clamping force; (S104) Operate an EMB; (S105) Detect the rotation angle and drive current of a motor; (S106) Calculate a correlation(Gradient); (S107) Calculate an EMB interference; (S108) Determine a correction amount relative to the target clamping force; (S109) Perform motor rotation angle tracking control

Description

Electric brake system and its control method {ELECTRO MECHANICAL BRAKE SYSTEM AND CONTROL METHOD THEREOF}

The present invention relates to an electric brake apparatus, and more particularly, to estimate the stiffness change of the electric brake due to pad wear, etc., from the amount of current supplied for driving the motor and the rotation angle of the motor shaft, and adjust the amount of current according to the stiffness change of the electric brake. The present invention relates to an electric brake apparatus and a control method thereof to provide a stable clamping force.

The brake device mounted on the vehicle is for decelerating, stopping or maintaining the vehicle while driving. The driving kinetic energy is converted into thermal energy by mechanical friction, and the frictional heat is released into the atmosphere to perform braking.

Brake devices are typically provided with drum brakes and disc brakes that use hydraulic or pneumatic pressure, and disc brakes obtain a braking force by tightly pressing disc-shaped disks that rotate together with wheels on both sides of the pads instead of drums.

Electro Mechanical Brake (EMB) is a key part of the Brake by Wire (BBW) system that generates braking force using electric power against the driver's braking will.

Electric brake system has better braking performance and pedaling than the hydraulic brake system, saves weight, can simplify the layout of vehicle, and reduce the environmental pollution because it does not need brake oil. have.

According to these various advantages, the development of technology for the electric brake device is actively progressing.

Japanese Patent Laid-Open No. 2006-070962 discloses a technique for electric brake devices that provides a technique for preventing the occurrence of drag between the pad and the disc by allowing the position of the pad to be estimated in a short time while minimizing the power consumption of the motor. It is becoming.

In addition, Japanese Laid-Open Patent Publication No. 2006-142935 provides a technique for accurately measuring whether the electric brake is on or off without using a rotation angle sensor.

 The electric brake device clamps the pad by bringing the pad into close contact with the disk according to the rotational force applied through the motor, which generates power by supplying electric current, and reduces the rotational force of the motor at a predetermined ratio to generate a high torque. It includes a rotating body for generating a force, a load sensor (torque sensor) for detecting the clamping force.

However, when the load sensor is mounted on the electric brake device, the clamping force of the pad can be detected directly, so that the braking force can be easily controlled. However, the load sensor is an expensive component that increases the production cost of the vehicle, which is burdened by the consumer. This may lead to consumer dissatisfaction and a disadvantage of price competitiveness.

The present invention has been proposed to improve the above-mentioned problems, and an object thereof is to estimate the stiffness change of the electric brake due to pad abrasion from the amount of current supplied for driving the motor and the rotation angle of the motor shaft, The control is intended to provide a stable and accurate clamping force.

A feature according to an embodiment of the present invention is a pad that is in close contact with the disk that is integrally rotated with the wheel; A cylinder for moving the pad toward the disk; A rotating body for horizontally moving the cylinder; A motor driven by the supply of current to generate rotational force; A reducer for rotating the rotating body with a high torque by reducing the rotational force of the motor at a set ratio; It includes a controller for controlling the rotation angle by supplying a current to the motor,

Rotation angle detecting means for detecting the rotation angle of the motor further comprises, the controller supplies a current to the motor in accordance with the pedal pedal effort to follow the target clamping force, and detects the amount of current and the rotation angle supplied to the motor There is provided an electric brake apparatus characterized by following the target clamping force by extracting the stiffness change according to the current amount and the rotation angle and then adjusting the amount of current supplied to the motor.

The controller may extract the target clamping force by applying the pedal force of the brake pedal to the set map.

The controller controls the rotation angle to be smaller than the reference by adjusting the amount of current supplied to the motor when the stiffness is increased to follow the target clamping force, and controls the rotation angle to be larger than the reference by adjusting the amount of current supplied to the motor when the stiffness is decreased. Can be.

The controller can extract the stiffness change by applying either a regression analysis or ARX (Auto Regressive with eXogenous input).

In addition, a feature according to another embodiment of the present invention is the process of extracting the target clamping force when the pedal effort of the brake pedal is detected; Detecting a motor rotation angle and an amount of current supplied to the motor while driving the motor to operate the electric brake; Detecting a stiffness change of the electric brake from the amount of current supplied to the motor and the motor rotation angle; Provided is a control method of an electric brake apparatus including adjusting a current amount supplied to a motor according to a rigid change of the electric brake to follow a target clamping force.

When the stiffness of the electric brake increases, the amount of current supplied to the motor is reduced to control the rotation angle smaller than the reference. When the stiffness of the electric brake decreases, the amount of current supplied to the motor may be increased to control the rotation angle larger than the reference.

As described above, the present invention can provide accurate and stable braking force control by estimating the stiffness change of the electric brake and controlling the clamping force according to the stiffness change without applying an expensive load sensor to the electric brake device.

1 is a view showing a schematic configuration of an electric brake apparatus according to an embodiment of the present invention.
2 is a view showing a detailed configuration of a cylinder in FIG.
3 is a view showing a control procedure of the electric brake apparatus according to an embodiment of the present invention.
4 is a view showing a correlation between the rotation angle of the motor shaft and the clamping force in the electric brake apparatus according to an embodiment of the present invention.
5 is a view showing a correlation between the rotation angle of the motor shaft and the motor current according to the wear of the pad in the electric brake device according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

The present invention can be embodied in various different forms, and thus the present invention is not limited to the embodiments described herein.

1 is a view showing a schematic configuration of an electric brake apparatus according to an embodiment of the present invention.

Referring to FIG. 1, an embodiment of the present invention provides a pad 131 and a pad 131 provided inside the caliper 110 to closely contact a disk 120 that is integrally rotated with a wheel to generate a clamping force. A cylinder 140 for moving the disk 120 toward the disk 120, a rotating body 150 for horizontally moving the cylinder 140, a motor 170 applied in a bidirectional rotation mode and driven by supply of current to generate a rotational force, and It includes a reducer 160 for reducing the rotational force of the motor 170 by a set ratio to rotate the rotating body 150 with a high torque and a controller 200 for controlling the driving of the motor 170.

The rotation axis of the motor 170 is provided with a rotation angle sensor 171 for detecting the rotation angle of the motor 170 when controlling the clamping force.

The cylinder 140 is composed of a rotating body 150 and a nut 142 as shown in FIG.

The rotating body 150 is configured to rotate in place, the screw thread 143 is formed on the outer peripheral surface is made in the form of a shaft, the nut 142 is formed through the hole having a screw thread in the center is inserted into the rotating body 150 Lose.

Since the rotational force of the motor 170 driven by the current supplied from the controller 200 is decelerated at a predetermined ratio set by the reducer 160 to rotate the rotating body 150, the rotating body 150 is screwed with the rotating body 150. The nut 142 moves in the longitudinal direction of the rotating body 150.

Since the nut 142 moving in the longitudinal direction of the rotating body 150 moves the cylinder 140 that is integrated, the cylinder 140 pushes the pad 131 toward the disk 120 and the pad 131. The disk 120 is rubbed to generate a clamping force.

The controller 200 calculates a target clamping force according to the pedal effort of the brake pedal by applying a set map when the pedal force of the brake pedal operated by the driver is detected, and supplies a current to the motor 170.

Therefore, the braking control in which the target clamping force is generated by the driving of the motor 170 is executed.

The controller 200 detects the rotation angle of the motor 170 from the rotation angle sensor 171 installed on the rotation shaft of the motor 170 in the state of executing the braking control as described above, and is supplied to the motor 170. By detecting the current amount and calculating the slope according to the correlation between the current amount and the rotation angle to extract the stiffness change according to the wear of the pad (131).

Thereafter, the controller 200 corrects the target clamping force by applying the stiffness change extracted from the correlation between the amount of current and the rotation angle, and then controls the rotation angle of the motor 170 by adjusting the amount of current supplied to the motor 170. Ensure a stable clamping force.

For example, in order to output the same clamping force, the rotation angle is controlled to be smaller than the reference according to the inclination that increases as the rigidity increases, and the rotation angle is controlled to be larger than the reference according to the inclination that decreases when the rigidity decreases.

The operation of the present invention including the functions as described above is executed as follows.

In the state in which the vehicle to which the electric brake apparatus according to the present invention is applied is operated (S101), the controller 200 determines whether the pedal force of the brake pedal which the driver operates to slow down or stop the speed of the vehicle is detected (S102). .

In step S102, the controller 200 calculates a target clamping force according to the pedal pedal effort by applying the set map when the pedal pedal pressure is detected (S103), and then supplies the current amount of the target clamping force to the motor 170 to supply the motor. Braking control is executed through the rotation of 170 (S104).

When the motor 170 rotates as described above, the rotational force of the motor 170 is decelerated at a predetermined ratio set by the reducer 160 to rotate the rotating body 150.

Accordingly, the nut 142 screwed to the rotating body 150 moves in the longitudinal direction of the rotating body 150 to form an integrated cylinder 140. The pad 140 pushes the pad 131 toward the disk 120. 131 and the disk 120 are rubbed to generate a clamping force.

Here, the rotation angle of the motor shaft, which is the displacement of the pad, and the clamping force have a correlation as shown in FIG. 4, and the clamping force is determined by Equation 1 below.

However, the pad 131 may change the thickness of the pad 131 due to friction due to the close contact with the disk 120, or may change the thickness of the electric brake due to the temperature change due to the friction between the pad 131 and the disk 120. Changes in stiffness will occur.

That is, in Equation 1, the constants α ₀ , α ₁ ,... Since α _n changes, the correlation between the rotational angle of the motor 170 and the clamping force is not constant due to the stiffness change.

Accordingly, the controller 200 detects the rotation angle of the motor 170 from the rotation angle sensor 171 installed on the rotation shaft of the motor 170 in the state of controlling the clamping force, and measures the amount of current supplied to the motor 170. It is detected (S105).

Subsequently, the controller 200 extracts a stiffness change according to the wear of the pad 131 or the change of temperature by calculating a slope according to the correlation between the amount of current supplied to the motor 170 and the motor rotation angle (S106).

Regression analysis, ARX (AutoRegressive with eXogenous input), or the like may be applied as a method of predicting the stiffness change from the amount of current supplied to the motor 170 and the rotation angle of the motor 170.

For example, when the least-squqre method is applied during the regression analysis in the most understandable manner, the controller 200 applies the following Equation 2 to reduce the rotation angle of the motor 170 and the slope of the current. We can calculate and predict the stiffness of the electric brake from the slope.

Here, x _i means the motor rotation angle, y _i means the current flowing through the motor.

The above Equation 1 is divided into partial derivatives with respect to α and β, respectively.

In the above equation, the stiffness change of the electric brake can be predicted from β which is the slope of the straight line.

Then, the controller 200 corrects the target clamping force by applying a stiffness change extracted from the correlation between the rotation angle of the motor 170 and the amount of current (S107) and then adjusts the amount of current supplied to the motor 170. By controlling the rotation angle of the motor 170 so that the target clamping force can be generated to ensure a stable braking force (S109).

As shown in FIG. 5, when a stiffness change occurs from ① to ② as the pad is worn in a state where the distance between the pad and the disk is always constant, the amount of current flowing through the motor should be increased even at the same motor rotation angle.

For example, in order to output the same clamping force, the rotation angle is controlled to be smaller than the reference according to the inclination that increases as the rigidity increases, and the rotation angle is controlled to be larger than the reference according to the inclination that decreases when the rigidity decreases.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

110: caliper 120: disc
131: pad 140: cylinder
150: rotating body 160: reducer
170: motor 171: rotation angle sensor
200:

Claims (7)

A pad for closely contacting the disk rotated integrally with the wheel from both sides;
A cylinder for moving the pad toward the disk;
A rotating body for horizontally moving the cylinder;
A motor driven by the supply of current to generate rotational force;
A reducer for rotating the rotating body with a high torque by reducing the rotational force of the motor at a set ratio;
It includes a controller for controlling the rotation angle by supplying a current to the motor,
Rotation angle detecting means for detecting the rotation angle of the motor further,
The controller follows the target clamping force by supplying current to the motor according to the pedal pedal's pedaling force, detects the current amount and rotation angle supplied to the motor, extracts the stiffness change according to the current amount and rotation angle, and then calculates the current amount supplied to the motor. The electric brake apparatus which adjusts and follows a target clamping force. The method of claim 1,
The controller extracts the target clamping force by applying the pedal force of the brake pedal to the set map. The method of claim 1,
The controller controls the rotation angle to be smaller than the reference by adjusting the amount of current supplied to the motor when the stiffness increases to follow the target clamping force, and controls the rotation angle to be larger than the reference by adjusting the amount of current supplied to the motor when the stiffness is decreased. Electric brake device, characterized in that. The method of claim 1,
The controller applies a regression analysis or ARX (Auto Regressive with eXogenous input) by applying any one of the electric brake device, characterized in that for extracting the stiffness change. Extracting a target clamping force when the pedaling force of the brake pedal is detected;
Detecting a motor rotation angle and an amount of current supplied to the motor while driving the motor to operate the electric brake;
Detecting a stiffness change of the electric brake from the amount of current supplied to the motor and the motor rotation angle;
Adjusting a current amount supplied to the motor according to the change in the rigidity of the electric brake to follow a target clamping force;
Control method of the electric brake device comprising a. The method of claim 5,
The stiffness change of the electric brake is a control method of the electric brake device, characterized in that due to the change in the thickness of the pad and the temperature change due to the friction between the pad and the disk. The method of claim 5,
When the stiffness of the electric brake increases, the amount of current supplied to the motor is reduced to control the rotation angle smaller than the reference. When the stiffness of the electric brake decreases, the amount of current supplied to the motor is increased to control the rotation angle larger than the reference. Control method of electric brake system.

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