CN-115771488-B - Electromechanical brake

Abstract

An electromechanical brake is disclosed that is configured such that a piston pulls a brake pad toward a wheel disc by a drive motor. The electromechanical brake includes a hysteresis data storage unit that stores rising section function data on a rising section and falling section function data on a falling section, wherein a braking force increases as a piston moves toward a wheel disc, and wherein the braking force decreases as the piston moves away from the wheel disc, a position detection unit that detects a position of the piston, a calculation unit that calculates a differential value of the detected position of the piston with respect to time, a past state data storage unit that stores data on a preceding section corresponding to a preceding piston position, and a braking force calculation unit that calculates the braking force based on the differential value of the piston position and the data on the preceding section.

Inventors

• LIN DONGHUAN

Assignees

• 现代摩比斯株式会社

Dates

Publication Date

20260505

Application Date

20220906

Priority Date

20210908

Claims (5)

1. 1. An electromechanical brake configured to cause a piston to pull a brake pad toward a wheel disc by a drive motor, the electromechanical brake comprising: a hysteresis data storage unit that stores ascending interval function data on an ascending interval and descending interval function data on a descending interval, wherein a braking force increases as the piston moves toward the wheel disc, and wherein the braking force decreases as the piston moves away from the wheel disc; a position detection unit that detects a position of the piston; A calculation unit that calculates a differential value of a detection position of the piston with respect to time; A past state data storage unit for storing data on a previous section corresponding to a previous piston position, and And a braking force calculation unit that calculates braking force based on the differential value of the piston position and the data on the preceding section.
2. 2. The electromechanical brake according to claim 1, wherein the braking force calculation unit calculates the braking force by following the ascending interval function when a differential value of the piston position with respect to time is a positive number.
3. 3. The electromechanical brake according to claim 1, wherein when the differential value of the piston position with respect to time is zero and the section corresponding to the preceding piston position is a rising section, the braking force calculation unit calculates the braking force by following the rising section function.
4. 4. The electromechanical brake according to claim 1, wherein when the differential value of the piston position with respect to time is zero and the section corresponding to the preceding piston position is a descent section, the braking force calculation unit calculates the braking force by following the descent section function.
5. 5. The electromechanical brake according to claim 1, wherein the braking force calculation unit calculates the braking force by following the descent interval function when a differential value of the piston position with respect to time is negative.

Description

Electromechanical brake Cross Reference to Related Applications The present application claims priority and rights of korean patent application No. 10-2021-019721 filed on the year 09 and 08 of 2021, the entire contents of which are incorporated herein by reference. Technical Field The present disclosure relates to an electromechanical brake. Background The matters described in this section merely provide background information of the present disclosure and do not constitute prior art. Electromechanical brakes (Electro-MECHANICAL BRAKE, EMB) are being widely used. Electromechanical brakes were developed as electronic parking brakes (Electronic Parking Brake, EPB), but the field of use of such brakes is expanding to foundation brakes instead of conventional hydraulic brakes. EMB is a device that mounts an actuator driven by a motor on a caliper so as to directly brake a vehicle by motor driving force without a medium such as brake fluid. Since the EMB has a similar mechanism to an Electronic Parking Brake (EPB), but unlike the EPB, the EMB is mainly used for a main brake, the EMB requires a higher brake response and operation durability than the EPB. In addition, compared to a hydraulic brake, an electromechanical brake can be simpler in structure, higher in brake response speed, and more precisely controlled, thereby improving brake stability. The EMB equipped with a load cell can accurately measure the clamping force. However, if the EMB is equipped with a load sensor, the design of the component to mount the sensor becomes complicated, and the manufacturing cost thereof increases. Furthermore, the size of the EMB may inevitably increase due to the sensor installation. In order to prevent an increase in manufacturing cost and an increase in size of the EMB, a current sensor may be used instead of the load sensor to estimate the clamping force. The EMB may be designed such that the current sensor measures a current flowing through the motor generating the braking force, and estimates the clamping force based on the measured current value. However, the method of estimating the clamping force by measuring the current flowing through the motor has a problem in that the estimation accuracy is deteriorated compared to the case of using the load sensor due to the measurement noise of the current sensor. Fig. 11A, 11B, and 11C are schematic diagrams showing the configuration of a conventional electromechanical brake. Referring to fig. 11A, 11B, and 11c, the emb includes a wheel disc 11_c, a pair of brake pads 11_b disposed at both sides of the wheel disc 11_c, and a piston 11_a configured to press the brake pads 11_b toward the wheel disc 11_c. When the piston 11_a moves toward the wheel disc 11_c, the braking force increases. Even if the relative positions of the piston 11_a and the brake pad 11_b are the same, the braking force has different values according to the movement path of the piston 11_a. That is, the braking force against the position of the piston 11—a has hysteresis characteristics. Therefore, if the moving path of the piston 11_a is not considered, the braking force of the EMB cannot be accurately estimated. Disclosure of Invention In view of the above, according to the electromechanical brake of the embodiment, the clamping force can be estimated with high accuracy by estimating the clamping force based on the position of the piston at which the specific current value is detected. According to the electromechanical brake of the embodiment, by calculating the braking force in consideration of the hysteresis characteristic of the braking force with respect to the position of the piston, the braking force can be calculated more accurately, so that the electromechanical brake is controlled with the calculated braking force. The problems to be solved by the present disclosure are not limited to the above-described problems, and other non-mentioned problems will be clearly understood by those skilled in the art from the following description. According to at least one embodiment, the present disclosure provides an electromechanical brake configured to cause a piston to pull a brake pad toward a wheel disc by a drive motor, the electromechanical brake including a hysteresis data storage unit that stores ascending interval function data on an ascending interval in which a braking force increases as the piston moves toward the wheel disc, and descending interval function data on a descending interval in which the braking force decreases as the piston moves away from the wheel disc, a position detection unit that detects a position of the piston, a calculation unit that calculates a differential value of the position of the piston with respect to time, a past state data storage unit that stores data on a previous interval corresponding to a previous piston position, and a braking force calculation unit that calculates the braking force based on the differential value of the piston position and the data on t