KR-20260066906-A - Electric Brake System And Control Method Therefor

KR20260066906AKR 20260066906 AKR20260066906 AKR 20260066906AKR-20260066906-A

Abstract

An electric brake system and a control method thereof are disclosed. According to one embodiment of the present disclosure, an electric brake system for a vehicle comprises: a wheel disc; a friction member that contacts or does not contact the wheel disc; and a processor that calculates a target clamping force based on a brake pedal signal, wherein the processor controls the friction member to generate a clamping force corresponding to the target clamping force when the speed of the vehicle exceeds a threshold speed, and corrects the target clamping force to calculate a corrected clamping force when the speed of the vehicle is less than or equal to the threshold speed, and controls the friction member to generate a clamping force corresponding to the corrected clamping force.

Inventors

김종성

Assignees

현대모비스 주식회사

Dates

Publication Date: 20260512
Application Date: 20241105

Claims (10)

In an electric brake system for a vehicle, Wheel disc; A friction member that contacts or does not contact the wheel disc; and It includes a processor that calculates a target clamping force based on a brake pedal signal, The above processor is, When the speed of the above vehicle exceeds a critical speed, the friction member is controlled to generate a clamping force corresponding to the target clamping force, and An electric brake system that, when the speed of the vehicle is below the threshold speed, calculates a corrected clamping force by correcting the target clamping force, and controls the friction member to generate a clamping force corresponding to the corrected clamping force.
In Article 1, The above correction-clamping force is, An electric brake system, which is the value obtained by multiplying the above target-clamping force by a pre-set correction factor.
In Article 2, If the speed of the vehicle is below the threshold speed and the brake pedal signal is maintained at a constant level over time, the processor, An electric brake system that controls the above correction-clamping force to increase and then decrease over time.
In Paragraph 3, An electric brake system in which the actual braking force actually acting on the wheel disc increases linearly over time.
In Article 2, An electric brake system in which the braking distance of the vehicle is the same regardless of what value the above-set correction factor has when the speed of the vehicle is below the above-mentioned threshold speed.
In a method for controlling an electric brake system for a vehicle, A first process for calculating a target clamping force based on a brake pedal signal; A second process of controlling a friction member to contact a wheel disc when the speed of the above vehicle exceeds a critical speed to generate a clamping force corresponding to the target clamping force; and A control method for an electric brake system comprising a third process of, when the speed of the vehicle is below the threshold speed, correcting the target clamping force to calculate a corrected clamping force, and controlling the friction member to generate a clamping force corresponding to the corrected clamping force.
In Article 6, The above correction-clamping force is, A control method for an electric brake system, wherein the value obtained by multiplying the above target-clamping force by a pre-set correction factor.
In Article 7, When the speed of the vehicle is below the threshold speed and the brake pedal signal is maintained constant over time, the correction-clamping force is controlled to increase over time and then decrease, and The actual braking force actually acting on the wheel disc is, A control method for an electric brake system that increases linearly over time.
In Article 7, A control method for an electric brake system in which, regardless of what value the above-mentioned correction factor has, the braking distance of the vehicle is the same when the speed of the vehicle is below the threshold speed.
In Paragraph 7, The above correction factor is, A control method for an electric brake system in which the front or rear wheels of the above vehicle are different from each other.

Description

Electric Brake System and Control Method Therefor The present disclosure relates to an electric brake system and a method for controlling the same. The content described in this section merely provides background information regarding the present disclosure and does not constitute prior art. Figure 1 is a diagram illustrating the nose dive phenomenon during vehicle braking. Figure 2 is a graph showing the frictional force in the stationary and moving regions. Figure 3 is a graph showing the difference between the expected braking force and the actual braking force occurring at the end of braking in a conventional brake. The nose dive phenomenon and the like will be explained with reference to FIGS. 1 to 3. The nose dive phenomenon is a phenomenon that occurs when a vehicle comes to a stop due to the influence of deceleration and acceleration caused by braking at the end of braking, and refers to a phenomenon in which a pitching motion occurs, causing the front part of the vehicle to tilt downward and the rear part of the vehicle to be lifted upward. In conventional brake systems, a braking clamping force is generated in response to the brake pedal signal produced when the driver presses the brake pedal. The braking clamping force refers to the force exerted by a friction member on a wheel disc that rotates together with the vehicle's wheel. Braking friction is generated by this braking clamping force. As shown in Figure 2, the static friction force (fs) in the stationary region and the kinetic friction force (fk) in the moving region have different magnitudes. The situation regarding braking control of a moving vehicle until the vehicle comes to a stop is explained. (i) When the vehicle is moving, the wheel disc is rotating, so a nearly constant level of kinetic friction force acts on the wheel disc due to the braking clamping force, but (ii) when the wheel disc stops and the vehicle comes to a stop, the maximum friction force acts on the wheel disc due to the braking clamping force. That is, the coefficient of friction continuously increases until the moment the wheel disc stops rotating and the vehicle comes to a stop, the friction force acting on the wheel disc increases rapidly, and the maximum friction force (Fig. 2) occurs. FIG. 3 is a graph illustrating the difference between the expected braking force and the actual braking force occurring at the end of braking in a conventional brake, and is a graph representing the situation in which the driver keeps the brake pedal pressed consistently during braking. That is, it is a case where the brake pedal signal is maintained at the same level. Referring to Fig. 3, a difference occurs between the expected braking force and the actual braking force. The main reason for this difference is that conventional brake systems control the braking clamping force to remain constant when the brake pedal signal remains constant. As previously explained, the kinetic friction force in the motion region increases until it reaches the maximum friction force (Fig. 2), and during this process, the coefficient of friction increases rapidly (Fig. 2). If the coefficient of friction is constant while the braking clamping force is maintained at the same level, a braking force of a magnitude corresponding to the curve of the expected braking force will act on the wheel disc; however, in reality, the coefficient of friction increases rapidly until the rotation of the wheel disc stops at the end of braking, generating the maximum friction force (Fig. 2), so the actual braking force generated at the end of braking becomes greater than the expected braking force, as shown in Fig. 3. As such, the fact that the actual braking force is greater than the expected braking force is a factor that further exacerbates the nose dive phenomenon. The nose dive occurs as the difference between the expected and actual braking forces increases rapidly over a short period of time. If nose dive is severe, the front-to-rear weight distribution becomes unbalanced, which may make it difficult for the driver to control the vehicle. Additionally, sudden nose dive impairs ride comfort by transmitting shocks to the occupants. In order to improve sensory quality and provide a high-quality user experience, a control method capable of preventing or minimizing the nose dive phenomenon is required. Figure 1 is a diagram illustrating the nose dive phenomenon during vehicle braking. Figure 2 is a graph showing the frictional force in the stationary and moving regions. Figure 3 is a graph showing the difference between the expected braking force and the actual braking force occurring at the end of braking in a conventional brake. FIG. 4 is a functional block diagram of an electric brake system according to one embodiment of the present disclosure. FIG. 5 is a drawing illustrating a braking force generating unit of an electric brake system according to one embodiment of the present disclosure. FIG. 6 is a diagram illus