Electromechanical Brake Clamping Force Feedback for Parking Hold
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Solution Overview
Problem
Conventional electromechanical brake systems face inaccuracies in estimating and maintaining the clamping force for parking brake function due to reliance on motor current and limited movement of the reducer, leading to inconsistent engagement of the solenoid lever with the stop ring.
Innovation Solution
An electromechanical brake system with a force sensor to detect clamping force and a controller that controls the parking actuator based on the detected force, ensuring accurate engagement and disengagement of the parking lever with the parking gear to maintain the target clamping force, thereby stabilizing the parking brake function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solenoid lever and stop ring are used to limit reducer movement, then the parking brake function is implemented, but the engagement accuracy between solenoid lever and stop ring is poor leading to unreliable clamping force
Solution Approach 1:
The patent introduces a force sensor that provides real-time feedback on the actual clamping force to the controller. The controller adjusts the motor current based on this feedback to achieve the target clamping force, replacing the unreliable mechanical stop ring engagement with a closed-loop control system that ensures accurate and reliable parking brake function.
Solution Approach 2:
The patent replaces the mechanical engagement system (solenoid lever and stop ring) with an electromechanical control system. Instead of relying on precise mechanical engagement, the system uses motor control with force feedback to achieve the desired clamping force, eliminating the precision problems associated with mechanical engagement.
2Ease of operation
If clamping force is estimated using motor current, then the parking brake function is controlled, but the estimation accuracy is insufficient leading to inconsistent parking brake performance
Solution Approach 1:
The patent introduces a force sensor that provides real-time feedback on the actual clamping force to the controller. The controller adjusts the motor current based on this feedback to achieve the target clamping force, replacing the unreliable mechanical stop ring engagement with a closed-loop control system that ensures accurate and reliable parking brake function.
Solution Approach 2:
The patent replaces the mechanical engagement system (solenoid lever and stop ring) with an electromechanical control system. Instead of relying on precise mechanical engagement, the system uses motor control with force feedback to achieve the desired clamping force, eliminating the precision problems associated with mechanical engagement.
3Reliability
If the reducer movement is limited mechanically, then the parking brake holding function is achieved, but the system cannot detect engagement status leading to control inaccuracies
Solution Approach 1:
The force sensor provides continuous feedback on the actual clamping force, enabling the controller to detect when the target force is achieved and maintain it. This eliminates the need for mechanical engagement detection while providing more accurate and reliable information about the parking brake status.
Solution Approach 2:
The force sensor acts as an intermediary that translates the physical state of brake pad contact into electrical signals that the controller can process. This allows the controller to accurately determine engagement status without relying on mechanical detection methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system accurately and stably implements the parking brake function by continuously monitoring and adjusting the clamping force, ensuring reliable engagement and disengagement of the parking mechanism, thus enhancing the precision and reliability of the parking brake operation.
Implementation Method 1
a force sensor configured to detect a clamping force due to a contact between the disc and the brake pad
Implementation Method 2
a parking motor configured to generate power; a power conversion part including a spindle member configured to rotate by receiving a rotational driving force of the parking motor
Implementation Method 3
a nut member screwed with the spindle member to move forward and backward
Implementation Method 4
a reduction gear part configured to decelerate the rotational force of the drive motor and transmit the decelerated rotational force to the power transfer part
Data Source
AI summary
An electromechanical brake system includes: a pair of pad plates to which a brake pad is attached, respectively, to press a disc that rotates with a wheel; a carrier on which the pair of pad plates are installed; a caliper housing slidably installed on the carrier; a piston movably installed in forward and backward direction inside the caliper housing; a power transfer part configured to press the pair of pad plates onto the disc by moving the piston; a brake actuator including a drive motor configured to provide a rotational force of the drive motor to the piston, and a reduction gear part configured to decelerate the rotational force of the drive motor and transmit the decelerated rotational force to the power transfer part; a parking actuator connected to the brake actuator to maintain a parking braking state of a vehicle; a force sensor configured to detect a clamping force due to a contact between the disc and the brake pad; and a controller configured to control the brake actuator and the parking actuator, wherein the controller is configured to control the parking actuator based on the clamping force detected through the force sensor.