Electric Parking Brake Release Using Motor Current Feedback
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Solution Overview
Problem
Existing electric brake devices struggle to accurately secure the clearance between the braking member and the braked member when releasing the braking force, leading to variability and potential increased rotational resistance.
Innovation Solution
An electric brake device with a control system that energizes the motor and adjusts the drive time based on current changes after a predetermined time, using filters with different time constants to accurately determine the disengagement state and secure the clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the drive time of the motor is extended to ensure clearance, then the clearance between braking member and braked member is improved, but the time required for brake release increases
Solution Approach 1:
The control device monitors the motor current in real-time during the brake release process. When the current value enters a predetermined range indicating that the braking member has disengaged from the braked member, the control device immediately stops motor drive. This feedback mechanism eliminates the need for extended drive time while ensuring adequate clearance is achieved.
Solution Approach 2:
The patent replaces traditional mechanical clearance measurement methods with electrical current monitoring. By detecting changes in motor current that correlate with the mechanical disengagement state, the system achieves precise clearance control without requiring extended operational time or complex mechanical sensors.
2Loss of time
If the drive time of the motor is reduced for faster release, then the time required for brake release is improved, but the clearance between braking member and braked member becomes insufficient
Solution Approach 1:
The control device continuously monitors motor current during the release process and compares it against predetermined thresholds. When the current enters the specified range, indicating successful disengagement, the drive is immediately terminated. This real-time feedback ensures adequate clearance is achieved while minimizing the release time.
Solution Approach 2:
The motor current itself serves as the indicator of the mechanical state. The electrical signal from the motor drive system provides information about the physical disengagement status, eliminating the need for separate sensing systems and enabling rapid response based on the system's own operational parameters.
3Loss of time
If the motor drive is stopped early based on current value, then the time required for brake release is reduced, but the clearance between braking member and braked member may be insufficient
Solution Approach 1:
The control device uses a predetermined current range as the feedback criterion for determining when clearance is sufficient. By monitoring whether the motor current enters this specific range, the system can accurately judge disengagement and stop the drive at the optimal moment, preventing both premature and excessive driving.
Solution Approach 2:
The patent changes the control parameter from fixed time-based drive termination to current-value-based termination. By using the motor current as the controlling parameter, the system adapts to varying mechanical conditions and achieves consistent clearance results regardless of temperature or rotational resistance variations.
4Reliability
If the motor drive continues longer to account for temperature and rotational resistance variations, then the clearance reliability is improved, but the time required for brake release increases
Solution Approach 1:
The control device monitors motor current and compares it against a predetermined range that accounts for variations in temperature and rotational resistance. This feedback mechanism allows the system to accurately determine disengagement under varying conditions without requiring extended drive time, as the current value automatically reflects the actual mechanical state regardless of environmental factors.
Solution Approach 2:
The patent uses motor current as a parameter that inherently reflects the mechanical state under varying conditions. By controlling drive termination based on current value rather than fixed time, the system automatically adapts to temperature and rotational resistance variations, maintaining reliable clearance achievement while minimizing release time.
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
This approach allows for precise control of the clearance, reducing variability and enhancing responsiveness during subsequent braking applications, regardless of temperature and rotational resistance conditions.
Implementation Method 1
detecting a current value of the electric motor; judging, based on the current value, that a brake pad has disengaged from a disc rotor
Data Source
AI summary
A parking brake control device is configured to, when releasing a hold on a braking force, energize an electric motor, and change a drive time of the electric motor based on a current change amount in a predetermined interval after a predetermined time has elapsed since a current value of the electric motor starts to decrease after increasing and a current value at which the current change amount of the electric motor converges to a predetermined value or less.