EPB Cable Positioning via Current Sensing and Spring Restoring Force
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Solution Overview
Problem
The existing electronic parking brake (EPB) systems for vehicles face challenges in accurately determining the release position of the cable operating member, leading to potential damage of the actuator housing due to excessive movement during brake release, and inefficiencies in brake operation due to scattered current values.
Innovation Solution
The implementation of an elastic member in the space part of the MOD-type EPB that restricts the movement of the cable operating member, allowing for accurate position recognition based on driving current changes and preventing excessive movement through a dual-force mechanism, along with a control unit that manages the driving motor's operation based on sensed current values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cable operating member is allowed to move freely during brake release, then the brake can be released completely, but the cable operating member may move excessively and damage the actuator housing
Solution Approach 1:
The patent introduces an elastic member (spring) that provides pre-compression force to restrict the cable operating member's movement. The spring is pre-compressed between the housing and the cable operating member, creating a restoring force that prevents excessive movement before damage can occur. This cushioning mechanism allows complete brake release while limiting the cable's travel distance to prevent housing damage.
2Object-affected harmful factors
If the cable operating member movement is restricted by an elastic member, then excessive movement and housing damage are prevented, but the cable operating member position recognition becomes less accurate
Solution Approach 1:
The patent employs a current sensing unit that continuously monitors the driving current of the driving motor during brake release. By detecting changes in current consumption, the control unit can infer the position of the cable operating member even with the elastic member's restriction. The feedback loop allows the system to recognize position accurately by correlating current values with cable position states.
3Measurement precision
If a position sensor is installed to accurately determine cable operating member position, then position recognition precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical position sensing approach with an electrical sensing method. Instead of using a position sensor to directly measure cable position, the system uses a current sensing unit to detect electrical current characteristics that correlate with position. This substitution simplifies the mechanical structure while maintaining position recognition capability through electrical parameter monitoring.
4Reliability
If the driving motor operates continuously during brake release, then the brake can be released fully, but energy consumption increases and the risk of excessive cable movement increases
Solution Approach 1:
The control unit uses feedback from the current sensing unit to monitor the brake release process in real-time. When the current value indicates that the brake has been sufficiently released (detected through current change patterns), the control unit stops the driving motor operation. This feedback-controlled stopping prevents continuous operation, reducing energy consumption while ensuring complete brake release.
5Object-affected harmful factors
If the elastic member applies strong restricting force to the cable operating member, then housing damage is prevented, but the brake release operation becomes less smooth and more resistant
Solution Approach 1:
The elastic member (spring) provides a dynamic restricting force that changes during the brake release process. The spring force is not constant but varies based on the compression distance, providing stronger restriction when the cable approaches the housing and softer restriction during normal operation. This dynamic force characteristic prevents housing damage while maintaining smooth brake release operation.
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 solution enables precise brake release determination without a position sensor, reduces the risk of actuator housing damage, and enhances brake operation reliability by controlling the driving motor's operation based on driving current changes.
Implementation Method 1
an elastic member restricting the movement of the cable operating member when the cable operating member is retreated by a preset distance or more during brake release
Implementation Method 2
a current sensing unit configured to sense a driving current of the driving motor and provide the sensed driving current
Implementation Method 3
a driving motor generating a driving force for braking the wheel
Data Source
AI summary
An electronic parking brake for a vehicle includes: a drum assembly braking a wheel; a driving motor generating a driving force for braking the wheel; a driving gear coupled to a driving shaft of the driving motor and rotated; a driven gear coupled to the driving gear and rotated; a cable operating member geared to the driven gear, and advanced or retreated by the rotation of the driven gear so as to operate a parking cable of the drum assembly; an elastic member restricting the movement of the cable operating member; a current sensing unit configured to sense a driving current of the driving motor and provide the sensed driving current; and a control unit configured to operate the driving motor during brake release, and control the operation of the driving motor based on a change of the driving current inputted from the current sensing unit during brake release.