Electric Drum Brake Release Timing for Thermal Drag Prevention
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Solution Overview
Problem
Existing electric drum brake systems face issues with drag due to insufficient reduction of clamping force when the temperature drops, leading to increased thermal stress and prolonged engagement.
Innovation Solution
An electric drum brake system with a controller that adjusts the parking release time based on the temperature of the drum brake, ensuring that the release operation is completed only when the motor current reaches a target current and the thermal contraction is adequately accounted for.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric drum brake is engaged at high temperature and the temperature drops, then the clamping force increases due to thermal stress of the drum, but the release operation is insufficient and causes vehicle drag
Solution Approach 1:
The patent applies dynamics by making the parking release time variable rather than fixed. The controller adjusts the release time based on real-time temperature feedback from the drum brake, creating a dynamic control system that adapts to thermal conditions. This resolves the contradiction by ensuring sufficient release time at high temperatures (preventing drag) while maintaining appropriate release time at low temperatures (ensuring reliability).
Solution Approach 2:
The patent implements feedback control by using a temperature sensor to continuously monitor the drum brake temperature and adjusting the parking release time accordingly. The controller receives temperature feedback and modifies the release operation duration, creating a closed-loop control system that prevents vehicle drag while maintaining brake engagement reliability under varying thermal conditions.
2Reliability
If the parking release time is extended to account for thermal contraction, then the clamping force is fully released, but the release operation takes longer
Solution Approach 1:
The patent makes the release time dynamic and temperature-dependent rather than excessively long in all conditions. At low temperatures, the release time is shorter since thermal contraction is minimal. At high temperatures, the release time is extended only as much as needed to compensate for thermal contraction. This dynamic adjustment achieves complete release of clamping force without unnecessary time loss.
Solution Approach 2:
The patent changes the release time parameter based on temperature conditions. The controller adjusts this critical parameter dynamically, increasing it only when thermal contraction is significant (high temperature) and decreasing it when thermal effects are minimal (low temperature). This parameter adaptation achieves complete clamping force release while minimizing time loss under each specific thermal condition.
3Device complexity
If the release operation is ended when motor current reaches target current, then the control is simple, but thermal contraction effects are not accounted for
Solution Approach 1:
The patent enhances the simple current-based control by adding temperature feedback. The controller now considers both motor current (indicating mechanical release status) and drum temperature (indicating thermal contraction level). This dual-parameter feedback approach maintains operational simplicity while reliably compensating for thermal stress effects that would otherwise cause vehicle drag.
Solution Approach 2:
The patent applies preliminary action by proactively extending the release operation duration based on predicted thermal contraction from current temperature readings. Before thermal effects fully manifest as drag, the controller has already adjusted the release time to compensate. This preliminary adjustment maintains control simplicity while ensuring reliable compensation for thermal stress.
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 effectively prevents vehicle drag by ensuring that the clamping force is fully released, even at varying temperatures, thereby maintaining optimal braking performance and reducing mechanical stress.
Implementation Method 1
an electric drum brake configured to be driven by an electric motor
Implementation Method 2
generates a parking brake force by operating a drum brake
Implementation Method 3
when an electric drum brake is engaged at a high temperature, as the temperature drops, a clamping force may increase due to thermal stress of a drum
Data Source
AI summary
Provided is an electric drum brake system, including: an electric drum brake configured to be driven by an electric motor; a current sensor configured to detect a current input to the electric motor; and a controller configured to, when parking is released, determine a parking release time based on a temperature of the electric drum brake, and when a maintenance time reaches the determined parking release time, end a parking release operation by stopping the electric motor, the maintenance time being a period of time while a state where a motor current detected by the current sensor reaches a target current is maintained.