Electric Parking Brake Motor Control for Oxide-Induced Line Break Errors
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Solution Overview
Problem
Conventional methods for monitoring electrical lines in electric braking devices often incorrectly identify a line break due to increased internal resistance caused by oxidation of commutation system components, leading to faulty state transitions and potential rendering of the braking device unusable.
Innovation Solution
The method involves determining the internal resistance of the electric motor, comparing it with a threshold value, and actuating the motor in the direction corresponding to its current operating state for a prespecified period to remove any oxide layer, thereby preventing incorrect line break detection and ensuring safe state transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance-based monitoring is used to detect line breaks, then line break detection capability is improved, but false detection increases due to oxidation-induced resistance changes
Solution Approach 1:
The system performs a preliminary actuation of the electric motor in the same rotation direction before conducting resistance-based line break detection. This preliminary action removes oxidation layers from commutation system components, ensuring that subsequent resistance measurements reflect actual line conditions rather than oxidation-induced resistance changes, thereby eliminating false detections
Solution Approach 2:
The system utilizes the electric motor's own actuation capability to remove the harmful oxidation layer. By deliberately actuating the motor before measurement, the harmful oxidation that causes false detections is converted into a removable condition, transforming the measurement problem into a preparatory action that benefits the detection accuracy
2Measurement precision
If the electric motor is actuated to remove oxide layer, then measurement accuracy is improved, but unintended state transitions may occur
Solution Approach 1:
The system determines the current rotation direction of the electric motor before actuation and uses this information to control the preliminary actuation. By maintaining actuation in the same rotation direction without commanding a state change, the system removes oxidation layers while preventing unintended transitions between active and inactive states of the braking device
Solution Approach 2:
The system uses feedback from the determined current operating state to control the preliminary actuation. By continuously monitoring the rotation direction and using this feedback to guide the actuation process, the system ensures that oxidation removal does not trigger unintended state transitions, maintaining safety while improving measurement accuracy
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 reduces the likelihood of incorrect line break identification, maintains the braking device's operational state, and prevents unintended state changes, enhancing safety and reliability by addressing oxidation-induced resistance issues.
Implementation Method 1
an electric motor (200) for an electric braking device (300), in particular for an electric parking brake of a vehicle, in particular motor vehicle, wherein the braking device (300) can be moved to a first operating state by operation of the electric motor (200) in a first direction of rotation and to a second operating state by operation of the electric motor (200) in a second direction of rotation
Implementation Method 2
components of a commutation system of the electric motor may oxidize, this leading to a higher internal resistance of the electric motor
Data Source
AI summary
A method for operating an electric motor for an electric braking device, in particular for an electric parking brake of a vehicle, in particular a motor vehicle, in which the braking device can be put into a first operational state by operation of the electric motor in a first direction of rotation and into a second operational state by operation of the electric motor in a second direction of rotation different from the first direction of rotation, includes determining a quantity which characterizes an internal resistance of the electric motor, comparing the first quantity with a predeterminable first threshold value, controlling the electric motor for a predeterminable first control duration according to the direction of rotation which corresponds to a current operational state of the braking device when the result of the comparison is that the first quantity exceeds the first threshold value.