Parking Brake Controller Fault Detection and Automatic Engagement
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Solution Overview
Problem
Existing brake systems fail to hold the parking brake when the parking switch malfunctions, causing inconvenience and potential safety issues.
Innovation Solution
A brake system with a parking-switch fault detecting mechanism that activates an electric motor to hold the parking mechanism when a fault is detected, using a combination of brake pedal operation and vehicle state conditions to ensure the parking brake is engaged, even if the parking switch is faulty.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the parking switch is used to control the parking brake, then the ease of operation is improved, but the reliability deteriorates when the switch fails
Solution Approach 1:
The control unit continuously monitors the parking switch status and prepares to automatically actuate the electric motor when a fault is detected. By detecting the fault condition (abnormal high or low voltage) and automatically engaging the parking brake without user intervention, the system performs the protective action in advance before the failure becomes critical, ensuring the vehicle remains secured even when the switch fails
2Reliability
If automatic fault detection and automatic parking brake engagement is implemented, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The control unit performs multiple functions: it controls the electric motor based on normal parking switch operation, detects faults by monitoring voltage levels, determines vehicle rest conditions through various sensors (wheel speed, ignition status), and automatically engages the parking brake when faults are detected. By consolidating these diverse functions into a single control unit, the system achieves high reliability without proportionally increasing overall system complexity
3Reliability
If the parking brake is automatically engaged upon fault detection, then the safety is improved, but the ease of operation deteriorates due to unintended engagement
Solution Approach 1:
The control unit continuously monitors the parking switch status and prepares to automatically actuate the electric motor when a fault is detected. By detecting the fault condition (abnormal high or low voltage) and automatically engaging the parking brake without user intervention, the system performs the protective action in advance before the failure becomes critical
Solution Approach 2:
The control unit continuously monitors the parking switch voltage and compares it against predetermined thresholds to detect faults. This feedback mechanism allows the system to distinguish between normal operation and fault conditions, enabling intelligent decision-making about when to automatically engage the parking brake, thereby avoiding unintended engagement while maintaining safety
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 effectively holds the parking brake in the event of a parking switch failure, ensuring the vehicle remains stationary and preventing discomfort to occupants by maintaining air conditioning functionality.
Implementation Method 1
a parking mechanism operated with an electric motor to hold the wheel non-rotatably and release it
Implementation Method 2
a brake mechanism for applying braking force by bringing friction members (pads, shoes) into contact with rotating members (discs and drums) rotating with the vehicle
Data Source
AI summary
A parking brake controller (19) activates an electric actuator (43) in response to operation of a parking switch (18) to hold a disc brake (31) to serve as a parking brake. If a failure (fault) is detected in the parking switch (18), the parking brake controller (19) activates the electric actuator (43) so as to hold the parking brake automatically upon detecting a condition that presumes the vehicle operator's intent not to drive any longer while the vehicle is at rest.