Valve Testing in Electric Parking Brake Systems
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Solution Overview
Problem
Modern electric parking brake systems face issues with actuator defects leading to unreliable operation, which can result in unsafe parking conditions and potential vehicle damage, as existing testing methods do not adequately identify malfunctions in time to prevent these issues.
Innovation Solution
A control unit that outputs error messages based on pressure changes measured by pressure sensors, allowing for the detection of actuator malfunctions by determining if the pressure difference is within a predetermined threshold, and strategically placing pressure sensors between valve devices to minimize errors, enabling timely identification of defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first valve assembly is frequently switched to control the electric parking brake, then the parking brake can be reliably opened and closed, but the valve assembly experiences increased wear and may develop defects
Solution Approach 1:
The system performs a self-test function that proactively checks the functionality of the first valve assembly before a defect leads to failure. The control unit activates the valve assembly and monitors pressure changes to detect wear or defects early, allowing for preventive maintenance before the valve assembly fails completely.
Solution Approach 2:
The pressure sensor provides continuous feedback about the pressure state in the control line to the control unit. This feedback loop allows the control unit to monitor the response of the first valve assembly when activated, detecting deviations from expected pressure changes that indicate wear or defects, thereby enabling early intervention.
2Reliability
If the first valve assembly develops a defect, then the electric parking brake malfunctions, but existing testing methods fail to detect the defect in time
Solution Approach 1:
The self-test function is executed proactively to detect valve assembly defects before they cause system failure. By continuously monitoring pressure changes after valve activation, the system identifies defects early in their development stage, providing timely warning to the driver before the defect leads to complete malfunction.
Solution Approach 2:
The control unit automatically performs the test function without requiring external intervention. The system self-monitors its own operational status by activating the first valve assembly and evaluating the pressure sensor response, enabling autonomous defect detection and early warning capability.
3Measurement precision
If pressure sensors are placed to monitor all valve devices, then detection accuracy improves, but system complexity and error sources increase
Solution Approach 1:
The pressure sensor is strategically positioned at a specific location in the control line where it can effectively monitor the functionality of the first valve assembly. This localized placement optimizes detection capability for the critical actuator while avoiding the complexities of multiple sensors, reducing error sources while maintaining necessary monitoring precision.
Data Source
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AI summary
The control device (32) has a valve device (34) which is operated as actuating element. Another valve device (36) is provided for locking or releasing the control line. The control device is suitable to display the error indication, if the pressure changes to maximum around a pre-determined difference after the actuation of the former valve device. The pressure is measured by a pressure sensor (60). An independent claim is also included for a method for testing the functionality of a valve device for aeration and ventilation of control lines of an electrical handbrake.