Window Lifter Control Circuit Inundation Detection
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Solution Overview
Problem
Existing control circuits for electric-motor-operated window lifters in vehicles fail to reliably operate the window in case of inundation due to undefined signal states caused by moisture and short-circuits, preventing the window from being opened for vehicle occupants in emergency situations.
Innovation Solution
A control circuit that monitors the lighting current of the switches for the window lifter, using a shunt resistor to detect overcurrent conditions indicative of inundation, and generates a control signal to actuate the window lifter in the opening direction, ensuring reliable operation even in flooded conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional inundation detector circuits or immersion opening switches are added to ensure reliable window opening in flooded conditions, then the reliability of window operation during inundation is improved, but the device complexity increases
Solution Approach 1:
The lighting element serves dual purposes: it illuminates the switch area for visibility and simultaneously acts as an inundation detection sensor. By monitoring the lighting current of this multi-functional element, the system detects water penetration without requiring separate detection circuits, thus improving reliability while avoiding additional complexity
Solution Approach 2:
The lighting element's own electrical characteristics (current consumption) are utilized to detect inundation conditions. The system monitors changes in the lighting current that occur when water penetrates the switch area, allowing the lighting element to effectively serve as its own sensor without needing external detection components
2Reliability
If separate inundation detection circuits are implemented to monitor switch signals, then the reliability of detecting inundation is improved, but the device complexity and cost increase
Solution Approach 1:
The lighting element is transformed into a multi-functional component that provides both illumination and inundation detection. The control device monitors the lighting current of this element to detect water penetration, eliminating the need for separate detection circuits and reducing overall system complexity
Solution Approach 2:
The lighting current serves as an intermediary parameter that indirectly indicates inundation conditions. Instead of directly monitoring switch signals for water penetration, the system uses the lighting element's current consumption as a mediator to detect the presence of water in the switch area
3Device complexity
If the lighting element is used as an inundation sensor by monitoring its lighting current, then the device complexity is reduced and cost is lowered, but the measurement precision of inundation detection must be sufficient
Solution Approach 1:
The control device continuously monitors the lighting current of the lighting element and compares it against threshold values to determine inundation conditions. This feedback mechanism ensures reliable detection by evaluating whether the measured current indicates the presence of water in the switch area
Solution Approach 2:
The system detects inundation by monitoring changes in the lighting current parameter. When water penetrates the switch area, it alters the electrical characteristics of the lighting element, causing measurable changes in current consumption that the control device can detect and interpret
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 solution provides a simple and reliable means to detect inundation and ensure the vehicle window can be opened safely, enhancing occupant safety by using the change in lighting current to trigger the window lifter drive, thus overcoming the issue of undefined states and short-circuits.
Implementation Method 1
monitoring a lighting current of a lighting element for the switches and generating an overcurrent signal if the lighting current exceeds an overcurrent threshold value
Data Source
AI summary
The invention in certain embodiments relates to a control circuit for an electric-motor-operated window lifter (10) of a motor vehicle (1), the control circuit having a first switch (11) for opening a vehicle window (7), a second switch (12) for closing the vehicle window (7), and a control device (15), which, when one of the switches (11, 12) is activated, actuates the window lifter (10) to move the vehicle window (7) in the opening direction or closing direction. The control device (15) monitors the lighting current (ILED) which flows across a lighting element (14) for the switches (11, 12), and generates a control signal (I12), if appropriate, for opening the vehicle window (7) if the lighting current (ILED) exceeds an overcurrent threshold value (IRef) thereby detecting inundation of the vehicle.