Hydrogen Tank Fill-Level Sensing via Horizontal Vibration Modes
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Solution Overview
Problem
Existing methods for accurately monitoring the filling level of fluid tanks, particularly in aircraft applications, are inadequate due to variations in gravity and flight dynamics, and conventional sensing solutions are unsafe for hydrogen tanks.
Innovation Solution
A filling level monitoring device using a pair of sensors mounted on opposite sides of a fluid container to measure the horizontal vibration mode, which is insensitive to external factors and highly correlated with the filling level, allowing for accurate determination through spectral analysis of resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If weight-based or flow-based methods are used to determine filling level, then filling level can be determined, but accuracy deteriorates under varying gravity conditions and flight dynamics
Solution Approach 1:
The patent uses mechanical vibration of the tank structure as the basis for filling level measurement. By exciting the tank and measuring its natural frequencies, the system determines filling level without relying on gravity or flow measurements, thereby achieving both high accuracy and adaptability to aircraft conditions.
Solution Approach 2:
The patent replaces traditional mechanical weighing systems or flow-based sensing with a vibration-based measurement system. This substitution eliminates the problems associated with gravity-dependent methods and enables accurate filling level determination in dynamic aircraft environments.
2Measurement precision
If conventional electronic sensing solutions are used in hydrogen tanks, then sensing capability is achieved, but safety and insulation requirements are compromised
Solution Approach 1:
The patent replaces electronic sensing systems with a mechanical vibration-based measurement system. This substitution maintains safety and insulation requirements by avoiding electronic instruments inside the hydrogen tank while still achieving accurate filling level sensing through external vibration excitation and measurement.
3Ease of operation
If vibration-based methods are used to monitor filling level, then non-intrusive sensing is achieved, but stable vibrational modes are difficult to determine and track
Solution Approach 1:
The patent segments the vibration measurement into two independent components: excitation (applied to the tank) and response (measured from the tank). By separating these functions and using spectral analysis to identify natural frequencies, the system achieves both non-intrusive sensing and stable mode tracking.
Solution Approach 2:
The patent uses feedback through spectral analysis to continuously identify and track the tank's natural frequencies. The system compares the excitation signal with the response signal, processes the spectral content, and adjusts to maintain accurate tracking of vibrational modes even as filling level changes.
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
Provides precise and stable monitoring of fluid levels in dynamic environments, enhancing safety and accuracy in aircraft fuel management.
Implementation Method 1
A signal source 30 and exciting elements 10 are configured to couple vibrational loads having a multitude of frequency components into a container 200. Resonance frequencies of the container 200 are depending on the filling level of the container 200.
Implementation Method 2
The first sensor 21 and the second sensor 22 are each connected to the processor 40 and are configured to sense vibrations within the fluid container 200 and to generate and send corresponding vibration signals to the processor 40.
Data Source
AI summary
A filling level monitoring device includes an exciting element, first and second sensors, a signal source, and a processor. The exciting element can be mounted to the fluid container. The first and second sensors can be mounted to the fluid container at opposite sides. The signal source is connected to the exciting element and can generate an input signal including frequency components. The first and second sensors are each connected to the processor to sense vibrations within the fluid container and to generate and send corresponding vibration signals to the processor. The processor can determine a horizontal vibration mode from the vibration signals of the first and second sensors and the input signal, to determine a modal frequency of the determined horizontal vibration mode, and to determine a current filling level of the fluid container based on the modal frequency of the determined horizontal vibration mode.