Digital Densitometer for Aircraft Fuel Gauging
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Solution Overview
Problem
Conventional fuel gauging systems in aircraft face inaccuracies in determining fuel density due to the expense, weight, and unreliability of densitometers, often relying on inferring density from fuel dielectric constant and temperature, which can lead to significant errors in mass calculations.
Innovation Solution
A digital densitometer system comprising a frequency detection device within the fuel tank, coupled with an electronic controller outside the tank, uses a digital interface to convert resonant frequency into digital form for accurate density determination, eliminating the need for on-board microprocessors and reducing wiring complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional densitometers are used to measure fuel density, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the complex signal processing and control functions from the densitometer itself and relocates them to an external electronic controller. The densitometer retains only the essential frequency detection capability, while all analog-to-digital conversion, calibration coefficient application, and density calculation are performed externally. This reduces the densitometer's complexity while maintaining measurement precision.
Solution Approach 2:
The patent introduces an intermediary electronic controller that acts as a bridge between the simple frequency detection device and the fuel quantity indication system. This intermediary handles the complex tasks of signal conditioning, digital conversion, and density calculation, allowing the densitometer to remain simple while achieving high measurement precision through the intermediary's processing capabilities.
2Measurement precision
If conventional densitometers with microprocessors are used, then measurement precision is improved, but wiring complexity increases
Solution Approach 1:
The patent removes the microprocessor and associated complex wiring from the densitometer unit itself. The frequency detection device becomes a simple sensor that outputs a frequency signal, eliminating the need for complex onboard processing electronics and their associated wiring. All intelligent processing is extracted to the external controller.
Solution Approach 2:
The patent replaces the mechanical/electronic processing system (microprocessor-based densitometer) with a simpler frequency output device paired with a digital communication system. The complex electronic processing is replaced by a clean digital interface that transmits frequency data directly to the external controller for processing, significantly reducing wiring complexity.
3Device complexity
If density is inferred from dielectric constant and temperature, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent makes the external electronic controller multi-functional by having it perform both the fuel quantity calculation functions and the density measurement functions. The same controller that manages fuel quantity indications also handles frequency detection, digital conversion, and density calculation, eliminating the need for separate dedicated density measurement equipment while maintaining high measurement precision.
Solution Approach 2:
The electronic controller serves as an intermediary that receives frequency data from the simple detection device and transforms it into accurate density measurements through digital processing and calibration coefficient application. This intermediary approach allows the use of simple sensing hardware while achieving high measurement precision through intelligent external processing.
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 digital densitometer system provides improved accuracy and reduced wiring requirements, simplifying the interface and enhancing electromagnetic interference resistance, while allowing for digital calibration and temperature sensing, thereby enhancing fuel quantity calculations and reducing installation challenges.
Implementation Method 1
conventional densitometers, which measure density as a function of the resonant frequency of a structure in contact with the fuel
Data Source
AI summary
A digital densitometer for a fluid gauging system includes a frequency detection device configured to be disposed within a fluid tank, wherein a frequency detected by the frequency detection device is indicative of a density of a fluid within the fluid tank, frequency detection circuitry configured to obtain the frequency from the frequency detection device and output the frequency in a digital form, and an interface for digital communication with an electronic controller, the digital communication comprising transmission of the digital form of the frequency for the electronic controller.