Optically Interfaced Fuel Density Sensor for Arcing Prevention
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Solution Overview
Problem
Existing fuel density sensors in aircraft fuel tanks face risks of electrical arcing and ignition due to conductive connections, which can be catastrophic during lightning strikes or short circuits, necessitating a solution to eliminate electrical communications within the fuel tank.
Innovation Solution
An optically interfaced vibrating spool densitometer with a fuel-tight housing and fiber optic connection ports, where light energy is used to power and communicate density measurements, eliminating the risk of electrical arcing by using a fiber optic connection to transmit both power and signals, and featuring sensor electronics entirely within the fuel tank to prevent fuel ingress and isolate electronics from high voltage hazards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical connections are used to power and communicate with the density sensor in the fuel tank, then power transmission and signal communication are achieved, but the risk of electrical arcing and ignition increases
Solution Approach 1:
The patent replaces the electrical/mechanical connection system with an optical system. Light energy is transmitted through optical fibers to power the sensor and carry measurement data out of the fuel tank, eliminating conductive paths that could cause electrical arcing or ignition hazards in the explosive fuel environment.
Solution Approach 2:
The patent introduces optical fibers as an intermediary medium to transmit both power and measurement data between the external control system and the in-tank density sensor. This intermediary optical connection allows energy and information transfer without direct electrical contact, preventing harmful electrical effects in the fuel tank.
2Measurement precision
If the density sensor is placed inside the fuel tank for direct measurement, then measurement accuracy is improved, but the risk of fuel ingress to electronics increases
Solution Approach 1:
The patent segments the density sensor system into two distinct parts: an in-tank measurement component that directly contacts fuel for accurate measurement, and an external electronics component that processes signals and is protected from fuel exposure. The optical fiber connection bridges these segments, allowing the measurement function to remain in the harsh fuel environment while protecting the sensitive electronics externally.
3Reliability
If optical fibers are used to transmit power and signals, then electrical arcing is eliminated, but the complexity of optical power conversion increases
Solution Approach 1:
The patent merges the optical power reception and signal communication functions into a single integrated optical fiber connection. The same optical fiber that carries measurement data also transmits power to the in-tank sensor, combining multiple functions into one component and reducing overall system complexity despite the sophisticated power-to-light conversion required.
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
This solution allows for accurate fuel density measurement while minimizing the risk of electrical arcing and ignition, ensuring safe operation during lightning strikes or short circuits by using optical communication to prevent conductive paths for voltage and current within the fuel tank.
Implementation Method 1
an optical power converter configured to convert the light energy communicated from the optical fiber to the optical power converter within the interior cavity via the fiber optic connection port. The light energy is converted into DC electrical energy.
Implementation Method 2
The vibrating spool transducer has a resonant frequency indicative of a density of the fuel
Data Source
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AI summary
Apparatus and associated methods relate to suppressing electrical arcing within a fuel tank in which a fuel density sensor (20) is located by isolating electronic components of the fuel density sensor within a cavity surrounded by a dielectric housing (32). The dielectric housing physically isolates the sensor electronics from fuel in the fuel tank via a fuel barrier. The dielectric housing electrically isolating the sensor electronics within the cavity from potential high voltage hazards outside the cavity. Light energy optically from a first environment outside the cavity is transmitted through the dielectric housing to a second environment within the cavity to provide operating power for the sensor electronics. The light energy is converted into DC electrical energy within the cavity. A light signal indicative of fuel density is optically transmitted from the second environment within the cavity through the dielectric housing to the first environment outside the cavity.