EMI Diverter Structure for Aircraft Composite Shielding
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Solution Overview
Problem
Current electronic circuits in aircraft with lightweight non-conducting composite materials lack effective shielding against lightning and radio frequency electromagnetic interference (EMI), as filter capacitors can create an undesirable path for lightning currents, necessitating improved EMI protection devices.
Innovation Solution
An external EMI diverting structure comprising a metallic conductor case with an isolated ground plane and a conducting enclosure that provides a capacitatively coupled return path to ground, diverting EMI away from electronic devices using a shunt, insulating layer, and exterior casing, which is attached to a larger structure for grounding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filter capacitors are used for EMI protection, then EMI filtering is improved, but lightning current conduction path is worsened
Solution Approach 1:
The patent extracts the harmful function of the filter capacitor by removing it from the circuit and replacing it with a resistive divider network. This eliminates the capacitor's ability to conduct lightning currents into sensitive equipment while preserving the EMI filtering function through the resistive network.
Solution Approach 2:
The patent changes the electrical parameters of the EMI protection circuit by replacing capacitive coupling with resistive coupling. The resistive divider network uses high-impedance resistors to maintain EMI filtering while preventing low-impedance lightning current paths, fundamentally altering the circuit's electrical characteristics.
2Weight of moving object
If lightweight non-conducting composite materials are used for aircraft structures, then weight is reduced, but EMI shielding is worsened
Solution Approach 1:
The patent introduces an intermediary EMI protection circuit between the external environment and sensitive electronic equipment. This intermediary circuit actively compensates for the lack of structural shielding provided by composite materials, creating a logical shielding layer through circuit-level protection rather than physical barriers.
3Object-affected harmful factors
If conventional EMI protection circuits are used, then EMI filtering is achieved, but reliability in hostile environments is worsened
Solution Approach 1:
The patent converts the potentially harmful effect of EMI signals into a beneficial protective mechanism. The resistive divider network is designed to present a high impedance to EMI signals while maintaining proper circuit operation, effectively using the EMI protection circuit itself as the protective element rather than relying on passive shielding.
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
Effectively shields electronic circuits from lightning and radio frequency EMI by interrupting fault paths and providing a safe return path for EMI, enhancing protection in hostile environments.
Implementation Method 1
a first conducting enclosure that encloses the electrical circuit and is electrically coupled to the electric circuit... a second conducting enclosure that encloses the first conducting enclosure and is electrically isolated from both of the first conducting enclosure and the electric circuit
Implementation Method 2
a first conducting enclosure that encloses the electrical circuit... a second conducting enclosure that encloses the first conducting enclosure
Data Source
AI summary
An external EMI diverting structure to electrically shield an electronic device from EMI is presented. The electronic device is physically isolated from the case ground which interrupts the EMI or lightning fault path. This shield provides a return path to ground for the EMI away from the electronic device and replaces conventional EMI filter capacitors, which are not connected to case ground. The external EMI diverter comprises a first conducting enclosure enclosing the electrical circuit and is electrically coupled to the electric circuit and a second conducting enclosure enclosing the first conducting enclosure and being electrically isolated from the first conducting enclosure and the electric circuit. The diverter is physically and electrically connected to the case ground at an attachment point.