Aircraft Ignition Lead Shielding and Cooling Design
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Solution Overview
Problem
Existing ignition leads in aircraft engines face challenges with labor-intensive installation, interference with cooling air flow, mechanical damage, and debris trapping due to braided sleeves, particularly in severe vibratory environments and air-cooled applications.
Innovation Solution
A coaxial ignition lead design featuring a center conductor, an insulating jacket, a low-resistance braid for current return, and a flexible non-collapsible metal conduit with a nickel-based overbraid for protection, eliminating the need for an inner braid and enhancing electromagnetic interference shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braided sleeve is used to protect the conductor, then mechanical protection and EMI shielding are improved, but installation becomes labor intensive and cooling air flow is interfered with
Solution Approach 1:
The patent removes the braided sleeve component entirely from the ignition lead design. Instead of using a separate braided sleeve for protection, the conductor is directly embedded in the insulating jacket material, which provides both mechanical protection and electrical insulation in a single integrated structure. This eliminates the labor-intensive installation of separate braided sleeves while maintaining protective functions.
2Strength
If a braided sleeve is used for protection, then mechanical strength is improved, but cooling air flow is blocked and debris trapping occurs
Solution Approach 1:
The patent merges the mechanical protection function and electrical insulation function into a single integrated insulating jacket structure. The conductor is embedded directly in the insulating jacket material, which provides both mechanical strength and electrical insulation without requiring separate braided sleeves. This integrated design eliminates cooling air flow obstruction while maintaining protective functions.
3Reliability
If multiple protective layers including braided sleeve are used, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple protective functions (mechanical protection, electrical insulation, EMI shielding) into a single integrated insulating jacket structure. The conductor is embedded in the insulating jacket material, which provides all necessary protection in one component rather than requiring multiple separate layers including braided sleeves, thereby reducing structural complexity while maintaining reliability.
4Reliability
If braided sleeve is used for EMI shielding, then electromagnetic interference protection is improved, but weight increases
Solution Approach 1:
The patent uses composite material properties of the insulating jacket, which combines dielectric materials with conductive fillers or mesh structures embedded within the insulation layer. This provides EMI shielding functionality integrated into the insulation material itself, eliminating the need for separate heavy braided metal sleeves while maintaining electromagnetic interference protection.
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 design improves mechanical robustness, reduces complexity, and maintains cooling air flow while providing superior shielding and reduced weight, eliminating labor-intensive manufacturing processes and potential radiation emission leaks.
Implementation Method 1
a center conductor 22 for conducting a high voltage ignition pulse from the exciter to the igniter
Implementation Method 2
an electrical insulation jacket 28 that electrically isolates the center conductor from the conduit and the electrical return path
Implementation Method 3
a low-resistance braid 9 used as a return path for the electrical current
Implementation Method 4
a flexible non-collapsible metal conduit 12 that protects the center conductor and provides the ignition lead with suitable structural integrity
Implementation Method 5
A nickel-based overbraid 14 may be provided over the conduit 12 to protect the internal components of the ignition lead 6 from abrasion and other damage as well as provide added EMI protection
Implementation Method 6
During operation of the ignition lead 6, air is able to flow through air passage 10 such that it cools the insulating jacket 8 as well as any other polymeric materials inside the igniter 5 and ignition lead 6
Data Source
Figure 1A
Figure 1B~1C
Figure 1D
AI summary
An ignition lead (20) in an engine for conducting a large current and high voltage ignition pulse from an exciter to an igniter, which may then transform the pulse received from the ignition lead into an electrical spark, which ignites a fuel and air mixture in the combustor of the engine. The ignition lead may include a construction for improved electromagnetic shielding.