Aviation Igniter Cable Sealing and Spring Design
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Solution Overview
Problem
General aviation aircraft engines face high stress conditions that compromise the integrity of igniter cable connectors, requiring moisture-proof and durable connections that can withstand temperature, pressure, and humidity variations, while also being easily maintainable and cost-effective.
Innovation Solution
A radio-shielded igniter cable assembly with a flexible conducting elbow tube, sealing sleeve, threaded nut, conducting ferrule, grommet, and double coil spring design that provides a moisture-resistant connection between the cable and spark plug, allowing for easy disassembly and reassembly, and airtight seals at both spark plug and magneto ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional igniter cable connectors are used in high stress conditions, then the electrical conductivity may be compromised, but the connectors become vulnerable to moisture ingress and temperature variations
Solution Approach 1:
The connector assembly employs nested sealing structures where an inner seal sits within an outer seal housing, creating multiple concentric barriers against moisture. The contact spring is nested within the seal assembly, and the entire structure is housed within the connector body, providing layered protection while maintaining electrical conductivity.
Solution Approach 2:
The elastomeric seal acts as an intermediary barrier between the external environment and the electrical contact components. The seal material is specifically chosen to be compatible with both the moisture environment and the electrical contacts, providing isolation without interfering with the electrical function.
2Object-affected harmful factors
If moisture-proof sealing structures are implemented, then protection against moisture ingress is improved, but the assembly complexity increases
Solution Approach 1:
The connector uses elastomeric seals and flexible grommets to provide moisture protection. These flexible elements conform to the mating surfaces and provide effective sealing without requiring complex rigid sealing mechanisms, thereby reducing overall assembly complexity while maintaining protection.
Solution Approach 2:
The sealing function is segmented into distinct components (inner seal, outer seal, grommets) that can be independently manufactured and assembled. This modular approach to sealing allows for easier manufacturing and assembly compared to a single complex sealing structure, paradoxically reducing overall complexity through functional decomposition.
3Ease of repair
If removable contact springs are used, then ease of maintenance is improved, but the connection reliability may be compromised
Solution Approach 1:
The contact spring is designed as a dynamic, resilient component that can be compressed and released. This allows the spring to be easily inserted and removed from the connector housing while automatically maintaining reliable electrical contact through its spring force, combining ease of maintenance with connection reliability.
Solution Approach 2:
The spring-loaded contact mechanism is self-adjusting and self-maintaining. The spring force automatically compensates for wear and dimensional variations, ensuring reliable contact without requiring complex adjustment mechanisms or specialized maintenance procedures, thereby achieving both ease of repair and reliability.
4Object-affected harmful factors
If multiple sealing layers are implemented, then protection against environmental factors is improved, but the manufacturing cost increases
Solution Approach 1:
The patent employs elastomeric seals and flexible grommets that can be extruded or molded as continuous pieces, providing effective sealing at low cost. These flexible sealing elements replace more expensive rigid sealing structures while maintaining protection against environmental factors.
Solution Approach 2:
The connector assembly uses composite construction combining metal components with elastomeric sealing materials. This composite approach leverages the cost-effectiveness of each material for its specific function, providing environmental protection through material properties rather than complex structures, thereby controlling manufacturing costs.
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 solution ensures reliable, long-lasting connections that maintain electrical conductivity and prevent moisture ingress, supporting extended duty cycles and easy maintenance without damage, addressing the deficiencies of prior art in durability, sealing, and ease of assembly.
Implementation Method 1
a coil spring acts on the ignition cable connection which in turn is held in position about the spark plug
Implementation Method 2
A sealing grommet is provided. The grommet is sized and shaped to fit slidably within a receiving collar of a magneto plate
Data Source
AI summary
An improved general aviation igniter cable assembly includes either a single or double coil spring. The double coil spring has inner and outer portions. The outer portion has first and second ends. The first end rotatably engages the cylindrical recess in the ferrule. The outer portion surrounds the first end of the grommet with the second end bearing against the retainer. The distal end of the inner portion is located within the outer portion and bears against the first end of the grommet to put pressure on the spark plug contact button. For the magneto end of the cable, a sealing grommet fits slidably over an insulating sleeve of the cable and seals against a magneto plate when a surrounding threaded nut is tightened into a collar of the magneto plate and the plate is attached to a magneto, providing an airtight seal to the magneto plate and the magneto.