Semi-Rigid High-Voltage Extender for Spark Plug Insulation
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Solution Overview
Problem
Existing high-voltage extenders for spark plugs face issues such as voltage puncture of insulation materials, component separation, high-temperature degradation, and complexity in manufacturing and installation, particularly when used in natural gas engines with high temperatures and complex engine configurations.
Innovation Solution
A semi-rigid high-voltage extender design featuring a spring connected to a rigid tube with a polymeric boot, providing a single, integrated structure that withstands high voltages, prevents radial deflection, and maintains dielectric integrity, while being resistant to high temperatures and component separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polytetrafluoroethylene sleeve is used to insulate the stainless steel rod, then electrical insulation is provided, but the insulation material is punctured by high voltage over time
Solution Approach 1:
The patent uses a composite insulation structure combining polytetrafluoroethylene (Teflon) sleeve with a polymeric boot material. This composite approach leverages the excellent electrical insulation properties of Teflon while the polymeric boot provides enhanced mechanical protection and environmental resistance, preventing puncture and degradation over time in high-voltage and high-temperature environments.
Solution Approach 2:
The patent modifies the insulation system by adding a polymeric boot that changes the physical parameters of the insulation assembly - providing greater mechanical strength, thermal resistance, and puncture resistance while maintaining electrical insulation properties, thereby extending the service life under high-voltage stress.
2Reliability
If multiple components (spring, cup, sleeve, O-ring) are used to ensure reliable connection, then electrical connectivity is maintained, but component separation occurs under thermal cycling
Solution Approach 1:
The patent integrates the spring, cup, and connection elements into a unified assembly where the spring is contained within the polymeric boot that also serves as the insulating structure. This merging eliminates separate O-rings and cups that could separate, while the integrated design ensures thermal expansion and contraction affect the entire assembly uniformly, maintaining component alignment and preventing separation.
Solution Approach 2:
The polymeric boot acts as a flexible yet stable enclosing structure that accommodates thermal cycling. The boot material provides flexibility to absorb thermal expansion while maintaining the structural integrity of the entire assembly, preventing component separation that would occur with rigid, separate components.
3Strength
If a rigid stainless steel structure is used for the extender, then mechanical strength is provided, but angular misalignment cannot be accommodated
Solution Approach 1:
The patent replaces the rigid stainless steel structure with a flexible polymeric boot that can bend and flex to accommodate angular misalignment between the high-voltage source and spark plug. The boot maintains sufficient mechanical strength through its material properties and structural design while providing the flexibility needed to adapt to varying installation angles and thermal expansion.
Solution Approach 2:
The patent changes the material parameters from rigid metal to flexible polymer, allowing the extender to dynamically adjust its shape and angle in response to thermal cycling and installation variations while maintaining electrical insulation and mechanical strength through the polymeric material's inherent properties.
4Ease of manufacture
If conventional insulation materials are used, then manufacturing is simple, but the materials degrade under high temperature conditions
Solution Approach 1:
The patent employs a composite insulation system using polymeric boot material specifically selected for high-temperature resistance. This material maintains its structural and insulating properties in the high-temperature environment of natural gas engines, overcoming the degradation issues of conventional insulation materials while remaining manufacturable through standard molding processes.
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 effectively prevents high-voltage tracking, maintains electrical connectivity under angular misalignment, and reduces manufacturing and maintenance costs by minimizing components, ensuring reliable operation in high-temperature environments like natural gas engines.
Implementation Method 1
During thermal cycling, the polytetrafluoroethylene expands and contracts lengthwise and creates a gap at the inner surface of the extender 10 and the insulating surface of the high-voltage connection of the ignition coil
Implementation Method 2
The boot is formed of a material having a rigidity less than a rigidity of a material of the tube... ensuring reliable operation in high-temperature environments
Implementation Method 3
During thermal cycling, the polytetrafluoroethylene expands and contracts lengthwise and creates a gap at the inner surface of the extender 10
Data Source
AI summary
An extender for connecting a high-voltage source to a spark plug has a spring adapted to electrically connect with the high-voltage source and the spark plug, a tube having said spring positioned within an interior passageway thereof, and a boot affixed over an exterior of the tube. The boot is formed of a material having a rigidity less than a rigidity of a material of the tube. The boot has a first end adapted to be connected with the high-voltage source and a second end adapted to be connected to the spark plug such that the spring is in direct electrical connection with the spark plug and the high-voltage source. The tube has one end that is spaced inwardly of the first end of the boot and an opposite end of the spaced inwardly of the second end of the boot.