Corona Igniter Insulator Diameter and Assembly

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Solution Overview

Problem

Existing corona igniter designs face challenges in achieving optimal electrical performance and assembly methods, particularly in maintaining dielectric properties of the fuel-air mixture and preventing thermal plasma formation, while also requiring complex assembly procedures.

Innovation Solution

The design incorporates a central electrode with a corona-enhancing tip, an insulator with a varying outer diameter, and a conductive shell with an intermediate part that allows for both forward and reverse assembly, ensuring the conductive inner diameter is less than the insulator outer diameter, which enhances electrical performance and simplifies assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulator outer diameter increases in a direction moving away from the grounded metal shell and towards the high voltage electrode tip, then electrical performance is improved, but assembly complexity increases due to reverse-assembly requirement

Engineering Contradiction:

Improveelectrical performanceVSAvoidassembly complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies reverse-assembly methodology where the insulator is inserted into the shell from the combustion chamber end rather than the traditional external end. This inversion of assembly direction allows the insulator outer diameter to increase towards the high voltage electrode tip while maintaining manufacturability and electrical performance

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The insulator outer diameter is designed to vary along its length, increasing in a direction moving away from the grounded metal shell and towards the high voltage electrode tip. This parameter change optimizes electrical performance by enhancing the insulator's electrical characteristics in the high voltage region

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the insulator outer diameter is made larger than the inner diameter of the grounded metal shell, then electrical performance is maximized, but assembly difficulty increases

Engineering Contradiction:

Improveelectrical performanceVSAvoidassembly ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

By inverting the assembly direction and inserting the insulator from the combustion chamber end, the patent enables the insulator outer diameter to be larger than the shell inner diameter at certain sections while still achieving successful assembly. This reverse approach transforms an otherwise impossible assembly into a feasible manufacturing process

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If the insulator outer diameter increases towards the high voltage electrode tip, then dielectric properties are maintained, but manufacturing complexity increases

Engineering Contradiction:

Improvedielectric propertiesVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The insulator is designed with a varying outer diameter that increases towards the high voltage electrode tip. This parameter change maintains dielectric properties by providing enhanced insulation where the electric field is strongest, while the reverse-assembly method keeps manufacturing complexity manageable

Inventive Principle:

Principle #35Parameter changes

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 configuration provides exceptional electrical performance by maintaining dielectric properties and allowing for efficient assembly, preventing thermal plasma formation and enabling the corona igniter to function effectively in combustion systems.

Implementation Method 1

a corona igniter for emitting a radio frequency electric field to ionize a fuel-air mixture and provide a corona discharge

Methodology Applied

Scientific EffectCorona discharge: Corona Discharge

Implementation Method 2

The electric field causes a portion of a mixture of fuel and air in the combustion chamber to ionize and begin dielectric breakdown

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

facilitating combustion of the fuel-air mixture. The electric field is preferably controlled so that the fuel-air mixture maintains dielectric properties and corona discharge occurs

Methodology Applied

Scientific EffectDielectric breakdown: Dielectric

Data Source

PatentUS11557882B2Corona ignition device with improved electrical performance

Publication Date: 2023.01.17 FEDERAL MOGUL MOTORPARTS LLC

AI summary

A corona comprises a central electrode surrounded by an insulator, which is surrounded by a conductive component. The conductive component includes a shell and an intermediate part both formed of an electrically conductive material. The intermediate part is a layer of metal which brazes the insulator to the shell. An outer surface of the insulator presents a lower ledge, and the layer of metal can be applied to the insulator above the lower ledge prior to or after inserting the insulator into the shell. The conductive inner diameter is less than an insulator outer diameter directly below the lower ledge such the insulator thickness increases toward the electrode firing end. The insulator outer diameter is also typically less than the shell inner diameter so that the corona igniter can be forward-assembled.