Corona Igniter Assembly With Deformed Shell for Joint Durability
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Solution Overview
Problem
Existing igniters for internal combustion engines face challenges in achieving optimal ignition performance and durability due to high electrical, mechanical, and thermal stresses at the joint between the insulator and secondary enlarging components, leading to corrosion, separation, and failure, while also increasing complexity and cost.
Innovation Solution
A corona igniter design featuring a monolithic insulator with enlarged upper and lower end regions and a plastically deformed metal shell that conforms to the insulator's contour, eliminating the need for secondary insulating components and reducing stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If secondary enlarging insulating components are added to the insulator, then the insulator diameter can be increased beyond the shell through passage diameter, but the joint between insulator and secondary components experiences high electrical, mechanical, and thermal stresses leading to corrosion, separation, and failure
Solution Approach 1:
The patent merges the insulator and shell into a single integrated component where the shell is plastically deformed to conform to the insulator contour, eliminating the need for separate secondary enlarging components and their associated joints. This integration removes the joint that was susceptible to corrosion and separation.
Solution Approach 2:
The patent changes the physical state of the shell through plastic deformation, transforming it from a rigid pre-formed component into a malleable material that can be shaped to match the insulator's contour. This parameter change allows the shell to envelop the insulator completely without requiring additional enlarging components.
2Volume of moving object
If secondary enlarging insulating components are added to the insulator, then the insulator diameter can be increased, but the complexity and cost of manufacturing increase
Solution Approach 1:
The patent combines multiple components (insulator and shell) into a simplified assembly process where the shell is plastically deformed around the insulator in a single operation, eliminating the need for separate secondary components and reducing manufacturing steps.
Solution Approach 2:
The patent utilizes plastic deformation as a manufacturing parameter change that allows the shell to be formed to match the insulator contour in one process, rather than requiring multiple precision manufacturing steps to create separate enlarging components.
3Reliability
If the insulator diameter is increased beyond the shell through passage diameter, then ignition performance improves, but the insulator cannot be inserted through the shell using conventional assembly techniques
Solution Approach 1:
The patent inverts the conventional assembly sequence by first inserting the insulator through the shell passage, then plastically deforming the shell outward to conform to the insulator contour. This reverses the traditional approach of pre-forming the shell to match the insulator, instead adapting the shell after assembly.
Solution Approach 2:
The patent applies plastic deformation as a post-assembly parameter change that allows the shell to transition from a pre-formed cylindrical shape to a custom-contoured shape that matches the insulator, enabling assembly of larger diameter insulators without modifying the insulator itself.
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 design enhances ignition performance and durability by distributing stress evenly and preventing corrosion, while simplifying the manufacturing process and reducing costs by eliminating the need for additional components.
Implementation Method 1
The shell is plastically deformed such that the shell inner surface conforms with the contour of the insulator intermediate region and at least a portion of the insulator upper end region
Data Source
Figure 1~2
Figure 3
Figure 4A~4C
AI summary
An igniter, such as a corona igniter for an internal combustion engine, and a method of manufacturing the igniter, are provided. The igniter includes an insulator with enlarged upper and lower end regions extending axially beyond opposite ends of a constrained, reduced diameter region of a shell through passage. The enlarged lower end region of the insulator is disposed axially outwardly of a lower end of the shell. The insulator is hermetically sealed to the shell and is permanently fixed against being removed axially outwardly from the shell. The method can include conforming the shell to the contour of the insulator by plastically deforming the shell, or casting the shell about the insulator. Alternatively, separate pieces of metal can be disposed around the insulator to form the shell which is conformed to the insulator.