Corona Ignition High Voltage Connection Insulator Design
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Solution Overview
Problem
Corona igniter assemblies face challenges in controlling the electric field to prevent unwanted corona discharge due to air gaps and material interface stresses, leading to material degradation and performance issues.
Innovation Solution
A corona ignition assembly design featuring a high voltage connection with a silicon rubber insulator, a metal shield, and metal inserts, where specific portions of the insulator surface adhere and others do not, to manage thermal expansion and reduce mechanical stress, along with a semiconductive sleeve and embedded metallic braid for field mitigation and stress control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple insulators formed of different materials are used to improve efficiency and performance, then robustness and overall performance are improved, but air gaps form at interfaces due to internal and interfacial stresses, leading to unwanted corona discharge and material degradation
Solution Approach 1:
The patent changes the physical and chemical parameters of the insulator material by using a single-material construction (ceramic or polymer) instead of multiple different materials. This eliminates the parameter mismatches (electrical properties, thermal expansion coefficients) that cause interface stresses and air gaps, thereby preventing unwanted corona discharge while maintaining reliability.
Solution Approach 2:
The patent employs composite material design by integrating the insulator, shielding, and structural components into a unified single-material structure. This composite approach eliminates the need for interfaces between dissimilar materials, preventing the formation of air gaps and interfacial stresses that lead to corona discharge, while still achieving the desired electrical shielding and mechanical strength.
2Use of energy by moving object
If metallic shielding and different insulator materials are used to control the electric field, then efficiency is improved, but internal and interface stresses create air gaps at interfaces, concentrating the electrical field and causing material degradation
Solution Approach 1:
The patent changes the material composition parameter by using a single homogeneous material for the insulator structure, eliminating the electrical and thermal property mismatches at interfaces. This prevents interface stress concentration and air gap formation, thereby maintaining material strength and preventing degradation while preserving electrical field control efficiency.
Solution Approach 2:
The patent uses the single-material insulator structure as an intermediary that performs multiple functions: electrical insulation, electromagnetic shielding, and mechanical support. This eliminates the need for separate metallic shielding layers and multi-material interfaces, preventing stress concentration and material degradation while maintaining efficient electric field control.
3Reliability
If dissimilar insulator materials are used to improve performance, then robustness is improved, but different coefficients of thermal expansion and creep lead to air gaps at interfaces during operation
Solution Approach 1:
The patent changes the thermal and mechanical property parameters by using a single-material construction throughout the insulator structure. This eliminates the mismatch in coefficients of thermal expansion and creep rates between different materials, preventing the formation of air gaps at interfaces during thermal cycling and operation, thereby maintaining both robustness and interface integrity.
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 effectively controls thermal expansion and mechanical stress, reducing internal and interface stresses, and prevents unwanted corona discharge, enhancing the reliability and performance of the corona igniter assembly by maintaining dielectric properties and suppressing electromagnetic noise.
Implementation Method 1
First portions of the insulator outer surface adhere to the shield, the upper insert, and the lower insert, and second portions of the insulator outer surface are not adhered to the shield, the upper insert, or the lower insert
Implementation Method 2
A high voltage connection includes a high voltage insulator formed of silicon rubber... The electric field is preferably controlled so that the fuel-air mixture maintains dielectric properties and corona discharge occurs
Implementation Method 3
The high voltage connection also includes a shield formed of metal surrounding the high voltage insulator... suppressing electromagnetic noise
Implementation Method 4
The electric field causes a portion of a mixture of fuel and air in the combustion chamber to ionize and begin dielectric breakdown, facilitating combustion of the fuel-air mixture. The ionized portion of the fuel-air mixture forms a flame front which then becomes self-sustaining
Implementation Method 5
The electric field causes a portion of a mixture of fuel and air in the combustion chamber to ionize and begin dielectric breakdown
Data Source
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AI summary
A corona ignition assembly including a firing end assembly (22) and an ignition coil assembly (23) connected by a high voltage connection (24) is provided. The high voltage connection includes a high voltage insulator 58 formed of silicon rubber. A shield 60 formed of metal surrounds the high voltage insulator. The high voltage connection also includes an upper insert 62 formed of metal connecting the shield to the ignition coil assembly and a lower insert 64 formed of metal connecting the shield to the firing end assembly. First portions (66) of the outer surface of the high voltage insulator adhere to the shield, the upper insert, and the lower insert, while second portions (68) of the outer surface do not adhere to at least one of the shield, the upper insert, and the lower insert. A metal braid (84) can be embedded in the high voltage insulator, realizing a ground connection between the upper and lower inserts.