Corona Ignition Device Radial Coating End Flashover Prevention
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Solution Overview
Problem
Corona ignition devices face premature failure due to flashovers and parasitic partial discharges, which are difficult to prevent with existing electrically conductive coatings, especially at the coating's end where field peaks can form, and previous solutions like undercuts increase manufacturing complexity.
Innovation Solution
The insulator of the corona ignition device features an annular shoulder where the electrically conductive coating ends, oriented radially to minimize field peaks, with a well-defined axial direction, and a method involving coating application and grinding to create a flush edge, reducing the risk of flashovers without complex shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an undercut is provided in the insulator to turn over the end of the coating, then flashovers are prevented, but the insulator shape becomes complicated and manufacturing costs increase
Solution Approach 1:
The patent applies a radially oriented coating section specifically at the critical end region of the insulator, while maintaining a simple cylindrical shape for the majority of the insulator body. This localized modification provides flashover protection only where needed (at the coating end) without requiring complex undercut structures throughout the entire insulator, thus resolving the contradiction between reliability improvement and device complexity.
2Ease of manufacture
If the coating end is left irregular, then manufacturing is simpler, but field peaks form and flashover risk increases
Solution Approach 1:
The patent incorporates the radially oriented coating section as a pre-planned design feature during the coating application process. By intentionally creating this radial orientation at the coating end from the beginning, the design ensures proper field distribution and flashover prevention without requiring complex post-processing or irregular manufacturing steps, thus maintaining ease of manufacture while improving reliability.
3Area of stationary object
If the coating extends further axially, then coverage is improved, but field peaks form at the end increasing flashover risk
Solution Approach 1:
The patent transitions the coating orientation from purely axial to radial at the end section. This dimensional change allows the coating to provide adequate coverage area while the radial orientation prevents field peak formation at the coating end, thus resolving the contradiction between maintaining sufficient coverage area and preventing flashovers.
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 design effectively reduces the risk of flashovers at the coating's end, maintaining a reasonable manufacturing cost by ensuring the coating's end is radially oriented and well-defined, thereby minimizing field peaks and preventing premature device failure.
Implementation Method 1
the dielectric strength of the insulator is of great importance. Bypasses, flashovers and parasitic partial discharges can lead to premature failure of a corona ignition device. The risk of flashovers and parasitic partial discharges can be reduced with an electrically conductive coating of the insulator.
Implementation Method 2
Any irregularities present on the end of the coating, in particular an irregular boundary, are largely insignificant for the electric field, since the area of electrically conductive coating is oriented radially at the end thereof so that a geometrical tangent extending coating points generally in the radial direction.
Data Source
AI summary
This disclosure relates to a corona ignition device having: an insulator, which bears an electrically conductive coating, which forms a tubular face; a central electrode, which sits in the insulator and leads to at least one ignition tip; and a holder, in which the insulator sits. According to this disclosure, the insulator has an annular shoulder, on which is situated the end of the tubular face of the coating that faces away from the at least one ignition tip. A method for producing a corona ignition device is also described.