Ignition Coil High Voltage Cup Annular Space Design
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Solution Overview
Problem
The existing ignition coils for internal combustion engines often have a void in the press fit area between the high voltage cup and the case, which can lead to electrical field concentration and potential performance issues.
Innovation Solution
The ignition coil design includes a cup with a first cylindrical wall press fit with the case and a second cylindrical wall radially spaced from the first, creating an annular space to minimize electrical field concentration at the press fit interface, and is made of conductive material for uninterrupted electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a high voltage cup is press fit within the case to facilitate coupling with a spark plug, then the ease of operation and connection is improved, but a void may form at the press fit interface causing electrical field concentration that worsens reliability
Solution Approach 1:
A conductive annular spacer is introduced as an intermediary component between the high voltage cup and the case. This spacer fills the void that would otherwise form at the press fit interface, eliminating the electrical field concentration problem while maintaining the press fit coupling mechanism. The spacer acts as a mediator that resolves the contradiction between ease of coupling and electrical field uniformity.
Solution Approach 2:
The conductive annular spacer provides localized electrical conductivity at the press fit interface between the cup and case. By placing conductive material specifically at the void-prone interface area, the solution addresses the electrical field concentration problem locally without altering the overall press fit coupling structure, thus maintaining ease of operation while improving reliability.
2Reliability
If insulating resin is introduced into the gap between the secondary winding and the case for insulating purposes, then electrical insulation is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The conductive annular spacer combines multiple functions into a single component: it provides mechanical support for the press fit coupling, fills voids to eliminate electrical field concentration, and works in conjunction with the insulating resin to maintain electrical insulation. This merging of functions reduces the need for separate insulating structures, thereby simplifying the overall manufacturing process while maintaining insulation reliability.
Data Source
AI summary
An ignition coil includes a central core, a primary winding, a spool, a secondary winding, and a case outward of the core, spool, primary winding, and secondary winding. The secondary winding is wound on the spool and includes a high voltage end. The ignition coil also includes a cup formed of a metal material in electrical communication with the high voltage end of the secondary winding and is configured to be contacted by a conductive connector that is suitable for connection to a spark plug. The cup includes a generally cylindrical first sidewall press fit with the case and defining a press fit area at the interface of the first sidewall and the case, a generally cylindrical second sidewall spaced radially from the first sidewall, and an annular space defined between the press fit area and the second sidewall.