Ignition Coil Asymmetric Core Offset for Dielectric Breakdown Prevention
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Solution Overview
Problem
Conventional ignition coils suffer from reduced durability due to dielectric breakdown caused by local electrical field concentration between the secondary coil and the outer periphery core, leading to premature degradation of the insulating plastic member.
Innovation Solution
The ignition coil design includes a secondary coil and an outer periphery core with a specific arrangement where the shortest distance from the outer edge of the opposing surface of the outer periphery core to the secondary coil is longer than the shortest distance between the opposing surface and the secondary coil, reducing electrical field concentration and preventing dielectric breakdown, thereby enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the outer edge of the opposing surface of the outer periphery core is arranged to exactly face the outer peripheral surface of the secondary coil, then the electrical insulation structure is simplified, but the electrical field concentrates on the outer edge causing treeing phenomenon and dielectric breakdown
Solution Approach 1:
The invention applies asymmetry by deliberately offsetting the outer edge of the opposing surface from the exact facing position of the secondary coil's outer peripheral surface. This asymmetric arrangement creates a non-uniform electrical field distribution that prevents concentration at the outer edge, thereby avoiding treeing phenomenon and dielectric breakdown while maintaining structural simplicity
Solution Approach 2:
The invention applies local quality by creating different spatial relationships at different locations: the outer edge is offset to prevent field concentration, while the central region maintains proper insulation. This localized modification of the geometric arrangement addresses the specific problem of edge field concentration without compromising overall insulation performance
2Volume of moving object
If the distance between the outer peripheral surface and the opposing surface is minimized, then the insulation member thickness is reduced and device size is decreased, but electrical field concentration increases causing premature degradation
Solution Approach 1:
The invention uses asymmetry to allow the insulation distance to vary spatially: the minimum distance A is maintained small for compactness, while the distance B from the offset outer edge is made larger to prevent field concentration. This asymmetric distance distribution enables small overall size while maintaining insulation reliability
Solution Approach 2:
The invention changes the geometric parameters of the arrangement by offsetting the outer edge position, creating a parameter relationship where B > A. This parameter modification allows the insulation structure to achieve both compact dimensions and adequate field distribution for preventing dielectric breakdown
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 restricts electrical field concentration, alleviates dielectric breakdown, and improves the durability of the ignition coil, allowing for longer lifespan and potential downsizing while maintaining performance.
Implementation Method 1
a secondary coil arranged at an outer peripheral side of a primary coil is increased in voltage through mutual induction with the primary coil
Data Source
AI summary
An ignition coil includes a primary coil (14), a secondary coil (16) disposed on an outer circumferential side of the primary coil and configured to be boosted by mutual induction with the primary coil, an outer periphery core (18) having an opposing surface (183), which is opposed to an outer peripheral surface (160) of the secondary coil, and an insulating member (20) disposed between the outer peripheral surface and the opposing surface. The secondary coil and the outer periphery core are arranged such that a shortest distance between the outer peripheral surface and an outer edge (183a, 183b) of the opposing surface is larger than a shortest distance between the outer peripheral surface and the opposing surface.