Ignition Coil Mat Barrier for Crack Propagation
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Solution Overview
Problem
Ignition coils fail due to cracks in the potting compound caused by mechanical and thermal stresses, allowing moisture to penetrate and lead to premature failure.
Innovation Solution
Embedding a mat within the potting compound to act as a barrier for crack propagation, which is attached to the transformer or housing before potting, using materials like woven or non-woven mats or foam mats, and optionally with cut-out holes for faster potting compound penetration and air escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mat is embedded into the potting compound to block crack propagation, then the reliability of the ignition coil is improved, but the device complexity increases
Solution Approach 1:
A mat is introduced as an intermediary barrier layer between the transformer and the potting compound surface. This mat serves as a crack propagation barrier, intercepting cracks before they reach the surface and compromising the sealing function. The mat is embedded into the potting compound during the potting process, creating a composite structure that maintains reliability without requiring additional separate components.
2Stability of the object's composition
If the mat is attached to the transformer or housing before potting, then the positioning stability is improved, but the ease of manufacture deteriorates
Solution Approach 1:
The mat is attached to the transformer or housing before the potting compound is applied. This preliminary attachment ensures proper positioning and prevents the mat from floating or shifting during the potting process. The mat can be secured using adhesives, clips, or integration into the housing structure, establishing its position in advance before the irreversible potting process begins.
3Productivity
If cut-out holes are provided in the mat, then the productivity of the potting process is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The mat is provided with cut-out holes or openings that segment the barrier layer into multiple sections. These holes serve dual purposes: they allow trapped air to escape during the potting process, preventing voids and defects, and they enable faster penetration of the potting compound through the mat. The segmentation reduces the overall resistance to potting compound flow, improving filling speed and productivity.
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
Prevents cracks from reaching the surface of the potting compound, maintaining the sealing and insulating function and reducing the risk of ignition coil failure.
Implementation Method 1
a mat is embedded into the potting compound, which forms a barrier to crack propagation. Cracks form mainly at edges and corners, for example at the edges of an iron core of the transformer. A mat that covers the transformer has at best little influence on the crack formation at such sites, but represents a barrier for crack growth
Implementation Method 2
To make it easier for the mat to be penetrated by the potting compound during potting, it can be advantageous to use an impregnated mat, or a mat made of impregnated fibers. In this way it is easier to wet the mat with potting compound.
Implementation Method 3
a mat is embedded into the potting compound, which forms a barrier to crack propagation. The transformer is covered by one or more mats, and the housing is then potted with potting compound, whereby the transformer and the mat(s) are embedded into the potting compound.
Data Source
AI summary
An ignition coil is described for an internal combustion engine, with a housing, a transformer, which is arranged in an interior space of the housing, and potting compound, with which the interior space of the housing is cast. In accordance with this disclosure provision is made for the transformer to be covered by a mat, which is embedded in the potting compound.