Ignition Coil Spool Circumference Reduction for Void-Free Epoxy Injection
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Solution Overview
Problem
Epoxy resin-based materials used in ignition coil assemblies often form voids when hardening due to lack of space for proper flow, leading to inadequate dielectric strength and potential arcing between coils, which can result in lower secondary voltage output and damage to the assembly.
Innovation Solution
The ignition coil assembly design includes a first spool that decreases its circumference when a coil is wound, increasing the annular space between the coils to allow for the injection of electrically insulating material without creating substantial voids, thereby preventing arcing and ensuring effective insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy resin-based material is used as electrically insulating material, then mechanical support is improved, but void formation occurs leading to inadequate dielectric strength
Solution Approach 1:
The spool is designed with a slot that allows dynamic circumference reduction during coil winding. This dynamic adjustment increases the annular space, enabling complete epoxy resin filling without voids while maintaining mechanical support and dielectric strength.
Solution Approach 2:
The spool structure is segmented with a slot that allows selective deformation. This segmentation enables the spool to change its circumference dynamically, creating sufficient space for complete epoxy resin injection and eliminating void formation.
2Reliability
If spaces are provided for epoxy flow, then void formation is reduced, but device complexity increases
Solution Approach 1:
Rather than providing permanent spaces or channels, the spool uses a dynamic slot mechanism that temporarily increases annular space during epoxy injection. After winding, the spool returns to its original configuration, maintaining structural integrity without permanent complexity.
Solution Approach 2:
The slot is pre-configured in the spool structure to enable circumference reduction during coil winding. This preliminary design feature ensures sufficient annular space is created automatically during the winding process, facilitating complete epoxy filling before the spool returns to its normal configuration.
Data Source
AI summary
A method of assembling the ignition coil assembly including a first spool, a first coil, and a second spool. The first coil is wound around a first spool outer surface. The first spool and the first coil are disposed within a cavity of the second spool and an electrically insulating material injected into an annular space defined between a first coil outer surface and a second spool inner surface. The first spool is configured to allow a decrease of a circumference of the first spool when the first coil is wound around an outer surface of the first spool. Decreasing the circumference of the first spool increases the annular space sufficient to inject the electrically insulating material into the annular space without creating substantial voids in the electrically insulating material.