Ignition Coil Plug Connector Creepage Distance
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Solution Overview
Problem
The dielectric strength of plug connectors in ignition coils is insufficient, particularly when the spark plug is not inserted deeply, leading to reduced creepage distances and potential high-voltage discharge issues.
Innovation Solution
A circumferential slot surrounding the terminal contact of the plug connector, into which an elastomeric cap is seated, lengthens the creepage distance, enhancing dielectric strength, and an electrically insulating sleeve with a collar facilitates production and further increases this distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the spark plug is not inserted deeply into the plug connector, then the plug connector length can be reduced, but the creepage distance decreases leading to reduced dielectric strength
Solution Approach 1:
The patent introduces a circumferential slot that creates an additional dimensional path for the creepage distance. Instead of relying solely on the axial insertion depth of the spark plug, the slot provides a circumferential route that extends the creepage path in a different spatial dimension, allowing the connector to be shorter while maintaining adequate dielectric strength.
Solution Approach 2:
The elastomeric cap is segmented by the circumferential slot, creating distinct regions that contribute to the overall creepage path. The slot divides the cap structure in a way that forces the electrical discharge to follow a longer, more circuitous path around the terminal contact, effectively increasing the creepage distance without increasing the overall connector length.
2Device complexity
If the plug connector is shortened, then the creepage distance becomes insufficient, but longer creepage distance is needed for adequate dielectric strength
Solution Approach 1:
The circumferential slot acts as an intermediary structural feature that mediates between the shortened connector length and the required creepage distance. It introduces an intermediate path that the electrical discharge must follow, effectively extending the protective barrier against high-voltage discharge without requiring a longer overall connector structure.
3Ease of manufacture
If the elastomeric cap completely fills the circumferential slot, then the structure is simplified, but the creepage distance may be reduced
Solution Approach 1:
The patent applies local quality by allowing the elastomeric cap to have different degrees of filling in different regions. The cap may completely fill the circumferential slot in some areas for manufacturing simplicity, while leaving partial gaps in other critical regions to maintain adequate creepage distance. This localized variation optimizes both manufacturability and electrical insulation performance.
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 configuration allows for a shorter plug connector design without compromising dielectric strength, ensuring effective sealing against moisture and high-voltage discharges, even with reduced spark plug insertion depth.
Implementation Method 1
the dielectric strength of the plug connector of an ignition coil can be improved
Implementation Method 2
An elastomeric cap can seal the plug connection with the spark plug against moisture
Implementation Method 3
the creepage distance from the terminal contact to the external side of the cap can be lengthened
Data Source
AI summary
Described is an ignition coil for an internal combustion engine having a housing with a plug connector, wherein the plug connector has an elastomeric cap slid onto a tubular housing section that surrounds a terminal contact. This disclosure provides that the terminal contact is surrounded by a circumferential slot, in which an inner edge of the cap sits.