Spark Plug Terminal Drainage for Oil Contaminant Removal
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Solution Overview
Problem
Spark plug terminals are prone to collecting engine oil or contaminants, which can interfere with energy transfer and degrade the interface between the spark plug and ignition coil spring, affecting the longevity and performance of the spark plug.
Innovation Solution
The spark plug design incorporates a cup post terminal with a sidewall that includes drainage openings and a tapered engagement surface to facilitate the drainage of oil or contaminants, ensuring they exit the pocket defined by the terminal and spring interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a cup post terminal with pocket structure is used to engage the ignition coil spring, then the mechanical connection and energy transfer interface is improved, but oil or contaminants can collect in the pocket and interfere with energy transfer
Solution Approach 1:
The patent extracts the harmful accumulation space by creating drainage openings that lead to an external drainage cavity in the terminal body. This allows oil and contaminants to be removed from the critical engagement interface and collected in a separate drainage cavity, preventing interference with energy transfer while maintaining the pocket structure for mechanical engagement.
Solution Approach 2:
The drainage cavity acts as an intermediary space between the engagement pocket and the external environment. It receives and contains oil and contaminants that drain from the engagement interface, preventing them from accumulating at the critical energy transfer surface while allowing the main engagement structure to remain intact.
2Ease of manufacture
If the engagement surface is made flat and horizontal, then manufacturing is simplified, but oil and contaminants drain poorly from the pocket
Solution Approach 1:
The patent applies a curved or sloped engagement surface that inclines toward the drainage opening. This curvature or slope facilitates the drainage of oil and contaminants toward the drainage opening by gravity and surface tension, improving drainage efficiency while remaining manufacturable through standard forming processes.
3Reliability
If drainage openings are added to the sidewall, then oil and contaminants can drain from the pocket, but the terminal structure becomes more complex
Solution Approach 1:
The patent implements drainage openings locally at specific positions on the sidewall where they are most effective for draining contaminants from the engagement pocket. The openings are strategically placed to maximize drainage functionality while minimizing the number of openings required, thus reducing structural complexity while maintaining reliability.
4Device complexity
If the terminal structure is simplified without drainage features, then manufacturing cost and complexity are reduced, but oil accumulation degrades the interface performance
Solution Approach 1:
The patent uses a thin-walled terminal structure with integrated drainage openings and an internal drainage cavity. The thin wall design allows for easy formation of drainage features during manufacturing while maintaining structural integrity. The drainage cavity is formed as an internal void space within the terminal body, adding minimal structural complexity while effectively preventing oil accumulation at the engagement interface.
Data Source
AI summary
A spark plug for an automotive engine includes a shell housing, and an insulator within the shell housing but extending axially beyond the shell housing. A terminal, referred to herein as a cup post terminal, is fixed to the proximal end of the insulator. The cup post terminal includes an engagement surface configured to engage an ignition coil spring for energy transfer to initiate a spark. The cup post terminal includes a sidewall extending axially from the engagement surface. The sidewall cooperates with the engagement surface to define a pocket for the ignition coil spring. The sidewall can have drainage openings to allow oil or contaminants to escape the pocket and drain away from the engagement between the engagement surface and the ignition coil spring. The engagement surface can also be sloped to facilitate the drainage toward the drainage openings.