Spark Plug Ground Electrode Texture for Stable Downstream Discharge
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Solution Overview
Problem
Existing spark plugs face challenges in maintaining discharge due to the extension of the discharge path downstream by combustion chamber flow, leading to instability in the discharge.
Innovation Solution
The spark plug design includes a ground electrode with an uneven surface opposite to the center electrode tip, featuring uneven portions with a maximum height of 3 μm or more, which facilitates the maintenance of discharge even when the discharge path is extended downstream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a smooth surface is used on the ground electrode, then the manufacturing process is simple, but the discharge cannot be maintained when the discharge path is extended downstream due to flow
Solution Approach 1:
The invention applies local quality by creating an uneven surface only at the discharge tip of the ground electrode, while the rest of the electrode maintains a smooth surface for simple manufacturing. The uneven surface includes protrusions and recesses within specific dimensional ranges (0.1-10μm height, 1-100μm width) that locally enhance discharge stability without complicating the overall structure
2Length of moving object
If the discharge path is extended downstream due to flow, then the discharge may reach further, but the discharge cannot be maintained according to circumstances
Solution Approach 1:
The invention changes the surface parameter of the ground electrode by introducing an uneven surface structure with controlled height (0.1-10μm) and width (1-100μm) parameters. This parameter change creates multiple potential discharge initiation points that ensure discharge stability even when the discharge path extends downstream due to combustion chamber flow
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
The uneven surface on the ground electrode ensures easy formation and maintenance of discharge, reduces overheating, and enhances the wear resistance and service life of the spark plug components.
Implementation Method 1
a discharge occurs mainly between the chip of the ground electrode and the center electrode
Implementation Method 2
the ground electrode includes a base material and a metal film covering the base material, a thermal conductivity of the metal film is higher than a thermal conductivity of the base material
Data Source
AI summary
A spark plug includes: a metal shell; a center electrode held by the metal shell in an insulated manner; a ground electrode including a first end portion and a second end portion, the ground electrode being connected to the metal shell at the first end portion and extending to the second end portion; and a chip disposed on an opposed surface, in the ground electrode, opposite to a tip end surface of the center electrode. The opposed surface includes an uneven surface including an uneven portion extending in a first direction, and, in the uneven surface, a maximum height that is a distance between a highest portion and a lowest portion is 3 μm or more.