Spark Plug Electrode Recess for Ignitability and Wear Resistance
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Solution Overview
Problem
Existing spark plugs with protrusions and fused portions experience rapid wear due to spark discharge, leading to reduced durability and potential ignition issues.
Innovation Solution
A spark plug design featuring a center electrode with a protrusion and a discharge member joined via a fused portion, where a recess is formed at the position including the protrusion, ensuring the volume of the discharge member and fused portion is maintained, thus reducing wear and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recess is formed in the fused portion to increase electrical field intensity, then ignitability is improved, but the volume of the fused portion is reduced leading to rapid wear and reduced durability
Solution Approach 1:
The invention applies local quality by forming a recess only at the discharge end of the fused portion where electrical field intensity is needed for ignition, while maintaining the full volume of the fused portion in other areas to ensure durability. This localized modification allows the recess to enhance ignitability without compromising the overall structural integrity and wear resistance of the fused portion.
2Use of energy by moving object
If the volume of the fused portion is reduced to form a recess, then electrical field intensity increases, but wear due to spark discharge accelerates
Solution Approach 1:
The recess is formed locally at the discharge end of the fused portion rather than reducing the overall volume. This localized geometric modification concentrates the electrical field at the recess edges to enhance ignition performance, while the bulk material volume remains sufficient to resist wear from spark discharge over the service life of the spark plug.
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 recessed design enhances the durability of the spark plug by reducing wear on the discharge member and fused portion, while maintaining increased electrical field intensity and improved ignitability by suppressing heat conduction.
Implementation Method 1
the volume of a portion formed of a discharge member and a fused portion can be ensured. The amount of wear of the portion, which is formed of the discharge member and the fused portion, due to spark discharge can be ensured, and thus, the durability can be ensured while maintaining advantageous effects of increasing the electrical field intensity by the recess
Implementation Method 2
maintaining advantageous effects of increasing the electrical field intensity by the recess and improving the ignitability by suppressing heat conduction
Data Source
AI summary
A spark plug includes a center electrode extending along an axial line, a metal shell holding the center electrode in an insulated manner, and a ground electrode connected to the metal shell by a connection portion. At least one of the center electrode and the ground electrode includes a protrusion. A discharge member joined to the protrusion via a fused portion forms a spark gap between the discharge member and the other one of the electrodes. A recess is formed at a position including the protrusion.