Spark Plug Electrode Geometry for Multiple Discharge Control
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Solution Overview
Problem
Spark plugs with multiple ground electrodes face issues with improper shape and position leading to spark deflection by gas flow, resulting in multiple discharge, which accelerates electrode consumption and shortens the spark plug's service life.
Innovation Solution
A spark plug design featuring a center electrode, a main ground electrode, and three auxiliary ground electrodes, where the auxiliary electrodes are positioned and configured to block gas flow effectively, with specific geometric relationships between their widths and distances to reduce multiple discharge occurrences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple ground electrodes are provided to improve fouling resistance and ignition performance, then ignition performance is improved, but multiple discharge occurs due to improper shape and position of electrodes
Solution Approach 1:
The patent applies local quality by creating distinct functional zones among the ground electrodes. The first auxiliary ground electrode has a specific width W and positioning (with distance Tp from the center electrode) that differs from the second and third auxiliary ground electrodes. This local differentiation in electrode geometry and position allows each electrode to perform its specific function: the first auxiliary electrode blocks gas flow to prevent multiple discharge, while the second and third electrodes provide additional discharge paths, thereby resolving the contradiction between improving ignition performance and preventing multiple discharge.
Solution Approach 2:
The patent employs asymmetry in the configuration of auxiliary ground electrodes. Specifically, the first auxiliary ground electrode is positioned at a distance Tp from the center electrode with width W ≥ Tp, while the second and third auxiliary ground electrodes are positioned at different locations. This asymmetric arrangement creates an effective gas flow barrier on one side (preventing multiple discharge) while maintaining discharge capability on other sides, thus resolving the technical contradiction between enhancing ignition performance and preventing harmful multiple discharge.
2Reliability
If multiple discharge occurs due to improper electrode configuration, then ignition performance may improve, but electrode consumption is accelerated and service life becomes shorter
Solution Approach 1:
The patent applies preliminary anti-action by pre-configuring the first auxiliary ground electrode with specific dimensions (width W and distance Tp from center electrode) to block gas flow before it can reach the discharge gap and cause multiple discharge. This preventive measure is built into the electrode geometry itself, counteracting the gas flow that would otherwise lead to accelerated electrode consumption and shortened service life, while still maintaining effective ignition performance.
3Object-affected harmful factors
If auxiliary ground electrodes are positioned to block gas flow, then multiple discharge is reduced, but device complexity increases due to additional electrodes and precise positioning requirements
Solution Approach 1:
The patent applies segmentation by dividing the ground electrode function into multiple distinct electrodes with specific roles. The first auxiliary ground electrode is segmented to perform the gas flow blocking function with width W and position Tp, while the second and third auxiliary ground electrodes are segmented to provide additional discharge paths. This functional segmentation allows the system to reduce multiple discharge occurrence while maintaining manageable complexity through clear functional differentiation of each electrode.
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 configuration significantly reduces multiple discharge occurrences by blocking gas flow, thereby extending the spark plug's service life and lowering the voltage required for discharge.
Implementation Method 1
the distal end portions of the three auxiliary ground electrodes which form the gaps in cooperation with the center electrode are located forward of the forward end of the insulator with respect to the axial direction... a relation W ≥ Tp is satisfied... blocking gas flow effectively
Implementation Method 2
a spark plug generates spark discharge for ignition at a discharge gap between a center electrode and a ground electrode
Data Source
Figure 1
Figure 2(A)~2(D)
Figure 3(A)~3(D)
AI summary
A technique of reducing the occurrence of multiple discharge in a spark plug is provided. The spark plug has a main ground electrode and three auxiliary ground electrodes. The position at which the first auxiliary ground electrode is joined to a metallic shell is located opposite the position at which the main ground electrode is joined to the metallic shell, with respect to a center electrode. The positions at which the second and third auxiliary ground electrodes are joined to the metallic shell are located opposite to each other with respect to the center electrode. When the width of the first auxiliary ground electrode is represented by W, the shortest distance between the second auxiliary ground electrode and the third auxiliary ground electrode is represented by T, and a distance which is a component of the shortest distance T in a direction orthogonal to the first auxiliary ground electrode is represented by Tp, a relation W ≥ tp is satisfied.