Spark Plug Ground Electrode Geometry for Stable Ignitability
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Solution Overview
Problem
The existing spark plugs for internal combustion engines face issues with ignitability due to airflow blockage by the ground electrode, which varies with mounting posture, and current solutions either compromise strength or increase manufacturing complexity and cost.
Innovation Solution
A spark plug design featuring a ground electrode with an erecting part and an inclined part, where the erecting part's dimensions (w/t ≤ 1, w ≤ 1.9 mm, t ≤ 2.3 mm) and inclination angle (30° ≤ θ ≤ 60°) ensure airflow is not blocked, regardless of mounting posture, maintaining ignitability without complex shapes or thin structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the ground electrode is made thick to prevent strength reduction, then the strength of the ground electrode is improved, but the airflow of the air-fuel mixture is easily blocked
Solution Approach 1:
The patent applies parameter changes by optimizing the dimensional ratios of the ground electrode. Specifically, it sets the width-to-thickness ratio w/t ≤ 1, with w ≤ 1.9 mm and t ≤ 2.3 mm, and the inclination angle θ between 30°-60°. These parameter optimizations allow the ground electrode to maintain sufficient strength while minimizing airflow blockage, resolving the contradiction between strength and airflow passage.
2Object-affected harmful factors
If drilling processing is performed on the ground electrode to suppress airflow blockage, then the airflow is improved, but the strength of the ground electrode is reduced
Solution Approach 1:
Instead of drilling processing that compromises strength, the patent uses parameter changes in the ground electrode geometry. By optimizing w/t ≤ 1, w ≤ 1.9 mm, t ≤ 2.3 mm, and inclination angle θ (30°-60°), the design achieves airflow optimization without structural weakening, directly resolving this contradiction.
3Object-affected harmful factors
If the ground electrode is joined to the housing by a plurality of thin plate members to suppress airflow blockage, then the airflow is improved, but the manufacturing complexity and cost are increased
Solution Approach 1:
The patent resolves this contradiction by optimizing the parameters of a single integrated ground electrode structure rather than using multiple thin plate members. The optimized geometry (w/t ≤ 1, w ≤ 1.9 mm, t ≤ 2.3 mm, θ = 30°-60°) achieves airflow improvement while maintaining manufacturing simplicity and avoiding increased complexity.
4Object-affected harmful factors
If the ground electrode is joined to the housing by a plurality of thin plate members to suppress airflow blockage, then the airflow is improved, but the manufacturing cost is increased
Solution Approach 1:
The patent achieves airflow improvement through optimized ground electrode parameters (w/t ≤ 1, w ≤ 1.9 mm, t ≤ 2.3 mm, θ = 30°-60°) rather than using complex multi-component assemblies. This approach reduces manufacturing cost by eliminating the need for multiple thin plate members and their associated assembly processes.
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 design ensures stable ignitability across various mounting postures without compromising strength or increasing manufacturing complexity, providing a simple and effective solution to airflow blockage issues.
Implementation Method 1
airflow of the air-fuel mixture, for example, such as swirl flow or tumble flow, is formed and the airflow moderately flows also at the spark discharge gap
Data Source
AI summary
There is provided a spark plug for an internal combustion engine with a simple configuration capable of ensuring stable ignitability regardless of mounting posture to the internal combustion engine. The spark plug includes a housing, an insulator, a center electrode, and a ground electrode. The ground electrode includes an erecting part that is erected from a tip part of the housing to a tip side and an inclined part that is bent from the tip of the erecting part to the center electrode side to extend obliquely toward a tip side. An end edge of the ground electrode on an opposite side to the housing side is a tip of the inclined part. The erecting part satisfies w/t≤1, w≤1.9 mm, and t≤2.3 mm, where t is a dimension in an alignment direction of the erecting part and the center electrode, and w is a dimension in a width direction orthogonal to each of the alignment direction and a plug axial direction. An inclination angle θ of the inclined part with respect to the plug axial direction satisfies 30°≤θ≤60°.