Spark Plug Injection Hole Layout for Sub-Chamber Swirl Ignition
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Solution Overview
Problem
Existing spark plugs lack consideration for airflow in the sub-chamber, leading to suboptimal ignitability in internal combustion engines.
Innovation Solution
A spark plug design with a tubular insulator, center electrode, and ground electrode, where the plug cover has inclined injection holes that create a swirl flow in the sub-chamber, directing airflow and fuel to enhance spark extension and ignitability, even under low temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ground electrode is fixedly assembled to the housing with the plug cover secured after adjustment, then the discharge gap is adjustable and manufacturing flexibility is improved, but the airflow in the sub-chamber is not considered leading to suboptimal ignitability
Solution Approach 1:
The patent changes the geometric parameters of the injection holes by inclining their center axes at specific angles (α1, α2) relative to the radial direction. This parameter modification creates a swirl flow pattern in the sub-chamber that directs airflow and fuel toward the discharge gap, thereby improving ignitability while preserving the adjustable discharge gap configuration
Solution Approach 2:
The patent introduces a new dimensional aspect by inclining the injection holes at angles in the radial direction rather than having them perpendicular to the housing end face. This angular dimensionality creates a rotational flow component that enhances spark extension and flame propagation into the main chamber
2Reliability
If injection holes are inclined at specific angles, then swirl flow is created improving spark extension and ignitability, but the device complexity increases
Solution Approach 1:
The patent modifies the geometric parameters of existing injection holes by specifying inclination angles (α1, α2) relative to the radial direction. This approach maintains the basic structure of the plug cover while optimizing airflow patterns, thereby improving ignitability without substantially increasing device complexity
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
Improves ignitability by extending the spark and increasing the strength of the flame jet into the main chamber, reducing cooling losses and enhancing fuel efficiency.
Implementation Method 1
The center axis of the at least one injection hole is inclined with respect to a radial direction of the spark plug as viewed in the axial direction of the spark plug... enables an airflow introduced into the sub-chamber through the at least one injection hole or an airflow flowing out from the sub-chamber through the at least one injection hole to produce a swirl flow in the sub-chamber
Implementation Method 2
one side of the ground electrode and a corresponding one side of the center electrode of the spark plug, which face each other, define a discharge gap therebetween
Data Source
AI summary
In a spark plug, at least one injection hole serves as a ground-directed injection hole arranged to face a facing side of a ground electrode. An extension line of the center axis of the at least one ground-directed injection hole intersects with the facing side of the ground electrode at an intersection point. The facing side of the ground electrode has a closer region closer to the projection-end edge of the ground electrode than the intersection point is. The closer region of the facing side intersects with the extension line of the center axis of the ground-directed injection hole at a predetermined angle as viewed in the axial direction of the spark plug. The predetermined angle being an obtuse angle.