Spark Plug Auxiliary Chamber Eccentric Injection Holes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spark plugs for internal combustion engines do not effectively improve ignition performance by extending the discharge in the auxiliary chamber, particularly during the expansion stroke, which is crucial for increasing catalyst temperature in exhaust gas purification filters.
Innovation Solution
A spark plug design featuring a cylindrical housing with a cylindrical insulator, center electrode, ground electrode forming a discharge gap, and an auxiliary chamber forming portion with axial and oblique injection holes, where the center of the axial injection hole is eccentric from the central axis towards the discharge gap, facilitating a strong air flow that extends the spark discharge into the auxiliary chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the discharge gap is positioned in the auxiliary chamber, then ignition performance is improved, but the spark discharge does not effectively extend into the auxiliary chamber during expansion stroke
Solution Approach 1:
The axial injection hole is positioned eccentrically relative to the central axis of the spark plug, specifically on the discharge gap side. This asymmetric positioning creates a non-uniform air flow distribution that directs the air flow toward the discharge gap, effectively extending the spark discharge into the auxiliary chamber during the expansion stroke and improving ignition performance.
2Reliability
If air flow is generated in the auxiliary chamber, then flame development is encouraged, but cooling losses increase
Solution Approach 1:
The air flow in the auxiliary chamber is generated periodically through the injection holes during specific engine strokes. The design allows air flow to be introduced when needed (during compression and expansion strokes) while maintaining a sealed configuration that prevents continuous cooling, thereby encouraging flame development during combustion while minimizing cooling losses during other phases.
3Reliability
If multiple injection holes are provided, then air flow distribution is improved, but device complexity increases
Solution Approach 1:
The injection holes are strategically positioned with different orientations (axial and oblique) at specific locations on the auxiliary chamber forming portion. The axial injection hole is eccentrically positioned on the discharge gap side, while oblique injection holes are positioned at specific angles. This localized, non-uniform distribution optimizes air flow patterns for spark discharge extension and flame development without requiring excessive numbers of holes, thereby balancing air flow improvement with device simplicity.
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 enhances ignition performance by effectively extending the spark discharge into the auxiliary chamber, improving the ejection of the flame into the main combustion chamber, thereby improving ignition efficiency and reducing cooling losses.
Implementation Method 1
The auxiliary chamber forming portion includes an axial injection hole. When viewed in an axial direction of the spark plug, a center of the axial injection hole is eccentric on a discharge gap side from a central axis of the spark plug. It is easy to form a strong air flow toward a distal end in the axial direction at the discharge gap
Implementation Method 2
a strong air flow toward a distal end in the axial direction at the discharge gap is formed. Accordingly, a spark discharge is likely to significantly extend toward the distal end in the auxiliary chamber
Implementation Method 3
Such a spark plug forms a flame by igniting an air-fuel mixture in the auxiliary chamber. Further, the flame formed in the auxiliary chamber is ejected from injection holes through which the auxiliary chamber is communicated with a main combustion chamber
Data Source
AI summary
A spark plug for an internal combustion engine includes a housing, an insulator, a center electrode, a ground electrode, and an auxiliary chamber forming portion. The ground electrode faces the center electrode from an outer peripheral side and forms a discharge gap between the ground electrode and the center electrode. An auxiliary chamber is formed inside the auxiliary chamber forming portion. A distance in an axial direction between the discharge gap and a distal end of the auxiliary chamber is equal to or greater than a maximum wall thickness of the auxiliary chamber forming portion. The auxiliary chamber forming portion includes injection holes. The injection holes are formed in a state where openings on an outer side are located closer to a distal end than openings on the auxiliary chamber side. At least one of the injection holes is an injection hole in the axial direction formed along an axial direction of a plug. When viewed in the axial direction of the spark plug, a center of the axial injection hole is eccentric from a central axis of the spark plug toward the discharge gap.