Spark Plug Electrode Orientation for High Airflow Ignition
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Solution Overview
Problem
Existing spark plugs face challenges in maintaining stable primary plasma flow in high airflow environments within combustion chambers, particularly in tumble engines, which affects the ignitability of the air-fuel mixture.
Innovation Solution
A spark plug design featuring a main ground electrode and a sub ground electrode with specific orientations and positions relative to the air flow direction, allowing the discharge spark to extend and move towards the sub ground electrode, thereby increasing the contact area with the air-fuel mixture and improving ignitability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single ground electrode is used to form a discharge gap, then the structure is simple, but the ignitability of the air-fuel mixture deteriorates in high airflow conditions
Solution Approach 1:
The ground electrode is divided into a main ground electrode and a sub ground electrode, creating multiple discharge gaps. The main discharge gap is formed between the center electrode and main ground electrode, while the sub discharge gap is formed between the center electrode and sub ground electrode. This segmentation allows the spark to propagate through multiple gaps, extending the ignition path and improving mixture ignitability without significantly increasing structural complexity.
Solution Approach 2:
The sub ground electrode is positioned downstream in the air stream direction relative to the main ground electrode, creating a spatial arrangement that utilizes the airflow direction. This dimensional positioning allows the discharge spark to be extended towards the sub ground electrode by the air stream, effectively using the airflow to enhance spark propagation and increase contact area with the air-fuel mixture.
2Stability of the object's composition
If the main ground electrode is positioned perpendicular to the air flow direction, then the air flow towards the plug center axis is prevented from being disturbed, but the discharge spark extension towards the downstream portion is limited
Solution Approach 1:
The sub ground electrode is positioned downstream in the air stream direction, creating a discharge gap that extends in the airflow direction. This dimensional arrangement allows the discharge spark to naturally extend towards the downstream portion along the airflow path, increasing the spark length and contact area with the moving air-fuel mixture while maintaining the perpendicular positioning of the main ground electrode for flow stability.
Solution Approach 2:
The sub ground electrode is pre-positioned in the downstream location before ignition occurs. When ignition takes place, the discharge spark is already oriented to extend towards this pre-positioned electrode, allowing the spark to naturally follow the airflow path and increase its effective length without requiring active control during the ignition process.
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 design enhances the ignitability of the air-fuel mixture by extending the discharge spark and increasing its contact area with the mixture, even in high airflow conditions, by positioning the sub ground electrode downstream and configuring it to receive the discharge spark from the main ground electrode.
Implementation Method 1
discharge is produced at the discharge gap. Sparks caused by the discharge make thermal contact with an air fuel mixture in the combustion chamber
Implementation Method 2
producing a primary plasma. The primary plasma flows together with an air fuel mixture stream in the combustion chamber
Data Source
AI summary
A spark plug includes a main ground electrode having a main connecting portion connected to the housing and forming a discharge gap between the main ground electrode and the center electrode, and a sub ground electrode having a sub connecting portion connected to the housing. The direction on which the main connecting portion and a plug center axis are arranged is set to be perpendicular to an air flow direction of an air stream in the combustion chamber. The sub connecting portion is located in a downstream side than the main connecting portion. The tip end position of the sub ground electrode in the plug axial direction is located in farther tip end side than that of the main ground electrode is. The sub ground electrode is configured such that an end point of the discharge spark is movable on the sub ground electrode.