Spark Plug Detector Electrode Positioning for Pre-ignition Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spark plug technologies fail to accurately detect pre-ignition caused by a flame kernel occurring inside the spark plug.
Innovation Solution
A spark plug design featuring a tubular insulator with a reduced diameter portion and a detector electrode positioned between the outer periphery of the insulator and the inner periphery of a metal shell, connected by a conductor, to enhance detection accuracy of pre-ignition by positioning the detector electrode in the space where the flame kernel forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a detector electrode is provided in the space between the insulator and metal shell, then detection accuracy of pre-ignition is improved, but device complexity increases
Solution Approach 1:
The spark plug is segmented into multiple functional zones: the detector electrode is positioned in the space between the insulator and metal shell to detect flame kernels, while the center electrode and ground electrode maintain their ignition function. This segmentation allows independent optimization of detection and ignition functions, resolving the contradiction by adding detection capability without compromising the existing ignition system.
Solution Approach 2:
The detector electrode acts as an intermediary element that detects the flame kernel in the space between the insulator and metal shell before the flame reaches the center electrode. This intermediary detection mechanism enables early pre-ignition detection, improving measurement precision while maintaining the original ignition pathway through the center and ground electrodes.
2Measurement precision
If the detector electrode area is increased, then detection sensitivity is improved, but the space available for detection is reduced
Solution Approach 1:
The detector electrode is designed with a width of 0.5 mm or more, which provides sufficient detection sensitivity without occupying the entire space between the insulator and metal shell. This partial action approach ensures adequate detection capability while leaving room for the flame kernel to form and be detected, resolving the contradiction between detection sensitivity and available space.
3Measurement precision
If the top end of the detector electrode is positioned at the rear end side with respect to the top end of the metal shell, then accuracy of detecting flame kernel inside spark plug is improved, but detection of external flame kernel is reduced
Solution Approach 1:
The detector electrode is strategically positioned with its top end at the rear end side relative to the metal shell top end, creating a localized detection zone focused on the internal space of the spark plug. This local quality approach optimizes detection accuracy for internal flame kernels while accepting reduced sensitivity to external flames, as the electrode geometry and positioning are tailored to the specific detection target.
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 detection accuracy of pre-ignition by allowing early detection of the flame kernel inside the spark plug, reducing error detection, and suppressing spark wear, while ensuring detection sensitivity and durability.
Implementation Method 1
detecting an ion current that is generated when a flame appears between a center electrode and a ground electrode of a spark plug and reaches the center electrode and the ground electrode
Data Source
AI summary
The present invention provides spark plug that can improve detection accuracy of pre-ignition caused by flame kernel occurring inside spark plug. Terminal is located at a rear end side with respect to thread portion of metal shell. Detector electrode is provided at a portion located at a top end side with respect to a top end of contact portion between reduced diameter portion and shelf portion or packing in a space formed between outer periphery of insulator and inner periphery of the metal shell. The detector electrode and the terminal are connected by conductor. The detector electrode and the conductor are insulated from center electrode, the metal shell and ground electrode. Since the detector electrode is located in the space between the outer periphery of the insulator and the inner periphery of the metal shell, an early detection of the flame kernel occurring in this space can be possible.