Spark Plug Electrode Recesses for Discharge Voltage Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spark plugs require higher voltages to achieve discharge due to suboptimal concentration of the electric field, necessitating further improvements in their structural design.
Innovation Solution
A spark plug design featuring a hollow cylindrical metal shell with a cylindrical center electrode and a ground electrode having a cylindrical inner peripheral surface, where recesses are formed on the outer periphery of the center electrode or inner periphery of the ground electrode to enhance electric field concentration, reducing the voltage required for discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the ground electrode is positioned to concentrate the electric field on the outer peripheral surface of the center electrode, then the voltage required to create discharge is decreased, but further voltage reduction is still needed
Solution Approach 1:
The patent applies local quality by forming recesses at specific locations on the center electrode or ground electrode surfaces. These recesses create localized regions of enhanced electric field concentration at their ends, which are positioned within the facing region between the center electrode outer periphery and ground electrode inner periphery. This localized modification allows for reduced discharge voltage while maintaining reliable spark generation.
Solution Approach 2:
The patent introduces a new dimensional feature by forming recesses that extend into the electrode surfaces. These recesses create additional spatial dimensions for electric field concentration, with their ends positioned strategically within the facing region. This three-dimensional structuring enhances field concentration beyond what flat surfaces can achieve, enabling further voltage reduction.
2Use of energy by moving object
If recesses are formed in the center electrode or ground electrode to enhance electric field concentration, then voltage required for discharge decreases, but the structural complexity increases
Solution Approach 1:
Rather than modifying the entire electrode structure, the patent applies local quality by forming recesses only at specific strategic locations on the center electrode or ground electrode. These localized recesses create the necessary electric field concentration without requiring complex modifications throughout the entire electrode, thus limiting the increase in structural complexity.
Solution Approach 2:
The patent segments the electrode surface by forming discrete recesses rather than creating continuous complex structures. Multiple recesses can be arranged at given intervals around the circumference, allowing the complex function of field concentration to be divided into simpler, repeatable units that are easier to manufacture.
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 recesses in the spark plug design concentrate the electric field effectively, leading to a decrease in the voltage needed for discharge, as demonstrated by experimental results showing a voltage ratio of 0.90 or less compared to a reference voltage.
Implementation Method 1
The recess has ends lying within a center-to-ground electrode facing region where the outer peripheral surface of the center electrode faces the inner peripheral surface of the ground electrode in a radial direction of the center electrode. This enhances concentration of electrical field on the ends of the recess, thereby facilitating emission of electrons from the center electrode.
Data Source
AI summary
A spark plug is provided which includes a hollow cylindrical center electrode disposed inside a metal shell and a ground electrode joined to the metal shell. The ground electrode has an inner peripheral surface facing an outer peripheral surface of the center electrode. At least one of the outer periphery of the center electrode and the inner periphery of the ground electrode has formed therein at least one recess whose ends lies in a center-to-ground electrode facing region where the outer peripheral surface of the center electrode faces the inner peripheral surface of the ground electrode in a radial direction of the center electrode. This decreases voltage required by the spark plug to achieve discharge.