Spark Plug Resistor Element ZrO2 Distribution for Noise Suppression
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Solution Overview
Problem
Conventional spark plugs face challenges in effectively suppressing radio wave noise and improving the durability of resistor elements, particularly in high-power engines where electrical noise and durability are critical.
Innovation Solution
The spark plug design incorporates a resistor element with a specific configuration of ZrO2 and carbon filler, including a rectangular target region with defined proportions of ZrO2 areas and a transverse line-shaped region, along with a controlled weight proportion of Ti to Zr, and a minimum outer diameter, to enhance noise suppression and service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a resistor element is arranged between the center electrode and terminal metal fitting, then radio wave noise suppression is improved, but the service life of the resistor element deteriorates
Solution Approach 1:
The patent applies local quality by creating specific regional variations in ZrO2 concentration within the resistor element. The target region is divided into first type regions (with ZrO2 proportion ≥25%) and second type regions (with ZrO2 proportion <25%), where the first type regions form transverse line-shaped patterns. This localized differentiation optimizes both noise suppression performance and durability in different areas of the resistor element simultaneously.
2Object-affected harmful factors
If the resistor element uses higher ZrO2 content, then radio wave noise suppression is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ZrO2 proportion parameter in different regions of the filler. The first type regions have ZrO2 proportion ≥25% while second type regions have ZrO2 proportion <25%, creating a controlled parameter variation that enhances noise suppression without excessive complexity. Additionally, the Ti to Zr weight proportion is controlled within 0.05-6, providing another controlled parameter for optimization.
3Area of moving object
If the resistor element outer diameter is reduced, then spark plug compactness is improved, but radio wave noise suppression performance deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the target region of the resistor element into multiple square regions (9 regions of 200 μm × 200 μm each), which are further organized into transverse line-shaped regions. This segmented structure allows the resistor element to maintain effective noise suppression performance even with reduced overall dimensions, as the segmented ZrO2 distribution pattern optimizes the electrical path complexity within the smaller volume.
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 configuration significantly improves both the suppression performance of radio wave noise and the service life of the resistor element, achieving favorable results in evaluation tests by creating a complex current path and dispersing current flow, thereby reducing noise and enhancing durability.
Implementation Method 1
The resistor element includes an aggregate, a filler containing ZrO2, and carbons. In a cross section including the axial line of the resistor element, a center line is defined by the axial line. A target region is defined by a rectangular region where a size in a direction perpendicular to the axial line is 1800 μm and a size in a direction of the axial line is 2400 μm.
Data Source
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AI summary
To improve the suppression performance of radio wave noise and the service life of a resistor element. A resistor element of a spark plug includes an aggregate, a filler containing ZrO 2 , and carbons. In the cross section including the axial line of the resistor element, a center line is defined by the axial line, and a target region is defined by a rectangular region where the size in the direction vertical to the axial line is 1800 µm and the size in the direction of the axial line is 2400 µm. In the case where the target region is divided into a plurality of square regions having lengths of 200 µm on a side, a line-shaped region is defined by a region in a line shape that is constituted of nine square regions arranged in the direction vertical to the axial line. A first type region is defined by the square region where a proportion of an area of ZrO 2 is 25% or more, and a second type region is defined by the square region where a proportion of an area of ZrO 2 is less than 25%. In this case, the total number of the line-shaped regions including two or more of the first type regions is equal to or more than 5.