Spark Plug Resistor Curved Surface Adhesion
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Solution Overview
Problem
The reduction in spark plug diameter to accommodate high engine power and efficiency requirements leads to insufficient mechanical strength and electrical connection issues due to reduced insulator thickness, causing exfoliation at the resistor-conductive glass sealing layer junction, especially under vibration or impact.
Innovation Solution
A spark plug design with a conductive glass sealing layer of specific dimensions and surface area ratios between the resistor and the center electrode, and a second sealing layer between the terminal metal piece and the resistor, both with curved surfaces, to enhance adhesion and mechanical strength, using a mixture of glass and metal powders for the sealing layers and ceramic and nonmetal conductive powders for the resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the through-hole of the insulator is reduced to achieve a smaller spark plug diameter, then the spark plug diameter is reduced, but the mechanical strength between the resistor and the conductive glass sealing layer becomes insufficient
Solution Approach 1:
The invention applies curvature to the joining surface of the resistor, transforming it from a flat surface to a curved surface. This curved surface design increases the contact area between the resistor and the conductive glass sealing layer, thereby enhancing the mechanical strength of the joining portion even when the overall spark plug diameter is reduced. The curved surface geometry allows for better distribution of stresses and improved adhesion.
Solution Approach 2:
The invention changes the geometric parameters of the resistor, specifically its diameter and the curvature radius of the joining surface. By optimizing these parameters, the resistor maintains sufficient mechanical strength and electrical connection reliability even in a reduced-diameter spark plug configuration. The parameter changes enable the resistor to accommodate the smaller through-hole diameter while preserving joining integrity.
2Volume of moving object
If the diameter of the through-hole of the insulator is reduced, then the spark plug diameter is reduced, but sufficient charging of the conductive glass powder becomes difficult
Solution Approach 1:
The curved surface of the resistor creates a geometric configuration that facilitates the charging and distribution of conductive glass powder. The curvature allows the powder to be more effectively packed and settled during the manufacturing process, ensuring sufficient charging even in the constrained space of a reduced-diameter through-hole.
Solution Approach 2:
By changing the diameter and curvature radius parameters of the resistor, the invention creates optimal geometric conditions for the charging process. These parameter adjustments enable better flow and distribution of conductive glass powder within the smaller space, making the manufacturing process feasible despite the reduced dimensions.
3Volume of moving object
If the diameter of the through-hole of the insulator is reduced, then the spark plug diameter is reduced, but exfoliation occurs at the joining surface of the resistor and conductive glass sealing layer under vibration or impact
Solution Approach 1:
The curved surface of the resistor significantly improves resistance to exfoliation under vibration and impact. The curvature distributes mechanical stresses more evenly across the joining interface, preventing concentration of stresses that would lead to delamination. This geometric feature enhances the reliability of the electrical connection in harsh operating conditions while maintaining a reduced spark plug diameter.
Solution Approach 2:
By optimizing the diameter and curvature radius parameters, the invention creates a resistor geometry that is inherently more resistant to vibration and impact. The parameter changes enable the joining structure to withstand mechanical shocks without exfoliation, ensuring reliable electrical connection in the reduced-diameter configuration.
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 strengthens the adhesion between the resistor and the conductive glass sealing layers, improving vibration resistance and extending the spark plug's life-span while allowing for a reduced diameter, thus enhancing engine design flexibility and reliability.
Implementation Method 1
a conductive glass sealing layer which is provided between the resistor and the center electrode in the through-hole without a gap
Implementation Method 2
a joining surface of the conductive glass sealing layer and the resistor is a curved surface
Data Source
Figure 1
Figure 2
Figure 3(a)~3(n)
AI summary
Provided is a spark plug with excellent vibration resistance performance and resistor load life-span characteristics, and a reduced diameter which is achieved by strengthening adhesion between a resistor and a conductive glass sealing layer. A resistor 18 and a center electrode 13 which are disposed in a through-hole 16 of an insulator 12 are joined by a conductive glass sealing layer 19 interposed therebetween. The diameter D of the conductive glass sealing layer 19 joined to the resistor 18 is equal to or greater than 1.9 mm and equal to or less than 3.3 mm (1.9mm ≤ D ≤ 3.3mm), a joining surface 23 of the conductive glass sealing layer 19 joined to the resistor 18 has a bowl shape, and Sa/S1 that can be obtained on the basis of a surface area Sa of the joining surface 23 and a cross-sectional area S 1 of the conductive glass sealing layer 19 is equal to or greater than 1.1 (Sa/S1 ≥ 1.1).