Spark Plug Electrical Connection Part Noise Suppression
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Solution Overview
Problem
Existing spark plugs face challenges in effectively suppressing high-frequency noise associated with increased discharge voltage, which can interfere with vehicle electronic control systems, despite various noise suppression techniques such as ferrite bodies and wound wires.
Innovation Solution
The spark plug design incorporates an electrical connection part with a conductor formed from a mix of conductive and Fe-containing oxide materials, including ferrite, and conductive seal layers to establish a controlled resistance and suppress high-frequency noise, featuring a specific area ratio and composition to maintain noise suppression efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If discharge voltage is increased for high output performance, then engine output performance is improved, but high-frequency noise increases that affects vehicle electronic control system
Solution Approach 1:
A conductor made of Fe-containing oxide material (such as ferrite) is introduced as an intermediary component between the center electrode and metal terminal. This conductor acts as a mediator that suppresses high-frequency noise generated during spark discharge while allowing the increased discharge voltage to maintain engine output performance. The conductor's specific material composition and resistance characteristics enable it to filter harmful high-frequency noise without interfering with the beneficial spark energy.
Solution Approach 2:
The electrical connection part utilizes composite material composition, specifically combining Fe-containing oxide material (ferrite) with other materials to create a conductor with optimized noise suppression properties. This composite approach allows the material to exhibit both electrical conductivity for power transmission and magnetic properties for noise suppression, resolving the contradiction between maintaining engine output and reducing high-frequency noise interference.
2Object-generated harmful factors
If a conductor made of Fe-containing oxide material is used in the electrical connection part, then high-frequency noise is suppressed, but resistance may become excessively high
Solution Approach 1:
The resistance of the Fe-containing oxide material conductor is precisely controlled by adjusting compositional parameters and physical dimensions. The patent specifies that the conductor's resistance should be within a particular range (e.g., 0.01 to 10 ohms) to ensure effective noise suppression without excessive resistance. By changing material composition ratios, particle size distribution, and conductor geometry, the resistance is optimized to balance noise suppression capability with reliable electrical conductivity for sustained engine operation.
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 solution effectively maintains low noise levels before and after discharge durability tests, ensuring reliable noise suppression and preventing resistance from becoming excessively high, thus addressing the challenge of high-frequency noise interference.
Implementation Method 1
a conductor (63) made of a mix of conductive and Fe-containing oxide materials, including ferrite
Implementation Method 2
Fe-containing oxide materials, including ferrite
Implementation Method 3
an electrical connection part (60) arranged between a center electrode (4) and a metal terminal (5) within the through hole (2) for electrical connection of the center electrode (4) to the metal terminal (5)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A spark plug includes an insulator having a through hole formed therein in a direction of an axis, a center electrode disposed in a front side of the through hole, a metal terminal disposed in a rear side of the through hole, an electrical connection part arranged in the through hole to establish electrical connection between the center electrode and the metal terminal and a metal shell holding therein the insulator. The electrical connection part has a conductor including a conductive material and at least one kind of Fe-containing oxide material. The Fe-containing oxide material contains at least FeO. The conductor satisfies a relationship of 0.06 ≤ S1/(S1+S2) ≤ 0.46 where, in a cross section taken along the axis, S1 is an area occupied by the conductive material and S2 is an area occupied by the Fe-containing oxide material.