Spark Plug Intermediate Member Hardness for Electrode Alignment
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Solution Overview
Problem
Existing spark plugs with noble metal tips on ground electrodes face misalignment issues due to inadequate consideration of mechanical properties during correction, leading to potential deformation and increased misalignment, which affects ignition performance and durability.
Innovation Solution
A spark plug design where the intermediate member, with a higher average hardness than the ground electrode, is used to correct misalignment by being bent and grasped, featuring a fibrous metallographic structure and a weld portion with a specific hardness to enhance resistance and prevent erosion, ensuring proper alignment and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the ground electrode is bent to correct misalignment between noble metal tips, then alignment accuracy is improved, but the intermediate member deforms and misalignment increases
Solution Approach 1:
The patent applies parameter changes by specifying that the intermediate member must have higher hardness than the ground electrode. This hardness parameter difference ensures that when the ground electrode is bent for alignment correction, the intermediate member maintains its shape and does not deform, thus preserving alignment accuracy while allowing necessary adjustments.
Solution Approach 2:
The patent applies local quality by creating a hardness gradient between different components - specifically making the intermediate member locally harder than the ground electrode. This localized property differentiation allows the ground electrode to be flexible enough for bending and alignment correction, while the intermediate member remains rigid enough to maintain alignment during the process.
2Strength
If the intermediate member has higher hardness, then resistance to deformation increases, but ease of manufacture decreases
Solution Approach 1:
The patent resolves this contradiction by changing the material parameter (hardness) of the intermediate member to be higher than the ground electrode. This parameter change achieves the desired resistance to deformation while the patent implies that suitable materials with these properties are selected to maintain manufacturability.
3Manufacturing precision
If the ground electrode is bent for misalignment correction, then alignment between tips is improved, but the ground electrode may deform permanently
Solution Approach 1:
The patent applies parameter changes by establishing a hardness relationship where the intermediate member is harder than the ground electrode. This allows the ground electrode to be sufficiently soft for bending and alignment correction, while the harder intermediate member provides structural support and maintains the corrected alignment without permanent deformation.
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 effectively corrects misalignment between the center and ground electrode noble metal tips, enhancing ignition performance and durability by preventing local erosion and ensuring stable spark gap formation.
Implementation Method 1
the intermediate member has an average hardness higher than an average hardness of a portion of the ground electrode, excluding the intermediate portion
Implementation Method 2
the noble metal tip is joined to a top surface of an intermediate member, which is a member separate from the ground electrode, to thereby be united with the intermediate member
Data Source
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AI summary
A spark plug 100 includes a center electrode 20, an insulator 10, a metallic shell 50, and a ground electrode 30. A noble metal chip 80 is disposed on a distal end portion 31 of the ground electrode 30 at a location facing a front end portion of the center electrode 20. The noble metal chip 80 is joined to the top surface of an intermediate member 81, which is a member separate from the ground electrode 30, to thereby be united with the intermediate member 81. The bottom surface of the intermediate member 81 is joined to the ground electrode 30, whereby the noble metal chip 80 is fixed to the ground electrode 30. The intermediate member 81 is formed such that its average hardness is higher than the average hardness of a portion of the ground electrode 30, excluding an intermediate portion 33 to be bent.