Multilayer Spark Plug Firing Tip with Nickel-Chromium Weld End
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Solution Overview
Problem
Spark plugs in internal combustion engines face challenges due to high temperatures and corrosive gases, leading to reduced longevity from spark erosion and corrosion, especially with traditional Nickel electrodes, and the use of expensive precious metals like Platinum and Iridium to mitigate these issues is costly and difficult to manufacture.
Innovation Solution
A multilayer firing tip is developed with a discharge end made from resistant materials like Iridium alloys and a weld end formed from Nickel and Chromium with a higher thermal expansion coefficient, minimizing precious metal usage while providing resistance to spark erosion and corrosion, and using a manufacturing process that joins and then severs these materials to attach the firing tip to the center electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metals like Platinum or Iridium are used to form the firing tip, then resistance to spark erosion is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by using precious metal only at the discharge end (spark surface) where it is most needed for erosion resistance, while the weld end uses a different material (Nickel-Chromium alloy) that is easier and cheaper to manufacture. This localized application of precious metal minimizes cost while maintaining reliability at the critical spark generation point.
Solution Approach 2:
The patent employs composite materials by combining two different materials in a single firing tip structure: a precious metal (Iridium or Platinum) at the discharge end and a Nickel-Chromium alloy at the weld end. This composite structure allows the spark erosion resistance of precious metal where needed while reducing overall manufacturing cost by using a more economical material for the non-critical weld portion.
2Ease of manufacture
If smaller amounts of precious metal are used to minimize cost, then manufacturing cost is reduced, but the spark may jump around the tip and arc between base material and ground electrode
Solution Approach 1:
The patent uses an intermediary material approach by selecting a Nickel-Chromium alloy for the weld end that has a thermal expansion coefficient higher than both the precious metal discharge end and the base electrode. This intermediary material properties help ensure reliable welding and thermal management, allowing the use of minimal precious metal while maintaining spark quality through proper thermal and mechanical bonding.
Solution Approach 2:
The patent applies parameter changes by carefully selecting materials with specific thermal expansion coefficients. The weld end material (Nickel-Chromium alloy) is chosen to have a thermal expansion coefficient higher than both the precious metal discharge end and the base electrode, which helps accommodate thermal stresses and ensures reliable attachment, thereby maintaining spark quality even with minimal precious metal usage.
3Ease of manufacture
If traditional Nickel electrodes are used, then manufacturing cost is reduced, but longevity is reduced due to spark erosion and corrosion
Solution Approach 1:
The patent applies local quality by protecting only the critical discharge end (spark surface) with precious metal material, while the weld end and base electrode can use more economical Nickel-Chromium alloys. This localized protection extends service life at the most vulnerable point (the spark surface) without requiring the entire electrode to be made of expensive corrosion-resistant material.
Solution Approach 2:
The patent uses composite materials to combine the corrosion and erosion resistance of precious metals at the discharge end with the cost-effectiveness of Nickel-Chromium alloys at the weld end and base electrode. This composite structure extends service life by protecting the critical spark surface while maintaining overall manufacturing economy.
4Stability of the object's composition
If intermediate material with thermal expansion coefficient between discharge end and base electrode is used, then thermal stress is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent uses an intermediary material (Nickel-Chromium alloy) at the weld end that serves as a thermal and mechanical bridge between the precious metal discharge end and the base electrode. This intermediary material has a thermal expansion coefficient higher than both adjacent materials, which helps accommodate thermal stresses during operation and welding, reducing the risk of cracking or detachment.
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 extends the service life of spark plugs, reduces material costs by minimizing precious metal usage, and ensures a secure and durable attachment of the firing tip, maintaining high-quality sparks for consistent engine performance and emission quality.
Implementation Method 1
The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode
Data Source
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AI summary
A spark plug having a multilayer firing tip that minimizes the amount of precious metal used and a method of assembling a spark plug with a multilayer firing tip. The firing tip includes a discharge end and a weld end, with the weld end being connected to a center electrode, and more specifically to a base electrode on the center electrode. The weld end has a coefficient of thermal expansion, which is not between the values for the coefficients of thermal expansion for the discharge end and the base electrode. More specifically, the weld end has a coefficient of thermal expansion which is greater than the coefficients of thermal expansion for the discharge end and base electrode. The weld end is formed from Nickel and Chromium with a limited amount of additional elements. The spark plug is assembled by providing a first elongated material formed from the material used for the discharge end and a second elongated material formed from a material used for the weld end. The two materials are then joined to form a single joined material and are severed to create a firing tip. The firing tip is welded to the center electrode of the spark plug and more specifically, the base electrode.