Additive-Manufactured Spark Plug Electrode Tips for Precise Spark Gaps
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Solution Overview
Problem
Spark plugs face challenges with erosion and corrosion of electrodes due to harsh engine environments, leading to performance degradation, and traditional joining methods like laser welding cause thermal stresses and precision issues with precious metal electrode tips.
Innovation Solution
The use of additive manufacturing processes, specifically powder bed fusion techniques, to form precious metal-based electrode tips that overhang the electrode base, creating a weldless joint and improving parallelism and tolerance of spark gaps, while reducing the need for expensive precious metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If laser welding is used to attach precious metal electrode tips to electrode bodies, then the electrodes are protected against erosion and corrosion, but thermal stresses cause cracking or damage to the electrode body, electrode tip, or joint
Solution Approach 1:
The patent replaces the mechanical/thermal joining process (laser welding) with an additive manufacturing process. The electrode tip is built layer-by-layer directly on the electrode body using powder bed fusion, eliminating the separate welding step and its associated thermal stresses. This substitution of joining methodology resolves the contradiction by achieving strong attachment without the harmful thermal cycles that cause cracking.
Solution Approach 2:
The patent changes the fundamental parameters of the joining process by transitioning from high-temperature welding to controlled-layer additive manufacturing. The build process uses lower temperatures and gradual material deposition, fundamentally altering the thermal profile and stress characteristics of the joining operation, thereby preventing thermal stress-induced cracking while maintaining attachment reliability.
2Reliability
If laser welding is used to attach precious metal electrode tips, then the electrodes are protected against erosion and corrosion, but the precision of spark gap alignment and parallelism of sparking surfaces deteriorates
Solution Approach 1:
The patent merges the electrode tip fabrication and attachment operations into a single additive manufacturing process. The electrode tip is built directly on the electrode body in the final position, combining forming and joining steps. This eliminates the separate welding operation that creates alignment errors, ensuring precise spark gap alignment and parallelism while maintaining corrosion protection.
Solution Approach 2:
The patent replaces the mechanical alignment and welding process with additive manufacturing. The layer-by-layer construction allows for precise digital control of geometry and position, substituting manual or fixture-based alignment with computer-controlled material deposition, thereby achieving superior spark gap alignment and surface parallelism.
3Reliability
If precious metals are used throughout the entire electrode body, then erosion and corrosion resistance is maximized, but the cost increases significantly
Solution Approach 1:
The patent applies local quality by concentrating precious metal material only where it is most needed - at the electrode tip surface that directly contacts the spark environment. The additive manufacturing process enables precise material placement, using precious metals locally at the tip while the electrode body can use less expensive materials, thereby reducing overall precious metal quantity while maintaining erosion and corrosion resistance where critical.
Solution Approach 2:
The patent employs composite material strategy by combining precious metal electrode tip material with less expensive electrode body materials. The additive manufacturing process creates a composite structure where the precious metal tip is integrally formed on the base material, achieving the necessary surface protection against erosion and corrosion while minimizing the total quantity of expensive precious metals used in the overall electrode assembly.
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 approach enhances the voltage requirements, flame growth, and overall performance of spark plugs by reducing erosion rates and costs associated with precious metals, while minimizing thermal stresses and ensuring precise spark gap alignment.
Implementation Method 1
directing a laser or electron beam towards the firing end such that it melts or sinters at least some of the thin powder layer
Implementation Method 2
melts or sinters at least some of the thin powder layer
Implementation Method 3
directing a laser or electron beam towards the firing end such that it melts or sinters at least some of the thin powder layer
Implementation Method 4
allowing the melted or sintered powder to at least partially solidify into a laser deposition layer
Data Source
AI summary
A spark plug electrode with one or more electrode tip(s) formed on one or more electrode base(s) using an additive manufacturing process, such as a powder bed fusion technique, such that each electrode tip overhangs an edge of a corresponding electrode base. The spark plug electrode may be a center electrode, a ground electrode, or an annular ground electrode and can be provided according to a number of different configurations. Each electrode tip includes a precious metal-based material, such as an iridium- or platinum-based alloy, and a plurality of laser deposition layers, and each electrode tip can be secured to an electrode base with a weldless joint. An additive manufacturing process is also provided.