Spark Plug Electrode Tip Thermal Coupling for Reduced Joint Stress
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Solution Overview
Problem
Spark plug electrodes face challenges due to erosion and corrosion in harsh engine environments, particularly at the joint where precious metal tips are attached to ground electrodes, leading to thermal stresses and increased wear.
Innovation Solution
A spark plug electrode design featuring a heat dissipating core within the electrode base, with the electrode tip directly thermally coupled to the core through an opening, using materials like nickel-based for the base, copper-based for the core, and precious metals for the tip, to manage thermal stresses and extend the service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precious metals are used for the entire electrode body, then erosion and corrosion resistance is improved, but manufacturing cost increases significantly
Solution Approach 1:
The patent applies local quality by using precious metals only at the electrode tip where erosion and corrosion occur most severely, rather than throughout the entire electrode body. The electrode base uses a more economical material, creating a gradient of material quality that matches the distribution of thermal and mechanical stresses, with the most durable material at the highest stress location.
Solution Approach 2:
The patent employs composite materials by combining precious metals with the electrode tip and a different material for the electrode base. This composite structure allows the expensive precious metal to be used only where necessary for durability, while the base provides structural support at lower cost, resolving the contradiction between reliability and material quantity.
2Quantity of substance
If precious metal tip is used without adequate cooling, then material savings are achieved, but thermal stresses increase leading to electrode wear and pre-ignition
Solution Approach 1:
The patent segments the electrode into distinct functional zones: a heat dissipating core that conducts thermal energy away from the precious metal tip, and the precious metal tip itself that resists erosion. This segmentation allows thermal management to be addressed separately from material selection, enabling the use of precious metals with improved thermal stress management.
Solution Approach 2:
The heat dissipating core acts as an intermediary between the precious metal tip and the electrode base, providing a dedicated thermal conduction path. This intermediary component facilitates heat removal from the tip without requiring the entire electrode structure to be optimized for thermal conduction, allowing material savings while managing thermal stresses.
3Temperature
If heat dissipating core is added to the electrode structure, then thermal stress is reduced, but device complexity increases
Solution Approach 1:
The patent merges the heat dissipating core with the electrode base structure, creating an integrated component rather than a separate assembly. The core is formed as an integral part of the base, eliminating the need for additional fasteners, interfaces, or assembly steps, thereby reducing device complexity while still providing thermal management functionality.
Solution Approach 2:
The electrode base serves multiple functions: it provides structural support, facilitates heat dissipation through the integrated core, and anchors the precious metal tip. This multi-functionality reduces the need for separate components, simplifying the overall device structure while achieving thermal stress reduction.
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 design effectively dissipates thermal energy, reducing stress and wear at the joint, allowing for the use of a wider range of precious metals, including less expensive options, while maintaining performance.
Implementation Method 1
the electrode tip is directly thermally coupled to the core extension of the heat dissipating core through the opening
Data Source
AI summary
A spark plug electrode includes an electrode tip that is attached to or formed on an electrode base so that the electrode tip is directly thermally coupled to a heat dissipating core through an opening in the electrode base. This direct thermal coupling may take place on a side surface of a ground electrode or a center electrode and removes thermal energy away from the electrode tip in order to reduce thermal and/or other stresses. The heat dissipating core may have one or more core extensions that diverge or branch off of a core main body and extend into the opening in the electrode base for better thermal coupling to the electrode tip. The electrode tip can be attached to the electrode base via welding or it can be formed on the electrode base using a suitable additive manufacturing process, such as a powder bed fusion technique.