Ceramic Firing Tip Spark Plug for Oxidation Resistance
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Solution Overview
Problem
Current spark plug electrode materials face challenges with high temperature oxidation, sulfidation, and corrosion, leading to deformation, cracking, and reduced performance in high-performance engines due to their material limitations and high costs.
Innovation Solution
A spark plug design featuring a thermally conductive body portion combined with a ceramic firing tip, including perovskite or spinel structures, which provides resistance to high temperature oxidation and sulfidation while effectively conducting heat away from the firing tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional Ni-based alloy electrodes are used, then the spark plug can conduct heat effectively, but the electrode suffers from high temperature oxidation, sulfidation, and corrosion leading to deformation and cracking
Solution Approach 1:
The invention uses a composite structure combining a Ni-based alloy body portion with a ceramic firing tip. The Ni-based alloy provides thermal conduction and structural support, while the ceramic material provides resistance to high temperature oxidation and corrosion. This composite approach allows the electrode to simultaneously achieve effective heat conduction and resistance to high temperature degradation mechanisms.
Solution Approach 2:
The invention applies different materials to different parts of the electrode: the body portion uses Ni-based alloy for thermal conduction and mechanical strength, while the firing tip uses ceramic material for oxidation and corrosion resistance. This local differentiation of material properties optimizes each region for its specific functional requirements, resolving the contradiction between heat conduction and resistance to high temperature oxidation.
2Reliability
If platinum group metal firing tips are used, then resistance to high temperature oxidation improves, but the cost increases significantly
Solution Approach 1:
The invention replaces expensive platinum group metal firing tips with a more economical ceramic material that provides similar resistance to high temperature oxidation and corrosion. This substitution significantly reduces manufacturing cost while maintaining the necessary reliability and performance characteristics for high performance engine applications.
Solution Approach 2:
The invention changes the material parameter from precious metals to ceramic materials, achieving comparable or superior resistance to high temperature oxidation and corrosion at a fraction of the cost. This parameter change in material selection resolves the contradiction between reliability and manufacturing cost.
3Temperature
If operating temperature is increased to improve engine efficiency, then engine performance improves, but electrode strength and resistance to deformation decrease
Solution Approach 1:
The composite structure combines Ni-based alloy with ceramic firing tip to enable operation at higher temperatures. The ceramic material maintains its mechanical strength and resistance to deformation at elevated temperatures where Ni-based alloys would suffer from significant strength reduction, creep rupture, and fatigue degradation.
Solution Approach 2:
The invention addresses thermal expansion mismatch between the Ni-based alloy body and ceramic firing tip through careful material selection and design. The ceramic material is chosen to have thermal expansion properties compatible with the Ni-based alloy, preventing deformation and cracking that would occur with incompatible materials under high temperature cycling conditions.
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 ceramic firing tip with a thermally conductive body portion extends the life of the spark plug, reduces operating temperatures, and is more economical compared to traditional platinum group metal tips, offering improved durability and performance.
Implementation Method 1
a body portion (28, 30) including a thermally conductive material... effectively conducting heat away from the firing tip
Implementation Method 2
provides resistance to high temperature oxidation, sulfidation, and related corrosion and erosion
Implementation Method 3
corrosive wear including deformation and fracture caused by high temperature oxidation and sulfidation
Data Source
AI summary
A spark plug (20) for igniting a mixture of fuel and air of an internal combustion engine comprises a center electrode (22) and a ground electrode (24). At least one of the electrodes (22, 24) includes a body portion (28, 30) formed of thermally conductive material and a firing tip (32, 34) disposed on the body portion (28, 30). The firing tip (32, 34) includes a ceramic material, providing an exposed firing surface (36, 38). The ceramic material is an electrically conductive, monolithic ceramic material. The ceramic material of the firing tip (32, 34) includes at least one perovskite structure and/or at least one a spinel structure.