Ni-Based Spark Plug Electrode Alloy Composition
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Solution Overview
Problem
Spark plugs face issues with pre-ignition and degradation of ignition properties due to high temperature and high oxygen concentration environments, leading to corrosion-like foreign substance formation that can cause short-circuits and poor heat dissipation.
Innovation Solution
A spark plug design using a Ni-based alloy electrode material with specific compositions of Y, rare earth elements, Mn, Ti, V, Nb, Si, Al, Cr, and C to suppress corrosion-like foreign substance formation while maintaining high thermal conductivity and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electrode size is decreased to reduce spark plug size, then the spark plug dimensions are reduced, but the heat dissipation capability deteriorates and electrode temperature increases
Solution Approach 1:
The patent changes the material parameters of the electrode by using a Ni base alloy with specific composition ratios (Cr: 0.5-5%, Mn: 0.1-3%, Si: 0.1-3%, Y: 0.00001-0.5%) to maintain thermal conductivity and heat dissipation capability despite the reduced electrode size. This allows the spark plug to be miniaturized while preventing excessive electrode temperature rise.
2Loss of energy
If the air-fuel ratio is increased for fuel mileage improvement, then fuel efficiency is improved, but the oxygen concentration and temperature in the combustion chamber increase
Solution Approach 1:
The patent adjusts the chemical composition parameters of the electrode material to enhance oxidation resistance and thermal stability. The specific alloy composition (including Cr, Mn, Si, and Y) enables the electrode to withstand higher temperatures and oxygen concentrations resulting from lean burn operation, preventing pre-ignition while maintaining improved fuel efficiency.
3Loss of energy
If high temperature and high oxygen concentration conditions occur, then fuel efficiency is improved, but corrosion-like foreign substances form on the electrode surface
Solution Approach 1:
The patent uses a composite Ni base alloy material combining multiple elements (Cr, Mn, Si, Y) with synergistic effects. Cr provides oxidation resistance, Mn enhances spark corrosion resistance, Si contributes to surface stability, and Y refines the grain structure. This composite material approach prevents the formation of corrosion-like foreign substances under high temperature and oxygen concentration conditions while maintaining fuel efficiency.
4Reliability
If corrosion-like foreign substances form on the electrode surface, then the spark discharge gap is narrowed, but ignition properties are degraded
Solution Approach 1:
The multi-element Ni base alloy (Cr: 0.5-5%, Mn: 0.1-3%, Si: 0.1-3%, Y: 0.00001-0.5%) creates a stable surface composition that resists forming corrosion-like foreign substances. This maintains the spark discharge gap dimensions and ensures reliable ignition properties even in demanding combustion environments.
5Ease of manufacture
If the electrode material uses conventional Ni base alloy composition, then manufacturing is simplified, but pre-ignition occurs due to poor heat dissipation
Solution Approach 1:
The patent modifies the compositional parameters of the Ni base alloy by adding specific amounts of Cr (0.5-5%), Mn (0.1-3%), Si (0.1-3%), and Y (0.00001-0.5%). These parameter changes enhance the material's thermal conductivity and heat dissipation capability, preventing pre-ignition while remaining compatible with conventional manufacturing processes.
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 effectively prevents the formation of corrosion-like foreign substances, ensuring reliable ignition, preventing pre-ignition, and maintaining mechanical strength even at high temperatures, thus enhancing the durability and performance of spark plugs.
Implementation Method 1
the temperatures at the central electrode and the ground electrode also become liable to increase
Implementation Method 2
a variety of Ni base alloys which are excellent in terms of oxidation resistance, spark corrosion resistance
Implementation Method 3
a spark plug brings about spark discharge at the spark discharge gap formed between the leading end of the central electrode and the leading end of the ground electrode
Data Source
Figure 1(a)~1(b)
Figure 2(a)~3
AI summary
The object of the invention is to provide a spark plug including a central electrode and/or a ground electrode, which can suppress generation of corrosion-like generated foreign substances while maintaining high thermal conductivity and high strength. The spark plug according to the invention is a spark plug including a central electrode and a ground electrode provided to have a gap between the central electrode and the ground electrode with at least one of the central electrode and the ground electrode formed from an electrode material including 96% by mass or more of Ni, in which the electrode material includes a total cont ent of from 0.05% by mass to 0.45% by mass of at least one selected from a group consisting of Y and rare earth elements, 0.05% by mass or more of Mn, and a total content of 0.01% by mass or more of at least one selected from a group consisting of Ti, V, and Nb, and the ratio (a/b) of the total content (a) of Ti, V, and Nb to the content (b) of Mn is from 0.02 to 0.40.