Ir-Rh-Ru-Pt Spark Plug Tip Composition for Oxidative Durability
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Solution Overview
Problem
Conventional spark plugs with Ir-Rh-Ru alloy tips face durability issues under varying oxygen concentration conditions, particularly at high oxygen concentrations, leading to oxidative consumption and insufficient durability.
Innovation Solution
A spark plug design featuring a tip with a composition of Ir as the main constituent, containing Rh between 7-31 mass% and Ru between 5-20 mass%, along with Pt ranging from one-twentieth to half of the Ru content, which reduces oxidative consumption and enhances durability across different oxygen concentration environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Ir-Rh-Ru alloy tips are used, then spark erosion resistance is improved, but oxidative consumption increases under high oxygen concentration conditions
Solution Approach 1:
The invention changes the compositional parameters of the tip alloy by specifying precise ranges for Rh (7-31 mass%), Ru (5-20 mass%), and Pt (one-twentieth to one-half of Ru content), while maintaining Ir as the main constituent. This parameter optimization resolves the contradiction by achieving both spark erosion resistance and reduced oxidative consumption under varying oxygen concentrations.
Solution Approach 2:
The invention uses a composite alloy material comprising Ir, Rh, Ru, and Pt in specific proportions. This multi-element composite structure provides synergistic effects where Rh and Ru contribute to spark erosion resistance while Pt addition suppresses oxidative consumption, particularly under high oxygen concentration conditions, thus resolving the technical contradiction.
2Reliability
If Rh content is increased to improve durability, then oxidative consumption is reduced, but manufacturing cost increases
Solution Approach 1:
The invention optimizes the Rh content parameter within a specific range (7-31 mass%) rather than using excessive amounts. This parameter optimization achieves the necessary durability and oxidative consumption resistance while controlling manufacturing costs, resolving the contradiction between durability and manufacturing cost.
Solution Approach 2:
The invention employs a composite alloy strategy where Rh works synergistically with Ru and Pt elements. This composite approach allows for reduced Rh content compared to conventional single-element or two-element alloys, achieving the same durability performance at lower cost by distributing the functional requirements across multiple elements.
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 proposed spark plug tip composition significantly reduces oxidative consumption and ensures good durability regardless of oxygen concentration, maintaining performance in both low and high oxygen environments.
Implementation Method 1
a material whose main constituent is a precious metal excellent in the oxidation resistance and spark erosion resistance is often used. The material includes Ir, an Ir alloy, a Pt alloy, or the like.
Implementation Method 2
each distal end portion of the ground electrode and the center electrode opposed to one another is likely to generate spark erosion. Therefore, there has been developed a method for improving the wear resistances of the ground electrode and the center electrode
Data Source
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AI summary
This invention provides a spark plug featuring good durability to solve a problem. The spark plug includes a tip provided on at least one of a center electrode and a ground electrode. The spark plug is achieved by reducing oxidative consumption without an influence from oxygen concentration under an environment of this tip being exposed. The spark plug includes a center electrode and a ground electrode disposed providing a gap with the center electrode. At least one of the center electrode and the ground electrode includes a tip forming the gap. The tip has a main constituent of Ir. The tip contains Rh of 7 mass% or more to 31 mass% or less, Ru of 5 mass% or more to 20 mass% or less, and Pt of one-twentieth or more to one-half or less of a Ru content.