Spark Plug Insulator Composition for High-Temperature Withstand Voltage
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Solution Overview
Problem
Spark plugs face challenges in maintaining sufficient withstand voltage at elevated temperatures, which are increasingly encountered in internal combustion engines to enhance output and fuel efficiency.
Innovation Solution
A tubular insulator for spark plugs is developed, comprising alumina as the primary component and a secondary component that includes silicon, magnesium, barium, calcium, and a rare earth element, with specific mass percentage ranges for these components to enhance insulation performance at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the temperature in the combustion chamber is elevated to enhance output and fuel efficiency, then engine performance is improved, but the withstand voltage of the spark plug deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the insulator material by specifying precise ranges of sintering aid components (SiO2: 15.5-55.1 mass%, MgO: 0.6-7.4 mass%, BaO: 26.7-68.5 mass%, CaO: 1.1-32.4 mass%, rare earth oxide: 11.4-46.5 mass%). This compositional parameter optimization maintains insulation performance at elevated temperatures up to 900°C, resolving the contradiction between engine power enhancement and spark plug reliability.
Solution Approach 2:
The patent employs a composite alumina-based sintered body material containing multiple sintering aid components working synergistically. The combination of SiO2, MgO, BaO, CaO, and rare earth oxide creates a composite material system that provides both high-temperature resistance and maintained insulation performance, allowing the spark plug to function reliably in high-power engine environments.
2Ease of manufacture
If conventional alumina sintered body with standard sintering aid is used, then manufacturing is simple, but insulation performance at high temperature is insufficient
Solution Approach 1:
The patent modifies the sintering aid composition parameters from conventional formulations to an optimized mix containing specific ranges of SiO2, MgO, BaO, CaO, and rare earth oxide. This parameter change maintains the sintering process simplicity while dramatically improving high-temperature insulation performance, achieving reliable operation at 900°C without complicating manufacturing.
3Reliability
If the insulator material composition is optimized for high temperature resistance, then withstand voltage improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses a multi-component composite sintering aid system where the synergistic interaction among SiO2, MgO, BaO, CaO, and rare earth oxide components provides robust high-temperature performance. This composite approach achieves high withstand voltage while the defined compositional ranges facilitate practical manufacturing control, balancing performance optimization with manufacturing feasibility.
Data Source
AI summary
A spark plug (1) includes a tubular insulator (50). The insulator contains alumina as a primary component, and further contains a secondary component. The secondary component contains a silicon (Si) component, a magnesium (Mg) component, a barium (Ba) component, a calcium (Ca) component, and a rare earth component. The amounts (mass %) of these components as reduced to oxide and relative to the total mass of the secondary component satisfy specific conditions.