Spark Plug Resistor Using Barium Alumino-Silicate Glass and Mullite
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Solution Overview
Problem
Existing spark plugs face challenges in maintaining tight resistance tolerance and durability due to temperature sensitivity and electromagnetic interference, which affects their performance and useful life in high-heat, corrosive engine environments.
Innovation Solution
A spark plug resistor made from a mixture of alkali-free barium alumino-silicate glass and mullite, combined with a specific fabrication method involving carbon and ceramic powders, is used to reduce resistance variation and improve durability, allowing for processing at a wider temperature range while minimizing electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing resistor materials are used in spark plugs, then the spark plug can function in high-heat environments, but the resistance tolerance varies widely and electromagnetic interference is high
Solution Approach 1:
The patent applies composite materials by combining glass particles (60-90 wt%), ceramic particles (10-40 wt%), and metal particles (1-20 wt%) to create a resistor material that simultaneously achieves low electromagnetic interference, stable resistance tolerance, and high-temperature durability. The glass matrix provides EMI shielding while the ceramic and metal particles contribute to thermal stability and electrical properties.
Solution Approach 2:
The patent changes the chemical composition parameters of the resistor material by specifying precise weight percentages of glass, ceramic, and metal particles, along with controlled pore volume (0.1-0.5 mL/g). This parameter optimization enables the resistor to maintain tight tolerance (±5% or better) while withstanding engine operating temperatures.
2Productivity
If traditional resistor materials are used, then manufacturing is simpler, but production yield is reduced due to tight resistance tolerance requirements
Solution Approach 1:
The multi-component composite structure with glass, ceramic, and metal particles in specific ratios provides inherent resistance to temperature-induced variation, enabling consistent electrical properties across production batches. This reduces the need for post-manufacturing sorting and rework.
Solution Approach 2:
The patent introduces controlled pore spaces (0.1-0.5 mL/g) within the resistor material structure, creating local regions that accommodate thermal expansion and stress without affecting overall resistance. This local structural quality enhancement maintains electrical stability during sintering and engine operation.
3Duration of action of stationary object
If the spark plug operates in high-temperature engine environments, then it can ignite fuel, but the resistor material degrades and reduces useful life
Solution Approach 1:
The glass-ceramic-metal composite structure provides exceptional thermal stability, with the glass matrix binding ceramic and metal particles to form a rigid, heat-resistant network that maintains structural integrity and electrical properties at engine operating temperatures for extended service life.
Solution Approach 2:
The patent optimizes the pore volume parameter (0.1-0.5 mL/g) to create a structure that accommodates thermal stress and expansion, preventing cracking and degradation during repeated heating and cooling cycles in the engine environment.
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 achieves reduced resistance variation, extended useful life, and lower electromagnetic interference, leading to improved production yields and longer spark plug performance with a wider processing window.
Implementation Method 1
a spark plug having a resistor made with glass materials with an increased glass transition temperature
Implementation Method 2
The carbon resistor glass is loaded into a sparkplug insulator. The sparkplug insulator-carbon glass assembly is heated to transform the carbon resistor glass into a semi-melt condition.
Data Source
AI summary
A spark plug is provided having a resistor. The resistor is made from resistor glass material containing an alkali free barium alumino-silicate glass mixed with mullite. In one embodiment, the resistor is a 15 to 30 wt % alkali free barium alumino-silicate glass and 10 to 25 wt % mullite. The resistor material provides for a greater processing kiln temperature range with reduced resistor variability and improved durability performance.