Spark Plug Insulator Ceramic Structure for High-Voltage Miniaturization
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Solution Overview
Problem
Current spark plug insulators struggle to meet increasing voltage requirements while maintaining a smaller size, as they often have limitations in dielectric strength and mechanical strength due to poor consolidation of ceramic materials, leading to issues with thinner cross-sections and crescent-shaped voids.
Innovation Solution
The development of high purity alumina ceramic bodies with a single-phase crystal structure and reduced porosity, manufactured using injection molding or specialized pressing methods, which enhance dielectric strength and allow for thinner cross-sections while maintaining mechanical integrity, enabling proportional increases in other components' thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the radial thickness of the insulator is reduced to enable smaller spark plug sizes (M10), then the size requirement is met, but the dielectric strength and mechanical strength deteriorate due to poor consolidation of ceramic materials
Solution Approach 1:
The patent changes the physical and chemical parameters of the ceramic material by using high purity alumina with controlled grain size (less than 10 microns, preferably less than 5 microns) and density (greater than 98% of theoretical density). These parameter changes enable the ceramic body to achieve sufficient dielectric strength even at reduced thicknesses, resolving the contradiction between miniaturization and reliability.
Solution Approach 2:
The patent employs a composite ceramic material system consisting of high purity alumina with specific grain size distribution and density characteristics. This composite material structure provides both the mechanical integrity needed for thin sections and the dielectric properties required for high voltage operation, enabling smaller spark plug sizes without sacrificing reliability.
2Length of stationary object
If the radial thickness of the insulator is reduced, then the cross-section becomes thinner allowing smaller spark plug sizes, but the mechanical strength deteriorates due to poor consolidation
Solution Approach 1:
The patent applies parameter changes by controlling the ceramic material's grain size (less than 10 microns, preferably less than 5 microns) and density (greater than 98% of theoretical density). These parameter changes enhance mechanical strength through improved grain boundary bonding and reduced defect density, allowing thinner insulator sections to maintain adequate mechanical integrity.
Solution Approach 2:
The patent applies local quality by ensuring uniform grain size distribution and consistent density throughout the ceramic body. This uniform microstructure eliminates weak points and ensures consistent mechanical strength across the entire insulator, particularly at critical thin-section areas, resolving the contradiction between reduced thickness and maintained strength.
3Reliability
If high purity alumina ceramic material is used with single-phase crystal structure and reduced porosity, then dielectric strength increases to 42 kV/mm or more, but manufacturing complexity increases due to specialized injection molding or pressing methods
Solution Approach 1:
The patent applies preliminary action by preparing the ceramic slurry with precise composition and particle size distribution before molding. The slurry is pre-formulated with high purity alumina particles and appropriate binders, and the injection molding or pressing process is pre-configured with controlled parameters. This preliminary preparation enables the production of complex-shaped insulators with consistent microstructure and high dielectric strength, offsetting the increased manufacturing complexity through process standardization.
4Volume of moving object
If the insulator thickness is reduced to enable M10 spark plugs, then smaller size is achieved, but the voltage handling capability may deteriorate without sufficient dielectric strength
Solution Approach 1:
The patent changes the material parameters by using high purity alumina with controlled grain size (less than 10 microns, preferably less than 5 microns) and high density (greater than 98% of theoretical density). These parameter changes increase the dielectric strength to 42 kV/mm or more, which compensates for the reduced thickness and maintains adequate voltage handling capability in smaller M10 spark plugs.
Solution Approach 2:
The patent employs a specialized ceramic composite material with optimized grain size distribution and density characteristics. This composite structure provides enhanced dielectric properties that enable thin-section insulators to withstand high voltages, resolving the contradiction between miniaturization and voltage handling capability.
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 a dielectric strength of 42 kV/mm or more, allowing for thinner insulator cross-sections and enabling the use of smaller spark plugs like M10 while maintaining performance equivalent to larger plugs, such as M12, with improved resistance to dielectric breakdown and mechanical strength.
Implementation Method 1
The insulator has a dielectric strength of 42 kV/mm or more
Data Source
AI summary
A spark plug and method of manufacturing, where the spark plug meets particular geometric relationships to maintain and potentially improve dielectric performance while downsizing other plug dimensions. The spark plug includes an insulator that can withstand higher voltages while having areas with a reduced cross-sectional thickness. In some embodiments, the insulator has a dielectric strength of 42 kV/mm or more with a radial thickness at the internal seal of 1.5 to 1.6 mm, inclusive, and a radial thickness at a gasket of 0.6 to 0.9 mm, inclusive.