Spark Plug Shoulder Radius for Compact High-Pressure Sealing
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Solution Overview
Problem
Existing spark plugs face challenges in achieving robustness, gas sealing, and temperature resistance, particularly with the trend towards smaller dimensions and increased demands from downsized engines.
Innovation Solution
The spark plug design incorporates an insulator, a housing, and a deformable sealing plate with a specific arched profile and radius, which allows for increased Hertzsche surface pressing during assembly, enhancing the sealing and robustness of the spark plug.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the spark plug dimensions are reduced to meet downsizing requirements, then the spark plug can be used in smaller engines, but the robustness and gas tightness deteriorate
Solution Approach 1:
The patent employs a sealing disc made of elastomeric material (such as FKM, VMQ, or SIL) that acts as a flexible sealing element. This sealing disc is inserted into a circumferential recess in the insulator and deforms under compression to create a gas-tight seal between the insulator and housing, enabling reliable sealing even in reduced-size spark plugs.
Solution Approach 2:
The patent changes the material parameters by introducing an elastomeric sealing disc with specific material properties (deformability, elasticity) that allow it to adapt to dimensional variations and maintain sealing under compression. The material selection (FKM, VMQ, SIL) provides optimal balance between sealing capability and compatibility with spark plug operating conditions.
2Reliability
If the sealing between insulator and housing is improved, then gas tightness increases, but the structural complexity increases
Solution Approach 1:
The patent segments the sealing function from the main structural components by introducing a separate sealing disc as an independent element. This sealing disc is placed in a dedicated circumferential recess, allowing the insulator and housing to maintain their structural integrity while the sealing disc provides the sealing function independently.
Solution Approach 2:
The sealing disc acts as an intermediary element between the insulator and housing, mediating the sealing function without requiring direct modification of the main structural components. This intermediary approach simplifies the overall structure by providing sealing through a dedicated component rather than through complex integrated sealing features.
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
This design enables reduced dimensions while achieving improved sealing and robustness, capable of withstanding higher pressures and temperatures, particularly in smaller engine applications.
Implementation Method 1
By choosing a small radius between 0.20 mm and 0.60 mm, an increased Hertzian surface pressure can be achieved during the assembly process
Implementation Method 2
The sealing disc is deformable and the insulator has a shoulder running around its entire circumference, which is arcuate in section and against which the sealing disc rests. The material of the sealing disc is selected such that the deformability of the insulator and the housing is less than the deformability of the sealing disc
Data Source
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AI summary
The present invention relates to a spark plug, comprising an insulator (2), a housing (3), and a sealing washer (4) which is arranged between the insulator (2) and the housing (3), wherein the sealing washer (4) is deformable, wherein the insulator (2) has an annularly circumferential shoulder (20), against which the sealing washer (4) bears, and wherein the shoulder (20) has a radius (R1) which lies in a range from 0.20 mm to 0.60 mm.