Pre-chamber Spark Plug Composite Ground Electrode Design
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Solution Overview
Problem
Existing pre-chamber spark plugs for combustion engines face challenges in achieving efficient lean-burn operation and reliable ignition, especially under high exhaust recirculation rates, with limitations in design that hinder flame growth and spark placement.
Innovation Solution
A pre-chamber spark plug design featuring a body with an external thread, a center electrode, and multiple ground electrodes made from precious metal alloys, where the ground electrodes form a spark gap with the center electrode, and a cap that allows gas exchange between the pre-chamber and combustion chamber, promoting swirl-free, high-turbulence flow for improved ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If ground electrodes are made from thin precious metal pins, then manufacturing cost is reduced, but mechanical strength and reliability deteriorate
Solution Approach 1:
The ground electrode is constructed as a composite structure combining a heat-resistant alloy supporting component (providing mechanical strength) with a precious metal reinforcing component (providing spark performance). This composite design reduces overall precious metal usage while maintaining both strength and electrical performance.
Solution Approach 2:
The ground electrode is divided into two functional segments: a supporting component made of heat-resistant alloy and a reinforcing component made of precious metal. This segmentation allows each part to be optimized for its specific function, reducing total precious metal consumption.
2Ease of manufacture
If ground electrodes are welded to the body end surface, then manufacturing simplicity is improved, but spark gap positioning precision deteriorates
Solution Approach 1:
The supporting component is pre-formed with an integrated mounting structure that includes a mounting surface and positioning features. This preliminary preparation ensures precise spark gap positioning is achieved before the final welding step, combining ease of assembly with manufacturing precision.
3Device complexity
If pre-chamber is supplied with fuel from combustion chamber only, then device complexity is reduced, but ignition reliability under high exhaust recirculation deteriorates
Solution Approach 1:
The cap geometry is specifically designed to generate high turbulence and swirl-free flow patterns during compression. This parameter optimization of the flow field ensures reliable ignition even under high exhaust recirculation conditions without requiring additional fuel supply conduits.
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 design enhances lean-burn operation, ensures reliable ignition, and extends the spark plug's service life by optimizing spark placement and turbulence, reducing precious metal usage, and supporting conventional coil ignitions.
Implementation Method 1
The center electrode and the ground electrode form a spark gap with one another
Implementation Method 2
promoting swirl-free, high-turbulence flow for improved ignition
Data Source
AI summary
A pre-chamber spark plug for an internal combustion engine having: a body with a passage in which an insulator is fastened and a center electrode protrudes; at least one ground electrode extending in a straight line forms a spark gap with the center electrode; a pre-chamber-forming cap which delimits a pre-chamber and shields the center and ground electrodes from a combustion chamber after the spark plug has been installed in the engine, wherein the cap has at least one opening which permits a gas exchange between the pre-chamber and the space outside the pre-chamber. The ground electrode includes a reinforcing component welded to an end surface of a supporting component, and the supporting component is either welded to an end surface of the body or is welded to a step that is formed on the end surface.