Inverted Spark Plug Insulator Tip for Soot Removal
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Solution Overview
Problem
Conventional spark plugs used in diesel engines are ineffective in burning off soot deposits and are not robust enough to withstand high cylinder pressures and corrosive exhaust environments, necessitating a more reliable igniter design for combustion control and exhaust treatment.
Innovation Solution
A spark plug design featuring a center electrode, insulator, and ground shield with a tip portion extending past the ground shield, and a cap that covers the distal end of the center electrode and insulator, creating a spark gap between the cap and ground shield to facilitate soot removal and ion sensing, utilizing high nickel or stainless steel alloys for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional spark plug design is used in a diesel engine, then the engine can perform combustion, but soot deposits accumulate on the insulator tip and are not burned off
Solution Approach 1:
The patent inverts the conventional spark plug design by making the insulator tip the active electrode instead of having the center electrode extend beyond it. This reversal allows the spark to occur at the insulator tip surface, directly burning off soot deposits that would otherwise accumulate there. The ground electrode wraps around the insulator to create the spark gap at the tip surface, fundamentally changing where combustion initiation occurs.
Solution Approach 2:
The patent converts the harmful soot accumulation problem into a beneficial self-cleaning mechanism. By positioning the spark gap at the insulator tip surface, the electrical discharge actively burns off soot deposits, transforming the insulator tip from a passive component that accumulates contaminants into an active element that self-cleans and maintains combustion efficiency.
2Reliability
If the center electrode extends past the insulator tip in a conventional design, then ignition can occur, but the insulator tip is exposed to corrosive combustion environment without protection
Solution Approach 1:
The patent inverts the conventional arrangement where the center electrode protrudes beyond the insulator. Instead, the insulator tip protrudes beyond the ground electrode, making the insulator material the active electrode. This inversion protects the metal center electrode from direct exposure to the corrosive combustion environment while maintaining ignition capability through the insulator tip.
Solution Approach 2:
The insulator tip serves as an intermediary element that replaces the conventional center electrode in direct contact with the combustion environment. The insulator material, being ceramic and chemically inert, acts as a mediator that can withstand corrosive conditions while still conducting the electrical discharge needed for ignition, thereby protecting the metal components from degradation.
3Productivity
If a spark plug is used for exhaust treatment in a burner system, then regeneration can be initiated, but soot accumulates on the insulator tip outside the spark gap and cannot be burned off
Solution Approach 1:
The patent inverts the conventional spark plug geometry so that the insulator tip, rather than being recessed or covered, extends as the leading element into the exhaust stream. The ground electrode wraps around the insulator to create a spark gap at the insulator tip surface, ensuring that soot particles in the exhaust are directly exposed to the spark discharge for burning off.
Solution Approach 2:
The patent applies local quality by concentrating the spark discharge activity specifically at the insulator tip surface where soot accumulation occurs most. The ground electrode is positioned to create the spark gap precisely at this location, ensuring that the electrical discharge occurs where it is most needed - at the boundary layer where soot deposits form - rather than in a conventional internal spark gap.
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 effectively burns off soot deposits on the insulator tip and enhances ion sensing capabilities, ensuring reliable operation in high-pressure diesel engine environments and supporting combustion control and exhaust treatment systems.
Implementation Method 1
a spark gap is disposed between a peripheral edge of the cap and the end portion of the ground shield or threaded portion
Implementation Method 2
This unique combination of needs for in-cylinder combustion sensing and combustion initiation can be supported with a spark plug designed to work well in the higher pressure diesel engine cylinder environment as an igniter and also as an ion sensor for combustion feedback and control
Implementation Method 3
The design effectively burns off soot deposits on the insulator tip
Data Source
AI summary
An igniter for an internal combustion engine includes a center electrode, an insulator disposed about the center electrode, and a ground shield or a threaded portion disposed about the insulator, wherein the insulator includes a tip portion extending past an end portion of the ground shield and a tip portion of the center electrode extending through and away from the tip portion of the insulator. The igniter further includes a cap secured to the center electrode, wherein the cap extends past and covers a distal end of the tip portion of the center electrode and a distal end of the tip portion of the insulator. A spark gap is disposed between a peripheral edge of the cap and the end portion of the ground shield or threaded portion wherein the peripheral edge of the cap is spaced away from a surface of the tip portion of the insulator.