Pre-Chamber Spark Plug Ground Electrode Stop for Stable Ignition Gap
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Solution Overview
Problem
Existing pre-chamber spark plugs face inaccuracies in ground electrode placement due to fluctuations in the ignition gap width, affecting their functional properties.
Innovation Solution
A stop is incorporated into the housing design to precisely position the ground electrode, using a blind hole or a step in the housing wall, with the electrode being welded in place using a laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ground electrode is inserted and secured in a through hole in the housing wall, then the ground electrode can be easily installed, but the placement of the ground electrode fluctuates affecting the width of the ignition gap
Solution Approach 1:
A blind hole is formed in the housing wall at a predetermined depth, and a stop is created at the bottom of the blind hole before the ground electrode is inserted. This preliminary preparation of the blind hole with a stop structure ensures that the ground electrode will be positioned at the correct depth and placement precision is achieved during installation.
Solution Approach 2:
A stop structure is introduced as an intermediary element within the blind hole to mediate the positioning of the ground electrode. The stop acts as a physical barrier that prevents the ground electrode from being inserted too deep, thereby ensuring consistent and precise placement of the ground electrode relative to the housing wall.
2Manufacturing precision
If the ground electrode is welded in the blind hole or on the step, then the placement precision is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The welding process is replaced or supplemented by laser beam technology. A laser beam is directed from the outside onto the housing to weld the ground electrode in place, eliminating the need for complex mechanical welding fixtures and procedures while achieving precise and reliable attachment of the ground electrode to the housing.
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
Ensures precise placement of the ground electrode, stabilizing the ignition gap width and improving the functional performance of the spark plug.
Implementation Method 1
The ground electrode is welded in the blind hole or on the step, in particular using a laser beam. The welding is carried out from the outside to the inside through the housing, preferably using a laser beam directed from the outside onto the housing.
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
The invention relates to a pre-chamber spark plug (1), comprising - a housing (2) having a bore along its longitudinal axis, the housing (2) thereby having an exterior (24) and an interior (23), - a cap (80) which is arranged on the housing (2) at the combustion-chamber end of the housing and which forms a pre-chamber (81) together with the housing (2), - an insulator (3) arranged within the housing (2), - a central electrode (4) arranged within the insulator (3), and - a ground electrode (5), wherein the ground electrode (5) and the central electrode (4) are arranged in such a way that both electrodes form an ignition gap, characterized in that the housing (2) has a blind borehole (52) which is open towards the interior (23) and in which the ground electrode (5) is placed; or that the housing (2) has on the interior (23) a step (53) pointing in the longitudinal direction, on which the ground electrode (5) is placed.