Spark Plug Grounding Electrode Laser Welding Strength
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Solution Overview
Problem
Existing spark plugs, including plasma jet ignition plugs, have inadequate joining properties between the grounding electrode and the metal shell, which can lead to reduced welding strength and potential damage to the insulator.
Innovation Solution
A spark plug design where the grounding electrode is fixed to the metal shell via a melting portion, with a melting depth of 40% or more of the grounding electrode's thickness and an area of 20% or more of the shell-side portion, ensuring a strong joining property through laser welding, and optionally featuring an outer arc portion and inner annular connection for enhanced attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the grounding electrode is joined to the inner wall surface of the metal shell using conventional methods, then the insulator may be damaged, but the joining property between the grounding electrode and the metal shell is insufficient
Solution Approach 1:
The invention changes the parameters of the melting portion by controlling the melting depth ratio (distance from bottom of melting portion to tip-side surface of grounding electrode) to be 5% or more, and the area ratio of the shell-side portion to be 10% or more. These parameter adjustments ensure adequate welding strength while preventing insulator damage.
Solution Approach 2:
The invention applies local quality by creating a melting portion with specific geometric characteristics at the joint between the grounding electrode and metal shell. The melting portion has a controlled depth and area distribution, with the shell-side portion occupying a specific area ratio, providing localized strengthening where needed without affecting the entire structure.
2Ease of manufacture
If conventional welding methods are used to join the grounding electrode to the metal shell, then the manufacturing process is simple, but the welding strength is insufficient
Solution Approach 1:
The invention maintains manufacturing simplicity by using conventional welding processes but improves welding strength through precise control of melting parameters. The melting depth ratio of 5% or more and shell-side portion area ratio of 10% or more are achieved by adjusting welding conditions such as laser power, welding speed, and focal position, keeping the process straightforward while enhancing joint strength.
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 enhanced joining property between the grounding electrode and the metal shell significantly increases the welding strength, improving the spark plug's durability and performance by securing the grounding electrode effectively.
Implementation Method 1
The grounding electrode is fixed to the metal shell via a melting portion in which the grounding electrode and the metal shell are melted to each other
Implementation Method 2
a melting portion in which the grounding electrode and the metal shell are melted to each other
Data Source
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AI summary
An ignition plug having a center electrode, a grounding electrode, an insulator, and a metal shell. The center electrode is held by the insulator, and the insulator is held by metal shell. A cavity is formed between the grounding electrode and the center electrode. The grounding electrode is joined to the inner wall surface of the metal shell via a melting portion. In the melting portion, in a predetermined cutting surface MS including a melting deepest point DP and a central axis CX, a percentage ratio MDD of a melting depth MD of the melting portion with respect to a thickness of the grounding electrode is 5% or more, and an area Sm of a portion included in an outer circumferential side of the metal shell is 10% or more of the entire area S.