Laser Welded Spark Plug Electrode with Folded Noble Metal Tip

Solution Overview

Problem

Conventional spark plug electrodes experience premature detachment of noble metal tips due to local stresses at the weld interface caused by thermal cycling, leading to inefficiency and inoperability.

Innovation Solution

A method involving a first weld to affix a noble metal tip to the electrode, followed by creating a fold around its periphery and applying a second weld with a laser beam to seal and reinforce the attachment, reducing internal stresses and enhancing durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single weld connection is created in a single thermal step to attach the noble metal tip to the electrode, then the manufacturing process is simple and fast, but local stresses are generated at the weld interface due to rapid heating and cooling, causing premature detachment during thermal cycling

Engineering Contradiction:

Improvewelding speedVSAvoidweld joint durability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The welding process is divided into two distinct thermal steps: a first weld that attaches the noble metal tip to the electrode, and a second weld that reinforces the attachment by welding the fold of the noble metal tip to the electrode. This segmentation allows each weld to serve a specific function, reducing stress concentration and improving joint durability while maintaining manufacturing efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first weld is performed as a preliminary action to establish the initial attachment between the noble metal tip and the electrode. This preliminary welding creates a base connection that can later be reinforced by the second weld, ensuring that the joint is pre-positioned correctly before final reinforcement.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If a single weld connection is used to attach the noble metal tip to the electrode, then the device complexity is low, but the noble metal tip detaches prematurely under thermal stress

Engineering Contradiction:

Improvewelding process complexityVSAvoidnoble metal tip attachment reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The welding process is divided into two distinct thermal steps: a first weld that attaches the noble metal tip to the electrode, and a second weld that reinforces the attachment by welding the fold of the noble metal tip to the electrode. This segmentation allows each weld to serve a specific function, reducing stress concentration and improving joint durability while maintaining manufacturing efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The noble metal tip is formed with a composite structure consisting of a base portion and a fold portion. The fold portion is wrapped around the electrode to create a redundant attachment mechanism. This composite geometry, combined with dual welding, creates a multi-layered attachment system that significantly improves reliability under thermal stress.

Inventive Principle:

Principle #40Composite materials

3Loss of time

If rapid heating and cooling is used in the welding process, then the welding cycle time is short, but local stresses are generated at the weld interface causing premature detachment

Engineering Contradiction:

Improvewelding cycle timeVSAvoidweld interface stress

Core Design Contradiction:

Loss of timeVSStress or pressure

Solution Approach 1:

The welding process is divided into two distinct thermal steps: a first weld that attaches the noble metal tip to the electrode, and a second weld that reinforces the attachment by welding the fold of the noble metal tip to the electrode. This segmentation allows each weld to serve a specific function, reducing stress concentration and improving joint durability while maintaining manufacturing efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fold structure of the noble metal tip serves as a cushioning element that absorbs and distributes thermal stresses. By wrapping the fold around the electrode and welding it in place, the design creates a stress-dissipating structure that protects the weld interface from premature failure during thermal cycling.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution significantly reduces the likelihood of noble metal tip detachment, resulting in a more durable and long-lasting spark plug with improved reliability.

Implementation Method 1

A laser beam from a laser is then applied to the electrode body and the noble metal tip to join the fold to the electrode body and to reinforce the first weld

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

A first weld affixes a noble metal tip to the electrode body... A second weld joins the fold of the noble metal tip to the electrode body

Methodology Applied

Scientific EffectWelding: Welding

Data Source

PatentUS8715025B2Laser welded spark plug electrode and method of forming the same

Publication Date: 2014.05.06 PGI NORTHSTAR LLC

AI summary

An electrode for a spark plug includes an electrode tip end. A first weld affixes at least a portion of the noble metal tip to the tip end of the electrode. The noble metal tip has a fold around its periphery. A second weld joins the fold of the noble metal tip to the tip end of the electrode and creates a seal over the first weld.