Spark Plug Central Electrode Laser Welding
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Solution Overview
Problem
Existing spark plugs with insufficiently fused parts between the electrode base material and the noble metal chip experience increased thermal stress, leading to cracking and instability in the joint, which affects the reliability and performance of the spark plug.
Innovation Solution
A spark plug design with a central electrode featuring a welded intermediate region formed by laser welding, where the components of the electrode base material and noble metal chip are mixed, with specific average ratios in primary and secondary measurement areas to reduce thermal stress and prevent cracking, ensuring a stable joint between the electrode base material and the noble metal chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fused part is formed between the electrode base material and the noble metal chip, then the joint strength is improved, but the manufacturing precision becomes difficult to control
Solution Approach 1:
The patent changes the welding parameters (laser power, welding speed, focal position) to control the fused area length within the specific range of 0.092mm to 0.108mm. By adjusting these parameters, the manufacturing precision of the fused area is improved while maintaining the joint strength.
Solution Approach 2:
The patent replaces traditional mechanical welding methods with laser welding technology. This substitution enables more precise control of the fused area length through optical parameter adjustment, resolving the contradiction between achieving sufficient joint strength and maintaining manufacturing precision.
2Reliability
If the fused area length is strictly adjusted, then the joint reliability is improved, but the device complexity increases
Solution Approach 1:
The patent establishes specific parameter ranges for the fused area length (0.092mm to 0.108mm) that ensure joint reliability without requiring complex adjustment mechanisms. By defining this optimal range, the system achieves reliable joints through controlled parameter variation rather than complex mechanical adjustments.
3Ease of manufacture
If the fused area is insufficient, then the manufacturing process becomes simpler, but the thermal stress increases causing cracking
Solution Approach 1:
The patent identifies and controls critical welding parameters (laser power, speed, focal position) to ensure the fused area length remains within the optimal range of 0.092mm to 0.108mm. This parameter control achieves sufficient thermal stress distribution to prevent cracking while maintaining manufacturing simplicity through standardized process parameters.
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 significantly reduces thermal stress and prevents cracking, providing a reliable and stable joint between the electrode base material and the noble metal chip, enhancing the spark plug's performance and durability.
Implementation Method 1
welded intermediate region formed by laser welding
Implementation Method 2
A spark discharge is generated between the noble metal chip of the central electrode and the ground electrode
Data Source
AI summary
A spark plug has a central electrode and a ground electrode. The central electrode has an electrode base material part and a noble metal chip of a cylindrical shape and is welded on the electrode base material part. A spark discharge is generated between the noble metal chip of the central electrode and the ground electrode when supplying a predetermined voltage to the spark plug. An intermediate region is formed on an overall surface between the electrode base material part and the noble metal chip. The intermediate region has a primary measurement part and a secondary measurement part. Components of the noble metal chip in the primary measurement area have a first average ratio of not less than 40 wt %, and components of the noble metal chip in the secondary measurement area have a second average ratio of not more than 80 wt %.