Spark Plug Ground Electrode Cr-Ni-Al Layering for Temperature Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High surface temperatures of ground electrodes in spark plugs can lead to abnormal combustion and dissolution loss due to excessive heat exposure in advanced internal combustion engines, where existing materials fail to effectively manage thermal conductivity and oxidation resistance.
Innovation Solution
A spark plug design featuring a ground electrode with a base material containing Ni, Cr, and Al, accompanied by a Cr-poor layer and a Cr-rich layer, where the Cr-poor layer enhances thermal conductivity and the Cr-rich layer reduces heat absorption, thereby controlling surface temperature rise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a ground electrode uses traditional electrode materials in high-temperature combustion chambers, then oxidation resistance may be maintained, but surface temperature rises excessively causing abnormal combustion and dissolution loss
Solution Approach 1:
The ground electrode employs a composite material structure consisting of a Ni-Cr-Al alloy base material with specific composition ratios (Cr: 14-33 mass%, Al: 0.3-2.0 mass%). This composite composition creates a synergistic effect where Cr provides oxidation resistance through Cr2O3 film formation, while Al enhances thermal conductivity and forms protective Al2O3. The combination achieves both thermal management and oxidation protection, preventing excessive temperature rise and associated reliability issues.
Solution Approach 2:
The invention optimizes the chemical composition parameters of the ground electrode material by specifying precise ranges for Cr (14-33 mass%) and Al (0.3-2.0 mass%). By adjusting these compositional parameters, the material achieves optimal balance between oxidation resistance (from Cr2O3 formation) and thermal conductivity (enhanced by Al), thereby controlling surface temperature and preventing abnormal combustion and dissolution loss.
2Reliability
If the ground electrode surface temperature is reduced to prevent abnormal combustion, then reliability improves, but heat dissipation capability may be compromised
Solution Approach 1:
The Ni-Cr-Al composite material structure inherently balances heat dissipation and temperature control. Aluminum's high thermal conductivity ensures efficient heat dissipation from the ground electrode surface, while chromium's oxidation resistance protects the material integrity. This composite approach maintains reliable heat management without causing excessive temperature rise that would lead to abnormal combustion.
Solution Approach 2:
By optimizing the Al content (0.3-2.0 mass%) in the alloy composition, the invention enhances thermal conductivity for improved heat dissipation capability. Simultaneously, the Cr content (14-33 mass%) is controlled to provide sufficient oxidation resistance. This parameter optimization ensures both effective heat dissipation and prevention of abnormal combustion.
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
This configuration effectively suppresses surface temperature increases, preventing abnormal combustion and dissolution loss by optimizing thermal conductivity and oxidation resistance, ensuring reliable operation in high-temperature environments.
Implementation Method 1
a Cr-poor layer disposed on a surface of the base material, having a lower Cr content and a higher Ni content than the base material, and having a thickness of 5 μm or more
Implementation Method 2
a Cr-rich layer disposed on a surface of the Cr-poor layer, having a higher Cr content than the base material, and having a thickness of 15 μm or less
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
[Object] It is an object of the present invention to provide a spark plug which includes a ground electrode and in which the occurrence of abnormal combustion and the dissolution loss of the ground electrode are suppressed by reducing a rise in a surface temperature of the ground electrode in a high-temperature environment. [Solution] A spark plug includes a ground electrode that includes a base material containing Ni as a main component and having a Cr content of 14 mass% or more and 33 mass% or less and an Al content of 0.3 mass% or more and 2.0 mass% or less, a Cr-poor layer disposed on a surface of the base material, having a lower Cr content and a higher Ni content than the base material, and having a thickness of 5 µm or more, and a Cr-rich layer disposed on a surface of the Cr-poor layer, having a higher Cr content than the base material, and having a thickness of 15 µm or less.