Spark Plug Ground Electrode Nickel Hardness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The demand for a thinner ground electrode in spark plugs to reduce size leads to deformation and wear issues due to bending or twisting during plating and joining, and inadequate heat transfer, resulting in quick wear and reduced deformation resistance.
Innovation Solution
A spark plug design with a ground electrode made of 97% or more nickel, controlled hardness between 130 to 260 Hv, and specific geometric ratios to enhance mechanical strength, thermal conductivity, and wear resistance, along with a manufacturing method involving heat treatment and plastic working to achieve the desired hardness and shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the ground electrode is made thinner to reduce spark plug size, then the spark plug diameter is reduced, but the ground electrode becomes prone to bending and twisting during plating and joining processes
Solution Approach 1:
The invention changes the material parameters of the ground electrode by specifying a nickel content of 97 mass% or more and controlling the hardness to 130-260 Hv. This parameter optimization allows the ground electrode to maintain sufficient mechanical strength and deformation resistance even when made thinner, thus resolving the contradiction between size reduction and strength maintenance.
2Volume of moving object
If the ground electrode is made thinner to reduce spark plug size, then the spark plug diameter is reduced, but the ground electrode becomes prone to quick wear due to inadequate heat transfer
Solution Approach 1:
The invention optimizes material parameters by specifying 97 mass% or more nickel content, which provides high thermal conductivity. Additionally, the hardness is controlled to 130-260 Hv to balance mechanical strength and thermal properties. These parameter changes ensure adequate heat transfer from the distal end portion to the metal shell, preventing quick wear even in thinner ground electrodes.
3Strength
If the ground electrode hardness is increased to improve deformation resistance, then the mechanical strength is improved, but the thermal conductivity may be reduced
Solution Approach 1:
The invention precisely controls the hardness parameter within the range of 130-260 Hv and specifies 97 mass% or more nickel content. This optimized parameter combination achieves the right balance between deformation resistance and thermal conductivity, as nickel provides excellent thermal conductivity while the controlled hardness ensures sufficient mechanical strength without excessive crystal grain distortion.
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 provides improved deformation resistance and wear resistance for the thin ground electrode, preventing bending and ensuring effective heat transfer, while maintaining ignition performance and corrosion resistance.
Implementation Method 1
heat will be transferred from the distal end portion of the ground electrode to the metal shell
Implementation Method 2
high thermal conductivity Ni so as to obtain further improvement in the thermal conductivity of the ground electrode
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A spark plug (1) includes a ceramic insulator (2) having an axial hole formed therethrough in an axis direction (CL1) of the spark plug, a center electrode (5) inserted in a front side of the axial hole (4), a metal shell (3) disposed around the ceramic insulator (2) and a ground electrode (27) joined to a front end portion of the metal shell (3) in such a manner as to define a gap (28) between the center electrode (5) and the ground electrode (27), wherein the ground electrode (27) has a cross-sectional area of 2.0 mm2 or smaller in any arbitrary cross section thereof taken in a direction perpendicular to a center line (CL2) of the ground electrode (27); the ground electrode (27) is made of a metal material containing 93 mass% or more of nickel; and the ground electrode (27) has a Vickers hardness of 130 to 260 Hv. In this spark plug where the ground electrode is relatively small in thickness, it is possible to improve both of the deformation resistance and wear resistance of the ground electrode.