Spark Plug Resistor Length Optimization
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Solution Overview
Problem
Existing spark plugs face challenges in maintaining noise reduction performance and load life at higher discharge voltages due to resistor degradation, where increasing resistor length for better noise reduction leads to density issues and reduced load life.
Innovation Solution
A spark plug design with a resistor length of 15 mm to 22.5 mm and a terminal fitting shaft length ratio of 1.25 or more, allowing for sufficient compression and increased resistor density, thereby improving noise reduction and load life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the length of the resistor is increased to improve noise reduction property, then the noise reduction performance is improved, but the density of the resistor becomes high during filling which reduces load life
Solution Approach 1:
The patent applies parameter changes by precisely controlling the resistor length to be 15 mm or more but not exceeding 22.5 mm, and setting the shaft length T to satisfy T/L ≥ 1.25. This optimization resolves the contradiction by finding the optimal parameter range that achieves sufficient noise reduction while preventing excessive density that would reduce load life.
2Power
If the discharge voltage is increased to improve ignition performance, then the ignition capability is improved, but the heat value of the resistor is increased which accelerates oxidation and degradation
Solution Approach 1:
The patent uses parameter changes by optimizing the resistor length to 15-22.5 mm and the shaft-to-resistor length ratio to 1.25 or more. This controlled parameter adjustment allows the system to handle higher discharge voltages while maintaining resistor durability through proper density control and compression management.
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 configuration enhances noise reduction performance and ensures extended load life by maintaining resistor density and reducing degradation at higher voltages.
Implementation Method 1
a resistor is disposed between the center electrode and the terminal fitting for reducing radio noise. The radio noise is caused due to application of the high voltage
Implementation Method 2
spark discharge is formed between a center electrode and a ground electrode. The spark discharge is generated by applying a high voltage to the center electrode
Data Source
AI summary
The spark plug has a shaft shaped center electrode, insulator, terminal fitting, ground electrode and resistor. The insulator has an axially penetrating shaft hole, and the center electrode is held in a tip end side of the shaft hole. The terminal fitting has a shaft and a terminal part. The shaft is held in a base end side of the shaft hole. The terminal part is projected from a base end of the shaft hole to a base end side of the spark plug. The ground electrode faces the center electrode in a tip end side of the shaft hole. The resistor is disposed between the center electrode and the terminal fitting in the shaft hole. An axial length L of the resistor is 15 mm≦L≦22.5 mm. An axial length T of the shaft satisfies a relation of 1.25≦T/L.