Spark Plug Insulator High Emissivity Surface Resistor Heat Dissipation
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Solution Overview
Problem
In internal combustion engines, the high temperatures in the combustion chamber cause the resistor in spark plugs to overheat, leading to increased resistance and potential misfires, while also compromising noise suppression performance.
Innovation Solution
A spark plug design featuring a high emissivity surface on the outer peripheral surface of the insulator with thermal emissivity of at least 0.7, allowing heat from the center electrode to be efficiently transferred to the housing and released, thereby reducing the resistor's temperature without compromising noise suppression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the resistor is disposed closer to the distal end of the center electrode to improve noise suppression performance, then the noise suppression capability is improved, but the temperature of the resistor increases causing oxidation and resistance value increase
Solution Approach 1:
A heat dissipation fin is introduced as an intermediary component between the center electrode and the resistor. The fin receives heat from the center electrode through thermal conduction and dissipates it to the surrounding environment through convection and radiation, thereby protecting the resistor from excessive heat while maintaining the resistor's close proximity to the distal end for effective noise suppression
Solution Approach 2:
The invention changes the thermal parameters of the system by introducing a heat dissipation structure with high surface area to volume ratio. The fin's geometry and material properties are optimized to maximize heat transfer efficiency, allowing the resistor to remain close to the distal end without experiencing excessive temperature rise
2Temperature
If the resistor is kept away from the distal end of the center electrode to reduce its temperature, then the resistor temperature is reduced, but the noise suppression performance deteriorates
Solution Approach 1:
The heat dissipation fin serves as a thermal mediator that decouples the thermal relationship between the center electrode and the resistor. This allows the resistor to be positioned close to the distal end for optimal noise suppression while the fin absorbs and dissipates the heat, maintaining the resistor at an acceptable temperature
3Productivity
If supercharging or compression ratio is increased to improve fuel consumption, then the fuel consumption is improved, but the temperature in the combustion chamber and spark plug increases causing resistor overheating
Solution Approach 1:
The heat dissipation fin acts as a thermal buffer that protects the resistor from the high temperatures generated in the combustion chamber during supercharged or high compression ratio operation. This enables the engine to operate at higher performance levels without compromising the resistor's functionality
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 design effectively suppresses the temperature rise of the resistor, ensuring reliable spark generation and maintaining noise suppression performance by efficiently transferring heat away from the resistor.
Implementation Method 1
there is formed a high emissivity surface of which thermal emissivity is at least 0.7 on at least a part of a portion facing an inner circumferential surface of the housing
Data Source
AI summary
A spark plug includes a tubular housing, a tubular insulator, a center electrode, a ground electrode, a resistor, and a stem. The insulator is supported inside the housing. The center electrode is supported inside the insulator so as a distal end portion thereof protrudes. The ground electrode forms a spark discharge gap G between the ground electrode and the center electrode. The resistor is supported inside the insulator at a proximal side of the central electrode. The stem is supported inside of the insulator at a proximal side of the resistor. Of an outer peripheral surface of the insulator, and closer to a distal end side than a proximal portion of the resistor is, there is formed a high emissivity surface of which thermal emissivity is at least 0.7 on at least a part of a portion facing an inner circumferential surface of the housing.