Spark Plug Insulator Impact Resistance via Talc Cushioning
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Solution Overview
Problem
Spark plugs with reduced diameters are prone to insulator breakage due to external impacts, and existing designs that avoid direct contact between the crimp portion and insulator may still fail to secure gastightness under combustion pressure.
Innovation Solution
A spark plug design featuring a tubular insulator with a large diameter portion and a cushioning member, such as talc powder or resin, interposed between the crimp portion and the insulator to absorb impacts and maintain gastightness, allowing for smaller diameters while enhancing impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the diameter of the insulator is reduced to decrease the spark plug size, then the spark plug diameter is reduced, but the insulator becomes more prone to breakage under external impact
Solution Approach 1:
The patent applies beforehand cushioning by providing a cushioning member (such as a resin layer or elastic material) between the crimp portion and the insulator before assembly. This cushioning member absorbs external impacts that would otherwise be transmitted to the insulator, preventing breakage while allowing the insulator diameter to be reduced for smaller spark plug sizes.
Solution Approach 2:
The cushioning member serves as an intermediary element between the crimp portion and the insulator. It mediates the transmission of impact forces, protecting the insulator from direct contact with the rigid crimp portion during assembly or use, thereby enabling reduced insulator dimensions without compromising strength.
2Reliability
If the crimp portion is designed to contact the insulator directly for secure assembly, then assembly reliability is improved, but the insulator may break under external impact
Solution Approach 1:
The cushioning member is pre-installed between the crimp portion and insulator to provide protective cushioning before any impact occurs. This allows the crimp portion to maintain its assembly function while the cushioning member prevents harmful impact forces from reaching the insulator.
Solution Approach 2:
The cushioning member acts as an intermediary that decouples the direct contact between the crimp portion and insulator. It maintains assembly reliability by ensuring proper positioning while simultaneously eliminating the harmful effect of impact-induced breakage through its energy-absorbing properties.
3Reliability
If a packing is used to secure gastightness under combustion pressure, then gastightness is improved, but the packing may transmit impact forces that cause insulator breakage
Solution Approach 1:
The cushioning member provides beforehand protection by being positioned between the packing/crimp portion and the insulator. It cushions against impact forces that would otherwise be transmitted through the packing to the insulator, while the packing maintains its gastightness function under combustion pressure.
Solution Approach 2:
The cushioning member serves as an intermediary layer that separates the packing from direct contact with the insulator. It allows the packing to fulfill its gastightness role while absorbing impact forces, preventing these forces from being transmitted to the insulator and causing breakage.
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 effectively reduces the likelihood of insulator breakage and maintains gastightness by using a cushioning member that absorbs external impacts and sustains combustion pressure without increasing the number of components.
Implementation Method 1
a cushioning member, such as talc powder or resin, interposed between the crimp portion and the insulator to absorb impacts
Implementation Method 2
the circumferential edge of a rear end portion of the metallic shell is crimped radially inward so as to form a crimp portion
Implementation Method 3
the packing must sustain the load. If the packing fails to sustain the load, gastightness cannot be secured
Data Source
AI summary
A spark plug and method of manufacturing the same. The spark plug includes a tubular insulator holding a center electrode, and a tubular metallic shell holding the insulator. The insulator is inserted into the metallic shell from the rear end side thereof until a portion of the insulator engages the metallic shell. In this state, the circumferential edge of the rear end portion of the metallic shell is crimped, whereby the insulator is unitarily fixed to the metallic shell. A talc charged layer is formed in a clearance portion between the insulator and the metallic shell, and a wire packing is placed on a rear end portion of the talc charged layer for engaging the crimp portion. A portion of the talc charged layer is interposed between the wire packing and the rear trunk portion of the insulator.