Spark Plug Assembly Radial Alignment Method
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Solution Overview
Problem
The challenge is to reduce the deviation between the axis of a metal shell and an insulator in spark plugs, particularly when the diameter of the spark plug is reduced, leading to potential spark discharges between the center electrode and the metal shell due to increased deviation and reduced spark gap distance.
Innovation Solution
A manufacturing method for spark plugs that involves assembling the insulator and metal shell using positioning members with tapered surfaces to limit radial displacement while allowing axial displacement, ensuring precise alignment and reducing deviation between the axes, which includes using elastic members and talc to apply pressure and secure the components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the diameter of the spark plug is reduced to improve design flexibility, then the inner diameter of the metal shell is decreased, but the deviation between the axis of the metal shell and the axis of the insulator increases, causing spark discharge between the center electrode and the metal shell
Solution Approach 1:
The patent applies preliminary action by providing positioning members (first and second positioning members) before the insulator is inserted into the metal shell. These positioning members are pre-positioned to define the axial direction and limit radial displacement, ensuring that when assembly occurs, the insulator is automatically guided into correct alignment with the metal shell axis, thereby preventing axis deviation even in reduced-diameter spark plugs
Solution Approach 2:
The patent uses positioning members as intermediary elements between the metal shell and the insulator. These positioning members act as mediators that transmit and constrain the positional relationship between the two components, limiting radial displacement while allowing axial movement, thus ensuring precise alignment without direct contact between the insulator and metal shell walls
2Length of moving object
If the distance between the center electrode and the ground electrode is increased to improve spark gap, but the deviation between the axis of the metal shell and the axis of the insulator increases, then spark discharge occurs between the center electrode and the metal shell
Solution Approach 1:
The positioning members are installed before the insulator insertion to pre-establish the correct axial alignment. This preliminary positioning ensures that even when the insulator is inserted deeper to increase the spark gap distance, the axis deviation is controlled, preventing spark discharge between the center electrode and metal shell
Solution Approach 2:
The positioning members serve as intermediary constraints that maintain the radial positional relationship between the metal shell and insulator. This intermediary constraint system allows the insulator to be positioned at the required depth for adequate spark gap while simultaneously limiting radial displacement that would cause axis deviation
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 method effectively limits radial positional displacement between the metal shell and insulator, reducing axis deviation and preventing unwanted spark discharges, ensuring proper ignition and reducing wear in internal combustion engines.
Implementation Method 1
bringing a front end portion of the metal shell in the axial direction into contact with the first positioning member to thereby limit displacement of the metal shell in the radial direction; bringing a front end portion of the insulator in the axial direction into contact with the second positioning member to thereby limit displacement of the insulator in the radial direction
Implementation Method 2
The dependent claims relate to advantageous features and embodiments of the invention, including using elastic members and talc to apply pressure and secure the components
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
Provided is a technique for limiting the radial displacement between a metal shell and an insulator in a spark plug. At the time of manufacturing a spark plug with a metal shell and an insulator, the metal shell and the insulator are assembled together by, while allowing relative positional displacement between the metal shell and the insulator in an axial direction (O-O), limiting relative positional displacement between the metal shell and the insulator in a radial direction intersecting with the axial direction in such a manner that the amount of deviation between an axis of the metal shell and an axis of the insulator becomes less than or equal to a predetermined level.