Spark Plug Ground Electrode Shield Removal Tool
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Solution Overview
Problem
Automotive technicians face difficulties in removing ground electrode shields from engine cylinder heads after they break away from spark plug assemblies, often requiring costly disassembly of the cylinder head due to excessive combustion deposits and breakage.
Innovation Solution
A tool comprising a rod with threaded ends and a hollow tube with a stepped exterior portion is used to engage the engine cylinder head shoulder, allowing a nut to generate axial force for removing the shield by screwing into the shield's upper tapped region and using a washer and jack nut to exert force through the tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If excessive force is applied to remove the spark plug due to combustion deposits, then the spark plug can be removed, but the ground electrode shield breaks away and becomes lodged in the cylinder head
Solution Approach 1:
The removal tool is divided into distinct functional segments: a threaded rod for engaging the shield, a hollow tube for guiding and centering, and a nut for applying controlled force. This segmentation allows each component to perform its specific function independently, enabling force application without direct hand-tightening that causes breakage.
Solution Approach 2:
Threads are pre-formed in the ground electrode shield before force application, and the tool components are pre-assembled in the correct configuration. This preliminary preparation ensures that when force is applied, the shield is already ready for controlled extraction without sudden stress concentration that would cause breakage.
2Ease of manufacture
If the ground electrode shield becomes lodged in the cylinder head, then the spark plug replacement is complete, but removing the lodged shield requires costly cylinder head disassembly
Solution Approach 1:
The hollow tube acts as an intermediary component between the force application point (nut) and the shield. It provides a guided path for the rod and shield, centers the assembly on the cylinder head shoulder, and distributes forces evenly, preventing the shield from becoming lodged while avoiding the need for complex cylinder head disassembly tools.
Solution Approach 2:
The problem is solved by adding the dimensional aspect of axial force application through the length of the rod and tube assembly. Instead of applying force laterally or through complex multi-axis mechanisms, the solution uses a simple linear axial extraction path that moves the shield straight out from the cylinder head bore.
3Device complexity
If a simple rod is used to engage the shield, then the tool is simple, but it cannot generate sufficient axial force to remove the shield lodged in the engine
Solution Approach 1:
The tool merges three simple components (threaded rod, hollow tube, and nut) into an integrated force application system. The rod engages the shield threads, the tube provides structural support and guidance, and the nut converts rotational motion into axial extraction force. Together, these merged components generate sufficient force while maintaining overall tool simplicity.
Solution Approach 2:
The manual hand-tightening mechanism is replaced with a dedicated threaded rod and nut assembly designed specifically for force application. This mechanical substitution allows for controlled, progressive force application that is more efficient and reliable than direct hand operation, generating the necessary axial force to extract the lodged shield.
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
Enables the safe and efficient removal of lodged ground electrode shields without disassembling the cylinder head, reducing costs and labor by applying axial force through the tool's design, effectively overcoming the challenge of broken shields.
Implementation Method 1
a rod having a threaded lower end for screwing into an upper threaded interior portion of the shield
Implementation Method 2
rotating the nut on the second threaded portion of the rod generates a force between the rod and the shield threaded to the rod
Data Source
AI summary
A tool for removing a spark plug from an internal combustion engine after such ground electrode shield has been broken away from an upper portion of a spark plug. The tool includes: a rod having a first end threaded to an interior portion of the shield; a hollow tube for receiving a portion of the rod between the first end of the rod and a second end of the rod, such tube having a stepped portion for engaging a shoulder of the engine; and an extracting means attached to the second end of the rod for generating a force axially along a longitudinal axis of the shield to remove the shield from the engine as such rod and shield are lifted by the generated force through the hollow region of the tube.