Ignition Coil Plug Cap With Local Strained Force
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Solution Overview
Problem
The existing ignition coil designs for internal combustion engines face issues with weakened fastening force leading to gaps between the plug cap and insulator, causing discharge and deterioration, which compromises insulation properties, and require strong forces for spark plug attachment and detachment.
Innovation Solution
An ignition coil with a plug cap formed from an elastic material having a cylindrical shape, featuring a strong strained force part at the base end-side close-contact area to ensure secure attachment and detachment of the spark plug without compromising insulation, and prevent discharge by maintaining close contact with the insulator head.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inner peripheral surface of the plug cap has a convexo-concave shape to facilitate attachment and detachment, then the ease of operation is improved, but the strained force for fastening the insulator is weakened and gaps are easily formed
Solution Approach 1:
The plug cap is designed with different surface characteristics in different regions: the insertion/removal portion has a convexo-concave shape for easy operation, while the close-contact portion has a smooth surface to maintain strong strained force and prevent gaps, thus resolving the contradiction between ease of operation and insulation reliability
Solution Approach 2:
The inner peripheral surface of the plug cap is segmented into distinct functional zones: an insertion/removal portion with convexo-concave features for mechanical engagement and a close-contact portion with smooth surface for electrical insulation, allowing each segment to optimize its specific function
2Reliability
If the strained force for fastening the insulator is increased throughout the plug cap to prevent gaps, then the insulation properties are improved, but strong force is required for spark plug attachment and detachment
Solution Approach 1:
The plug cap concentrates strong strained force locally in the close-contact portion through a smooth surface design, while the insertion/removal portion has reduced strain with convexo-concave features, enabling both strong insulation and easy operation without requiring strong force throughout the entire cap
3Reliability
If the plug cap is formed with strong strained force to prevent gaps, then the insulation properties are maintained, but discharge is repeatedly caused in the gap and the inner surface deteriorates
Solution Approach 1:
The smooth surface in the close-contact portion maintains consistently strong strained force to prevent gap formation and discharge, eliminating the cyclic stress and carbonization that occur with convexo-concave surfaces, thus extending the plug cap's service life while maintaining insulation
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 solution ensures reliable insulation properties and easy attachment/detachment of the spark plug with reduced sliding friction, preventing discharge and extending the lifespan of the plug cap by distributing the strained force effectively.
Implementation Method 1
The plug cap is formed of an elastic member having a cylindrical shape. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position. At least part of the base end-side close-contact part is provided with a strong strained force part that has strained force for fastening the insulator head
Data Source
AI summary
In an ignition coil for an internal combustion engine, a spark plug is incorporated which has an insulator including an insulator head that has no corrugation. The ignition coil has a coil body part generating high voltage and a joint part, which holds therein a conducting member electrically connecting the coil body part and a spark plug. The joint part has a plug cap into which the insulator head of the spark plug is inserted and which is formed of an elastic member having a cylindrical shape. The plug cap has a close-contact part whose inner peripheral surface is closely brought into contact with an outer peripheral surface of the insulator. The close-contact part has a tip end-side close-contact part positioned at a tip end side with respect to a middle position in an axial direction, and a base end-side close-contact part positioned at a base end side with respect to the middle position. At least part of the base end-side close-contact part is provided with a strong strained force part that has strained force for fastening the insulator head, the strained force being stronger than strained force of all portions of the tip end-side close-contact part.