Ignition Coil Protective Casing Stiffness via Spring Shoulder Support
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Solution Overview
Problem
Existing ignition coils with metal sleeves in their protective casings increase manufacturing costs and reduce flexibility, making them less suitable for engines with smaller spark plug diameters and less reliable in axial force absorption.
Innovation Solution
The protective casing is made stiffer without additional components by supporting the spring's block section on a shoulder within the casing, allowing for reduced material usage and a smaller diameter, enhancing axial force absorption and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal sleeves are integrated into the protective casing to reinforce it, then the protective casing becomes stiffer and more reliable, but manufacturing costs increase and the diameter of the protective sheath increases
Solution Approach 1:
The invention removes the metal sleeves from the protective casing design, extracting the reinforcing function to the support shoulder integrated into the casing structure itself. This eliminates the need for additional metal components while maintaining structural integrity.
Solution Approach 2:
The support shoulder is merged directly into the protective casing as an integrated structural feature rather than a separate component. This combines the casing and support functions into a single piece, reducing part count and manufacturing complexity.
2Reliability
If metal sleeves are integrated into the protective casing to reinforce it, then the protective casing becomes stiffer and more reliable, but the flexibility of the protective sheath is reduced
Solution Approach 1:
The metal sleeves are removed from the design, extracting the rigid reinforcing elements that constrained the flexible protective sheath. The support shoulder provides necessary structural support without compromising the overall flexibility of the casing.
3Strength
If metal sleeves are integrated into the protective casing, then the protective casing becomes stiffer, but the diameter of the protective sheath increases
Solution Approach 1:
The support shoulder is integrated into the protective casing as a built-in feature rather than an external addition. This merging of functions allows the casing to provide both protection and support without requiring additional radial space.
Solution Approach 2:
The protective casing is designed as a flexible shell that can provide structural support through its geometry and material properties without requiring thick walls or additional rigid components that would increase diameter.
4Force
If the spring block section is supported on a support shoulder within the protective casing, then the protective casing becomes stiffer and can absorb higher axial forces, but the spring axial position must be precisely controlled
Solution Approach 1:
The support shoulder is pre-formed as an integral feature of the protective casing during molding. This preliminary formation of the support structure eliminates the need for separate positioning operations and ensures consistent spring placement.
Solution Approach 2:
The support shoulder geometry is optimized to provide adequate spring positioning through its dimensional parameters (height, radius, position). By carefully selecting these parameters during design, the system achieves both force absorption capability and acceptable positioning tolerance without requiring ultra-precise manufacturing.
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 configuration reduces production costs, improves axial force absorption, and ensures reliable attachment to spark plugs, making the ignition coil suitable for smaller engines with reduced risk of spring dislodgment.
Implementation Method 1
a spring (15) for electrically connecting the high-voltage connection (9) to the spark plug (5)... the protective jacket (16) can absorb comparatively high axial forces
Implementation Method 2
The support shoulder (20) also secures the axial position of the spring (15) in the protective casing (16), so that the spring (15) cannot fall out of the protective casing (16)
Implementation Method 3
the spring (15) is axially prestressed between the high-voltage connection (9) and the support shoulder (20)... The axial pretensioning of the spring results in a higher flexural rigidity of the protective casing
Data Source
AI summary
Known ignition coils have a high-voltage connection, a spring for electrically connecting the high-voltage connection to a spark-plug and an elastic protective jacket that surrounds the spring. The windings of the spring lie in a block against one another in a block section that faces the high-voltage connection and are interspaced in a spring section designed to contact the spark-plug. To permit the ignition coil with the elastic protective jacket to be pushed easily onto the spark-plug, said protective jacket is reinforced by the integration of two metal sleeves. However, the disadvantage of these sleeves is that they involve higher production costs and increase the diameter of the protective jacket. In addition, the sleeves reduce the flexibility of the protective jacket. In the ignition coil according to the invention, the rigidity of the protective jacket is increased without additional components, thus cutting production costs and reducing the diameter of the protective jacket. According to the invention, the end of the block section (15.1) of the spring (15), facing the spring section (15.2), is supported on at least one support shoulder (20) of the protective jacket (16).