Ignition Device Spring Vibration Control via Local Geometry
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Solution Overview
Problem
Conventional ignition devices for internal combustion engines face challenges in preventing lateral vibration of the spring and maintaining design flexibility while controlling costs, especially with complex cylinder head layouts that increase the distance between the ignition plug and coil, leading to limitations in setting the spring constant and resonance frequency.
Innovation Solution
The ignition device incorporates a cylindrical plug boot with a reduced-inner-diameter portion and a coil-shaped spring with larger diameter portions, forming clearances between the spring and the boot's inner wall, which helps suppress lateral vibration and enhances the setting of spring constant and resonance frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between ignition plug and ignition coil is increased due to complex cylinder head layout, then various devices can be attached to improve fuel efficiency, but the length of plug boot is increased and spring lateral vibration occurs
Solution Approach 1:
The plug boot is designed with a reduced inner diameter portion at specific locations where the spring has larger diameter portions. This local modification creates reduced clearances that prevent spring lateral vibration without requiring changes to the overall plug boot length or spring design parameters.
2Reliability
If the inner diameter of plug boot is locally reduced to prevent lateral vibration, then spring stability improves, but the shape of ignition plug and inner diameter of plug boot are limited
Solution Approach 1:
Instead of uniformly reducing the plug boot inner diameter, the invention applies local reduction only at specific positions where the spring has larger diameter portions. This allows the majority of the plug boot to maintain its original dimensions, preserving design flexibility while preventing spring lateral vibration at critical locations.
Solution Approach 2:
The plug boot inner diameter is segmented into different sections: a reduced inner diameter portion at specific locations and normal inner diameter portions at other locations. This segmentation allows different functional requirements to be met in different regions of the same component.
3Reliability
If another member (metal pipe) is inserted into plug boot to prevent lateral vibration, then spring stability improves, but device complexity and cost increase
Solution Approach 1:
The vibration prevention function is merged into the plug boot structure itself by creating a reduced inner diameter portion, eliminating the need for a separate metal pipe component. This integrates multiple functions into a single component, reducing overall device complexity.
Solution Approach 2:
The unnecessary metal pipe component is extracted from the system. The vibration prevention function is achieved directly through the plug boot's geometric design rather than through an additional extracted component.
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 effectively prevents lateral vibration, reduces costs, and improves design flexibility by allowing for appropriate setting of spring constants and resonance frequencies, ensuring reliable operation and assembly without spring detachment.
Implementation Method 1
a spring that is formed in a coil shape and electrically connects, to the high-voltage output terminal, an ignition plug terminal
Implementation Method 2
the plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of another portion, the spring has a larger diameter portion having a diameter size larger than that of another portion, and a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and an inner wall surface of the plug boot
Implementation Method 3
an iron core magnetically coupling the primary coil and the secondary coil to each other
Implementation Method 4
a high voltage generated in the secondary coil when conduction of an excitation current flowing in the primary coil is interrupted
Data Source
AI summary
This invention is concerning an ignition device for an internal combustion engine, wherein a plug boot has a reduced-inner-diameter portion having an inner diameter size smaller than that of the other portion, a spring has a larger diameter portion having a diameter size larger than that of the other portion, and a plurality of reduced clearances each having a width reduced by the reduced-inner-diameter portion and the larger diameter portion are formed between the spring and the inner wall surface of the plug boot.