Ignition Coil Spring-Joint Structure to Reduce Corona Discharge
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Solution Overview
Problem
Existing ignition coils for internal combustion engines face challenges in minimizing the risk of corona discharge and improving production efficiency, particularly due to the complexity of embedding springs in joints using insert molding techniques.
Innovation Solution
The design incorporates a cylindrical joint with electrical insulation and elasticity, featuring a spring with a spring base section, intermediate section, and head section, where the spring intermediate section is wound more densely than the base and head sections, ensuring direct contact with the joint's inner peripheral surface to prevent air layer formation and facilitate easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insert molding techniques are used to embed the spring in the joint, then the spring can be fixed in place, but the production process becomes complex and time-consuming
Solution Approach 1:
The invention extracts the spring embedding process from the complex insert molding technique and replaces it with a simple press-fit method. The spring is directly inserted into the joint without requiring molding operations, thereby eliminating the need for specialized molds and complex positioning procedures while maintaining reliable spring fixation.
Solution Approach 2:
The joint is segmented into a through-hole portion and a pressing portion, allowing the spring to be inserted through the through-hole and then secured by the pressing portion. This segmentation enables a simpler assembly process that does not require insert molding, improving productivity while ensuring the spring remains firmly in place.
2Ease of manufacture
If the spring is made with uniform winding density, then manufacturing is simpler, but air layers may form between the joint and spring causing corona discharge
Solution Approach 1:
The spring is designed with non-uniform winding density, where the intermediate section has higher winding density compared to the base and head sections. This local quality variation ensures that the spring fits tightly against the joint's inner peripheral surface, preventing air layer formation and corona discharge, while the other sections maintain adequate flexibility and ease of assembly.
Solution Approach 2:
The spring acts as an intermediary element between the joint and the electrical connection, with its intermediate section specifically designed to contact the joint's inner peripheral surface. This intermediary function ensures electrical insulation and mechanical stability while preventing harmful corona discharge through proper contact pressure.
3Manufacturing precision
If the joint is made rigid for precise alignment, then assembly accuracy improves, but the assembly process becomes more difficult and time-consuming
Solution Approach 1:
The joint is designed with elastic properties, changing the material parameter from rigid to flexible. This elasticity allows the joint to deform during assembly to accommodate the spring, facilitating easier and faster assembly while maintaining precise alignment through the elastic recovery and controlled deformation characteristics of the material.
Solution Approach 2:
The joint incorporates dynamic elastic behavior, allowing it to adapt during the assembly process. The elastic joint can deform to accommodate the spring insertion and then return to its original shape, ensuring precise alignment without requiring complex rigid positioning mechanisms, thereby improving assembly speed and productivity.
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 reduces the likelihood of corona discharge and enhances the productivity of the ignition coil by ensuring proper contact between the joint and spring, thereby improving the overall performance and production efficiency of the ignition device.
Implementation Method 1
The joint has electrical insulation and elasticity. The spring intermediate section wound more densely than spring base and head sections when the spring is subjected to no load facilitates that the spring and the joint are placed in direct contact with each other
Implementation Method 2
The spring base section lies on a base side of the length of the spring and electrically connecting with the coil unit. The spring head section lies on a head side of the length of the spring opposed to the base side in the through-hole lengthwise direction and electrically connects with the spark plug
Data Source
AI summary
An ignition coil includes a coil unit, a hollow cylindrical joint, and a spring. The joint couples the coil unit with a spark plug. The spring is inserted into a through-hole in the joint to electrically connect the coil unit and the spark plug together. The joint has electrical insulation and rubber elasticity. The spring includes a spring base section, a spring head section, and a spring intermediate section lying between the spring base and head sections. The joint has an inner peripheral surface placed in direct contact with the spring intermediate section in a radial direction of the joint. The spring intermediate section is wound more densely than each of the spring base section and the spring head section in a condition where the spring is subjected to no load. This structure serves to minimize a risk of generation of a corona discharge in the ignition coil and an ignition device equipped with the ignition coil and improve the productivity thereof.