Ignition Coil Conductive Terminal with Spherical Head

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Solution Overview

Problem

Existing ignition coils face challenges in ensuring reliable electrical connection between the conductive member and the terminal metal fitting of a spark plug due to limited contact area and precision requirements in manufacturing, leading to potential connectivity issues.

Innovation Solution

The ignition coil design incorporates a conductive terminal with a concave or convex surface that elastically deforms to create an annular contact area with the terminal metal fitting, enhancing connection reliability and accommodating eccentric or tilted configurations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional conductive member with limited contact area is used, then the structure is simple, but the electrical connection reliability deteriorates

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidcontact area precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The conductive terminal is designed with a spherical head portion that contacts the terminal metal fitting. This spherical geometry allows the contact portion to form an annular shape when pressed against the fitting, significantly increasing the contact area from a point contact to a ring-shaped contact zone, thereby improving electrical connection reliability without requiring high manufacturing precision

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The elastic portion of the conductive member is designed to be elastically deformable, allowing it to change its contact parameters dynamically. When the conductive member is inserted, the elastic portion deforms to press the spherical head against the terminal metal fitting, creating optimal contact pressure and annular contact area, thus ensuring reliable electrical connection while accommodating variations in assembly precision

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high manufacturing precision is required for contact area, then connection reliability improves, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveconnection reliabilityVSAvoidmanufacturing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The spherical head portion is formed by simple spheroidization treatment of the conductive terminal, which is a straightforward manufacturing process. This curved surface design inherently creates an annular contact area when pressed against the terminal metal fitting, eliminating the need for complex precision machining while ensuring reliable electrical connection

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The elastic portion automatically adjusts the contact pressure and contact area through its own elastic deformation properties. The system self-regulates the contact conditions without requiring external adjustment mechanisms or high-precision manufacturing, making the product easier to manufacture while maintaining connection reliability

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If the conductive member is rigid, then the structure is simple, but it cannot accommodate eccentric or tilted configurations

Engineering Contradiction:

Improveconfiguration adaptabilityVSAvoidstructural complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The conductive member incorporates an elastic portion that can dynamically deform to accommodate various installation conditions. This elastic component allows the conductive member to adapt to eccentric or tilted configurations by flexing and adjusting its position, providing configuration adaptability without requiring complex adjustment mechanisms

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The elastic portion acts as a flexible element within the conductive member structure, allowing it to bend and deform to accommodate misalignments. This flexible component enables the conductive member to adapt to eccentric or tilted installations while maintaining electrical connectivity, adding adaptability without significant structural complexity

Inventive Principle:

Principle #30Flexible shells and thin films

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 design increases the contact area between the conductive terminal and the terminal metal fitting, improving the reliability of the electrical connection and correcting eccentricity or tilting issues, thereby ensuring stable operation.

Implementation Method 1

The elastic portion elastically deforms in a longitudinal direction of the conductive member

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11276524B2Ignition coil

Publication Date: 2022.03.15 DENSO CORP

AI summary

An ignition coil includes a coil main body portion, a conductive member, and a protective portion. The coil main body portion generates a high voltage. The conductive member electrically connects the coil main body portion and a terminal metal fitting of a spark plug. The conductive member is arranged inside the protective portion. The protective portion has an electrically insulating property. The conductive member includes an elastic portion that elastically deforms in a longitudinal direction of the conductive member, and a conductive terminal that is arranged on a distal end side of the elastic portion. The conductive terminal has a distal end surface that includes a concave surface or a convex surface that abuts on the terminal metal fitting of the spark plug. A contact portion between the concave surface or the convex surface and the terminal metal fitting of the spark plug has an annular shape.