Ribbed Ignition Coil Joint for Bent Plug Hole Alignment

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Solution Overview

Problem

Existing ignition coils face challenges in being mounted into bent plug holes of internal combustion engines, experiencing axial misalignment and wear due to compressive forces and vibrations, which affect their durability and performance.

Innovation Solution

The ignition coil design includes a tubular joint part with first and second ribs on its outer surface, where the first ribs guide the coil through the bend and the second ribs enhance rigidity at the entrance, ensuring proper alignment and reducing wear by maintaining coaxiality with the plug hole.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the joint part is formed of an elastic material to facilitate insertion into bent plug holes, then the ease of operation is improved, but axial misalignment occurs due to compression and deflection

Engineering Contradiction:

Improveinsertability into bent plug holeVSAvoidaxial alignment precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The joint part incorporates ribs at specific locations (distal end and proximal end) that provide localized rigidity and alignment guidance, while the main body remains elastic for bendability. This local reinforcement prevents axial misalignment during insertion without compromising the overall flexibility needed for bent plug hole accommodation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The plug hole is designed with a bent configuration rather than a straight cylindrical shape. The joint part is configured to match this curved path, allowing it to follow the bent trajectory while the ribs maintain axial alignment throughout the insertion process, resolving the conflict between flexibility and precision.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If the joint part has a thin wall part to facilitate bending, then the adaptability to bent plug holes is improved, but wear occurs due to vibration and contact with the bend

Engineering Contradiction:

Improveadaptability to bent plug hole shapeVSAvoidwear resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The ribs are strategically positioned at the distal and proximal ends of the joint part, creating localized reinforcement zones. The main body between the ribs remains thin-walled for adaptability to the bent shape, while the ribbed sections provide wear resistance where contact with the plug hole bend occurs during operation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The ribs act as preemptive protective elements that bear the brunt of vibrational contact and wear forces before they can affect the thin-walled main body. This beforehand reinforcement ensures the thin-walled structure can adapt to the bent shape without sacrificing reliability under vibrational conditions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If the plug hole has a constant diameter to simplify manufacturing, then the ease of manufacture is improved, but axial misalignment occurs during insertion into bent sections

Engineering Contradiction:

Improveplug hole manufacturing simplicityVSAvoidaxial alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The plug hole is manufactured with a bent configuration that follows a curved path. While the diameter remains substantially constant for ease of manufacture, the bent shape requires the joint part to be flexible enough to follow the curve, which is achieved through the elastic material with localized rib reinforcement.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The ribs on the joint part provide localized guidance and alignment features that work in conjunction with the bent plug hole geometry. These ribs ensure axial alignment is maintained throughout the insertion process, even as the joint part navigates the bent section of the plug hole with its constant diameter.

Inventive Principle:

Principle #3Local quality

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 improves the insertability and assemblability of the ignition coil into bent plug holes, preventing axial misalignment and wear, thereby enhancing the coil's durability and maintaining its electrical characteristics.

Implementation Method 1

a joint part formed of a tubular elastic body that is bendable and deformable

Methodology Applied

Scientific EffectElasticity: Elasticity

Implementation Method 2

the first ribs guide the coil through the bend and the second ribs enhance rigidity at the entrance, ensuring proper alignment

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS20260071603A1Ignition coil

Publication Date: 2026.03.12 DENSO CORP

AI summary

An ignition coil includes a joint part that is formed of a tubular elastic body. The join part has a distal end mounted to an ignition plug arranged in a plug hole having a bend, and a proximal end mounted to a coil main body part arranged at a proximal-side entrance part of the plug hole which has a greater inner diameter than the bend. On an outer circumferential surface of a main tubular portion opposed to the bend, there are formed first ribs each extending along an axis of the joint part. On an outer circumferential surface of a proximal-side tubular portion, there are formed second ribs each extending along the axis of the joint part. When viewed along the axis of the joint part, a maximum value of a first rib diameter and a maximum value of a second rib diameter satisfy the relationship of d2 > d1.