Combustion Fan Blade Geometry for Rapid Ignition

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Solution Overview

Problem

Existing gas-powered tackers face challenges in achieving rapid ignition and efficient turbulence generation in the combustion chamber, limiting their performance.

Innovation Solution

A fan design with a low moment of inertia, featuring inwardly increasing blade twisting and varying blade geometries, including angled and saber-like curves, is implemented to enhance turbulence and ignition speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the blade width increases radially outward to generate more turbulence, then turbulence generation improves, but the moment of inertia increases and ignition speed decreases

Engineering Contradiction:

Improveignition speedVSAvoidfan acceleration speed

Core Design Contradiction:

TemperatureVSSpeed

Solution Approach 1:

The blade geometry is optimized with non-uniform width distribution - the blade width increases radially inward rather than outward, creating local variations in blade cross-section that generate turbulence while minimizing the overall moment of inertia. This local quality variation allows turbulence generation without the penalty of increased rotational inertia.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of the conventional design where blade width increases radially outward, this invention inverts the approach by having the blade width increase radially inward. This inversion reduces the moment of inertia while still achieving effective turbulence generation through the altered blade geometry and flow interaction.

Inventive Principle:

Principle #13The other way round (Inversion)

2Temperature

If conventional blade geometry is used, then manufacturing is simple, but turbulence generation is insufficient

Engineering Contradiction:

Improvecombustion efficiencyVSAvoidblade geometry complexity

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The blade geometry parameters are changed from conventional designs - specifically the width distribution pattern is inverted (increasing inward rather than outward) and the twist distribution is optimized. These parameter changes enhance turbulence generation and combustion efficiency while remaining manufacturable through standard machining processes.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2650086B1Setting tool

Publication Date: 2017.02.01 HILTI AG

AI summary

The driving tool has a tank (5) for storing a fuel, particularly a liquefied petroleum gas, and a ventilator that acts on a combustion chamber (2) and rotates about an axis, where multiple blades extending radially to the axis. Each blade has a section of one third of a radial length of the blade, where the section has a projected width in the axial direction that does not increase radially toward the outside. The section has an angle of inclination around a blade axis that increases from the outside toward the inside.