Eccentric Spring Combustion Chamber Tilting Moment

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Solution Overview

Problem

Existing hand-held tackers experience tilting moments due to the central alignment of the spring force vector, leading to potential jamming and reduced reliability, especially under conditions like dirt or icing.

Innovation Solution

The spring force vector is eccentrically arranged to minimize tilting moments by being radially offset from the central axis, with a linkage system that decouples forces perpendicular to the axis, ensuring smooth operation and reduced jamming risks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the spring force vector is centrally aligned with the combustion chamber axis, then the structure is simpler and symmetric, but tilting moments increase causing jamming and reduced reliability

Engineering Contradiction:
Improveoperational reliabilityVSAvoidspring arrangement complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The spring force vector is deliberately arranged eccentrically relative to the combustion chamber central axis, creating an asymmetric force distribution. This asymmetric arrangement generates a counteracting moment that compensates for tilting moments from the actuating mechanism, thereby reducing jamming risks and improving operational reliability despite the increased structural complexity.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If the spring force vector is eccentrically arranged to reduce tilting moments, then reliability improves, but the spring positioning becomes more complex

Engineering Contradiction:
Improveoperational reliabilityVSAvoidspring positioning precision
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The eccentric spring arrangement creates a specific local force distribution pattern where the spring is positioned at a predetermined offset from the central axis. This localized asymmetric positioning generates the necessary counter-moment to balance tilting forces, improving reliability while the offset distance is optimized to balance manufacturing feasibility with functional performance.

Inventive Principle:
Principle #3Local quality

3Reliability

If the combustion chamber is designed to collapse for safety, then safety function is achieved, but the mechanism may jam under adverse conditions like dirt or icing

Engineering Contradiction:
Improvesafety function reliabilityVSAvoidjamming from dirt or icing
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The eccentric spring arrangement proactively generates a counter-moment that prevents tilting before jamming can occur. By anticipating and compensating for tilting moments from the actuating mechanism and environmental factors like dirt or icing, the system maintains smooth movement of the combustion chamber wall during the collapse safety function, preventing jamming before it happens.

Inventive Principle:
Principle #9Preliminary anti-action

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 significantly reduces tilting moments and enhances operational reliability by allowing the combustion chamber to collapse safely and maintain contact with the workpiece, minimizing jamming and improving fastening quality.

Implementation Method 1

A force is applied to the movable combustion chamber wall in the axial direction by a spring

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

a combustion chamber is charged with a combustion gas, with a driving piston being accelerated against the nail after an ignition process

Methodology Applied
Scientific EffectCombustion: Combustion

Data Source

PatentEP3233379B1Driving device with adjustable combustion chamber
Publication Date: 2018.09.19 HILTI AG
  • EP3233379B1 patent drawingFigure 1
  • EP3233379B1 patent drawingFigure 2~3
  • EP3233379B1 patent drawingFigure 4~5

AI summary

The invention relates to a drive-in device, comprising a drive-in piston (4) which is guided in a cylinder (3) for driving a nail element into a workpiece and comprising a combustion chamber (2) which is arranged over the drive-in piston (4) and which can be filled with a combustion gas, said combustion chamber (2) comprising a cylindrical portion which is symmetrical about a central axis (A). A movable combustion chamber wall (7) of the combustion chamber (2) can be adjusted along the central axis (A), and a spring (8) is supported between the movable combustion chamber wall (7) and a housing (1a). A force vector (F) of the spring (8) has a lateral offset (V) with respect to the central axis (A).