Combustion Fastener Tool Back Pressure Release

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Solution Overview

Problem

Conventional combustion-powered fastener-driving tools experience premature component failure due to increased shock impact from reduced back pressure, which is alleviated by back pressure release openings but results in excessive piston force on the bumper.

Innovation Solution

The tool incorporates back pressure release openings aligned with the piston at the cylinder's lower end, sealing residual air to create a dampening effect that reduces shock impact on the bumper, thereby maintaining sufficient back pressure and preventing premature tool failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If back pressure release openings are provided to reduce back pressure on the piston, then fastener driving power is increased, but shock impact on the bumper increases causing premature component failure

Engineering Contradiction:
Improvefastener driving powerVSAvoidcomponent failure resistance
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The piston is designed with a specific lower surface profile that creates a progressive sealing effect against the cylinder wall as it approaches the bumper. This localized geometric feature ensures that back pressure is maintained in specific regions (near the bumper) while allowing pressure release in other areas, thus resolving the contradiction between power and reliability

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The invention modifies the physical parameters of the piston-cylinder interface by changing the piston lower surface profile and cylinder inner surface profile. These geometric parameter changes create a progressive seal that dynamically controls back pressure retention, allowing the system to maintain both high driving power and reduced shock impact

Inventive Principle:
Principle #35Parameter changes

2Productivity

If back pressure is reduced to increase piston speed and driving force, then productivity is improved, but the force of piston impact on the bumper becomes excessive

Engineering Contradiction:
Improvefastener driving efficiencyVSAvoidpiston-bumper impact force
Core Design Contradiction:
ProductivityVSForce

Solution Approach 1:

The resilient bumper is positioned and designed to engage the piston before complete back pressure release occurs. This beforehand cushioning effect absorbs the impact force progressively, preventing excessive shock while maintaining the productivity benefits of reduced back pressure

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 enhances the driving power of the tool while reducing the risk of premature component failure by balancing back pressure release and dampening, ensuring effective fastener impact without excessive piston-bumper force.

Implementation Method 1

a lower end provided with a resilient bumper

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

these openings allow the escape to ambient of air pushed in front of the advancing piston. By removing this trapped air from the cylinder, back pressure on the piston is reduced

Methodology Applied
Scientific EffectGas compression and expansion: Compression

Implementation Method 3

This residual volume of air creates a dampening effect on the advancing piston, which works in conjunction with the bumper to reduce shock impact

Methodology Applied
Scientific EffectGas compression damping: Damping

Data Source

PatentEP2340153B1Combustion power source with back pressure release for combustion powered fastener-driving tool
Publication Date: 2017.10.04 ILLINOIS TOOL WORKS INC
  • EP2340153B1 patent drawingFigure 1
  • EP2340153B1 patent drawingFigure 2
  • EP2340153B1 patent drawingFigure 3~4

AI summary

A combustion tool includes a cylinder having a lower end provided with a resilient bumper, a piston dimensioned for reciprocation within the cylinder to impact the bumper at an end of the cylinder and having a driver blade depending therefrom for impacting fasteners. At least one back pressure release opening is disposed in the cylinder to be in alignment with the piston and to be closed by the piston when the piston impacts the bumper.