Combustion-Driven Setting Tool Adjustable Pre-Chamber Flow

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Solution Overview

Problem

Existing combustor-powered setting devices for driving fastening elements into substrates face inefficiencies due to energy losses in the pre-combustion chamber, which affect the performance and energy usage of the device.

Innovation Solution

The solution involves a control device with an adjustable passage opening between the pre-chamber and the main combustion chamber, allowing for adjustable flow cross-sections to minimize energy losses, which can be mechanically or electromechanically controlled, enabling operation across different energy classes without significant modifications to the device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the pre-chamber is connected to the main combustion chamber via a passage opening, then the device can operate, but energy losses occur due to unwanted gas flow through the passage

Engineering Contradiction:
Improveenergy losses in pre-chamberVSAvoidoperation in different energy classes
Core Design Contradiction:
Loss of energyVSEase of operation

Solution Approach 1:

The passage opening is made adjustable rather than fixed, allowing the flow cross-section to be dynamically modified. This enables the device to adapt to different operating conditions and energy classes while minimizing energy losses through optimized flow control.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The flow cross-section parameter of the passage opening is made variable, allowing adjustment between different opening states. This parameter change enables optimization of gas flow to reduce energy losses while maintaining operational flexibility across different energy classes.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the passage opening flow cross-section is fixed, then the device structure is simple, but energy losses cannot be optimized for different operating conditions

Engineering Contradiction:
Improveoperation in different energy classesVSAvoidcontrol device structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The passage opening incorporates an adjustable mechanism that allows modification of the flow cross-section. This dynamic element enables the device to adapt to different energy classes while the control mechanism remains relatively simple, balancing versatility with structural complexity.

Inventive Principle:
Principle #15Dynamics

3Loss of energy

If gas flows freely through the passage opening, then the device operates smoothly, but energy is lost to the gas cushion in the pre-chamber

Engineering Contradiction:
Improveenergy loss to gas cushionVSAvoiddriving piston performance
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The flow cross-section parameter is adjusted to optimize the balance between smooth operation and energy efficiency. By controlling the opening size, the device minimizes energy loss to the gas cushion while maintaining sufficient gas flow for effective driving piston operation.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3393718B1Combustion-driven setting tool and method for operating such a setting tool
Publication Date: 2021.10.20 HILTI AG
  • EP3393718B1 patent drawingFigure 1
  • EP3393718B1 patent drawingFigure 2
  • EP3393718B1 patent drawingFigure 3

AI summary

The invention relates to a fuel-powered setting device (1) for driving securing elements into a substrate, comprising at least one main combustion chamber (6) for a fuel, a drive piston (10) that can be driven out of the main combustion chamber (6) in a setting direction (15) by means of expandable gases, and a prechamber (25) with which an ignition device (26) is associated and in which a pressure acting on the main combustion chamber (6) can build up prior to a fuel-air mixture being ignited in said main combustion chamber (6). To improve efficiency and/or functionality when driving in securing elements, the setting device (1) can be operated in different energy classes by means of an energy adjustment.