Pyrotechnic Driving Device Combustion Chamber Segmentation
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Solution Overview
Problem
Existing handheld driving devices with propellant charges face challenges in achieving uniform and complete combustion of pyrotechnic charges, as unburnt powder grains can escape and not be fully ignited due to the design of the combustion chamber.
Innovation Solution
A driving device with a separating member that includes a contiguous, non-perforated central region with a recess and perforations, where discharged particles are deflected and scattered, ensuring uniform distribution and ignition within the upper partial chamber, and the design of the energy transmission element and fastening means facilitates optimal combustion and energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the combustion chamber is separated by a perforated sieve into upper and lower partial chambers, then powder grains are held back and combusted in the upper partial chamber, but unburnt powder grains can still escape through the perforations and combustion uniformity is not achieved
Solution Approach 1:
The separating member is segmented into two distinct functional zones: a central region with a contiguous non-perforated surface and a peripheral region with perforations. This segmentation allows different parts of the charge to be treated differently - central particles are reflected back for complete combustion while peripheral particles pass through for controlled burning, resolving the contradiction between combustion completeness and structural complexity.
Solution Approach 2:
Different regions of the separating member are given different properties: the central region has a smooth non-perforated surface for reflecting particles back into the upper chamber, while the peripheral region has perforations for controlled particle passage. This local differentiation of properties enables the system to achieve both complete combustion and manageable structural complexity.
2Productivity
If powder grains are initially driven ahead of a flame front following ignition, then combustion progresses through the charge, but unburnt grains escape before complete combustion occurs
Solution Approach 1:
The contiguous central surface of the separating member acts as a preliminary anti-action by reflecting unburnt particles back into the upper partial chamber before they can escape. This pre-empts the problem of incomplete combustion by reversing the escape trajectory of unburnt grains, allowing them to be ignited by the flame front that subsequently passes through the perforations.
Solution Approach 2:
The rapid discharge of particles ahead of the flame front, which initially causes incomplete combustion, is converted into a benefit by using the separating member to reflect these particles back. The same particle velocity that causes escape is now utilized to drive particles back into the combustion zone where they can be completely burned, transforming the harmful escape effect into a beneficial recirculation effect.
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 ensures uniform and complete combustion of the propellant charge, preventing unburnt residues and optimizing the expansion of combustion gases for efficient energy transmission to the fastening means, thereby enhancing the reliability and performance of the driving device.
Implementation Method 1
particles of the charge that are discharged into the combustion chamber after ignition are first reflected or deflected, regardless of their size, before they come into contact with one of the perforations
Implementation Method 2
the particles can distribute themselves uniformly in the upper partial chamber while they are caught by the flame front and likewise ignited
Implementation Method 3
the resulting combustion gases, following the ignition of a pyrotechnic charge, expand in a combustion chamber. Thereby a piston as an energy transmission means is accelerated and drives a fastening means into a workpiece
Data Source
AI summary
The invention relates to a driving device, comprising a hand-held housing having an energy transmission element accommodated therein for transmitting energy to a fastening element to be driven in, an exchangeable propellant charge and a combustion chamber arranged between the propellant charge and the energy transmission element, said combustion chamber extending about a central axis, wherein the combustion chamber is subdivided by means of a dividing member having a number of interruptions into a first subchamber adjoining the propellant charge and at least one second subchamber adjoining the energy transmission element, wherein an ejection region, enclosing a central axis, for the propellant charge is provided in the first subchamber, said ejection region extending between the propellant charge and a central region of the dividing member, wherein the ejection region is bounded at the central region of the dividing member by a closed surface of the dividing member.