Adjustable Piston Driving Device Combustion Control

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Solution Overview

Problem

Existing driving devices with propellant charges face challenges in optimizing driving energy and achieving residue-free combustion, as particles are not efficiently distributed and burned within the combustion chamber, leading to inconsistent driving energy delivery.

Innovation Solution

The driving device incorporates a movable slide to adjust the starting position of the piston member, creating a larger combustion chamber volume and utilizing a separating member with a central ejection area to deflect and distribute particles evenly, ensuring complete combustion and adjustable driving energy through a variable blow-off channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed combustion chamber volume is used, then the device structure is simple, but the driving energy cannot be adjusted

Engineering Contradiction:
Improveadjustability of driving energyVSAvoidcomplexity of combustion chamber structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The piston member is made movable relative to the combustion chamber, allowing the combustion chamber volume to be dynamically adjusted. The slide mechanism enables the piston to be positioned at different starting locations along the combustion chamber axis, transforming a static combustion chamber into a dynamic one that can adapt to different driving energy requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The combustion chamber is effectively segmented into variable sections by the movable piston. By adjusting the piston position, the usable combustion chamber volume is divided differently, allowing optimization of the combustion space for different propellant charges and driving energy requirements without redesigning the entire chamber.

Inventive Principle:
Principle #1Segmentation

2Reliability

If particles are not efficiently distributed in the combustion chamber, then the structure is simple, but combustion is incomplete and produces residue

Engineering Contradiction:
Improvecombustion completenessVSAvoidcomplexity of particle distribution mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The separating member introduces a radial dimension to particle distribution. By deflecting particles radially outward from the central axis onto the combustion chamber walls, the system transforms axial particle motion into radial motion, ensuring particles are distributed across the entire combustion chamber cross-section rather than concentrating along the central path.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The separating member acts as an intermediary element between the propellant charge and the combustion chamber. It intercepts particles ejected from the charge and redistributes them, mediating the interaction between particles and combustion chamber walls to achieve uniform distribution and complete combustion.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Adaptability or versatility

If multiple propellant charges of different strengths are used, then driving energy can be adjusted, but the device complexity increases

Engineering Contradiction:
Improverange of driving energiesVSAvoidnumber of propellant charge types
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single propellant charge design serves multiple functions by combining it with the adjustable piston mechanism. The same propellant charge can produce different driving energies depending on the piston starting position, eliminating the need for multiple specialized propellant charges and simplifying the overall system.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

Instead of changing the propellant charge composition or mass to adjust driving energy, the system changes the geometric parameter of the combustion chamber volume. By adjusting the piston position, the effective combustion volume parameter is changed, which directly affects the energy conversion efficiency and resulting driving force from the same propellant charge.

Inventive Principle:
Principle #35Parameter changes

4Power

If the piston acceleration path is long, then driving energy is high, but the combustion chamber volume must be large

Engineering Contradiction:
Improvedriving energyVSAvoidcombustion chamber volume
Core Design Contradiction:
PowerVSVolume of stationary object

Solution Approach 1:

The piston acceleration path is made dynamic and adjustable. By changing the piston starting position, the acceleration path length can be optimized for different power requirements without permanently increasing the combustion chamber volume. The same chamber serves multiple path length configurations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The piston position is preliminarily adjusted before ignition to set the desired acceleration path length. This preliminary positioning allows optimization of the combustion process parameters before the propellant charge is ignited, ensuring maximum energy transfer efficiency for the specific application requirements.

Inventive Principle:
Principle #10Preliminary 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 configuration allows for a wide range of driving energies to be achieved with a single propellant charge, ensuring efficient and reproducible combustion, reducing residue and the need for multiple propellant strengths, while maintaining a simple and effective mechanical implementation.

Implementation Method 1

a piston member (2) which is accelerated by expanding combustion gases resulting from the ignition of a pyrotechnic charge

Methodology Applied
Scientific EffectCombustion: Combustion

Implementation Method 2

the combustion chamber (3) is separated into a first partial chamber (3a) and a second partial chamber (3b) by means of a separating member (5) having a plurality of openings (6)... the powder grains are mainly burned in the upper partial chamber

Methodology Applied
Scientific EffectParticle distribution and combustion: Diffusion

Data Source

PatentEP3083154B1Driving device
Publication Date: 2018.10.10 HILTI AG
  • EP3083154B1 patent drawingFigure 1~2
  • EP3083154B1 patent drawingFigure 3~4
  • EP3083154B1 patent drawingFigure 5~6

AI summary

The invention relates to a driving-in tool, comprising a hand-held housing (1), having a piston member (2) received therein for transferring energy to a fastening element to be driven in, an interchangeable propelling charge and a combustion chamber (3) arranged between the propelling charge and the piston member (2), which preferably extends about a central axis (A), and an actuator (104) by means of which the energy transferred from the propellant charge to the piston member (2) can be variably adjusted, wherein a discharge channel (111) connected to the combustion chamber (3) can be unblocked by means of a movable slide (105) of the actuator (104), wherein a start position of the piston member (2) is variably adjustable by means of the slide (105).