Striker-Controlled Pneumatic Air Spring for Hand-Held Power Tools

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Solution Overview

Problem

Existing hand-held percussion tools with pneumatic percussion mechanisms have complex and costly air spring control systems, requiring numerous components and increasing device weight and manufacturing costs.

Innovation Solution

The air spring is directly controlled via a striker that acts as a shut-off body, simplifying the control mechanism and reducing the number of components, with a pot-shaped striker and seals to manage ventilation openings, allowing for reduced length and weight while enabling precise control of the air spring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex air spring control system with multiple components is used, then the air spring can be controlled reliably, but the device weight and manufacturing costs increase

Engineering Contradiction:
Improveair spring control reliabilityVSAvoiddevice weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The control function for the air spring is merged into the striker itself. The striker is designed with an integrated control element that directly controls the ventilation openings of the air spring, eliminating the need for separate control components. This integration maintains reliable control while significantly reducing device weight and component count.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The striker is given multiple functions: it serves as both the impact tool that strikes the workpiece and the control element that regulates the air spring. By making the striker universal, the patent eliminates dedicated control components, reducing overall device weight while maintaining functional reliability.

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

2Reliability

If a complex air spring control system with multiple components is used, then the air spring can be controlled reliably, but manufacturing costs increase

Engineering Contradiction:
Improveair spring control reliabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The control function for the air spring is merged into the striker itself. The striker is designed with an integrated control element that directly controls the ventilation openings of the air spring, eliminating the need for separate control components. This integration maintains reliable control while significantly reducing device weight and component count.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The striker is given multiple functions: it serves as both the impact tool that strikes the workpiece and the control element that regulates the air spring. By making the striker universal, the patent eliminates dedicated control components, reducing overall device weight while maintaining functional reliability.

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

3Weight of moving object

If the striker is designed with integrated air spring control, then the number of components and device weight are reduced, but the control mechanism must be simplified

Engineering Contradiction:
Improvedevice weightVSAvoidcontrol mechanism complexity
Core Design Contradiction:
Weight of moving objectVSDevice complexity

Solution Approach 1:

The control function for the air spring is merged into the striker itself. The striker is designed with an integrated control element that directly controls the ventilation openings of the air spring, eliminating the need for separate control components. This integration maintains reliable control while significantly reducing device weight and component count.

Inventive Principle:
Principle #5Merging (Combining)

4Volume of stationary object

If the striker directly controls the air spring, then the space required and manufacturing costs are reduced, but the valve control mechanism must be simplified

Engineering Contradiction:
Improvespace requiredVSAvoidvalve control complexity
Core Design Contradiction:
Volume of stationary objectVSDevice complexity

Solution Approach 1:

The control function for the air spring is merged into the striker itself. The striker is designed with an integrated control element that directly controls the ventilation openings of the air spring, eliminating the need for separate control components. This integration maintains reliable control while significantly reducing device weight and component count.

Inventive Principle:
Principle #5Merging (Combining)

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 solution simplifies air spring control, reduces device weight and manufacturing costs, and allows for adjustable impact power based on the force applied to a workpiece, enhancing operational efficiency and reliability.

Implementation Method 1

an air spring (25) which can be switched on and off and which, when switched on, stores energy elastically

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the striker (24) forms a shut-off body of a valve (26) that controls the air spring (25)

Methodology Applied
Scientific EffectValve control: Valve

Implementation Method 3

a first seal (27) of the valve (26) is provided between the guide tube (21) and the valve section (36)

Methodology Applied
Scientific EffectSealing:

Data Source

PatentEP1955823B1Hand held power tool with pneumatic striking mechanism
Publication Date: 2013.07.17 HILTI AG
  • EP1955823B1 patent drawingFigure 1
  • EP1955823B1 patent drawingFigure 2
  • EP1955823B1 patent drawingFigure 3

AI summary

The invention relates to a hand-held power tool with a pneumatic impact mechanism (20) driven by a motor, comprising an exciter element (22) movable back and forth in a guide tube (21), a striking piston (23) movably guided in the guide tube (21) and driven by an air spring (25) via the exciter element (22), which acts on a striker (24), wherein the air spring (25) can be switched on and off. To improve such a hand-held power tool, the air spring (25) can be switched on and off directly via the striker (24).