Segmented Guide Tube Vibration Damping for Hand-Held Tools

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Solution Overview

Problem

Hand-held tools with long guide tubes, such as hedge trimmers and pole pruners, experience vibrations during operation due to excitation forces, which are transferred to the grip points, leading to ergonomic issues and discomfort for users.

Innovation Solution

The guide tube is divided into two rigid sections connected via a vibration-damping element, such as a spring-damper, allowing for a change in vibration mode and reducing amplitudes at the gripping points, without requiring a telescopic design that extends the entire length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the guide tube is connected rigidly to the housing, then structural stability is improved, but vibration amplitudes at grip points increase

Engineering Contradiction:
Improvestructural stabilityVSAvoidvibration amplitudes at grip points
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The guide tube is divided into multiple sections (first section, second section, and further sections) that can be connected either rigidly or via anti-vibration elements. This segmentation allows different parts of the guide tube to have different connection characteristics, enabling structural stability in some regions while reducing vibrations in others, particularly at the grip points.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the connection parameter between guide tube sections from rigid to elastic by introducing anti-vibration elements. These elements modify the mechanical properties of the connection, allowing the system to adjust vibration transmission characteristics while maintaining structural integrity. The anti-vibration elements act as dampers that reduce vibration amplitudes without completely compromising structural stability.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a telescopic mechanism is used to adjust guide tube length, then adaptability is improved, but structural complexity increases

Engineering Contradiction:
Improvelength adjustabilityVSAvoidstructural complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The guide tube is constructed from multiple discrete sections that can be connected in different configurations. For telescopic applications, these sections can be arranged to allow length adjustment while maintaining the benefit of anti-vibration connections. The segmented structure enables both rigid and telescopic embodiments without requiring a completely different design approach.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The anti-vibration element design is universal and can be applied to both fixed-length and telescopic guide tubes. The same basic principle of connecting sections via anti-vibration elements works in both rigid and adjustable configurations, reducing the need for specialized components for each application type.

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

3Object-affected harmful factors

If the guide tube is made from multiple sections connected via anti-vibration elements, then vibration amplitudes are reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvevibration amplitudesVSAvoidmanufacturing complexity
Core Design Contradiction:
Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Dividing the guide tube into standardizable sections allows each segment to be manufactured independently using similar processes. The anti-vibration elements can also be produced as separate standardized components. This modular approach simplifies manufacturing by enabling parallel production of identical or similar parts, which can then be assembled through standardized connection procedures.

Inventive Principle:
Principle #1Segmentation

4Ease of operation

If grip points are positioned at antinodes for ergonomic reasons, then ease of operation is improved, but vibration amplitudes at grip points increase

Engineering Contradiction:
Improveergonomic positioningVSAvoidvibration amplitudes at grip points
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

By changing the connection parameters between guide tube sections from rigid to elastic, the patent modifies the vibration mode and natural frequency of the guide tube. This parameter change allows the system to maintain ergonomic grip point positioning while reducing the vibration amplitudes at those locations through the damping effect of the anti-vibration elements.

Inventive Principle:
Principle #35Parameter changes

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 reduces vibration amplitudes at the gripping points, enhancing ergonomics by altering the vibration pattern and providing sufficient rigidity to prevent buckling, while maintaining a fixed overall length or allowing adjustable length without rigid connection.

Implementation Method 1

A damping element is arranged between the guide tube and the housing of the drive motor

Methodology Applied
Scientific EffectVibration damping: Damping

Implementation Method 2

The anti-vibration element is, in particular, a spring-damper element, i.e., an element that possesses both spring and damping properties

Methodology Applied
Scientific EffectSpring-damper mechanism: Spring

Implementation Method 3

The second anti-vibration element consists at least partially of elastomer

Methodology Applied
Scientific EffectViscoelastic damping: Viscoelasticity

Data Source

PatentEP3533562B1Manually operated work device
Publication Date: 2022.04.06 ANDREAS STIHL AG & CO KG
  • EP3533562B1 patent drawingFigure 1~2
  • EP3533562B1 patent drawingFigure 3~5
  • EP3533562B1 patent drawingFigure 6~7

AI summary

A hand-held tool has a guide tube (2), wherein a first mass body (4) is arranged at a first end (3) of the guide tube (2) and a second mass body (7) is arranged at a second end (6) of the guide tube (2). One of the mass bodies (4) comprises at least a housing (5) and the other mass body (7) comprises at least one tool (8). The tool (8) is driven by a drive motor (9). Inside (10) of the guide tube (2), means (11) for energy transmission for driving the tool (8) are guided between the first end (3) and the second end (6) of the guide tube (2). A first anti-vibration element (12) is arranged between the first end (3) of the guide tube (2) and the first mass body (4). In the direction of its longitudinal central axis (21), the guide tube (2) comprises at least a first rigid section (13) and a second rigid section (14) which are connected to each other at a joint (15).At the joint (15) the first subsection (13) and the second subsection (14) are connected to each other via at least one second anti-vibration element (16).