Telescopic Guide Tube Clamp for Tool-Free Tube Locking

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Solution Overview

Problem

Existing telescopic devices with clamping mechanisms face challenges in simplicity of operation and reliability, particularly in fixing the inner tube relative to the outer tube, often requiring overcoming friction on conical surfaces or using components like screws that can be lost.

Innovation Solution

A hand-held tool with a telescopic section featuring a clamping device where a rotatably mounted clamping piece is connected to the outer tube via a threaded connection, utilizing a curved clamping ring that compresses axially to fix the inner tube, allowing for adjustable clamping force without tools and accommodating non-circular cross-sectional shapes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a clamping element with conical surfaces is used to fix the telescopic section, then the clamping force can be adjusted, but friction on the conical surfaces must first be overcome making operation difficult

Engineering Contradiction:
Improveclamping forceVSAvoidoperation difficulty
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The patent replaces the conical surfaces with a curved clamping ring that has a circular cross-section. This curved design eliminates the friction problem associated with conical surfaces while maintaining the ability to apply adjustable clamping force through axial compression of the ring.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If screws are used to tighten the clamping piece, then the telescopic section can be fixed securely, but components may be lost when fully released

Engineering Contradiction:
Improvefixing reliabilityVSAvoidcomponent loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent removes screws and other small fastening components from the clamping mechanism. The clamping piece is designed to be retained on the outer tube through its structural integration, eliminating the risk of component loss while maintaining secure fixing capability.

Inventive Principle:
Principle #2Taking out (Extraction)

3Device complexity

If a simple clamping mechanism is used, then the design is simple, but the clamping force cannot be easily adjusted

Engineering Contradiction:
Improvedesign simplicityVSAvoidadjustability
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The patent employs a resilient clamping ring that can be dynamically compressed axially to adjust the clamping force. This dynamic compression capability allows easy adjustment of clamping force while maintaining a simple overall design without complex mechanisms.

Inventive Principle:
Principle #15Dynamics

4Speed

If a threaded connection with large pitch is used, then the clamping piece moves quickly, but the torque required is high requiring tools

Engineering Contradiction:
Improveadjustment speedVSAvoidtool requirement
Core Design Contradiction:
SpeedVSEase of operation

Solution Approach 1:

The patent uses a fine-pitch threaded connection that requires low torque to operate, enabling manual adjustment without tools. The fine pitch design trades some adjustment speed for reduced torque requirements, making the mechanism operable by hand.

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

The solution provides a simple, tool-free operation for fixing and loosening the telescopic section, ensuring secure clamping with adjustable force, suitable for various cross-sectional shapes, and reduces the risk of lost components, enhancing operational efficiency and user convenience.

Implementation Method 1

The clamping piece (13) is connected to the outer tube (11) via a threaded connection (16), wherein the clamping piece (13) is movable relative to the outer tube (11) via the threaded connection (16)

Methodology Applied
Scientific EffectThreaded connection: Screw

Implementation Method 2

At least one resilient clamping ring (14) is arranged on an outer circumference of the inner tube (10), which is supported with one axial side against the outer tube (11) and with the other axial side against the clamping piece (13), wherein the clamping ring (14) is compressible in an axial direction

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3058808B1Hand-held work device with a telescopic section
Publication Date: 2021.08.18 ANDREAS STIHL AG & CO KG
  • EP3058808B1 patent drawingFigure 1~3
  • EP3058808B1 patent drawingFigure 4~7
  • EP3058808B1 patent drawingFigure 8~12

AI summary

A hand-held tool has a drive motor (41) and a tool unit (3) comprising a tool driven by the drive motor (41). The tool has a guide tube (4) with a telescopic section (9) comprising an outer tube (11) and an inner tube (10) guided longitudinally within it. Means for transmitting the drive energy to the tool are routed through the guide tube (4). A clamping device (12) is provided to fix the inner tube (10) relative to the outer tube (11). The clamping device (12) comprises a clamping element (13) which is rotatably mounted relative to the inner tube (10) and connected to the outer tube (11) via a threaded connection. The clamping device (12) includes at least one curved clamping ring (14) arranged on the outer circumference of the inner tube (10). Compressing the clamping ring in the direction of a longitudinal center axis (39) of the guide tube (4) reduces the opening of the clamping ring.The at least one clamping ring (14) is supported on one axial side against the outer tube and on the other axial side against the clamping piece (13).