Telescopic Lock Wedge Sleeve Axial Positioning

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Solution Overview

Problem

Existing locking devices for inner and outer tubes face challenges in providing a reliable and easy-to-operate locking function while maintaining low production costs, especially in applications requiring full control over locking and resistance to axial loads, with many devices being complex, costly, or unsuitable for demanding applications due to insufficient locking forces and complicated assembly.

Innovation Solution

A locking device featuring a tubular locking sleeve with a wedge-shaped slot and tangentially aligned wedge surfaces, actuated by a drive member rotating around the outer tube's axis, which presses the locking sleeve against the outer tube to achieve axial locking, allowing for self-locking without special friction materials and easy operation with minimal torque.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a locking member with conical expansion bodies and radially expendable clamping part is used, then locking force is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvelocking forceVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The locking member is divided into two functional parts: a locking sleeve that provides the locking interface and a drive member that actuates the locking action. This segmentation allows each component to be optimized independently, reducing overall complexity while maintaining locking force.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of using expansion bodies that radially expend a clamping part, the invention inverts the approach by using a locking sleeve with wedge-shaped slots that are pressed axially against the outer tube. The locking force is generated by the wedge shape converting axial pressure into radial clamping force, simplifying the mechanism.

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If a non-circular torsion rod with locking bodies is used, then locking reliability is improved, but ease of operation deteriorates due to large operating forces

Engineering Contradiction:
Improvelocking reliabilityVSAvoidease of operation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The invention replaces the torsion rod mechanism with a screw thread mechanism. The screw thread provides mechanical advantage, converting small rotational forces into large axial locking forces, thereby improving ease of operation while maintaining reliable locking through the wedge-shaped locking surfaces.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If a tubular locking sleeve with longitudinal wedge-shaped slot is used, then ease of operation is improved with minimal torque, but device complexity increases

Engineering Contradiction:
Improveease of operationVSAvoiddevice complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The drive member is designed to integrate multiple functions: it acts as the actuating mechanism, provides the screw thread for mechanical advantage, and includes a flange that interfaces with the locking sleeve. This merging of functions reduces the number of separate components, thereby reducing device complexity while maintaining ease of operation.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If multiple inner tubes and complicated assembly are used for self-locking, then locking reliability under axial loads is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvelocking reliability under axial loadsVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking sleeve is designed to be self-locking through its interaction with the outer tube. The wedge-shaped slots and the geometry of the locking surfaces create a self-locking mechanism that maintains reliability under axial loads without requiring additional inner tubes or complicated assembly procedures.

Inventive Principle:
Principle #25Self-service

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 reliable, easy-to-operate locking function with full control over locking, low production costs, and effective self-locking capabilities under axial loads, suitable for demanding applications with minimal operator effort and reduced wear.

Implementation Method 1

The locking member includes a tubular locking sleeve slotted by an axially aligned slot that has a wedge-shaped cut-out with essentially tangentially aligned wedge surfaces facing each other

Methodology Applied
Scientific EffectWedge: Wedge

Implementation Method 2

The displacement being effected by rotating the drive member around an axis that is essentially parallel with the outer tube's longitudinal axis

Methodology Applied
Scientific EffectScrew: Screw

Data Source

PatentEP2255096B1Telescopic lock
Publication Date: 2018.08.29 FAST INDPRODR
  • EP2255096B1 patent drawingFigure 1~2
  • EP2255096B1 patent drawingFigure 3~8
  • EP2255096B1 patent drawingFigure 9~10

AI summary

A locking device interacting with a drive member and including an inner tube (1) and an outer tube (3); where the inner tube (1) has a first free end that projects from, and is axially displaceable from, a first end of the outer tube; where there is a locking member (4) on the other end of the inner tube (1), said locking member (4) providing the means whereby the inner tube (1) and the outer tube (3) can be releasably locked in various axial positions relative to each other; where the locking member (4) includes a tubular locking sleeve (9) that is slotted by at least one axially aligned slot (13) - said slot including a wedge-shaped cut-out (113) with essentially tangentially aligned wedge surfaces (16) - and a wedge (14) that includes wedge surfaces (15), said wedge surfaces being, when acted upon by a drive member (41) that includes a thread groove (42), displaceable along and relative to interacting wedge surfaces (16) of the locking sleeve (9), such displacement pressing the locking sleeve (9) against the outer tube, the inner tube (1) and the outer tube (3) being thereby axially locked relative to each other, said displacement occurring through the drive member (41) being rotated around an axis that is essentially parallel with the longitudinal axis of the inner tube (1), the thread groove (42) thereby interacting with a thread (35); and, where the rotation of the drive member (41) occurs via a torsion rod (7) when the torsion rod (7) is rotated, relative to the inner tube (1), around a longitudinal axis that is essentially parallel with the longitudinal axis of the inner tube (1).