Rotatable Tie Rod Cable Pulling Device

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Solution Overview

Problem

Existing cable pulling devices often require twisting the draw-in spring to prevent sticking, leading to increased tensile forces and potential cable damage, necessitating repeated retraction processes.

Innovation Solution

A device with a freely rotatable and captive tie rod within a cylindrical sleeve, featuring a plastic sleeve extension and a robust connection system, including a thickened end region and a stop, allows the cable to rotate freely and reduces the risk of disruptive gaps, ensuring a resilient and simplified cable retraction process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the draw-in spring is twisted during advance to prevent sticking, then the cable can be pulled through, but increased tensile forces occur which can result in the cable tearing off the device

Engineering Contradiction:
Improvecable retraction reliabilityVSAvoidtensile force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The tie rod is designed to be freely rotatable within the sleeve, allowing the cable to rotate dynamically during retraction instead of being constrained in a fixed position. This rotational freedom prevents the cable from getting stuck and reduces tensile forces by allowing natural movement and alignment adjustments during the retraction process.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the tie rod is fixed in the sleeve, then the connection is stable, but the cable cannot rotate freely leading to sticking and increased tensile forces

Engineering Contradiction:
Improvetie rod connection stabilityVSAvoidcable retraction ease
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The tie rod is designed to be freely rotatable within the sleeve, allowing the cable to rotate dynamically during retraction instead of being constrained in a fixed position. This rotational freedom prevents the cable from getting stuck and reduces tensile forces by allowing natural movement and alignment adjustments during the retraction process.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The plastic sleeve acts as an intermediary element between the tie rod and the extension, providing a low-friction surface that enables free rotation while maintaining structural integrity. This intermediary component facilitates smooth relative movement between parts without compromising the overall connection stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a robust connection is made between the tie rod and sleeve, then the device is reliable, but production complexity increases

Engineering Contradiction:
Improvedevice reliabilityVSAvoiddevice structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The plastic sleeve acts as an intermediary element between the tie rod and the extension, providing a low-friction surface that enables free rotation while maintaining structural integrity. This intermediary component facilitates smooth relative movement between parts without compromising the overall connection stability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The design changes the friction parameter at the interface between the tie rod and sleeve by introducing the plastic sleeve, which has lower friction characteristics. This parameter change enables free rotation while maintaining a relatively simple structural design without requiring complex mechanisms.

Inventive Principle:
Principle #35Parameter changes

4Strength

If the extension fully covers the plastic sleeve, then the connection is secure, but disruptive gaps may occur affecting cable retraction

Engineering Contradiction:
Improveconnection strengthVSAvoidcable retraction reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The extension partially covers the plastic sleeve rather than fully enclosing it, creating a deliberate local opening that prevents gap formation. This local quality change in the coverage design allows the cable to pass through smoothly without creating disruptive gaps, while still maintaining sufficient connection strength through the partial coverage and friction fit.

Inventive Principle:
Principle #3Local quality

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 prevents cable damage by allowing free rotation of the cable relative to the draw-in spring, reducing tensile forces and simplifying the retraction process, while maintaining a robust and reliable connection.

Implementation Method 1

that at the second end of the sleeve a plastic sleeve partially covering extension is arranged

Methodology Applied
Scientific EffectFriction reduction: Friction

Implementation Method 2

a first opening at a first end for connection to a pulling element, preferably a pulling spring

Methodology Applied
Scientific EffectElastic energy storage: Elasticity

Data Source

PatentEP3114739B1Device for pulling in cables
Publication Date: 2018.12.12 HASLACHER & HASLACHER IMMOBILIEN & PATENTVERW
  • EP3114739B1 patent drawingFigure 1~3
  • EP3114739B1 patent drawingFigure 4~6
  • EP3114739B1 patent drawingFigure 7~13

AI summary

The invention relates to a device for pulling in cables or the like, comprising a substantially cylindrical sleeve (1), which at a first end (8) has a first opening (9) for connecting to a retracting spring (2), wherein at a second end (11) of the sleeve (1) located opposite the first end (8) thereof, a flexible retracting spring tip is mounted, composed of a tension rod (4) having a plastic sheath (5), and of a head piece (6) having a receptacle (7, 7a) for a cable to be pulled in. The device is characterized in that the tension rod (4) is accommodated in the sleeve (1) in a freely rotatable and captive manner.