Profiled Tube Node Connection with Elastic Spring Element

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Solution Overview

Problem

Existing connection systems between profile tubes and node elements face issues with security and stability over time, especially under high loads and shaking movements, due to materials like plastic reinforced with glass fibers 'creeping' and partially slotted pins losing spring effect, leading to a wobbly and unreliable connection.

Innovation Solution

The use of metal coupling elements with a narrow web connecting two halves of an insert part, featuring a film hinge and a permanently elastic spring element, such as steel or beryllium bronze, to ensure resilient mobility and self-locking frictional engagement, allowing for a secure, compact, and non-wobbly connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If plastic reinforced with glass fibers is used for insert parts, then elasticity is provided, but the material creeps over time causing connection loosening

Engineering Contradiction:
Improveconnection stabilityVSAvoidconnection reliability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the material parameter from plastic to metal (specifically spring steel), fundamentally altering the elastic properties and creep resistance of the insert part. This material substitution eliminates the creeping issue while maintaining the necessary elasticity for the frictional connection mechanism to function.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite construction by combining metal insert parts with spring elements, creating a hybrid structure that leverages the high strength and creep resistance of metal while incorporating elastic components to maintain the frictional engagement capability under load.

Inventive Principle:
Principle #40Composite materials

2Stability of the object's composition

If partially slotted pins are used to provide elasticity, then spring effect is enabled, but the spring effect decreases towards the end of slots causing wobbly connection

Engineering Contradiction:
Improveconnection stabilityVSAvoidconnection firmness
Core Design Contradiction:
Stability of the object's compositionVSEase of operation

Solution Approach 1:

The patent changes the geometric parameter of the pin from partially slotted to fully slotless, eliminating the progressive rigidification issue. The complete slot configuration ensures uniform spring effect distribution along the entire pin length, preventing the wobbly connection that occurs with partial slotting.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent segments the pin into two separate contact areas (first and second contact areas) that can independently engage with the bore, allowing each area to spring uniformly without the diminishing effect caused by slot termination in partial slotting designs.

Inventive Principle:
Principle #1Segmentation

3Strength

If insert parts are made solid and pressed into profile tubes, then non-detachable connection is achieved, but resilient mobility is lost

Engineering Contradiction:
Improveconnection strengthVSAvoidresilient mobility
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The patent segments the solid insert part into two separate contact areas connected by a narrow web, creating a hinge-like structure. This segmentation allows the insert part to flex and provide resilient mobility while maintaining the overall structural integrity and press-fit connection strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The narrow web connecting the two contact areas acts as a flexible hinge, similar to a thin film structure, that enables controlled flexing and resilient mobility. This thin web provides the necessary flexibility while maintaining the connection strength of the press-fit assembly.

Inventive Principle:
Principle #30Flexible shells and thin films

4Ease of manufacture

If contact surfaces are made cylindrical, then simple manufacturing is achieved, but self-locking frictional engagement is not possible

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfrictional engagement reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent employs asymmetric contact surfaces where the pin and bore have non-cylindrical, elliptical cross-sections. This asymmetry creates the necessary geometric interference for self-locking frictional engagement, as the elliptical shapes cannot rotate freely and must engage at specific orientations, providing reliable mechanical locking.

Inventive Principle:
Principle #4Asymmetry

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 provides a secure, long-lasting, and compact connection that remains firm even under high loads and shaking movements, with the ability to be easily assembled and disassembled by hand, while maintaining axial rigidity and preventing axial movement of insert parts.

Implementation Method 1

a spring element (17) which allows the two contact areas (12, 13) to approach one another

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

two coupling elements (4, 5) that are plugged into one another come into self-locking frictional contact when they rotate against one another

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP2087244B8System of connection bewteen profiled tubes via node elements
Publication Date: 2011.10.05 REINHARD SACHSELN

AI summary

The invention relates to a system of connection between profiled tubes via node elements. This system comprises pin-shaped and bore-shaped coupling elements for the releasable connection of the profiled tubes to the node elements, wherein coupling elements can be fitted into one another and can at the same time be connected, at both ends of a profiled tube, to a node element in a force-fitting manner by means of a turning movement, wherein the pin-shaped coupling elements each comprise an insert part, which can be plugged into the profiled tubes at the end side, and two adjoining contact regions (12, 13). In order to releasably interconnect the coupling elements permanently, it is proposed to provide between the contact regions (12, 13) a slot (11) which extends over the entire axial length of the coupling element, and in the slot to arrange a spring element (17) which presses the contact regions (12, 13) into engagement with the bore-shaped coupling elements.