Non-Round Metallic Snap Ring for Rosette Fitting Assembly

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Solution Overview

Problem

Existing rosette fittings for doors and windows are complex to assemble, risk damaging elastomer components during disassembly, and have a deep overall structure, which complicates manufacturing and increases assembly time and transport costs.

Innovation Solution

A rosette set using a non-round metallic snap ring that can be clipped into the substructure part's outer groove and expands radially into the cover rosette's inner groove, allowing for orthogonal assembly and providing a secure, anti-twist connection without requiring high dimensional accuracy, and can be easily detached using a rosette lifter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a torsion spring is used as the retaining element, then the connection between substructure part and cover rosette is secure, but the mounting process becomes complicated and time-consuming

Engineering Contradiction:
Improveconnection securityVSAvoidmounting time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the geometric parameter of the snap ring from circular to non-circular (oval or elliptical shape). This parameter change allows the snap ring to be easily inserted in a compressed state and then expand to engage with the grooves, transforming a complex torsion spring mechanism into a simple elastic deformation process that reduces mounting time while maintaining secure connection

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of extending the retaining element (as required by torsion springs), the patent uses compression to insert the snap ring. The snap ring is compressed to fit into the outer circumferential groove, then naturally expands to lock in place. This inverted approach (compression vs. extension) simplifies the mounting process significantly

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

2Ease of operation

If an O-ring-shaped elastomeric element is used, then the assembly is simple, but the elastomeric part is damaged or destroyed during disassembly

Engineering Contradiction:
Improveassembly simplicityVSAvoidcomponent durability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the material parameter from elastomeric to metallic, and the geometric parameter from circular to non-circular. The metallic snap ring with oval/elliptical cross-section provides both the simplicity of elastomeric assembly and the durability of metal construction, as it can be repeatedly compressed and expanded without damage

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The snap ring is designed to dynamically change its diameter through elastic deformation. During assembly, it is compressed to a smaller diameter for insertion, then expands to its natural diameter to engage the grooves. This dynamic behavior allows easy assembly and disassembly while maintaining structural integrity and component durability

Inventive Principle:
Principle #15Dynamics

3Strength

If traditional rosette designs are used, then sufficient retaining strength is achieved, but the overall installation depth becomes large

Engineering Contradiction:
Improveretaining strengthVSAvoidinstallation depth
Core Design Contradiction:
StrengthVSLength of stationary object

Solution Approach 1:

The patent moves the retaining function from the axial dimension to the radial dimension. The snap ring engages with grooves through radial expansion, creating a secure connection without requiring significant axial depth. This dimensional shift allows shallow installation while maintaining strong retaining capability

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The snap ring is nested within the grooves of the substructure part and cover rosette. The oval/elliptical snap ring fits within the outer circumferential groove, and when expanded, engages with the inner circumferential groove, creating a compact nested arrangement that minimizes installation depth while providing secure retention

Inventive Principle:
Principle #7Nested doll (Nesting)

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 design simplifies assembly and disassembly, reduces the overall depth of the rosette set, lowers assembly time, and allows for mass production of doors with reduced transport volume, minimizing the risk of damage and theft by enabling on-site assembly of cover rosettes with a minimal axial construction depth.

Implementation Method 1

the snap ring can be displaced radially inwards and then snaps into the inner circumferential groove of the cover rosette with elastic expansion radially outwards

Methodology Applied
Scientific EffectElastic expansion: Elasticity

Implementation Method 2

the snap ring can be displaced radially outwards by slight expansion and subsequently snaps into the outer circumferential groove of the substructure part by elastic contraction radially inwards

Methodology Applied
Scientific EffectElastic contraction: Elasticity

Data Source

PatentEP3243983B1Rosette fitting for key or locking cylinder opening or for handles for doors or windows
Publication Date: 2020.07.22 HAFI BESCHLÄGE GMBH
  • EP3243983B1 patent drawingFigure 1
  • EP3243983B1 patent drawingFigure 2
  • EP3243983B1 patent drawingFigure 3

AI summary

The invention relates to a rosette set (2) for a key or cylinder opening or for handles on doors or windows, comprising a substructure part (4) mountable against a door or window sash, having an outer circumferential groove (14), a cover rosette (8) with an inner circumferential groove (32), and a metallic retaining element (6) that does not extend circumferentially and has a circumferential shape deviating from the circular shape, and which, in the mounted state, is received between the substructure part (4) and the cover rosette (8) and, in this state, bears against the substructure part (4) in some areas with its inner circumference and against the cover rosette (8) in some areas with its outer circumference.