Plastic Tie-Rod Fork Coupling for Secure Snap-On Rotary Assembly

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Solution Overview

Problem

Existing assemblies face challenges in providing an easy and secure coupling between a rotating element and a tie-rod, often leading to unwanted release during operation.

Innovation Solution

A coupling mechanism featuring a rotating element with a protruding coupling formation and grooves, and a tie-rod with elastically deformable tongues, allowing snap-on assembly without tools and preventing unintended uncoupling through angular orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a traditional coupling mechanism is used between the rotating element and tie-rod, then the connection is secure, but the assembly process becomes complex and requires fastening tools

Engineering Contradiction:
Improveease of assemblyVSAvoidcoupling mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The coupling formation is designed to perform multiple functions automatically: the wedge portion spreads the tongues apart to receive pins, the through hole guides pin insertion, and the grooves automatically engage with protrusions to lock the tie-rod in place. The entire coupling process occurs without external tools or additional fastening components, as the coupling formation itself provides all necessary functions for secure attachment.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If the tie-rod uses a simple snap-on coupling, then the assembly is easy, but the tie-rod may inadvertently release during operation

Engineering Contradiction:
Improveease of assemblyVSAvoidconnection stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The coupling mechanism incorporates dynamic elements that adapt to operational conditions. The grooves are positioned to engage with the protrusions only within a specific angular range of the tie-rod's stroke. During normal operation, when the tie-rod rotates within this angular range, the grooves maintain continuous engagement with the protrusions, providing automatic locking that prevents inadvertent release while allowing the necessary angular movement for function.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The grooves are pre-positioned on the coupling formation at specific angular locations that correspond to the operational range of the tie-rod. This preliminary positioning ensures that when the tie-rod is assembled and rotates into its working position, the protrusions automatically engage with the grooves before any operational forces are applied, establishing the locking action in advance to prevent unintended uncoupling during use.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If the coupling formation uses a wedge portion to spread tongues, then the tie-rod can be easily mounted, but the structure becomes more complex

Engineering Contradiction:
Improveease of mountingVSAvoidcoupling formation structure
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The coupling formation integrates multiple functional elements into a single unified structure: the wedge portion for spreading tongues, the through hole for pin reception, and the grooves for angular locking are all combined in one coupling formation that protrudes from the rotating element. This merging eliminates the need for separate components for each function, reducing overall assembly complexity while maintaining ease of mounting through the elastic deformation mechanism.

Inventive Principle:
Principle #5Merging (Combining)

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

Facilitates easy assembly and secure attachment of the tie-rod to the rotating element, preventing accidental release during operation.

Implementation Method 1

a top end of the coupling formation having a wedge portion configured to cause the tongues of the fork to temporarily spread apart during mounting of the tie-rod onto the rotating element

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

on said surface of the rotating element there is formed a pair of grooves arranged on opposite sides of the coupling formation, said grooves being configured to be engaged by respective end protrusions of the tongues in a partial range of the angular stroke of the tie-rod relative to the rotating element

Methodology Applied
Scientific EffectMechanical engagement: Mechanical Fastener

Data Source

PatentEP4357171B1Assembly comprising a rotating element and a tie-rod
Publication Date: 2025.07.16 DENSO THERMAL SYST SPA
  • EP4357171B1 patent drawingFigure 1~2
  • EP4357171B1 patent drawingFigure 3~4
  • EP4357171B1 patent drawingFigure 5~7

AI summary

Assembly comprising a rotating element (10, 20) of plastic material and a tie-rod (30) of plastic material coupled to the rotating element (10, 20), wherein the tie-rod (30) comprises a fork (32) formed by a pair of tongues (33) having respective pins extending towards each other, wherein the rotating element (10, 20) comprises on a surface (41) thereof facing towards the end of the tie-rod (30), a coupling formation (42) wherein a through hole, adapted to receive said pins, is formed, a top end of the coupling formation (42) having a wedge portion configured to cause the tongues (33) of the fork (32) to temporarily spread apart during mounting of the tie-rod (30) onto the rotating element (10, 20), on said surface (41) of the rotating element (10, 20) there is formed a pair of grooves (44) arranged on opposite sides of the coupling formation (42), and said grooves (44) being configured to be engaged by respective end protrusions of the tongues (33) in a partial range of the angular stroke of the tie-rod (30) relative to the rotating element (10, 20).