Elastic Bushing With Gradual Coupling Surfaces for Force-Fit Assembly

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Solution Overview

Problem

Existing elastic bushings for connecting axles or pins to frames in vehicles are prone to torsional fatigue, require precise mechanical working, and have high assembly costs and complexity, with issues like difficult insertion and potential breakage under radial loads, leading to reduced reliability and increased assembly time.

Innovation Solution

An improved elastic bushing design featuring a cylindrical tubular element of self-lubricating material, an intermediate elastically deformable ring, and a plastic outer ring with gradual coupling surfaces and stop collars, allowing for force-fitting assembly without lubricants and reducing the risk of deformation or breakage, while providing enhanced resistance to slipping and radial compression.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If discrete ribs are used on the rubber ring for friction connection, then assembly precision requirements are reduced, but assembly time increases and lubricants are required

Engineering Contradiction:
Improveassembly precisionVSAvoidassembly speed
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent uses a continuous flexible ring made of thermoplastic elastomer material instead of discrete rigid ribs. This continuous ring provides uniform friction contact with the seat during assembly, eliminating the need for lubricants while maintaining ease of assembly. The flexibility of the thin film ring allows it to deform during insertion and then maintain continuous contact for friction-based fixation.

Inventive Principle:
Principle #30Flexible shells and thin films

2Strength

If high assembly force is applied to force-fit the bushing, then connection strength is improved, but the rubber ring deforms excessively and may break the collar

Engineering Contradiction:
Improveconnection strengthVSAvoidrisk of breakage
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the material parameter of the outer ring from traditional rubber to thermoplastic elastomer, which has different mechanical properties including higher elasticity and recoverability. This material parameter change allows the ring to withstand high assembly forces without permanent deformation or breakage, while still providing sufficient connection strength through controlled elastic deformation during force-fitting.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The design incorporates a collar with controlled thickness and material properties that acts as a cushioning element before the high assembly force reaches the tubular element. The collar deforms elastically under assembly load, absorbing and distributing the stress to prevent breakage of more critical components while maintaining connection integrity.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Strength

If the outer ring is made rigid for structural support, then radial load resistance is improved, but assembly difficulty increases and lubricants are needed

Engineering Contradiction:
Improveradial load resistanceVSAvoidassembly ease
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent employs a dynamic material solution using thermoplastic elastomer that exhibits different mechanical behaviors during assembly versus operation. During assembly, the material is sufficiently flexible to allow force-fitting without lubricants. During operation under radial loads, the material maintains adequate rigidity through its elastic properties and the reinforcing annular section, providing structural support while retaining assembly ease.

Inventive Principle:
Principle #15Dynamics

4Reliability

If the bushing design requires precise mechanical working of seats, then connection reliability is improved, but manufacturing cost and complexity increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The continuous flexible ring design naturally conforms to the seat geometry during assembly through elastic deformation, providing self-aligning and self-centering effects. This flexibility compensates for variations in seat manufacturing precision, maintaining connection reliability without requiring complex machining operations or tight tolerances on the seat, thereby reducing manufacturing complexity.

Inventive Principle:
Principle #30Flexible shells and thin films

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 improved bushing facilitates quicker, cost-effective assembly with reduced wear and increased reliability, enabling efficient absorption of radial stresses and thrusts without compromising the structural integrity of the tubular element, thus enhancing operational performance and longevity.

Implementation Method 1

cylindrical tubular element made of self-lubricating material

Methodology Applied
Scientific EffectSelf-lubrication: Lubrication

Implementation Method 2

intermediate ring made of an elastically deformable material

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 3

outer ring made of plastic material adapted to deform, on assembly

Methodology Applied
Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP2992230B1Improved elastic bushing
Publication Date: 2018.07.18 SAV
  • EP2992230B1 patent drawingFigure 1~7
  • EP2992230B1 patent drawingFigure 8~10

AI summary

The present invention relates to an elastic bushing, particularly for use in the goods transport vehicle sector. More specifically, the invention relates to an improved elastic bushing (1) comprising: - a cylindrical tubular element (2) made of self-lubricating material, - an intermediate ring (3) made of an elastically deformable material, wherein said tubular element (2) and said intermediate ring (3), at one end (2', 3') thereof, are respectively provided with stop collars (4, 5). Said elastic bushing (1) further comprises an outer ring (6) made of plastic material adapted to deform, on assembly, to allow the bushing (1 ) to be forced into a respective assembly seat (100), wherein said outer ring (6) has along its side wall a reinforced annular section (16) and at least one gradual coupling surface (26) between said reinforced annular section (16) and the end (6") of said outer ring opposite said stop collars (4, 5).