Shock Absorber Rebound Stop on Outer Tube

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Solution Overview

Problem

Traditional single-tube shock absorbers face stress and potential deterioration during the rebound phase due to the piston rod absorbing shock, leading to a limited lifespan.

Innovation Solution

A single-tube shock absorber design where the axial guide sleeve, with an annular piece carrying an elastic means, redirects the rebound force away from the piston rod, using an elastic stopper positioned between the inner and outer tubes to absorb shocks, ensuring the force is transmitted without passing through the main piston rod.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rebound stop is positioned on the piston to dampen shock during rebound contact, then the shock during rebound is dampened, but the piston rod is violently stressed and can lead to its deterioration

Engineering Contradiction:
Improveshock absorption during reboundVSAvoidpiston rod durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The rebound stop function is extracted from the piston assembly and relocated to the outer tube. The rebound stop is now positioned on the outer tube at a location that prevents contact with the piston during normal operation, thereby eliminating the stress transmission path to the piston rod while maintaining shock absorption capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

A new structural arrangement is introduced where the rebound stop on the outer tube acts as an intermediary element. When the piston contacts the rebound stop during rebound, the force is transmitted through the outer tube structure rather than through the piston rod, serving as a mediator that protects the piston rod from violent stresses

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the inner tube is allowed to move freely in the outer tube, then the shock absorber can respond to road irregularities, but the piston rod is subjected to violent stresses during rebound contact

Engineering Contradiction:
Improvemovement freedom for dampingVSAvoidpiston rod strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The rebound stop function is extracted from the piston assembly and relocated to the outer tube. The rebound stop is now positioned on the outer tube at a location that prevents contact with the piston during normal operation, thereby eliminating the stress transmission path to the piston rod while maintaining shock absorption capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of placing the rebound stop on the moving piston component, the invention inverts the approach by placing it on the stationary outer tube. This inversion changes the force transmission path from piston-rod to outer-tube structure, protecting the piston rod while maintaining the necessary movement freedom

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

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 configuration effectively absorbs rebound shocks without stressing the piston rod, thereby extending its lifespan and preventing damage, ensuring consistent performance.

Implementation Method 1

said annular part carries an elastic means capable of being compressed in abutment by a compression member linked to the structure of said inner tube

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP1930621B1Shock absorber with rebound stop fixed on the outer tube
Publication Date: 2009.10.28 DELPHI TECHNOLOGIES INC
  • EP1930621B1 patent drawingFigure 1
  • EP1930621B1 patent drawingFigure 2

AI summary

The absorber (100) has an inner tube (14) displaced in an outer tube (12), and a main piston (24) sliding inside the inner tube. The piston is connected to a bottom end (20) of the outer tube by a piston rod (18). An axial guiding sleeve (40) is positioned between the tubes and is terminated at its lower part by an annular piece i.e. cylindrical ring (44), which closes a cavity between the tubes. The piece carries an elastic unit e.g. rebound stop (136), which is compressed in thrust by a compression unit e.g. rebound stop surface (134), that is connected to a structure of the inner tube.