Fluid Damper Guide Bushing Wear Reduction

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Solution Overview

Problem

Existing fluid dampers for furniture components suffer from frictional wear and tear, leading to reduced durability and performance, as well as difficulties in adjustment and manufacturing complexity.

Innovation Solution

A fluid damper design featuring a guide bushing with disc-shaped flange portions and multiple fluid passages, along with elastic material and a resilient spring, which maintains the bushing's axial position and reduces counter-pressure, minimizing frictional contact and wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a piston ring made of resiliently deformable material is used to provide frictional force during piston stroke, then damping force is generated, but the piston ring is highly prone to frictional wear and tear

Engineering Contradiction:
Improvedamping forceVSAvoidwear resistance
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The patent replaces the mechanical friction-based damping system (piston ring rubbing against cylinder wall) with a fluid-based damping system. The piston rod moves through fluid passages in the guide bushing, creating damping force through fluid resistance rather than direct mechanical friction. This substitution eliminates the wear problem while maintaining the damping function.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces fluid (hydraulic/pneumatic system) into the damping mechanism. Fluid passages are formed in the guide bushing, and the piston rod moves through these passages, generating damping force through fluid viscosity and pressure. This hydraulic approach replaces the worn-prone mechanical piston ring with a wear-resistant fluid-based system.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Adaptability or versatility

If the guide bushing is made movable with the piston rod, then the damper assembly can be adjusted, but the bearing point rubs against the cylinder inner wall causing frictional wear and tear

Engineering Contradiction:
ImproveadjustabilityVSAvoidwear resistance
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the mechanical sliding contact between the movable guide bushing and cylinder wall with fluid-based damping. Instead of the bushing rubbing against the wall, fluid passages are created through the bushing, and damping occurs through fluid resistance as the piston rod moves through these passages, eliminating direct mechanical friction.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The guide bushing is designed with fluid passages (porous structure) that allow fluid flow while providing damping. The passages can be formed by drilling, boring, or other methods, creating a porous-like structure that enables fluid-based damping without requiring mechanical sliding contact, thus preventing wear.

Inventive Principle:
Principle #31Porous materials

3Force

If slight spatial allowance is provided between the mechanism and cylinder inner wall for fluid flow, then damping force is generated, but this raises counter-pressure within the cylinder

Engineering Contradiction:
Improvedamping forceVSAvoidcounter-pressure
Core Design Contradiction:
ForceVSStress or pressure

Solution Approach 1:

The patent divides the fluid flow path into multiple segmented passages within the guide bushing. Instead of relying on a single narrow gap between the mechanism and cylinder wall, the fluid flows through multiple defined passages, distributing the flow and reducing pressure buildup while maintaining damping force.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The guide bushing with its internal fluid passages acts as an intermediary structure that mediates between the piston rod movement and the fluid pressure. The passages provide controlled fluid flow paths that reduce counter-pressure while still generating adequate damping force, serving as a mediator that optimizes the pressure-flow relationship.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 design enhances durability and ease of assembly, reduces frictional wear, and maintains damping performance by stabilizing the guide bushing and allowing efficient fluid displacement, resulting in a robust and easily manufactured fluid damper.

Implementation Method 1

The interior space of the housing is filled with a viscous fluid, so when the mechanism moves within the interior space, it experiences some degree of drag owing to its obstruction against fluid flow from one side of mechanism to another.

Methodology Applied
Scientific EffectViscous drag: Viscous Damping

Implementation Method 2

a deformable fluid absorbent coat having a longitudinal slit is provided. This coat encompasses the central portion of the guide casing and lowers the counter-pressure within the cylinder so that a smaller force is required when depressing the piston rod of the fluid damper.

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP2016248B1Fluid damper
Publication Date: 2010.05.05 HARN MARKETING
  • EP2016248B1 patent drawingFigure 1~2B
  • EP2016248B1 patent drawingFigure 3
  • EP2016248B1 patent drawingFigure 4~5B

AI summary

A fluid damper for use in applications such as furniture is provided. The fluid damper comprises a cylinder (10) having an open end (13) and a closed end (14) with a piston disposed within the cylinder. The piston has a piston rod (2) for moving the piston between the open and closed end of the cylinder with the piston rod extending out of the cylinder open end through a seal (4). A guide bushing (100, 200) having a central hollow shaft (110, 210) for guiding the piston rod is disposed within the cylinder. The guide bushing allows damping fluid to flow in the space (17) between the central shaft and cylinder wall. In one embodiment, elastic material (5) is located in the space between the guide bushing central shaft and cylinder wall with the elastic material comprising multiple pieces that are individually compressible by the damping fluid as the piston moves to the closed end of the cylinder. In another embodiment, a respective flange portion (130, 140, 230, 240) is provided at each longitudinal end of the guide bushing with each flange portion extending radially to the cylinder wall. The two flange portions constitute the sole bearing surfaces for the piston rod within the cylinder.