Spherical Surface Link Mechanism With Rigid Intermediate Hub Coupling

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Solution Overview

Problem

The existing parallel link mechanisms lack sufficient rigidity, particularly in the coupling of intermediate link members, which limits their operational efficiency and stability.

Innovation Solution

A spherical surface link mechanism with intermediate link hubs connected by a shaft member and bearings to enhance rigidity, allowing for improved coupling and reduced friction between components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If intermediate link members are not coupled to one another, then the structure is simpler, but the rigidity is insufficient

Engineering Contradiction:
ImproverigidityVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent couples intermediate link members together through intermediate link hubs and shaft members, merging previously separate components into an integrated structure. This coupling increases the overall rigidity of the parallel link mechanism while maintaining manageable structural complexity through systematic arrangement of the coupled components.

Inventive Principle:
Principle #5Merging (Combining)

2Ease of operation

If bearings are added to reduce friction, then the operation smoothness improves, but the device complexity increases

Engineering Contradiction:
Improveoperation smoothnessVSAvoidcomponent quantity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent introduces bearings as intermediary elements between the shaft members and intermediate link hubs. These bearings serve as mediators that reduce friction and enable smooth relative motion between coupled components, improving operational smoothness while containing the increase in device complexity through the use of standardized bearing components.

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 mechanism achieves enhanced rigidity, improved positioning accuracy, reduced interference, and lower manufacturing costs while maintaining smooth operation and reduced wear, as demonstrated by finite element analysis.

Implementation Method 1

A bearing that reduces friction between at least one of the plurality of intermediate link hubs and the shaft member

Methodology Applied
Scientific EffectFriction reduction: Lubrication

Data Source

PatentEP4238716B1Spherical surface link mechanism and spherical surface link actuating device
Publication Date: 2025.08.20 NTN CORP
  • EP4238716B1 patent drawingFigure 1
  • EP4238716B1 patent drawingFigure 2
  • EP4238716B1 patent drawingFigure 3

AI summary

A spherical surface link mechanism includes a proximal end link hub, a distal end link hub, a plurality of links, a plurality of intermediate link hubs, and a shaft member. Each of the plurality of links includes a first end link member, a second end link member, and an intermediate link member. The first end link member is coupled, at one end, to the proximal end link hub to be rotatable about a first rotation axis. The second end link member is coupled, at one end, to the distal end link hub to be rotatable about a second rotation axis. The intermediate link member is coupled, at one end, to the other end of the first end link member to be rotatable about a third rotation axis and is coupled to, at the other end, the other end of the second end link member about a fourth rotation axis.