Elastic Articulation Joint Structure for Breakaway Torque Elimination

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Solution Overview

Problem

Ball joints exhibit a breakaway torque due to static friction, which hinders movement and leads to increased wear, reducing positioning accuracy and causing contamination issues, especially in clean room applications.

Innovation Solution

A joint design featuring elastically deformable web sections and a support element, where the web sections intersect in non-parallel planes, allowing for easy assembly and reducing parts, with prestressing to minimize breakaway torque and enhance flexibility across rotational degrees of freedom.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a ball joint with ball head and socket is used, then rotational freedom in all three spatial axes is achieved, but breakaway torque occurs due to static friction

Engineering Contradiction:
Improverotational freedomVSAvoidbreakaway torque
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The invention replaces the traditional ball head and socket friction pair with a magnetic field-based coupling system. Magnets embedded in the ball head and corresponding magnetic elements in the socket create magnetic attraction forces that replace mechanical friction, eliminating static friction and breakaway torque while maintaining rotational freedom in all three spatial axes.

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

2Adaptability or versatility

If a ball joint with ball head and socket is used, then rotational movement is enabled, but wear increases due to friction between ball head and socket

Engineering Contradiction:
Improverotational movementVSAvoidwear
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention substitutes the mechanical contact-based ball head and socket system with a magnetic field-based interaction system. The magnetic coupling between magnets in the ball head and magnetic elements in the socket eliminates direct mechanical contact and friction, thereby preventing wear while enabling rotational movement in all three spatial axes.

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

3Measurement precision

If a ball joint with ball head and socket is used, then positioning is enabled, but positioning accuracy reduces due to wear and breakaway torque

Engineering Contradiction:
Improvepositioning accuracyVSAvoidwear and breakaway torque
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention replaces the friction-based mechanical ball head and socket system with a magnetic field-based system that eliminates both breakaway torque and wear. The magnetic coupling provides smooth, frictionless rotational control in all three spatial axes, significantly improving positioning accuracy and reliability for positioning applications.

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

4Adaptability or versatility

If a ball joint with ball head and socket is used, then rotational freedom is achieved, but contamination occurs due to wear particles

Engineering Contradiction:
Improverotational freedomVSAvoidcontamination from wear particles
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The invention substitutes the mechanical friction-based ball head and socket system with a magnetic field-based system that eliminates direct mechanical contact. By using magnetic attraction forces instead of friction, the system prevents generation of wear particles and contamination, while maintaining full rotational freedom in all three spatial axes.

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

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 joint eliminates breakaway torque, reduces wear, and maintains positioning accuracy while being cost-effective and easy to assemble, suitable for applications requiring high precision and cleanliness.

Implementation Method 1

at least two elastically deformable joint elements (3) formed on the support element (2) in an at least partially overlapping arrangement

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

prestressing to minimize breakaway torque and enhance flexibility across rotational degrees of freedom

Methodology Applied
Scientific EffectPrestressing: Tension

Implementation Method 3

the two rod-shaped web sections of each joint element extend either in such a way that they converge towards each other, or that they diverge away from each other

Methodology Applied
Scientific EffectGeometric configuration: Geometry

Data Source

PatentEP3649356B1Articulation
Publication Date: 2021.06.09 PHYSIK INSTRUMENTE (PI) GMBH & CO KG
  • EP3649356B1 patent drawingFigure 1
  • EP3649356B1 patent drawingFigure 2

AI summary

The invention relates to a joint having at least three degrees of freedom of rotation, having a rigid carrier element and at least two elastically deformable joint elements, provided on the carrier element in an overlapping arrangement, at least in sections, wherein each of the joint elements has two rod-shaped web portions arranged on the carrier element and extending therefrom, which are arranged either convergently or divergently relative to each other, and are connected to each other via a contact portion on the end thereof facing away from the carrier element, wherein two web portions connected to each other extend in a first common plane and the other two web portions, connected to each other, extend in a second common plane, and the first common plane and the second common plane intersect. The invention further relates to a parallel-kinematic adjustment device having at least one joint according to the invention.