Swivel Joint Assembly with Spherical Contact Surfaces

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Solution Overview

Problem

Existing mechanical joint assemblies, such as ball joint assemblies, have limited contact accommodation capacity, high contact pressures, and poor lubricant retention, leading to reduced service life and increased complexity in assembly due to the need for additional blocking components to prevent translation along the axis of articulation.

Innovation Solution

A swivel assembly design featuring an elastic ring and complementary truncated spherical surfaces that allow for rotation while preventing translation, reducing contact pressures and enhancing lubricant retention without the need for additional blocking components, resulting in a compact, simple, and long-lasting assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If flat and parallel surfaces are used to allow translation movement, then movement freedom is improved, but contact accommodation capacity deteriorates

Engineering Contradiction:
Improvemovement freedomVSAvoidcontact accommodation capacity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces flat support planes with curved spherical surfaces. The intermediate member has a spherical outer surface that articulates within a spherical chamber of the outer body, creating point contact rather than line contact. This curvature increases contact accommodation capacity while still allowing the desired translation movement through the spherical geometry.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Ease of manufacture

If flat surfaces are used for support-plane connections, then manufacturing is simplified, but contact pressures increase

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidcontact pressures
Core Design Contradiction:
Ease of manufactureVSStress or pressure

Solution Approach 1:

The spherical contact surfaces distribute contact pressures more evenly across the interface between the intermediate member and outer body. The curved geometry increases the effective contact area compared to flat surfaces, reducing peak contact pressures while remaining manufacturable through standard spherical machining processes.

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Ease of operation

If flat surfaces are used for support-plane connections, then assembly is simplified, but lubricant retention capacity deteriorates

Engineering Contradiction:
Improveassembly simplicityVSAvoidlubricant retention capacity
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The spherical chamber geometry creates a self-retaining environment for lubricant. The curved surfaces naturally trap and retain lubricant through capillary action and geometric confinement, preventing lubricant escape during operation. This spherical configuration improves lubricant retention while maintaining assembly simplicity through the single-piece intermediate member design.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Stability of the object's composition

If blocking components are added to prevent translation along the axis of articulation, then positional stability is improved, but device complexity increases

Engineering Contradiction:
Improvepositional stabilityVSAvoidassembly complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The spherical contact geometry inherently prevents unwanted translation along the axis of articulation. The curved surfaces guide the intermediate member's movement, allowing translation perpendicular to the articulation axis while naturally constraining axial movement through the spherical interface. This eliminates the need for separate blocking components, reducing assembly complexity while maintaining positional stability.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP2261521B1Articulation device and method of assembly for such a device
Publication Date: 2013.02.13 SKF AEROSPACE FRANCE SAS
  • EP2261521B1 patent drawingFigure 1~3
  • EP2261521B1 patent drawingFigure 4
  • EP2261521B1 patent drawingFigure 5~6

AI summary

This assembly (1) comprises an inner ring (10), an intermediate member (20) housing the inner ring (10) around a pivot axis (Z20), and an outer body (30) retaining the intermediate member (20). The intermediate member (20) defines two first surfaces formed by cylindrical portions having the same first axis of revolution. The outer body (30) defines two second surfaces formed by cylindrical portions having the same second axis of revolution. The pivot axis and the first axis of revolution intersect. In the assembled state, the first and second axes of revolution coincide, and the first and second surfaces cooperate to allow rotation of the intermediate member relative to the outer body around the first axis of revolution, while preventing translation of this member parallel to the pivot axis or parallel to an axis orthogonal to the pivot axis and the second axis of revolution.