Swivel Joint Axial Stiffness Spider Segmentation

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Solution Overview

Problem

Universal joints currently exhibit low strength and stiffness in the axial direction due to bending stresses and deflection of the spider, making them inadequate for effectively transmitting tension and compression forces.

Innovation Solution

A swivel joint design featuring a center support and bearing support elements with arcuate surfaces, along with shim elements and connector assemblies, provides high axial stiffness and load capacity by creating a primary and secondary load path that can handle compressive and tensile forces without backlash.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a universal joint uses a traditional spider structure, then it allows motion in two degrees of freedom, but it exhibits low axial stiffness and strength due to bending stresses and deflection

Engineering Contradiction:

Improvemotion capabilityVSAvoidaxial stiffness

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The spider is divided into multiple bearing support elements (first, second, third, and fourth bearing support elements) that are distributed around the center support. Each bearing support element independently supports radial loads, preventing bending stresses and deflection of the entire spider structure, thereby maintaining axial stiffness while allowing rotational motion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bearing support elements are arranged in a three-dimensional configuration around the center support, with arcuate bearing surfaces that contact the yokes. This spatial distribution transforms the load-bearing capability from a planar structure susceptible to bending into a three-dimensional structure that resists axial loads effectively while maintaining rotational freedom.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Strength

If shims are added between bearing support elements and center support, then axial stiffness and load capacity increase, but device complexity increases

Engineering Contradiction:

Improveaxial load capacityVSAvoidnumber of components

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

Shims are introduced as intermediary elements positioned between the bearing support elements and the center support. These shims provide precise spacing and load distribution, enhancing the axial load capacity by creating a more rigid connection path while allowing for easy adjustment and assembly. The shims act as mediators that simplify the connection geometry while improving structural performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS8113733B2System having a high axial stiffness swivel joint

Publication Date: 2012.02.14 MTS SYSTEMS CORPORATION

AI summary

A system includes a support, an actuator and a swivel joint coupling the actuator to the support. The swivel joint includes a first base member, a second base member, and a spider positioned between the first and second base members. The spider includes a center support and first and second bearing support elements. Each bearing support element has an arcuate surfaces adapted to form joints with the first and second base members. In one embodiment, at least one shim element disposed is between at least one of the first and second bearing support elements and the center support.