Central Universal Joint Connector for Wear-Resistant Torque Transfer

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Solution Overview

Problem

Universal joints experience premature wear and failure due to undue stress on the interior surfaces of the central connectors, leading to misalignment of the male and female connectors, making them difficult to maneuver and operate over time, and the relatively weak axles are prone to breakage.

Innovation Solution

A central connector with a substantially cylindrical body featuring a male spherically concave surface and a female spherically concave surface, allowing spherical tips to engage and maximize torque transfer surface area, along with a positioning spring housed in a separate opening to maintain connector alignment without wear.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If torque is transferred through the interior surfaces of openings housing the axles, then the universal joint functions to transmit torque, but the interior surfaces experience undue stress causing them to wear and widen over time

Engineering Contradiction:
Improvetorque transferVSAvoidopening integrity
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The invention divides the torque transfer function into two separate paths: one through the axle (for positioning) and one through the interior surface (for torque transfer). This segmentation allows each component to specialize in its optimal function, preventing the opening from bearing both loads simultaneously.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The interior surface acts as an intermediary element that transfers torque directly between the opening and the axle, eliminating the need for the opening to support the full torque load alone. This mediator distributes the stress and prevents opening degradation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If the axles are made relatively thin to fit within the openings, then the universal joint structure remains compact, but the axles become weak and prone to breakage under torque stress

Engineering Contradiction:
Improvestructural compactnessVSAvoidaxle strength
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The invention merges the torque transfer function with the opening structure by allowing the interior surface to actively participate in torque transfer. This combination means the axle no longer needs to be oversized to handle torque alone, maintaining compact dimensions while achieving sufficient strength through the combined torque path.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If the openings are enlarged to accommodate stronger axles, then the axles can handle higher torque, but the set springs can no longer maintain their bias to hold connectors in the desired position

Engineering Contradiction:
Improveaxle strengthVSAvoidconnector positioning
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The invention segments the functional requirements: the opening size is optimized for spring positioning (smaller), while torque capacity is achieved through the combined interior surface and axle torque path. This segmentation resolves the conflict between positioning accuracy and torque handling capability.

Inventive Principle:
Principle #1Segmentation

4Ease of manufacture

If the tips of the male and female drivers are cylindrically rounded, then the stirrup type central connector can receive them, but the rounded tips play no part in transferring torque

Engineering Contradiction:
Improveconnector compatibilityVSAvoidtorque transfer efficiency
Core Design Contradiction:
Ease of manufactureVSPower

Solution Approach 1:

The invention applies spherical curvature to the tips of the male and female drivers, which naturally conform to the spherical recesses in the central connector. This curved geometry maximizes surface area contact and enables the tips to actively participate in torque transfer, unlike cylindrical designs.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP3885596B1Universal joint connector and universal joint
Publication Date: 2023.08.16 STANLEY BLACK & DECKER MEA FZE
  • EP3885596B1 patent drawingFigure 1~2
  • EP3885596B1 patent drawingFigure 3
  • EP3885596B1 patent drawingFigure 4

AI summary

The present invention relates to a central connector for a universal joint and a universal joint utilizing said central connector. The central connector includes a substantially cylindrical body. The connector further includes a first and second pair of arms positioned orthogonal to one another. The body of the central connector also includes a male spherically concave surface between the first pair of arms, a female spherically concave surface between the second pair of arms. The body further defines an opening allowing communication between the male and female spherically concave surfaces.