Universal Joint Stranded Cable Torque Transmission

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Solution Overview

Problem

Conventional universal joints in downhole drilling operations are vulnerable to abrasion and erosion due to constant relative movement and harsh downhole conditions, leading to reduced operational life and increased maintenance costs.

Innovation Solution

A universal joint design featuring a stranded cable with flexible strands and terminating members that accommodate misalignment, transmitting torque and axial forces while minimizing wear and erosion, and incorporating a service life indicator to facilitate timely replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional universal joints with bearing surfaces are used, then torque transmission is achieved, but abrasion and erosion occur due to sliding or rotating contact surfaces

Engineering Contradiction:

Improveoperational lifeVSAvoidabrasion and erosion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional mechanical bearing surfaces with a flexible cable assembly that transmits torque through elastic deformation and strand flexing rather than sliding or rotating contact. This substitution eliminates the harmful friction and wear mechanisms inherent in traditional bearing surfaces while maintaining torque transmission capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a flexible cable composed of multiple strands that can bend and flex to accommodate misalignment between shafts. This flexible structure transmits torque through the elasticity and flexibility of the cable itself, avoiding rigid contact surfaces that are susceptible to abrasion and erosion in harsh downhole environments.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If conventional sealing arrangements are implemented, then protection against abrasive drilling mud is improved, but difficulties arise due to constant relative movement of components

Engineering Contradiction:

Improveprotection against abrasionVSAvoidsealing arrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the sealing arrangement entirely by replacing the conventional universal joint mechanism with a flexible cable assembly. Since the cable flexes rather than relying on sliding contact between rigid components, there are no mating surfaces requiring sealing, thus removing the complexity and failure points associated with sealing in constant relative movement applications.

Inventive Principle:

Principle #2Taking out (Extraction)

3Length of moving object

If drill string components are positioned closer together, then drill string length is reduced, but misalignment accommodation becomes more challenging

Engineering Contradiction:

Improvedrill string lengthVSAvoidmisalignment accommodation

Core Design Contradiction:

Length of moving objectVSAdaptability or versatility

Solution Approach 1:

The flexible cable assembly inherently accommodates misalignment between shafts through its ability to bend and flex at various angles. This flexibility allows components to be positioned closer together while still maintaining the capability to absorb and accommodate rotational eccentricity and angular misalignment that occurs in downhole drilling operations.

Inventive Principle:

Principle #30Flexible shells and thin films

Data Source

PatentUS10316895B2Universal joint

Publication Date: 2019.06.11 ULTERRA DRILLING TECHNOLOGIES LP

AI summary

A universal joint assembled to a drill string transfers torque and axial force between two components where the shafts of the components are not completely aligned. The universal joint includes end members connected to opposite ends of a cable for connecting to components of the drill string. As the joint rotates the cable flexes to accommodate misalignment between the connected drill string components.