Spindle Sleeve Load Transfer for Dual-Pipe Axial Force Capture

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Solution Overview

Problem

In horizontal directional drilling, dual pipe systems face misalignment issues during pipe section makeup, leading to potential damage from axial forces transmitted to inner drive shaft bearings, which are not designed to handle such loads.

Innovation Solution

The spindle assembly redirects axial forces from the inner drive rod to the outer member and subsequently to the outer drive shaft, utilizing a stop member and hollow sleeve configuration that allows torque transmission while enabling independent rotation of inner and outer pipes, thereby distributing axial loads to larger, more robust outer gearbox bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If axial force is transmitted through the inner drive shaft bearings during pipe section makeup, then the pipe sections can be connected, but the bearings are damaged due to being not designed to handle such loads

Engineering Contradiction:

Improvepipe section makeupVSAvoidbearing damage

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The hollow sleeve acts as an intermediary component that redirects the axial force path. During pipe section makeup, the axial force is transmitted through the hollow sleeve to the outer drive shaft rather than directly through the inner drive shaft bearings, which are not designed to handle such loads. This mediator component protects the vulnerable bearings while enabling the pipe connection operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The drive system is segmented into independent inner and outer members that can rotate independently. The inner drive shaft and outer drive shaft are separated by the hollow sleeve, allowing each to handle specific force components. This segmentation enables the outer shaft to bear the axial loads during makeup while the inner shaft focuses on torque transmission for rotation.

Inventive Principle:

Principle #1Segmentation

2Strength

If the inner and outer pipes are connected rigidly, then axial force transmission is direct, but the inner drive shaft bearings are not designed to handle such loads

Engineering Contradiction:

Improveaxial force transmissionVSAvoidbearing load capacity

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The hollow sleeve serves as a mediator that redirects axial force from the inner drive shaft to the outer drive shaft. This allows strong axial force transmission through the robust outer shaft while protecting the weaker inner shaft bearings from excessive loads.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The force transmission path is shifted from one dimension (inner shaft vertical load) to another dimension (outer shaft vertical load). By utilizing the outer drive shaft as the primary load-bearing element for axial forces, the system leverages the structural advantages of the outer member while preserving the inner member for rotational functions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If the inner drive shaft bearings handle axial loads, then pipe makeup is simplified, but the bearings suffer potential damage

Engineering Contradiction:

Improvemakeup operation efficiencyVSAvoidbearing damage from axial loads

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The hollow sleeve mediates the force transmission during makeup operations, directing axial loads through the outer drive shaft instead of the inner drive shaft bearings. This protects the bearings from harmful loads while maintaining efficient pipe section connection operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The design converts the potential harm of axial load transmission into a beneficial arrangement where the robust outer drive shaft absorbs the axial loads that would otherwise damage the inner bearings. The hollow sleeve structure itself, which might seem to add complexity, actually provides the force redirection pathway that protects the system.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

This configuration prevents damage to the gearbox by transferring axial loads to the outer drive shaft, ensuring reliable operation and reducing the risk of mechanical failure during drilling operations.

Implementation Method 1

The hollow sleeve is joined to the inner member in sliding, torque-transmitting engagement with the inner drive shaft

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

The at least one pin is configured to transmit axial force from the hollow sleeve to the outer member

Methodology Applied

Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentUS11708724B2Apparatus for capturing axial force on an inner drive member

Publication Date: 2023.07.25 CHARLES MACHINE WORKS INC

AI summary

A spindle with a mechanism for transferring axial force from an inner drive assembly to an outer drive assembly. The spindle's inner drive shaft is connected to an inner member of a dual-rod pipe by a drive rod having a sliding sleeve. The sleeve is fixed rotationally with the drive shaft, but not axially. When axial force drives the drive rod toward the drive member of the spindle, the sleeve contacts a stop member which is paired to the outer drive assembly. The stop member may be a pair of dowel pins. Axial force is thereby transferred from the inner member to the outer member, allowing such forces to be absorbed by the outer member's larger drive components.