Mechanical Shaft Lock Assembly for Hydraulic Isolation Plug Backup

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Solution Overview

Problem

Existing pipeline isolation tools rely on hydraulic actuation for locking, which can fail due to leaks or hydraulic system failures, leading to potential damage and operational failures from axial movement or rotation of shafts during maintenance or repairs.

Innovation Solution

A mechanical lock mechanism using teeth-form split grippers and a spring-loaded lock piston to securely lock the shaft against axial movement, allowing rotation while maintaining engagement, providing an additional safeguard against hydraulic lock failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If hydraulic actuation is used for locking, then the device can be operated remotely with high force, but the system becomes vulnerable to leaks and hydraulic failures

Engineering Contradiction:

Improvelocking forceVSAvoidsystem reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The locking system is segmented into two independent subsystems: a hydraulic actuation system for remote operation and a mechanical tooth engagement system for reliable locking. The mechanical lock with teeth-form split grippers and teeth-form ring provides a fail-safe mechanism that operates independently of the hydraulic system, thereby segmenting the functions to improve overall reliability while maintaining high locking force capability.

Inventive Principle:

Principle #1Segmentation

2Stability of the object's composition

If thread engagement is used for mechanical locking, then the shaft can be securely locked against axial movement, but the shaft cannot rotate without losing engagement

Engineering Contradiction:

Improveaxial position stabilityVSAvoidrotation capability

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The tooth geometry is designed with asymmetric features where the tooth profile includes a leading face that allows rotation and a trailing face that prevents reverse movement. This asymmetric tooth design enables the shaft to rotate in one direction while maintaining axial locking, resolving the contradiction between position stability and rotation capability.

Inventive Principle:

Principle #4Asymmetry

3Reliability

If a mechanical lock with teeth engagement is added to the hydraulic system, then reliability increases, but the device complexity increases

Engineering Contradiction:

Improvelock reliabilityVSAvoidmechanical structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The teeth-form split grippers are nested within the housing and can be radially collapsed around the shaft. The mechanical lock components are integrated into the existing hydraulic piston assembly, with the teeth-form ring mounted on the shaft and the split grippers positioned within the hydraulic cylinder bore. This nesting arrangement minimizes the additional space required and reduces overall structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Strength

If the shaft is mechanically locked with high load capacity, then the lock can withstand high working loads, but the dimensions of the lock increase

Engineering Contradiction:

Improveload capacityVSAvoidlock dimensions

Core Design Contradiction:

StrengthVSVolume of moving object

Solution Approach 1:

The tooth surfaces are designed with curved profiles that optimize stress distribution and engagement geometry. The circumferential teeth are arranged in a circular pattern around the shaft, and the tooth faces are angled to distribute loads evenly across multiple teeth during engagement. This curved geometry allows for high load capacity in a more compact configuration compared to straight-tooth designs.

Inventive Principle:

Principle #14Spheroidality (Curvature)

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

The mechanical lock enhances the reliability of the seal, reduces the risk of operational failure, and maintains high load capacity with compact dimensions, ensuring the shaft remains locked even under high working loads and pressure differentials.

Implementation Method 1

springs between them are compressed by the lock piston, which is pushed horizontally by a spring-loaded mechanism

Methodology Applied

Scientific EffectElastic potential energy: Elasticity

Data Source

PatentUS11346485B2Shaft mechanical lock for pipeline isolation tools

Publication Date: 2022.05.31 TDW DELAWARE INC

AI summary

A mechanical lock unit with a shaft lock assembly and method of achieving a self-lock mode for, e.g., hydraulically activated isolation plug module. The shaft lock assembly includes a teeth-form ring that surrounds a shaft. The teeth-form ring defines a plurality of teeth. A teeth-form split gripper assembly is positioned to surround the teeth-form ring. The teeth-form split gripper assembly has at least a first teeth-form split gripper and a second teeth-form split gripper with a spring therebetween for biasing the first teeth-form split gripper away from said second teeth-form split gripper. The first teeth-form split gripper and the second teeth form split gripper having an inner surface that defines a plurality of teeth for cooperative engagement with the plurality of teeth of the teeth-form ring.