Mechanical Shaft Lock Assembly for Pipeline Isolation Under Pressure Loss
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Solution Overview
Problem
Existing pipeline isolation tools face challenges in securely locking the shaft against axial movement and rotation, especially under high loads and in scenarios where hydraulic lock failure occurs due to leaks or pressure changes.
Innovation Solution
A mechanical lock system utilizing teeth-form split grippers and a spring-loaded lock piston for axial locking, allowing parallel teeth engagement that prevents axial movement while allowing rotation, providing an additional safeguard against hydraulic lock failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic actuation is used to lock the shaft, then the locking mechanism can be activated remotely, but the system becomes vulnerable to hydraulic leaks and pressure changes that can cause lock failure
Solution Approach 1:
A mechanical intermediary system (teeth-form split grippers and teeth-form ring) is introduced between the hydraulic actuation system and the shaft locking function. The hydraulic system activates the packer setting, while the mechanical teeth engagement provides independent shaft locking that prevents axial movement even if hydraulic pressure is lost, thus resolving the contradiction between remote activation and lock reliability
Solution Approach 2:
The patent implements a backup mechanical locking system that engages beforehand to prevent shaft movement. The teeth-form split grippers and teeth-form ring are designed to mechanically lock the shaft in position, serving as a pre-established safeguard against hydraulic system failures, thereby cushioning against the risk of lock failure while maintaining remote activation capability
2Reliability
If thread engagement is used for locking, then the shaft can be securely locked against axial movement, but the shaft cannot rotate without losing engagement
Solution Approach 1:
The patent employs asymmetric tooth geometry where the teeth are formed with specific orientation and shape that allows unidirectional engagement. The teeth-form split grippers and teeth-form ring feature asymmetric profiles that engage to prevent axial movement in one direction while allowing free rotation, thus resolving the contradiction between axial locking reliability and rotation capability through geometric asymmetry
3Reliability
If a mechanical lock system with teeth engagement is added, then the shaft locking reliability increases, but the device complexity increases
Solution Approach 1:
The mechanical locking system is segmented into modular components: teeth-form split grippers (itself segmented into multiple gripper elements), teeth-form ring, and spring-loaded actuator. This segmentation allows each component to be independently manufactured, assembled, and maintained, reducing overall system complexity while achieving reliable shaft locking through the collective action of simplified individual parts
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 and reduces the risk of operational failure by securely holding the shaft under high loads and maintaining engagement even at high pressures, ensuring the pipeline isolation tool functions effectively even when hydraulic lock is lost.
Implementation Method 1
The spring-loaded lock piston functions to maintain teeth engagement, which prevents the shaft from moving in an axial direction
Data Source
Figure 1A~1B
Figure 2~3
Figure 4~5
AI summary
A mechanical lock unit (10, 100, 210, 410) with a shaft lock assembly (12) and method of achieving a self-lock mode for, e.g., hydraulically activated isolation plug module. The shaft lock assembly (12) includes a teeth-form ring (30, 130, 230) that surrounds a shaft (14, 114, 214). The teeth-form ring (30, 130, 230) defines a plurality of teeth (38, 138, 238). A teeth-form split gripper assembly (340) is positioned to surround the teeth-form ring (30, 130, 230). The teeth-form split gripper assembly (340) has at least a first teeth-form split gripper (342) and a second teeth-form split gripper (344) with a spring (346) therebetween for biasing the first teeth-form split gripper (342) away from said second teeth-form split gripper (344). The first teeth-form split gripper (342) and the second teeth form split gripper (344) having an inner surface (348) that defines a plurality of teeth (350) for cooperative engagement with the plurality of teeth (38, 138, 238) of the teeth-form ring (30, 130, 230).