Integrated Axial Locking Device for Subsea Motor-Compressor Bearing Protection

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Solution Overview

Problem

Subsea motor-compressor units face damage to landing bearings due to shocks during installation or transportation, as existing axial locking devices require external access to the rotating shaft and lack protection once disconnected from piping.

Innovation Solution

An axial locking device is integrated within the casing, comprising an actuator member that can selectively lock and unlock the shaft, using a pressurized fluid system to apply a thrust force parallel to the rotation axis, preventing shocks from damaging the bearings during installation and allowing operation once correctly positioned.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an axial locking device is placed externally to lock the shaft, then the bearings are protected from shock damage, but the device requires external access to the shaft which is not available once the turbomachine is connected to piping

Engineering Contradiction:

Improvebearing protectionVSAvoidshaft accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The axial locking device is nested inside the casing, with the locking element positioned within the internal volume of the turbomachine. The actuator operates through the drive end cover without requiring external shaft access, effectively placing the locking mechanism 'inside' the protected environment while maintaining operational capability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The drive end cover acts as an intermediary element that transmits the locking action from the external actuator to the internal shaft. The actuator applies force through the cover, which then engages the locking element with the shaft, eliminating the need for direct external shaft access while maintaining the locking function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the axial locking device is activated continuously, then the bearings are always protected from shocks, but the device cannot be easily deactivated for normal operation

Engineering Contradiction:

Improvebearing protectionVSAvoidoperational flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The axial locking device transitions from a static locked state to a dynamic controllable state. The actuator enables the locking element to be engaged or disengaged from the shaft based on operational requirements, allowing the system to adapt between protection mode during installation and normal operation mode when deployed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The locking device operates periodically rather than continuously - engaged during installation and transportation, disengaged during normal operation, and re-engaged when needed. This periodic activation pattern provides both bearing protection when required and operational flexibility when the turbomachine is in its final position.

Inventive Principle:

Principle #19Periodic action

3Strength

If a mechanical locking mechanism is used, then the shaft is securely locked against shocks, but the mechanism increases the complexity of the device

Engineering Contradiction:

Improvelocking forceVSAvoidlocking mechanism complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The complex control and power transmission mechanisms are extracted from the locking element itself and placed in the actuator. The locking element is simplified to contain only the essential locking feature that engages with the shaft, while the actuator handles all the complexity of force generation and transmission.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Complex mechanical power transmission through gears, linkages, or multiple moving parts is replaced with a more direct actuation system. The actuator applies force directly through the drive end cover to engage the locking element, eliminating intermediate mechanical stages and reducing overall system complexity while maintaining locking strength.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 axial locking device effectively prevents damage to bearings during installation and transportation by locking the shaft internally, ensuring the motor-compressor unit can be safely placed on the seafloor without external access, and can be easily activated or deactivated for operation, enhancing reliability and reducing maintenance costs.

Implementation Method 1

using a pressurized fluid system to apply a thrust force parallel to the rotation axis

Methodology Applied

Scientific EffectPressurized fluid system: Hydraulic Press

Implementation Method 2

magnetic bearings, or active magnetic bearings have been introduced in this kind of machinery

Methodology Applied

Scientific EffectMagnetic bearings: Maglev

Data Source

PatentUS10697421B2Integrated turbomachine with an axial locking device

Publication Date: 2020.06.30 NUOVO PIGNONE SPA

AI summary

An integrated turbomachine is described, comprising: a casing; an electric motor and a driven turbomachine component housed in the casing; a rotating shaft drivingly connecting the electric motor and the driven turbomachine component; a thrust bearing and a radial bearing rotatingly supporting the shaft; an axial locking device housed inside the casing, for applying a thrust to the shaft, parallel to the rotation axis (A-A) of the shaft, and comprised of an actuator member, configured to selectively activate and/or deactivate the axial locking device.