Retractable Thruster Lifting Spindle Layout to Prevent Buckling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing retractable thruster systems for marine vessels face challenges with buckling risks due to compressive loads, particularly with hydraulic cylinders and spindles, which lead to complex and costly structures with increased space requirements and handling difficulties.

Innovation Solution

A lifting spindle arrangement with a lifting spindle and nut, supported by lower and upper assemblies with locking members that allow axial movement, reducing the risk of buckling by maintaining tensile stress and eliminating the need for external locking systems, enabling the use of smaller diameter spindles and electric motor-driven operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hydraulic cylinders are used to push the thruster upward, then the system is reliable and simple to design, but the build-in space is larger and there is risk of buckling of the rods

Engineering Contradiction:

Improvesystem reliabilityVSAvoidbuild-in space

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

Instead of using hydraulic cylinders to push the thruster upward (compressive force), the patent uses spindles to pull the thruster upward (tensile force). This inversion of the force direction eliminates buckling risk and reduces build-in space requirements while maintaining system reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent replaces the hydraulic cylinder mechanical system with a spindle-based mechanical system that uses tensile rather than compressive forces, eliminating the need for hydraulic fluid and associated piping while reducing space requirements.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Volume of stationary object

If threaded spindles are used to push the thruster upward, then the build-in space is compact, but the spindles are subject to buckling loads and require large diameter

Engineering Contradiction:

Improvebuild-in spaceVSAvoidspindle strength

Core Design Contradiction:

Volume of stationary objectVSStrength

Solution Approach 1:

The patent inverts the force application from compressive (pushing) to tensile (pulling). By having the spindle pull the thruster upward rather than push it, the spindle is subjected to tensile loads only, eliminating buckling risks and allowing for smaller, more efficient spindle dimensions.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If large diameter spindles are used to resist buckling, then the buckling risk is reduced, but the driving torque requirement increases and the structure becomes complex

Engineering Contradiction:

Improvebuckling resistanceVSAvoiddriving torque

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

By inverting the force direction from compressive to tensile, the patent eliminates buckling risks entirely. This allows the use of smaller diameter spindles with lower moment of inertia, significantly reducing the driving torque requirement and simplifying the overall structure while maintaining or improving reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

4Ease of operation

If external locking systems are added to hydraulic cylinders, then the locking function is achieved, but the device complexity and cost increase

Engineering Contradiction:

Improvelocking functionVSAvoidsystem complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the hydraulic cylinder system with a spindle system that inherently provides positioning through its threaded engagement with the nut. This eliminates the need for separate external locking systems, reducing device complexity and cost while maintaining the locking function.

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 solution reduces the risk of buckling, allows for compact and cost-effective designs with no underwater parts, and simplifies installation by maintaining tensile stress in the spindle, enabling higher load application with smaller diameters and reducing complexity and cost.

Implementation Method 1

a lifting spindle arrangement having a lifting spindle, a lifting nut, and a motor, and having a lower end and an upper end

Methodology Applied

Scientific EffectScrew mechanism: Screw

Implementation Method 2

one of the lifting spindle and the lifting nut is fixed and the other is rotatable for moving the retractable thruster unit

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS11427292B2Lifting spindle arrangement for a retractable thruster unit of a marine vessel

Publication Date: 2022.08.30 WARTSILA NETHERLANDS

AI summary

A lifting spindle arrangement is disclosed for a retractable thruster unit of a marine vessel, the lifting spindle having a lower end and an upper end and being supported at its lower end to a lower support structure by a lower support assembly and at its upper end to an upper support structure by an upper support assembly. The lifting spindle is provided at its both ends with a locking member for such a connection to the support structures such that each end of the lifting spindle may freely move in an axial direction away from the opposite end of the lifting spindle.