Fin Stabilizer Sliding-Tooth Drive for Low-Backlash Torque Control

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Solution Overview

Problem

Traditional fin roll stabilizers for marine vessels face challenges with hydraulic systems, including complexity, maintenance difficulties, environmental concerns, and potential for fires, as well as inefficiencies and backlash issues with direct drive electric motors.

Innovation Solution

An oscillating separate individual sliding tooth drive system using a logarithmic spiral design for improved torque control and reduced backlash, allowing for flexible motor placement and the use of standardized components to accommodate varied fin and torque requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If traditional hydraulic systems are used to power fin roll stabilizers, then sufficient torque and power can be achieved, but the system complexity increases significantly with multiple components including pumps, valves, cylinders, and extensive plumbing

Engineering Contradiction:

ImprovetorqueVSAvoidsystem complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The drive system is divided into modular units, each with its own motor and drive element assembly that can be independently installed and maintained. The housing contains integrated bearing assemblies and drive mechanisms that are segmented from the hydraulic system entirely, allowing for simplified installation and maintenance while delivering required torque to the fin shaft.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the hydraulic mechanical system with an electric motor system. Electric motors directly drive the stabilizer fins through integrated drive elements, eliminating the need for hydraulic pumps, valves, cylinders, and extensive plumbing while providing sufficient torque and power for vessel stabilization.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Power

If hydraulic systems are used for fin roll stabilizers, then power transmission is achieved, but maintenance becomes difficult due to enclosed plumbing and components requiring system shutdown and disassembly

Engineering Contradiction:

Improvepower transmissionVSAvoidmaintenance access

Core Design Contradiction:

PowerVSEase of repair

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electric motor system is inherently more maintainable than hydraulic systems. Motors can be easily accessed, inspected, and replaced without specialized hydraulic equipment or extensive disassembly of enclosed plumbing. The modular design allows for quick swaps and minimal downtime during maintenance operations.

Inventive Principle:

Principle #25Self-service

3Power

If hydraulic systems are used in marine vessels, then power transmission is achieved, but environmental harm occurs when hydraulic oil leaks into the bilge and is pumped out into the ocean

Engineering Contradiction:

Improvepower transmissionVSAvoidenvironmental harm

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Device complexity

If direct drive electric motors with planetary gear sets are used, then hydraulic system complexity is reduced, but backlash and positioning errors increase due to gear wear

Engineering Contradiction:

Improvesystem complexityVSAvoidpositioning precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

Instead of using traditional planetary gear sets that suffer from backlash, the patent employs a direct drive configuration where the motor shaft is directly coupled to the fin shaft through integrated drive elements. This eliminates intermediate gears and their associated backlash, maintaining positioning precision while reducing mechanical complexity.

Inventive Principle:

Principle #13The other way round (Inversion)

5Manufacturing precision

If strain wave gear sets are used to eliminate backlash, then positioning precision improves, but torque capacity is limited and the system becomes less efficient

Engineering Contradiction:

Improvepositioning precisionVSAvoidtorque capacity

Core Design Contradiction:

Manufacturing precisionVSPower

Solution Approach 1:

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3724063B1Fin stabilizer

Publication Date: 2023.03.22 NAIAD MARITIME GRP

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AI summary

A vessel hull stabilization system includes a housing having a rotatable shaft mounted thereto, the shaft configured to connect to a fin such that the fin is located on an outside of the vessel hull and the housing is located on an inside of the vessel hull. A drive system is mounted to the housing and includes a motor and a drive element. The motor is connected to a central shaft of the drive element and an outer element of the drive element is connected to the fin shaft. The drive element includes a plurality of teeth positioned between the outer element and the central shaft such that when the motor rotates the central shaft, the plurality of teeth oscillate in a direction perpendicular to an axis of the central shaft to interact with and rotate the outer element.