Rotor Shaft Sleeve Coupling for Easier Tidal Seal Maintenance

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Solution Overview

Problem

The existing rotor shaft connections in tidal plants are expensive to produce and complex to assemble and disassemble, particularly due to the difficulty in accessing and maintaining the sealing units around the rotor shaft.

Innovation Solution

A rotor shaft unit that uses a sleeve with a frictional engagement to connect the rotor shaft to the main frame, eliminating the need for a flange connection, allowing for easy assembly and disassembly, and providing access for sealing unit replacement through a frictional connection achieved by conical or cylindrical designs and hydraulic nut mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flange connection is used to connect the rotor shaft to the main frame, then the connection is rigid and stable, but the assembly and disassembly become complex and costly

Engineering Contradiction:
Improveconnection stabilityVSAvoidassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The connection system is segmented into three independent components: the main frame with its bore, the rotor shaft, and the removable sleeve. This segmentation allows the sleeve to be inserted into the bore and engage with the rotor shaft, providing a stable connection while enabling simple disassembly by removing the sleeve, thus resolving the contradiction between connection stability and assembly complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sleeve acts as an intermediary component between the main frame and the rotor shaft. It provides the frictional connection to the rotor shaft while being held by the main frame, creating a stable yet easily removable connection that eliminates the need for complex flange assemblies and welding operations

Inventive Principle:
Principle #24Intermediary (Mediator)

2Strength

If a flange connection is used to connect the rotor shaft to the main frame, then the connection is strong and secure, but the manufacturing cost increases

Engineering Contradiction:
Improveconnection strengthVSAvoidmanufacturing cost
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The complex flange connection and welding operations are extracted from the manufacturing process. Instead, a simple sleeve component is used that relies on frictional engagement, eliminating the need for expensive welding equipment, skilled welders, and complex flange manufacturing, thus reducing manufacturing costs while maintaining connection strength

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The sleeve is designed as a simple, inexpensive component that can be easily manufactured and replaced if needed. This disposable-like approach to the connection component reduces manufacturing costs significantly compared to permanent flange connections, while the frictional design ensures adequate connection strength during operation

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Reliability

If a flange connection is used, then the rotor shaft is securely fixed to the main frame, but the access to the sealing unit becomes difficult

Engineering Contradiction:
Improvefixing reliabilityVSAvoidsealing unit accessibility
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The connection system is segmented to allow the sealing unit to be accessed independently. The sleeve can be removed from the rotor shaft while the rotor shaft remains in the bore, providing easy access to the sealing unit for maintenance while the rotor shaft stays securely positioned in the main frame, thus resolving the contradiction between fixing reliability and repair accessibility

Inventive Principle:
Principle #1Segmentation

4Device complexity

If a frictional connection with conical seat is used, then the assembly is simplified, but the manufacturing precision requirements increase

Engineering Contradiction:
Improveassembly simplicityVSAvoidconical seat precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The conical seat provides self-centering and automatic alignment during assembly, which compensates for minor variations in manufacturing precision. The frictional engagement is designed to be sufficient without requiring extremely tight tolerances, allowing for practical manufacturing capabilities while achieving reliable assembly with simplified procedures

Inventive Principle:
Principle #16Partial or excessive action

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

This solution simplifies the assembly and disassembly of the rotor shaft unit, reduces manufacturing costs by eliminating the need for a flange, and facilitates easy maintenance of the sealing unit by allowing the rotor shaft to be removed and replaced without damaging the main frame.

Implementation Method 1

The sleeve (12) is connected to the rotor shaft (2) by frictional engagement

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3767116B1Rotor shaft unit
Publication Date: 2022.04.20 AB SKF SKF PATENT DEPARTMENT
  • EP3767116B1 patent drawingFigure 1

AI summary

A rotor shaft unit (1) for a tidal system is disclosed, comprising a rotor shaft (2) designed to be connected to a main frame (10) of the tidal system, and comprising at least one bearing unit (6) for supporting the rotor shaft (2) in a housing (4), wherein the housing (4) is designed to be connected to a rotor (8) of the tidal system, wherein the rotor shaft unit (1) has a sleeve (12) arranged around the rotor shaft (2) and connected to the rotor shaft (2) by friction, wherein the sleeve (12) is attached to the main frame (10).