Modular Rotor Bearing Assembly for Dry Generator Maintenance

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Solution Overview

Problem

Existing generator systems in flow power plants, such as tidal and hydroelectric power plants, require complex disassembly for servicing, leading to potential water ingress and increased corrosion of the rotor bearing due to the need for disassembly of sealing arrangements, which complicates maintenance.

Innovation Solution

A generator design with a rotor bearing arrangement that allows easy assembly and disassembly, featuring a detachable rotor bearing assembly unit with a hollow cylindrical bearing support and a locking device, enabling the rotor to be locked in place during removal, and a sealing arrangement to prevent water ingress, allowing the assembly to be removed as a whole without disassembling the generator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bearing is sealed using special seals that interact with the axle journal, then the bearing is protected from water and contaminants, but complex disassembly is required for servicing and water can penetrate into the bearing interior

Engineering Contradiction:
Improveprotection of bearing from waterVSAvoiddisassembly complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The bearing assembly is segmented into a modular unit that includes the bearing, sealing arrangement, and locking device as integrated components. This modular bearing assembly can be removed as a complete unit from the generator, allowing servicing without complex disassembly of the entire generator while maintaining water protection through the integrated sealing system.

Inventive Principle:
Principle #1Segmentation

2Ease of repair

If the rotor bearing assembly is removed for maintenance, then the bearing can be serviced, but water can ingress into the bearing interior leading to corrosion

Engineering Contradiction:
Improvemaintenance accessibilityVSAvoidwater ingress and corrosion
Core Design Contradiction:
Ease of repairVSObject-affected harmful factors

Solution Approach 1:

The locking device is designed to pre-lock the rotor in its mounted position before removal of the bearing assembly begins. This preliminary locking action prevents unwanted rotor movement and ensures stable conditions during the removal process, allowing the bearing assembly to be extracted without exposing it to water ingress risks.

Inventive Principle:
Principle #10Preliminary action

3Ease of repair

If the entire generator is disassembled for bearing servicing, then the bearing can be accessed, but the generator housing and other components must be reassembled

Engineering Contradiction:
Improvebearing accessibilityVSAvoiddisassembly and reassembly time
Core Design Contradiction:
Ease of repairVSLoss of time

Solution Approach 1:

The bearing assembly is extracted as a complete modular unit from the generator housing through the stator opening. The bearing, sealing arrangement, and locking device are taken out together as one assembly, allowing maintenance to be performed on the bearing without requiring disassembly of the generator housing or other components, thus eliminating reassembly time.

Inventive Principle:
Principle #2Taking out (Extraction)

4Ease of operation

If the rotor is not locked during removal, then the rotor bearing assembly can be removed, but the rotor may collide uncontrollably with the stator due to magnetic forces

Engineering Contradiction:
Improveassembly removalVSAvoidrotor position stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The locking device applies a preliminary counteracting force to the magnetic forces acting on the rotor before the bearing assembly is removed. By pre-locking the rotor in its mounted position, the device counteracts the magnetic attraction between the rotor and stator, preventing uncontrolled collision and ensuring stable rotor positioning throughout the removal operation.

Inventive Principle:
Principle #9Preliminary anti-action

Data Source

PatentEP4174307B1Rotor bearing assembly for a fluid power plant
Publication Date: 2025.09.10 AB SKF SKF PATENT DEPARTMENT
  • EP4174307B1 patent drawingFigure 1
  • EP4174307B1 patent drawingFigure 2

AI summary

A rotor bearing arrangement (100) for a generator (1), in particular an underwater generator, of a tidal power plant, in particular a tidal power plant, is disclosed, comprising a stationary axle journal (22) designed to spatially arrange a rotor (4) in a stator (2) and to hold it at a predetermined distance from the stator (2), and a bearing arrangement (25) designed to rotatably mount the rotor (4) on and around the axle journal (22), wherein the bearing arrangement (25) has a bearing support (26) that is rotationally fixed to the rotor (4) and has a hollow cylindrical bearing support section (26a) that defines a bearing support interior (50), and wherein the axle journal (22) extends into the bearing support interior (50), and wherein the hollow cylindrical bearing support section (26a) is dimensioned such that it can be inserted into a rotor interior (13) defined by the rotor (4) and detachably connectable to the rotor (4),so that the axle journal (22) and the bearing arrangement (25) are designed as an assembly unit which, as a whole, can be inserted into and removed from the rotor interior (13).