Coupling Mechanism for Wind Turbine Gearbox and Generator Misalignment

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Solution Overview

Problem

Wind turbines with integrated medium-speed electric generators face challenges in compensating for axial, radial, and angular misalignments, leading to increased forces and moments that affect the torsional moment transfer, making it difficult to achieve a weight-optimized construction.

Innovation Solution

A coupling means, such as a sun wheel shaft or double-disk clutch, is arranged between the planetary gear and the generator shaft to compensate for these misalignments, with a transmission output shaft designed to have a specific length and configuration to minimize the impact of these displacements, and a sealing element to maintain lubrication and isolation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the gearbox and generator are directly flanged to one another in a compact integrated drive train, then the overall length and device complexity are reduced, but axial, radial and angular misalignments occur due to manufacturing and assembly tolerances, leading to increased forces and moments that affect torsional moment transfer

Engineering Contradiction:
Improveoverall length of drive trainVSAvoidtorsional moment transfer
Core Design Contradiction:
Length of moving objectVSReliability

Solution Approach 1:

A coupling device is introduced as an intermediary component between the gearbox output shaft and the generator drive shaft. This coupling device includes a first coupling element connected to the gearbox output shaft and a second coupling element connected to the generator drive shaft, with a coupling arm connecting these two elements. The coupling device compensates for misalignments while maintaining reliable torsional moment transfer, resolving the contradiction between compact design and reliable power transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If a common bearing is used for the gearbox output shaft and generator drive shaft in a coaxial arrangement, then device complexity is reduced, but the bearing is subjected to extraordinary stresses from both the rotor and generator forces combined with static and dynamic torques

Engineering Contradiction:
Improvenumber of bearingsVSAvoidbearing load capacity
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The bearing support function is segmented into separate bearings for the gearbox output shaft and the generator drive shaft. Instead of using a single common bearing that must withstand combined loads from both the rotor and generator, the invention employs separate bearing arrangements that can be independently sized and optimized for their specific load conditions, reducing the stress on each individual bearing.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If the transmission output shaft is made short to achieve a compact design, then device complexity is reduced, but the ability to compensate for misalignments and minimize torsional moment transfer is compromised

Engineering Contradiction:
Improveshaft configurationVSAvoidmisalignment compensation
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The coupling device introduces dynamic elements that allow the system to adapt to misalignments. The coupling arm and coupling elements are designed to accommodate axial, radial, and angular displacements through controlled movement and deformation, enabling the system to compensate for manufacturing tolerances and load-dependent deformations without requiring excessive shaft length or rigid precision.

Inventive Principle:
Principle #15Dynamics

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 effectively transmits only the torsional moment, allowing for a weight-optimized generator design and reducing the overall weight of the system while maintaining efficient energy transfer.

Implementation Method 1

the coupling means is designed as a sun wheel shaft arranged between the planetary gear and the generator shaft and gimballed on the generator side

Methodology Applied
Scientific EffectGimbal: Gimbal

Data Source

PatentEP2677171B1Wind energy system with a coupling between the planetary gear and generator to compensating for axial, radial and angular displacement
Publication Date: 2018.07.18 ZF FRIEDRICHSHAFEN AG
  • EP2677171B1 patent drawingFigure 1
  • EP2677171B1 patent drawingFigure 2
  • EP2677171B1 patent drawingFigure 3

AI summary

The wind power plant (1) has rotor (3) and integrated medium-speed electric generator (4). A planetary transmission (2) is provided for converting slow rotary motion of rotor into rapid rotary motion to operate generator. The transmission is provided with transmission input shaft (5) connected indirectly to rotor, and transmission output shaft connected to generator indirectly via generator shaft (6). A coupling mechanism is arranged between generator and transmission to compensate axial, radial and angular misalignment between transmission and generator shaft.