Securing Pen-Type Bushings in Wind Turbine Blade Roots

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Solution Overview

Problem

Existing methods are not suitable for securing pen-type bushings in the blade root of a wind turbine blade, and there is a need for a method that can replace existing bushings without requiring an axial cavity.

Innovation Solution

A method involving a cap with a sealing element and dispensing channels to secure a pen-type bushing in the blade root, using a bonding compound to fill the space between the bushing and cavity, and a closing element to align and seal the bushing during curing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If an additional cavity in axial direction is used to secure a T-bolt type bushing, then the bushing can be accommodated, but the device complexity increases and the method is not suitable for pen-type bushings

Engineering Contradiction:
Improvesuitability for pen-type bushingVSAvoidcavity structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of creating an additional axial cavity to accommodate the bushing, the invention inverts the approach by placing the bushing in the existing radial cavity and using a rod inserted through the bushing's inner channel to transfer bonding compound. This eliminates the need for axial cavity modification while enabling pen-type bushing installation.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention introduces a rod as an intermediary element that passes through the inner bushing channel of the pen-type bushing. This rod serves as a conduit for injecting bonding compound into the cavity space, enabling securement without requiring axial cavity modification. The rod acts as a mediator between the bonding compound delivery system and the bushing-cavity interface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the inner bushing channel is left open, then the bushing can be installed, but the inner thread is exposed and vulnerable to damage

Engineering Contradiction:
Improvebushing installationVSAvoidinner thread protection
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The sealing element is installed in the inner bushing channel before the bonding compound curing process begins. This preliminary action protects the inner thread from bonding compound contamination and damage during the installation and curing process, while still allowing the bushing to be properly positioned and secured.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A sealing element is introduced as an intermediary component within the inner bushing channel. This sealing element protects the exposed inner thread from harmful factors such as bonding compound intrusion while maintaining the open channel configuration necessary for bushing installation and rod insertion.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If bonding compound is injected without pressure control, then the injection process is simple, but the bonding compound may not fill the entire space between cavity and bushing

Engineering Contradiction:
Improvebonding compound injectionVSAvoidbonding compound distribution
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention implements a pressure-controlled bonding compound injection process with feedback monitoring. Pressure sensors detect the injection pressure and provide feedback to the injection system, which adjusts the injection parameters to ensure complete filling of the cavity-bushing interface space. This feedback mechanism guarantees proper bonding compound distribution while maintaining process simplicity.

Inventive Principle:
Principle #23Feedback

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 method effectively secures the bushing in the blade root without an axial cavity, ensuring a strong connection and extending the service life of the blade root by replacing existing bushings.

Implementation Method 1

the bonding compound is inserted in the cavity via a free end of the inner rod channel, thereby flowing through the inner rod channel via the first outer rod end; through the through channel of the sealing element to the end of the cavity; from the end of the cavity towards the first end of the bushing thereby filling the space between the cavity and the bushing

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 2

selecting and placing a sealing element in the inner bushing channel near the second outer end of the bushing for sealing off the inner bushing channel at the second outer bushing end

Methodology Applied
Scientific EffectSealing:

Implementation Method 3

securing a closing element to the blade root in an airtight manner, thereby closing the cavity

Methodology Applied
Scientific EffectAirtight sealing:

Implementation Method 4

a pressure difference is applied between the free end of the inner rod and the openings during insertion of the bonding compound

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Implementation Method 5

allowing the compound to cure until the bushing is secured in the cavity

Methodology Applied
Scientific EffectCuring: Photopolymerisation

Data Source

PatentEP4423389B1Method for securing a bushing in a blade root of a wind turbine blade and cap for use in said method
Publication Date: 2026.01.28 VIVENTUS HLDG
  • EP4423389B1 patent drawingFigure 1A~1D
  • EP4423389B1 patent drawingFigure 1E~1F
  • EP4423389B1 patent drawingFigure 1G

AI summary

The invention relates to a method for securing a bushing in a blade root of a wind turbine blade according to the preamble of claim 1. The method is known in the state of the art. The known method uses an additional cavity in axial direction of the blade root. The cavities in axial and radial direction are used for accommodation of a T-bolt type bushing. The known method is not suitable for pen-type bushing. The invention has for its purpose to provide a method, which is suitable for securing a pen-type bushing in the blade root, which method can also be used to replace an existing pen-type bushing in a blade root.