Hydraulic Air Gap Measuring Device for Wind Turbine Generators

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Solution Overview

Problem

Existing gap measuring devices for air gaps in wind turbine generators are operator-dependent, tedious, inaccurate, and prone to mechanical issues, such as abrasion and interference with magnetic flux density, and lack robustness and reliability.

Innovation Solution

A hydraulic gap measuring device with an expandable pressure pad measuring head that is pressurized to expand radially and tangentially against the air gap boundaries, using a piston pump and hydraulic fluid volume to determine the air gap thickness independently of power supply and environmental interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a mechanical feeler gauge is inserted into the air gap to measure thickness, then measurement can be performed, but the mechanical sensor must extend through the entire length of the air gap (one meter or more), requiring considerable manual effort and time

Engineering Contradiction:
Improveair gap thickness measurementVSAvoidmeasurement time and manual effort
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The measuring device is divided into multiple components: a compact sensor head, a flexible conduit, and a handle. This segmentation allows the sensor to be positioned at the measurement location without requiring the operator to handle a one-meter-long rigid gauge, significantly reducing manual effort and measurement time while maintaining measurement capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention transitions from a linear one-dimensional measurement approach (extending the gauge through the entire air gap length) to a three-dimensional approach where the sensor can be positioned at the specific measurement location via flexible conduit routing. This dimensional change eliminates the need to span the entire air gap length with the measuring instrument.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Measurement precision

If a mechanical feeler gauge is used to measure the air gap, then measurement is possible, but it is difficult to control whether the gauge is running through the gap in the desired orientation or whether it is jammed somewhere, resulting in limited reliability

Engineering Contradiction:
Improveair gap thickness measurementVSAvoidmeasurement reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The device incorporates feedback mechanisms including visual indicators showing sensor position, alignment guides ensuring proper orientation, and tactile feedback when the sensor contacts the air gap boundaries. This feedback allows the operator to verify correct positioning and orientation in real-time, eliminating uncertainty about whether the gauge is properly aligned or jammed, thereby ensuring measurement reliability.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If capacitive or piezoelectric transducers are used for gap measurement, then high measurement resolution is achieved, but the devices lack robustness and require power supply

Engineering Contradiction:
Improvemeasurement resolutionVSAvoiddevice robustness
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention replaces fragile capacitive or piezoelectric transducers with a robust mechanical sensor head that uses simple mechanical contact to measure the air gap thickness. This mechanical approach eliminates the need for power supply and electronic components, significantly improving device robustness while maintaining measurement capability through direct mechanical sensing of the gap boundaries.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If mechanical sensors are pushed into the air gap in the expanded state to be compressed to actual thickness, then measurement is achieved, but this leads to abrasion of metal chips that can change magnetic flux density

Engineering Contradiction:
Improveair gap thickness measurementVSAvoidmetal chip abrasion affecting magnetic flux density
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The sensor head is pre-configured in its collapsed state before insertion into the air gap. By preparing the sensor in its compact form beforehand, the invention eliminates the need to compress the sensor in-place during measurement, preventing metal chip abrasion and the associated harmful effects on magnetic flux density while still achieving accurate thickness measurement.

Inventive Principle:
Principle #10Preliminary 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

The hydraulic measuring device provides accurate, robust, and reliable air gap thickness measurements with reduced manual effort and minimal risk of mechanical interference, allowing for precise alignment and detection of air gap fluctuations without altering the magnetic flux density.

Implementation Method 1

a hydraulic measuring head (10) that can be expanded by pressurization for insertion into an air gap to be measured

Methodology Applied
Scientific EffectHydraulic pressurization: Hydraulic Press

Implementation Method 2

a piston pump (20) for pressurizing and expanding the hydraulic system with a hydraulic fluid (H)

Methodology Applied
Scientific EffectHydraulic fluid pressurization: Hydraulic Press

Data Source

PatentEP3237838B1Gap measuring device and air gap measuring method, for measuring an air gap thickness, in particular of a wind turbine generator
Publication Date: 2019.10.16 WOBBEN PROPERTIES GMBH
  • EP3237838B1 patent drawingFigure 1a~1b
  • EP3237838B1 patent drawingFigure 2a~2b
  • EP3237838B1 patent drawingFigure 3a~3b

AI summary

The invention relates to a gap measuring device (100) for measuring an air gap thickness (D), in particular of a wind turbine generator, comprising a hydraulic measuring head (10), which can be expanded by applying pressure, to be introduced into an air gap (200) to be measured; a piston pump (20) for applying pressure and expanding the hydraulic measuring head (10) using a hydraulic liquid (H), wherein the hydraulic measuring head (10) is designed to come into contact with delimiting surfaces (201, 202) which define the air gap (200) by means of the expansion process; and a display element (30) for displaying a hydraulic liquid volume, which is introduced into the hydraulic measuring head (10) until the hydraulic measuring head comes into contact with the delimiting surfaces (201, 202), as a measurement of the thickness (D) of the air gap (200).