Lock Washer Compression Lock for Vane Strut Gap Control

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Solution Overview

Problem

Conventional methods for mounting and securing vane struts in gas turbine engines are not cost-effective in a production environment, particularly in maintaining a small gap between the upstream strut and downstream flap to prevent leakage, which is critical for performance enhancement.

Innovation Solution

A vane strut positioning and securement system utilizing a lock washer with a compression lock interface, including features like knurling, radial serrations, or hard coatings, that is press-fit into the housing to securely position and deform under compression, allowing precise control of the strut's position relative to the flap.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If individual custom fabrication with very low tolerances is used to achieve a small gap between strut and flap, then the gap control precision is improved, but the manufacturing cost increases and production efficiency decreases

Engineering Contradiction:
Improvegap control precisionVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system divides the gap control function into separate components: the lock washer with compression lock interface handles the positioning and gap control, while the strut and flap maintain their structural functions. This segmentation allows each component to be manufactured with standard tolerances rather than requiring the entire assembly to be custom-fabricated with very low tolerances.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The lock washer acts as an intermediary component between the strut and the flap assembly. Its compression lock interface mediates the gap control by deforming under compression to securely position the strut at the predetermined location, thereby achieving precise gap control without requiring custom fabrication of the entire strut-flap assembly.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If conventional mounting systems are used, then the manufacturing process is simple, but the gap control precision and leakage prevention are insufficient

Engineering Contradiction:
Improvemounting simplicityVSAvoidgap control precision
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The lock washer is designed to be self-positioning and self-securing through its compression lock interface. When compressed between the strut washer and the housing, the interface deforms to automatically lock the strut in the predetermined location defined by the washer aperture. This self-service mechanism achieves precise gap control without requiring complex mounting procedures or specialized tools.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The compression lock interface utilizes material deformation under compression to change the physical state of the lock washer. This parameter change (from uncompressed to compressed state) enables the lock washer to transition from a loose fit to a secure locked position, achieving precise gap control through a simple compression action rather than complex mounting procedures.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the lock washer is designed with a compression lock interface that deforms under compression, then the securing reliability is improved, but the complexity of the component increases

Engineering Contradiction:
Improvesecuring reliabilityVSAvoidcomponent complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The compression lock interface is implemented only at the specific location where the lock washer contacts the housing and strut washer. This localized feature provides the necessary deformation capability for secure locking without requiring the entire lock washer to be complex. The majority of the lock washer remains a simple annular component, maintaining manufacturing simplicity while achieving high securing reliability at the critical interface.

Inventive Principle:
Principle #3Local quality

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 system achieves a highly controlled and minimized gap between the strut and flap, enhancing performance by securely positioning the vane strut while allowing for easy overhaul and maintaining tight tolerances without damaging the housing, thus improving the overall efficiency and reliability of the turbomachine.

Implementation Method 1

compressing the strut washer against the lock washer such that a deformation fit is created therebetween

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

The compression lock interface may include at least one of knurling, radial serrations, cubic boron nitride coating, aluminum oxide coating, or colloidal silica

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

The lock washer may be press fit into the washer aperture

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3098390B1Vane strut positioning and securing systems including locking washers
Publication Date: 2020.10.21 RTX CORP
  • EP3098390B1 patent drawingFigure 1
  • EP3098390B1 patent drawingFigure 2~3A
  • EP3098390B1 patent drawingFigure 3B~4

AI summary

A vane strut positioning and securement system (200) includes a housing (201) including a washer aperture (203) defined in an inner diameter thereof and a lock washer (205) disposed within the washer aperture of the housing, the lock washer configured to lock a vane strut orientation under compression against a vane strut washer. The washer aperture is defined partially through a thickness of the housing, and the housing includes a strut post opening (209) defined through the housing from the inner diameter to an outer diameter of the housing.