Annular Clamping Nut with Segmented Passages for Gas Turbine Tie Bars

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Solution Overview

Problem

Existing clamping nuts in gas turbines face issues with high temperature-induced lubricant escape and microscopic deformations, leading to stuck clamping screws, making dismantling difficult and time-consuming, especially under high mechanical and thermal loads.

Innovation Solution

An annular clamping nut with an external thread on its outer surface and passages for clamping screws, along with a clamping device that applies tensioning force via a counter-thread, allowing for controlled tensioning and dismantling by distributing force more evenly and reducing the load on individual screws.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If multiple clamping screws are used to apply high total clamping force, then the clamping force is sufficient, but the tensioning process becomes very time-consuming and individual screws may become twisted or stuck

Engineering Contradiction:

Improvetotal clamping forceVSAvoidtensioning process time

Core Design Contradiction:

ForceVSLoss of time

Solution Approach 1:

The clamping nut is divided into multiple segments with individual passages for clamping screws, allowing independent access and tensioning of each screw. This segmentation enables parallel working and simplifies maintenance by isolating individual screws that may need attention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A tie bar is introduced as an intermediary element that runs through the shaft and components, providing a centralized mechanism for applying and distributing clamping force. The tie bar system allows for more efficient force transmission and reduces the complexity of directly managing multiple clamping screws.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If individual clamping screws are tightened uniformly to prevent twisting, then the clamping force distribution is even, but the tensioning process becomes extremely time-consuming

Engineering Contradiction:

Improveuniform clamping force distributionVSAvoidtensioning process time

Core Design Contradiction:

Stability of the object's compositionVSLoss of time

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent allows for practical tensioning where not all screws need to be perfectly uniformly tightened. The design accommodates some variation in screw tightening while still achieving sufficient clamping force, reducing the time required for the tensioning process.

Inventive Principle:

Principle #16Partial or excessive action

3Force

If clamping screws are used at high temperatures, then the clamping function is maintained, but lubricant escapes and microscopic deformations occur causing screws to become stuck

Engineering Contradiction:

Improveclamping forceVSAvoidscrew loosening reliability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent addresses high temperature effects by designing the clamping system to accommodate thermal expansion and lubricant degradation. The passages and screw design allow for parameter changes in the operating environment while maintaining functional reliability.

Inventive Principle:

Principle #35Parameter changes

4Ease of repair

If the clamping nut is destroyed to enable dismantling, then the tie bar system can be accessed, but the tie bar and entire rotary engine are destroyed

Engineering Contradiction:

Improvedismantling accessibilityVSAvoidcollateral destruction

Core Design Contradiction:

Ease of repairVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tie bar is extracted as a separate, removable component that runs through the shaft and components. This allows the tie bar to be removed independently for maintenance without destroying the clamping nut or other engine components, enabling access to the tie bar system while preserving the overall engine structure.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10422225B2Annular clamping nut for a tie bar

Publication Date: 2019.09.24 NORD LOCK SWITZERLAND GMBH

AI summary

An annular clamping nut which is provided for being placed onto the end of a tie bar, in order to brace the latter, and which has in addition to a central recess for receiving the tie bar parallel to a longitudinal direction passages at uniform radial spacings in the ring circumferential direction which are directed parallel to the longitudinal direction of the central recess and are provided for receiving clamping screws. An external thread is provided on the outer surface of the clamping nut, which outer surface is arranged on a side which lies substantially opposite the wall of the central recess, which external thread runs substantially in the ring circumferential direction of the outer surface.