Self-Locking Closure Bucket for Turbomachine Rotor

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Solution Overview

Problem

Existing turbomachine systems face stress concentration and significant remachining issues during reassembly due to conventional mechanisms used to secure the closure bucket, which can damage the rotor.

Innovation Solution

A self-locking closure bucket assembly is introduced, featuring a closure bucket with a single wedge that secures within a groove of the rotor disk or stage, utilizing centrifugal force to block circumferential movement without a locking screw through the rotor, thus avoiding stress concentrations and enabling reassembly without remachining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional mechanisms are used to secure the closure bucket to the rotor portion, then the closure bucket is locked in place, but stress concentration occurs in the rotor and significant remachining is required during reassembly

Engineering Contradiction:

Improveclosure bucket locking reliabilityVSAvoidstress concentration and rotor damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A wedge element is introduced as an intermediary component between the closure bucket and the rotor groove. The wedge transmits the locking force through friction and geometric constraint rather than direct mechanical fastening, eliminating stress concentration in the rotor while maintaining secure closure bucket positioning

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The conventional mechanical fastening system (locking screws penetrating the rotor) is replaced with a friction-based wedge locking mechanism. The wedge utilizes friction forces and geometric interlocking within the groove to secure the closure bucket, eliminating the need for penetrative fasteners that cause stress concentration

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If conventional locking mechanisms with multiple components are used, then the closure bucket is secured, but the device complexity increases and remachining is required

Engineering Contradiction:

Improvebucket securing reliabilityVSAvoidlocking mechanism complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking function is segmented into distinct operational phases: insertion of the wedge into the groove, engagement with the closure bucket, and friction-based locking. This segmentation allows for a simpler overall design compared to multi-component mechanical fastening systems, reducing device complexity while maintaining reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The complex multi-component locking mechanism (multiple screws, washers, and fastening elements) is extracted and replaced with a single wedge element. This extraction simplifies the device structure, reduces the number of parts, and eliminates the need for remachining during maintenance

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If locking screws are used to secure the closure bucket, then the buckets are locked in place, but significant remachining of the rotor is required during reassembly

Engineering Contradiction:

Improvebucket positioning stabilityVSAvoidreassembly ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The wedge is pre-positioned in the groove before the closure bucket is installed. This preliminary action ensures that the locking mechanism is already in place, eliminating the need for remachining or modification of the rotor during reassembly operations

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The wedge serves as a mediator that enables reversible installation and removal of the closure bucket without damaging the rotor. The friction-based interaction allows for easy disassembly and reassembly, improving manufacturing ease while maintaining secure positioning

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively secures the closure bucket without stress concentrations, allowing for reassembly of turbomachine stages without damage or remachining, enhancing maintenance efficiency and reducing operational risks.

Implementation Method 1

a single wedge disposed between and contacting the second surface of the closure bucket and the second groove surface to secure the closure bucket within the groove

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS9422820B2Method and system for self-locking a closure bucket in a rotary machine

Publication Date: 2016.08.23 NUOVO PIGNONE SPA

AI summary

A system includes a turbomachine that includes at least one rotor disk or stage having a peripheral portion disposed about a rotational axis of the rotor disk or stage. The peripheral portion includes a groove that extends circumferentially about the peripheral portion. The groove has a first groove surface and a second surface disposed opposite the first groove surface. The turbomachine also includes a closure bucket disposed adjacent at least one bucket within the groove. The closure bucket has a first surface that interfaces with the first groove surface and a second groove surface disposed opposite the first surface. The closure bucket blocks circumferential movement of the at least one bucket within the groove relative to the rotor disk or stage. The turbomachine further includes a single wedge disposed between and contacting the second surface of the closure bucket and the second groove surface to secure the closure bucket within the groove.