Turbomachine Rotor Balancing Arrangement and Oil Expulsion

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Solution Overview

Problem

Rotors for turbomachines face challenges in balancing and oil accumulation, requiring effective balancing solutions that minimize wear and maintenance, especially at high speeds, while preventing oil contamination of cabin air flows.

Innovation Solution

A rotor stage design featuring a rotor base body with at least two rotor arms and a balancing arrangement, where the downstream rotor arm has a balancing arrangement between its axial end and the rotor disk, allowing for efficient balancing and oil expulsion through a centrifugal opening, reducing the need for additional balancing arrangements and minimizing oil accumulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple balancing arrangements are provided on rotor arms, then balancing precision is improved, but device complexity increases

Engineering Contradiction:
Improvebalancing precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts the balancing function from multiple distributed balancing arrangements and concentrates it into a single balancing arrangement located on one rotor arm. This single arrangement includes a balancing cavity with adjustable balancing elements that can compensate for imbalances throughout the entire rotor stage, thereby achieving precise balancing while reducing device complexity by eliminating the need for multiple balancing arrangements across different rotor arms.

Inventive Principle:
Principle #2Taking out (Extraction)

2Adaptability or versatility

If rotor arms are designed with cavities for balancing, then balancing adjustability is improved, but oil accumulation risk increases

Engineering Contradiction:
Improvebalancing adjustabilityVSAvoidoil accumulation
Core Design Contradiction:
Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potential harm of cavities (which can trap oil) into a benefit by designing the balancing cavity with a specific configuration that includes drainage features. The balancing cavity is positioned and shaped such that it allows oil to drain out through designated openings while still providing space for balancing elements. This converts the harmful oil trapping effect into a functional design where oil management is integrated into the balancing structure.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The invention introduces drainage openings and positioning features as intermediary elements between the balancing cavity and the rotor arm structure. These intermediaries allow the cavity to serve its balancing function while preventing oil accumulation by providing escape paths for oil through the rotor arm wall, thus mediating between the need for balancing adjustability and the need to prevent oil trapping.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If balancing arrangements are placed on upstream rotor arms, then balancing effectiveness is improved, but oil cavity formation increases

Engineering Contradiction:
Improvebalancing effectivenessVSAvoidoil cavity formation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the spatial dimension of the balancing arrangement by positioning it on the downstream rotor arm rather than the upstream rotor arm. This dimensional repositioning in the axial direction of the rotor stage allows the balancing cavity to be located in a region where oil accumulation is less problematic, as the downstream position is further from the oil supply sources and has better drainage characteristics, thereby maintaining balancing effectiveness while reducing oil cavity formation.

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

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 design simplifies unbalance compensation, reduces rotor vibrations, and prevents oil contamination by efficiently expelling bearing oil, achieving cost-effective and reproducible balancing results while maintaining low wear and maintenance.

Implementation Method 1

possible oil accumulations in cavities in the rotor interior, for example of bearing oil accumulations, should be able to flow out of the rotor interior

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3301256B1Rotor stage for a fluid flow machine, rotor drum and rotor
Publication Date: 2020.04.08 MTU AERO ENGINES GMBH
  • EP3301256B1 patent drawingFigure 1
  • EP3301256B1 patent drawingFigure 2

AI summary

The present invention relates to a rotor stage (200) for a turbomachine, comprising several rotor blades (9), a rotor body (7) with at least two rotor arms (3), and a balancing arrangement (1) for balancing the rotor stage (200). The rotor arm (3), located downstream of the rotor body (7), includes the balancing arrangement (1). The balancing arrangement (1) is arranged between the axial end region of the rotor arm (3) and the rotor disk (27) of the rotor body (7). The present invention further relates to a rotor drum (17, 18) for a turbomachine and a rotor (1000) for a turbomachine.