Unbalanced Rotor Structure With Retainer-Based Load Path

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Solution Overview

Problem

Existing devices used for rotor balancing are not suitable for unbalance testing, as they do not effectively simulate an unbalanced condition to evaluate the behavior of aircraft power plants under such conditions.

Innovation Solution

An unbalanced rotor design for aircraft power plants, featuring a hollow body with a retainer and an unbalancing weight installed inside to intentionally vibrate the rotor during rotation, utilizing a radial load path that excludes fasteners to securely attach the weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If existing balancing devices are used, then rotor balancing can be achieved, but they cannot effectively simulate unbalanced conditions for testing

Engineering Contradiction:

Improvetesting capabilityVSAvoidsimulation accuracy

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The unbalancing weight is designed to be adjustable and removable, allowing the rotor to transition between balanced and unbalanced states. This dynamic configuration enables the same rotor to serve both balancing purposes and unbalance testing purposes, resolving the contradiction between versatility and reliability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

An unbalancing weight is introduced as an intermediary element between the rotor and the testing objective. This additional component enables the simulation of unbalanced conditions without modifying the rotor itself, allowing existing balancing devices to be used for unbalance testing by simply adding or removing the weight.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If an unbalancing weight is installed inside the hollow body, then unbalance testing capability is improved, but the structural complexity increases

Engineering Contradiction:

Improveunbalance testing capabilityVSAvoidrotor structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The unbalancing weight is nested inside the hollow body of the rotor, utilizing the existing internal space. This nesting approach adds the unbalance testing capability without requiring external modifications or increasing the overall rotor dimensions, thus minimizing the increase in structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The hollow body structure is designed to accommodate both the retainer mechanism and the unbalancing weight, serving multiple functions. The same structural elements (hollow body, retainer, fasteners) support both the rotor's primary function and the unbalance testing function, reducing the overall complexity increase.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Strength

If the unbalancing weight is fastened with one or more fasteners, then the weight is securely attached, but the radial load path includes the fasteners which may affect testing accuracy

Engineering Contradiction:

Improveattachment securityVSAvoidvibration measurement

Core Design Contradiction:

StrengthVSMeasurement precision

Solution Approach 1:

The attachment system is segmented into two distinct load paths: one through the fasteners for secure attachment, and another radial load path through the retainer for force transmission. This segmentation allows the fasteners to provide secure attachment while the retainer provides a clean radial load path for accurate vibration measurement during unbalance testing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The retainer acts as an intermediary element between the unbalancing weight and the hollow body, providing a dedicated radial load path. This intermediary structure transmits the radial forces generated by the unbalancing weight directly to the hollow body, excluding the fasteners from the radial load path and thereby improving measurement precision.

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

This design allows for effective simulation of unbalanced conditions during testing, enabling the evaluation of aircraft power plants' behavior under rotor unbalance, thereby improving testing capabilities without requiring hardware modifications.

Implementation Method 1

an unbalancing weight installed inside of the hollow body to intentionally vibrate the rotor during rotation of the rotor

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP4567259A1Unbalanced rotor for unbalance testing of an aircraft engine

Publication Date: 2025.06.11 PRATT & WHITNEY CANADA CORP

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AI summary

An unbalanced rotor (12) is provided to perform unbalance testing on an aircraft power plant (10). The unbalanced rotor (12) includes a hollow body (26, 30) rotatable about a rotation axis (RA) and an unbalancing weight (20; 120) installed inside of the hollow body (26, 30). The unbalancing weight (20; 120) is installed inside of the hollow body (26, 30) to intentionally vibrate the rotor during rotation of the rotor (12). The unbalancing weight (20; 120) is fastened to the hollow body (26, 30) via one or more fasteners (34). A portion of the unbalancing weight (20; 120) is disposed radially inwardly of a retainer (60) of the hollow body (26, 30) and is engaged with the retainer (60) to define a radial load path (LP) between the unbalancing weight (20; 120) and the hollow body (26, 30) via the retainer (60). The radial load path (LP) excludes the one or more fasteners (34).