Frangible Squirrel Cage Bearing Housing for Seizure Load Decoupling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Gas turbine engine bearings face performance degradation due to operational loads and vibrations, with existing bearing assemblies lacking effective mechanisms to manage load differentials and prevent damage to functioning bearings during seizure events.

Innovation Solution

A bearing assembly featuring a squirrel cage with a frangible section between two axially spaced bearings, designed to fail upon exceeding a preselected load threshold, allowing for controlled load distribution and decoupling to protect the remaining bearing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If bearings are rigidly connected via squirrel cage, then structural stability is improved, but load differential protection is worsened

Engineering Contradiction:

Improvestructural stabilityVSAvoidload differential protection

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The squirrel cage is segmented into a frangible section with reduced cross-sectional area between the two bearings. This segmentation creates a weak link that can fail independently, allowing the structure to maintain stability through the remaining intact sections while protecting against catastrophic failure from load differentials.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The frangible section has locally reduced cross-sectional area compared to other sections of the squirrel cage. This local quality change creates a predetermined failure point that selectively fails under excessive load differential, while other stronger sections maintain structural integrity.

Inventive Principle:

Principle #3Local quality

2Reliability

If frangible section is designed to fail under load, then bearing protection is improved, but structural strength is worsened

Engineering Contradiction:

Improvebearing protectionVSAvoidstructural strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The frangible section is pre-designed with reduced cross-sectional area during manufacturing, creating a predetermined failure point before actual operation. This preliminary action ensures that when excessive load differential occurs, the failure happens at the intended location rather than at a random weak point, protecting the bearings while maintaining overall structural adequacy.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If squirrel cage connects both bearings, then load distribution is improved, but seizure propagation risk is worsened

Engineering Contradiction:

Improveload distributionVSAvoidseizure propagation risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The frangible section effectively extracts or removes the rigid connection between the two bearings at the critical interface. By creating a separable joint that can fail, it takes out the harmful rigid coupling that would otherwise propagate seizure from one bearing to the other, while still allowing normal load distribution during healthy operation.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP3715651B1Bearing housing

Publication Date: 2022.02.09 PRATT & WHITNEY CANADA CORP

Figure 1
Figure 2
Figure 3

AI summary

A bearing assembly (110) for a gas turbine engine (10) including at least two bearings (110) axially spaced from one another relative to a central axis (11), and a squirrel cage (140) secured to a casing (28) of the gas turbine engine (10). The squirrel cage (140) supports respective bearing loads of the at least two bearings (110). The squirrel cage (140) has a frangible section (140a') between the at least two bearings (110) configured to preferentially fail upon application of a load greater than a preselected threshold bearing load.