Blade-root bearing retention system for lubricant leakage

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing blade root bearings in aircraft propellers face challenges with lubricant leakage due to centrifugal forces, leading to operational unbalance and potential damage, while current designs aim to maximize bearing forces while minimizing size.

Innovation Solution

A bearing design featuring a retention system with a retention body and threading/tapping system, including a radial slot and biasing system to secure the distal sealing system against centrifugal forces, and an assembly/disassembly relief for easy maintenance, enhances sealing and prevents unscrewing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the bearing operates at high rotational speed, then power and productivity are improved, but lubricant leakage increases due to centrifugal force

Engineering Contradiction:
Improverotational speedVSAvoidlubricant leakage
Core Design Contradiction:
ProductivityVSLoss of substance

Solution Approach 1:

The distal sealing system is pre-loaded by the retention body to create initial compression force that counteracts the centrifugal force acting on the lubricant. This preliminary anti-action ensures the sealing system is already prepared to resist lubricant leakage before the bearing operates at high speeds

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The centrifugal force that causes lubricant leakage is converted into a beneficial pre-loading mechanism. The retention body utilizes the centrifugal force direction to apply compression on the distal sealing system, transforming the harmful effect into a useful pre-loading action that enhances sealing performance

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

2Device complexity

If the bearing size is minimized, then device complexity is reduced, but the ability to retain lubricant under centrifugal force deteriorates

Engineering Contradiction:
Improvebearing sizeVSAvoidlubricant retention
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The solution moves from considering only radial sealing to adding an axial dimension of sealing. The distal sealing system and retention body create an axial compression force that prevents lubricant leakage in the axial direction, providing multi-dimensional sealing without significantly increasing bearing size

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

3Reliability

If the retention body is made secure against unscrewing, then reliability is improved, but ease of operation for assembly and disassembly deteriorates

Engineering Contradiction:
Improveretention securityVSAvoidassembly and disassembly
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking element acts as a flexible mechanical component that can be easily inserted and engaged. Its simple geometric form allows it to be quickly positioned in the locking groove, providing secure retention while maintaining ease of operation during assembly and disassembly

Inventive Principle:
Principle #30Flexible shells and thin films

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 retains the lubricant, improving sealing and preventing operational unbalance, thereby enhancing the performance and reliability of the blade root bearings under rotational stress.

Implementation Method 1

the lubricant is subjected to centrifugal force. This results in risks of lubricant leakage

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

a biasing system biasing the proximal portion and the distal portion opposite each other tending to open said slot

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 3

At least one row of rolling bodies mounted in the interior space, rolling on the exterior and interior raceways

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3173326B1Blade-root bearing and manufacturing method, system, oscillating system and rotary system including such a bearing
Publication Date: 2019.03.27 NTN SNR ROULEMENTS
  • EP3173326B1 patent drawingFigure 1
  • EP3173326B1 patent drawingFigure 2
  • EP3173326B1 patent drawingFigure 3a~3b

AI summary

The blade root bearing comprises an outer ring (13) and an inner ring (12) forming an internal space, which is closed by a sealing system (47) between the outer and inner rings. A retention system (57) for the sealing system comprises a retention body (58) and a threading/tapping system formed on a peripheral mounting surface of the retention body and on a peripheral surface of the opposing inner or outer ring. The retention body can be screwed into a retention position in which an axial stop surface (61) of the retention body forms an axial stop for the sealing system in the proximal-to-distal direction.