Lubrication System for Planetary Gear Misalignment

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Solution Overview

Problem

Planetary gear trains in aircraft engines face component breakage and wear due to misalignments, which existing lubrication systems fail to adequately address, leading to increased maintenance costs and reduced operational efficiency.

Innovation Solution

A lubricating system for planetary gear trains that includes a stationary oil transfer bearing with a flexible link to distribute lubricant effectively across misaligned components, utilizing a network of conduits and spray bars to ensure consistent lubrication of bearings and gears, while minimizing the need for multiple parts and enhancing rigidity and strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If gear train components are made larger and stronger to reduce wear and breakage, then component strength and wear resistance are improved, but the compactness of the planetary gear train is reduced and weight increases

Engineering Contradiction:
Improvecomponent strengthVSAvoidgear train compactness
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The patent introduces flexible couplings that preemptively accommodate misalignments between the sun gear axis and planet carrier axis, cushioning the gear components against harmful moments and forces before they can cause wear or breakage. This allows the use of optimally sized components without excessive safety margins.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the flexibility parameter of the coupling mechanisms, allowing them to adapt to misalignment conditions. By making the couplings flexible rather than rigid, the system can tolerate axis deviations without transmitting harmful loads to the gear components, thereby maintaining component strength without increasing their size.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If high strength materials and wear resistant coatings are used to reduce wear, then component durability is improved, but manufacturing cost increases

Engineering Contradiction:
Improvecomponent durabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent converts the harmful effect of misalignment into a manageable parameter by designing flexible couplings that actively accommodate axis deviations. This transforms what would be a source of wear and failure into a controlled degree of freedom, reducing the need for expensive high-strength materials and wear-resistant coatings.

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

Solution Approach 2:

The flexible couplings are designed to self-adjust to misalignment conditions without requiring external control systems or expensive active compensation mechanisms. The passive flexibility of the couplings automatically accommodates axis deviations, providing a cost-effective solution that reduces reliance on expensive materials.

Inventive Principle:
Principle #25Self-service

3Reliability

If flexible couplings are used to reduce misalignment stresses, then gear component wear is reduced, but the coupling system itself requires lubrication and is susceptible to wear

Engineering Contradiction:
Improvegear component wear resistanceVSAvoidcoupling system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the flexible coupling function directly into the existing gear train structure, eliminating the need for separate, complex coupling components. By integrating the flexibility into the sun gear or planet carrier themselves, the design reduces the number of additional parts that would require lubrication and maintenance.

Inventive Principle:
Principle #5Merging (Combining)

4Adaptability or versatility

If prior art flexible couplings are used to accommodate misalignment, then adaptability to misalignment is improved, but torsional rigidity and strength are reduced making them unsuitable for high torque applications

Engineering Contradiction:
Improvemisalignment accommodationVSAvoidtorsional rigidity
Core Design Contradiction:
Adaptability or versatilityVSStrength

Solution Approach 1:

The patent segments the torque transmission path by introducing flexible elements only in the radial direction (for misalignment accommodation) while maintaining rigid torque transmission paths. This segmentation allows the system to be flexible where needed for alignment tolerance while remaining rigid for torque transmission.

Inventive Principle:
Principle #1Segmentation

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 system effectively reduces wear and breakage of gear components by ensuring consistent lubrication across misaligned parts, enhancing the reliability and longevity of the gear train without increasing weight or cost, thus maintaining the compactness and efficiency of the gear train.

Implementation Method 1

A lubricating system for planetary gear trains that includes a stationary oil transfer bearing with a flexible link to distribute lubricant effectively across misaligned components

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2441923B1Lubrication system in a planetary gear system of a gas turbine
Publication Date: 2019.05.01 UNITED TECH CORP
  • EP2441923B1 patent drawingFigure 1
  • EP2441923B1 patent drawingFigure 2
  • EP2441923B1 patent drawingFigure 3~4

AI summary

A lubricating system for lubricating components across a rotation gap has an input (120) that provides lubricant to a stationary first bearing (75). The first bearing has an inner first race (160) in which lubricant flows. A second bearing (70) rotates within the first bearing (75) and has a first opening (185) in registration with the inner first race (160) such that lubricant may flow from the inner first race (160) through the first opening (160) into a first conduit (180). The lubricant system is particularly useful in a planetary gear system, with the lubricant passing through the first conduit lubricates a first component of the planetary gear system. Second and third inputs (115, 130) may be provided to second and third races (170, 175) may be provided, in registration with second and third openings (195, 205), to allow further components of the planetary gear system to be lubricated.