Planetary Gear Reducer Oil Supply via Centrifugal Buffer

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Solution Overview

Problem

The existing planetary gear reduction gears in turbomachines face challenges with oil supply failures, leading to increased complexity, mass, and dimensions due to the need for accumulators, which are difficult to produce and maintain.

Innovation Solution

A planetary gear reducer with a chamber in the planet carrier that acts as an oil buffer, featuring a main channel and secondary channels, utilizing centrifugal force to supply oil to plain bearings, ensuring continued lubrication during oil supply failures by reducing oil flow through the secondary channels, preventing seizing and allowing for auxiliary pump startup or turbine shutdown.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If accumulators are added to the planet carrier to maintain oil supply during pump failure, then the reliability of lubrication is improved, but the device complexity, mass, and dimensions increase

Engineering Contradiction:
Improvelubrication reliabilityVSAvoidplanet carrier complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the accumulator function with the planet carrier structure itself. The chamber is formed directly in the planet carrier, combining the lubrication storage function with the structural component, thereby avoiding additional separate accumulator components and reducing overall device complexity while maintaining lubrication reliability during pump failure

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The planet carrier is given multiple functions: it serves as both the structural support for the satellite gears and as an oil reservoir (accumulator). The chamber formed in the planet carrier allows it to store oil and maintain supply during pump failure, making the component universal and eliminating the need for separate dedicated accumulator components

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Duration of action of moving object

If accumulators are added to the planet carrier to maintain oil supply during pump failure, then the operational duration during failure is improved, but the mass and dimensions of the planet carrier increase

Engineering Contradiction:
Improvelubrication duration during failureVSAvoidplanet carrier mass
Core Design Contradiction:
Duration of action of moving objectVSWeight of stationary object

Solution Approach 1:

The accumulator function is merged into the planet carrier structure, utilizing the existing component's volume rather than adding separate heavy accumulator components. This integration maintains lubrication duration during failure while minimizing additional mass by using the planet carrier's own structural volume for oil storage

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If secondary channels are added to the chamber to prevent particle clogging, then the reliability of oil flow is improved, but the device complexity increases

Engineering Contradiction:
Improveoil flow reliabilityVSAvoidchannel structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The oil supply path is segmented into multiple channels: a main channel for primary oil flow and secondary channels for backup supply. This segmentation ensures that if the main channel becomes clogged with particles, the secondary channels can maintain oil flow, thereby improving reliability while adding only minimal structural complexity through additional flow paths

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 solution provides reliable and compact oil supply means that maintain lubrication for a sufficient period during oil supply failures, preventing bearing seizing and allowing for safe operation during turbomachine startup or shutdown, while avoiding particle clogging of the secondary channels.

Implementation Method 1

In operation, under the effect of centrifugal force, the oil present in the chamber is pushed radially outwards. The chamber formed in the planet carrier therefore fills first in the lower zone, away from the axis of rotation of the planet carrier, then in the upper zone.

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2893221B1Speed-reducing unit having an epicyclic gear train, in particular for a turbine engine
Publication Date: 2019.08.14 SAFRAN TRANSMISSION SYST
  • EP2893221B1 patent drawingFigure 1~2
  • EP2893221B1 patent drawingFigure 3~5
  • EP2893221B1 patent drawingFigure 6~9

AI summary

The invention relates to a speed-reducing unit (1) having an epicyclic gear train, in particular for a turbine engine, comprising an inner planetary gear (2) and an outer planetary gear (3) which are coaxial, the inner planetary gear (2) being rotatable about the axis (X) thereof, the outer planetary gear (3) being stationary, at least one planetary wheel (4) rotatably mounted on a planetary wheel carrier (6) and engaging with both the inner planetary gear (2) and the outer planetary gear (3), the planetary wheel carrier (6) pivoting about the axis (X) of the inner planetary gear (2) and of the outer planetary gear (3), the planetary wheel (4) comprising an inner cylindrical surface pivotably mounted about a cylindrical surface of the planetary wheel carrier (6). The speed-reducing unit (1) further comprises an improved means for supplying oil at the interface between said cylindrical surfaces.