Split-Ring Sun Gear Structure for Uniform Turbine Reducer Loading

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Solution Overview

Problem

Current mechanical reducers in turbomachinery, particularly in aircraft turbofan engines, face issues with uneven loading and stress distribution on the sun gear teeth due to imbalances in force transmission, leading to manufacturing defects and flexibility challenges at the input shaft or interface.

Innovation Solution

Incorporating a solar element with an annular shape that includes two independent rings and an annular web connecting them, providing flexibility in both radial and axial directions through elastic deformation, allowing the rings to move relative to each other and absorb stresses during torque transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If flexibility is provided at the input shaft or interface between input shaft and solar panel using bellows or flexible joints, then the shaft gains elastic deformation capabilities, but the force transmission becomes imbalanced and solar element teeth are unevenly loaded

Engineering Contradiction:
ImproveflexibilityVSAvoidloading uniformity
Core Design Contradiction:
Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The solar element is segmented into two independent rings (first and second rings) connected by a web, allowing each ring to independently absorb stresses while maintaining balanced force distribution across the teeth. This segmentation enables the structure to accommodate deformations without compromising loading uniformity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The web connecting the two rings is designed with specific geometric parameters (thickness, length, cross-sectional area) that give it controlled elastic deformation characteristics. By adjusting these parameters, the solar element achieves optimal flexibility while maintaining homogeneous load distribution on the teeth.

Inventive Principle:
Principle #35Parameter changes

2Strength

If a rigid solar element is used, then the structure is simple and strong, but it cannot absorb stresses and is sensitive to manufacturing defects and external forces

Engineering Contradiction:
Improvestructural strengthVSAvoidstress absorption capability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

Dividing the solar element into two rings connected by a web creates a structure that maintains overall strength while introducing flexibility. The web acts as a stress-absorbing element that can elastically deform under external forces, protecting the rigid tooth structures from stress concentrations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The solar element combines rigid components (the two rings with teeth) and a flexible component (the web connecting them). This composite structure integrates the strength of rigid elements with the stress-absorption capability of flexible elements, achieving both durability and reliability.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If the solar element is made as a single rigid piece, then manufacturing is simple, but it lacks flexibility to compensate for external forces and manufacturing defects

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidflexibility
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The solar element is divided into two rings connected by a web, which can be manufactured separately and then assembled. This segmentation allows each component to be optimized independently for manufacturing while the final assembly provides the required flexibility to compensate for external forces and manufacturing tolerances.

Inventive Principle:
Principle #1Segmentation

4Strength

If the web is made thick and rigid, then the solar element is stronger, but it loses its ability to deform elastically and absorb stresses

Engineering Contradiction:
Improveweb strengthVSAvoidelastic deformation capability
Core Design Contradiction:
StrengthVSStability of the object's composition

Solution Approach 1:

The web's geometric parameters (thickness, length, cross-sectional area) are carefully optimized to achieve the right balance between strength and flexibility. The parameters are selected so that the web has sufficient strength to support the solar element while maintaining enough elasticity to deform under stresses and absorb shocks.

Inventive Principle:
Principle #35Parameter changes

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 solution ensures a homogeneous distribution of loads on the sun gear teeth, reducing stress and manufacturing defects while maintaining operational efficiency and simplicity, compatible with various gearbox types and architectures.

Implementation Method 1

an annular web connecting the internal and external parts, this web being located between the internal and external parts and having a shape giving the solar element a capacity for deformation, particularly in bending

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP4471295B1Solar for a mechanical gear of an aircraft turbine engine
Publication Date: 2026.04.01 SAFRAN TRANSMISSION SYST
  • EP4471295B1 patent drawingFigure 1
  • EP4471295B1 patent drawingFigure 2
  • EP4471295B1 patent drawingFigure 3

AI summary

Solar (50) for a mechanical reducer (6) of an aircraft turbomachine (1), this solar (50) having an annular shape around an axis (X) and comprising: - an internal annular part (52) having on its internal periphery coupling splines (53), - an external annular part (54) having on its external periphery at least one meshing tooth (56), this external part (54) extending around the internal part (52), and - an annular web (58) for connecting the internal and external parts (52,54), at least one of the internal and external parts (52, 54) comprising two independent rings (60, 62) each having splines (53) or teeth (56), and the web (58) comprising two annular branches (64, 66) connected respectively to these two rings (60, 62).