Epicyclic Reduction Gear Layout for Turbomachine Space Constraints

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Solution Overview

Problem

Existing epicyclic reduction gear configurations in turbomachines require free space upstream of the sun gear, which is not compatible with all turbomachine architectures, especially when there is a guiding system for the turbine shaft relative to the fan shaft upstream of the reduction gear.

Innovation Solution

An epicyclic reduction gear design where the item of equipment, such as a rotor, is fitted to the bearing of the planet carrier and rotatably driven by the ring gear carrier, allowing the rotor to be driven by the ring gear carrier via a gear train, which includes a spur gear and a drive shaft with rolling bearings, enabling compatibility with various turbomachine architectures and reducing the overall dimensions of the accessory gearbox and nacelle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the item of equipment is fitted upstream of the sun gear, then the space requirement of the AGB is reduced, but this configuration is not compatible with all turbomachine architectures (especially when there is a guiding system for the turbine shaft upstream of the reduction gear)

Engineering Contradiction:

Improvespace requirement of AGBVSAvoidcompatibility with turbomachine architectures

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

Instead of fitting the item of equipment upstream of the sun gear (conventional approach), the invention inverts the arrangement by fitting it downstream of the ring gear. This reversal of position allows the item of equipment to be integrated into the reduction gear without requiring upstream space, thereby maintaining compact dimensions while achieving compatibility with various turbomachine architectures including those with guiding systems upstream.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The downstream fitting position of the ring gear serves multiple functions: it transmits mechanical power to the item of equipment while also being compatible with different turbomachine architectures (including those with upstream guiding systems). This multi-functional positioning resolves the contradiction between space optimization and architectural versatility.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If the item of equipment is fitted downstream of the ring gear, then compatibility with various turbomachine architectures is improved, but the space requirement of the AGB increases

Engineering Contradiction:

Improvecompatibility with turbomachine architecturesVSAvoidspace requirement of AGB

Core Design Contradiction:

Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The item of equipment is nested within the downstream space of the ring gear assembly, utilizing the existing structural envelope. This nesting approach allows the item of equipment to be accommodated within the reduction gear's footprint without significantly increasing the overall AGB dimensions, thus minimizing the volume penalty while maintaining architectural compatibility.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Volume of moving object

If the rotor is driven by the ring gear carrier via a gear train, then the overall dimensions of the AGB are reduced, but the device complexity increases

Engineering Contradiction:

Improveoverall dimensions of AGBVSAvoidgear train structure

Core Design Contradiction:

Volume of moving objectVSDevice complexity

Solution Approach 1:

The gear train is arranged in a compact three-dimensional configuration within the downstream space of the ring gear carrier. By utilizing spatial arrangement in multiple dimensions rather than linear extension, the gear train achieves high power transmission density with minimal impact on the overall AGB dimensions, balancing compactness against complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 design allows for the reduction of the overall dimensions of the accessory gearbox and nacelle while increasing available electrical or hydraulic power, and is compatible with more turbomachine architectures by enabling the rotor of the item of equipment to be driven by the ring gear carrier, thus addressing the space constraints and architectural limitations of traditional configurations.

Implementation Method 1

The gear train comprises a spur gear between an inner toothing of the ring gear carrier and a toothed wheel with outer toothing

Methodology Applied

Scientific EffectGear meshing: Gear

Implementation Method 2

the drive shaft being rotatably guided via at least one rolling bearing

Methodology Applied

Scientific EffectRolling bearing: Ball Bearing

Data Source

PatentUS11802514B2Epicyclic reduction gear for a turbomachine

Publication Date: 2023.10.31 SAFRAN TRANSMISSION SYST

AI summary

An epicyclic reduction gear for a turbomachine includes a sun gear that is rotatable about a first axis and a ring gear surrounding the sun gear and also rotatable about the first axis. The ring gear is secured to a ring gear carrier that rotates a fan shaft. At least one planet gear is rotatable about a second axis and is meshed with the sun gear and the ring gear. The planet gear is guided in rotation about the second axis relative to a bearing of the planet carrier. A piece of equipment comprising a rotor. The piece of equipment is attached to the bearing of the planet carrier and has a rotor rotated by the ring gear carrier.